JP6955656B2 - Method for producing ultraviolet-emitting phosphor, ultraviolet-emitting device, and ultraviolet-emitting phosphor - Google Patents

Description

The present invention relates to an ultraviolet emitting phosphor based on rare earth aluminum garnet, an ultraviolet emitting device provided with the ultraviolet emitting phosphor, and a method for producing an ultraviolet emitting phosphor.

The development of light sources in the deep ultraviolet UVB (approximately 280 to 320 nm) and UVC (approximately 200 to 280 nm) wavelength regions that do not use mercury is an urgent matter in line with the progress of mercury-free activities by the government. Nitride semiconductor light emitting diodes are being actively studied as a mercury-free light source to replace mercury lamps, but the reality is that high-intensity light emission has not been realized at wavelengths shorter than 365 nm, which is determined by the band gap of gallium nitride. .. This is because the light emitting diode must be constructed by sandwiching it with a bandgap material that is larger than the active layer material of light emission, but even if it is sandwiched with aluminum nitride having the maximum bandgap in order to obtain light emission in the deep ultraviolet region. Carrier confinement is inadequate, and there is no excellent ohmic electrode material for large bandgap materials, which makes it difficult to achieve due to the factor that the luminous efficiency drops extremely.
In addition, conventional ultraviolet emitting phosphors represented by lutetium aluminum garnet crystals (Lu ₃ Al ₅ O ₁₂ ; hereinafter referred to as LuAG) have low emission brightness for light source application, and have wavelengths required for various applications. It was difficult to realize the light emission in.

One of the present inventors has already provided an ultraviolet light source device having an anode substrate having an ultraviolet emitting phosphor crystal in which aluminum nitride is used as a host material and gadolinium (Gd) rare earth ions are added in order to provide a high-brightness ultraviolet light source device. It has been proposed (see Patent Document 1). In order to overcome the problem that the emission intensity decreases due to concentration quenching when the content of gadrinium ion, which is the center of emission, becomes high, the ultraviolet emission phosphor crystal in the proposed ultraviolet light source device is a residual gas inside the vacuum chamber in the sputtering apparatus. By positively removing the water component in the aluminum nitride and crystallizing it by adding rare earth metal ions using aluminum nitride as a host material in this water-removed atmosphere, a high content of gadolinium ions can be obtained in the aluminum nitride. Dope.

On the other hand, a target for generating ultraviolet light that enhances the efficiency of generating ultraviolet light is known (see Patent Documents 2 and 3). The ultraviolet ray generating target disclosed in Patent Documents 2 and 3 includes a substrate that transmits ultraviolet light and a light emitting layer that receives an electron beam to generate ultraviolet light, and the light emitting layer contains a rare earth-containing aluminum garnet crystal. So, for example, a material for generating ultraviolet light to which an activator of lanthanum (La) or scandium (Sc) is added to LuAG or YAG (Yttrium Aluminum Garnet) is disclosed. In the examples of Patent Documents 2 and 3, there is no one in which La and Sc are co-added, and only the emission peak wavelength when La and Sc are added as activators is shown, and La and Sc are co-added. There is no idea of controlling the emission center wavelength and increasing the brightness by adding it.

Further, a method for producing a LuAG crystal material for radiation detection is known (see Patent Document 4). Patent Document 4 discloses that a LuAG crystal material in which at least one or more rare earth elements such as La and Sc are substituted is used as a part of Lu, but in the examples of Patent Document 4, LuAG is used. Although the material to which Ce is added is shown, there is no idea of controlling the emission center wavelength and increasing the brightness by co-adding La and Sc.

Further, Non-Patent Document 1 discloses a material in which La or Sc is added to LuAG, but by co-adding La and Sc, the emission center wavelength is controlled and the brightness is increased. There is no such idea. Non-Patent Document 2 discloses a material in which La or Sc is added to Y-LuAG (Y-Lu-Al-Garnets), but the emission center wavelength is controlled by co-adding La and Sc. Moreover, there is no idea of increasing the brightness. Non-Patent Documents 3 and 4 show materials in which Sc is added to LuAG, but there is no idea of controlling the emission center wavelength and increasing the brightness by co-adding La and Sc. ..

Re-table 2009/031584 Gazette Japanese Unexamined Patent Publication No. 2014-84402 Japanese Unexamined Patent Publication No. 2014-86255 Japanese Unexamined Patent Publication No. 2006-16251

"Luminescence of Sc3 + and La3 + isoelectronic impurities in Lu3Al5O12 single-crystal films", Yu. V. Zorenko, Optics and Spectroscopy, April 2006, Volume 100, Issue 4, pp 572-580. "Novel UV-emitting single crystalline film phosphors grown by LPE method", Y.Zorenko et al., Radiation Measurements, 45 (2010), pp 444-448. "Luminescence of undoped and Ce3 + -doped Lu (Sc, Y) AG crystals l., V. Babin et al., Journal of Luminescence, 122-123 (2007), pp 332-334. "SCINTILLATION PROPERTIES OF LU3Al5-xSCx012 CRYSTALS", N.N. RYSKIN et al., JOURNAL OF PHYSICS CONDENSED MATTER 6 (1994), pp 10423-10434.

As described above, the conventional ultraviolet-emitting phosphor has a low emission brightness for application as a light source, and it is difficult to realize light emission at a wavelength required by various applications.
In view of the above situation, it is an object of the present invention to provide an ultraviolet emitting device capable of simultaneously realizing high brightness and controllability of the emission center wavelength by using an ultraviolet emitting phosphor based on a rare earth aluminum garnet crystal. ..

In order to solve the above problems, the ultraviolet luminescent phosphor of the present invention is a rare earth aluminum garnet crystal (Lu _x Y _1-x ) ₃ (Al _y Z _{1-y ) 5} O ₁₂ (however, 0 ≦ x ≦ 1, 0). <Y≤1, Z is an ultraviolet emitting phosphor based on B, Ga, In, Tl) to which at least two or more transition element ions other than Lu and Y forming a light emitting center are co-added. It is characterized in that it irradiates excitation light and is excited by the irradiation of the excitation light to emit ultraviolet light.
The addition ratio of each of the transition element ions to be co-added is adjusted so as to reach the target emission center wavelength in the ultraviolet region in the range of 240 to 400 nm, and the emission center wavelength and the emission center wavelength and at least one of x and y are used as parameters. It is preferable that the brightness is adjusted.

According to the ultraviolet-emitting phosphor of the present invention, it is possible to realize high-efficiency excitation by widening the emission spectrum in the ultraviolet region and controlling the band gap of the host crystal to increase the brightness. In addition, the emission center wavelength can be controlled by changing the combination of two or more types of transition element ions other than Lu and Y that form the emission center and adjusting the addition ratio by taking advantage of the characteristics of the broadband emission center. Higher brightness can be achieved by doping a high content of transition element ions beyond the limit concentration due to concentration quenching.
By setting the ultraviolet region in the range of 240 to 400 nm as the emission center, it is possible to obtain an ultraviolet luminescent phosphor having excellent sterilization and sterilization ability. It is possible to realize light emission at the wavelength required for various applications such as photodecomposition of highly toxic tetrachlorodioxins, sterilization application using DNA decomposition, and photocatalyst application.

In the ultraviolet emitting phosphor of the present invention, the composition of aluminum (Al) is partially replaced with B, Ga, In, or Tl to prepare the emission center wavelength and the brightness. That is, in (Lu _x Y _1-x ) ₃ (Al _y Z _1-y ) ₅ O ₁₂ , the emission center wavelength and the brightness are adjusted by controlling the parameter y, and the target emission center wavelength and the brightness are realized. By substituting the composition of aluminum with other Group 13 elements, boron (B), gallium (Ga), indium (In), and thallium (Tl), the emission center wavelength and brightness can be controlled.
Here, when x and y are changed as parameters, the emission center wavelength and the brightness change. This is due to the change in the bandgap of the garnet crystal, which is the host crystal. For example, when plasma excitation is used, the excitation wavelengths are 147 nm and 172 nm, but the excitation wavelength of 172 nm is low because it is close to the band gap of the garnet crystal which is the host crystal. Therefore, if the band gap is reduced by controlling the parameters of x and y, the excitation efficiency is increased and the brightness is improved.

The rare earth aluminum garnet crystal in the ultraviolet luminescent phosphor of the present invention is (Lu _x Y _1-x ) ₃ (Al _y Z _1-y ) ₅ O ₁₂ (where 0 <x <1, 0 <y ≦ 1, Z). Is preferably B, Ga, In, Tl). Neither Lu ₃ Al ₅ O ₁₂ (LuAG) crystals nor Y ₃ Al ₅ O ₁₂ (YAG) crystals, but two or more types that form a light emitting center based on a rare earth aluminum garnet crystal in which Lu and Y are mixed. It is possible to shift the emission center wavelength by changing the strain applied to the transition element ions other than Lu and Y.

In the ultraviolet-emitting phosphor of the present invention, the transition element ion to be co-added is a rare earth ion, and gadolinium (Gd), ytterbium (Eu), ytterbium (Dy), lanthanum (La), terbium (Ce), and samarium (Sm). , Yttrium (Y), Neodymium (Nd), Terbium (Tb), Placeozim (Pr), Elbium (Er), Thulium (Tm), Ytterbium (Yb), Scandium (Sc), Promethium (Pm), and Holmium (Ho) ) Is one kind of ion selected from the group consisting of.
The inner core electronic transition (4f orbital electronic transition) ^{of the Gd 3+} ion of the trivalent rare earth metal ion efficiently emits narrow band ultraviolet light of about 310 nm.

More preferably, the transition element ions to be co-added are La ion and Sc ion, and the addition amount of each is an addition ratio and a concentration at which the target emission center wavelength is obtained in the ultraviolet region in the range of 280 to 320 nm. It is the amount of addition near the limit where quenching occurs.
Based on the rare earth aluminum garnet crystal, the emission center wavelength is controlled by the addition ratio of La and Sc ions, and the sum of both ions exceeds the concentration limit addition amount in the case of each single ion of La and Sc ions. The brightness is controlled by increasing the amount added.
La and Sc ions form the emission center, but the emission center wavelength shifts when the strain applied to these atoms changes. In particular, in the case of Sc ions, the outermost shell orbital is a 3d orbital, which is closer to the ion center than the 5d orbital of La ions, and the effect of shifting the emission center wavelength by exchanging peripheral atoms is large.
Further, by increasing the amount of Y added, it is possible to control the high-efficiency absorption of excitation energy based on _{the (Lu x} Y _1-x ) ₃ (Al _y Z _1-y ) ₅ O _{12 crystals.}

In the ultraviolet luminescent phosphor of the present invention, the rare earth aluminum garnet crystal is (Lu _x Y _1-x ) ₃ Al ₅ O ₁₂ (where 0 <x <1), and the transition element ion to be co-added is lanthanum (Lutetium). La) ion and scandium (Sc) ion, each of which has an addition ratio of the target emission center wavelength in the ultraviolet region in the range of 280 to 320 nm, and an addition amount near the limit where concentration quenching occurs. Is a preferred embodiment.

According to another viewpoint, the ultraviolet luminescent phosphor of the present invention is a rare earth aluminum garnet crystal (Lu _x Y _1-x ) ₃ (Al _y Z _{1-y ) 5} O ₁₂ (provided that 0 ≦ x ≦ 1, 0). <Y≤1, Z is a phosphor to which at least one or more transition element ions other than Lu and Y forming a light emitting center are added based on B, Ga, In, Tl). The transition element ions are replaced by both Lu or Y rare earth sites and Al or Z Group 13 element sites, and are irradiated with excitation light, and are excited by the irradiation of the excitation light to emit ultraviolet light. It is characterized by doing.

The amount of the transition element ion to be added is adjusted so as to reach the target emission center wavelength in the ultraviolet region in the range of 240 to 400 nm, and the emission center wavelength and the brightness are adjusted with at least one of x and y as parameters. It is preferably prepared.
According to the ultraviolet-emitting phosphor of the present invention, it is possible to realize high-efficiency excitation by widening the emission spectrum in the ultraviolet region and controlling the band gap of the host crystal to increase the brightness. In addition, the emission center wavelength can be controlled by controlling the substitution sites of two or more types of transition element ions other than Lu and Y that form the emission center by utilizing the characteristics of the broadband emission center, and the limit concentration due to concentration quenching can be controlled. It is possible to achieve high brightness by doping with a high content of transition element ions.

Also in the ultraviolet emitting phosphor of the present invention, the emission center wavelength and the brightness can be adjusted by partially substituting the composition of aluminum (Al) with B, Ga, In, or Tl. That is, in (Lu _x Y _1-x ) ₃ (Al _y Z _1-y ) ₅ O ₁₂ , the emission center wavelength and the brightness are adjusted by controlling the parameter y, and the target emission center wavelength and the brightness are realized. When x and y are changed as parameters, the emission center wavelength and the brightness change because the band gap of the garnet crystal, which is the host crystal, changes.

In the ultraviolet emitting phosphor of the present invention, the rare earth aluminum garnet crystal is (Lu _x Y _1-x ) ₃ Al ₅ O ₁₂ (where x = 0 or 1), and the added transition element ion is Lu or Y. It is preferable that the site is replaced with both the rare earth site and the Al site.
Here, the transition element ions to be added are La ions or Sc ions, and the amount of each added is at an addition ratio that becomes the target emission center wavelength in the ultraviolet region in the range of 280 to 340 nm, and the concentration quenching is achieved. It is the amount of addition near the limit that occurs.
La and Sc ions form the emission center, but the emission center wavelength shifts when the strain applied to these atoms changes. In particular, in the case of Sc ions, the outermost shell orbital is a 3d orbital, which is closer to the ion center than the 5d orbital of La ions, and the effect of shifting the emission center wavelength by exchanging peripheral atoms is large.

Next, the ultraviolet light emitting device of the present invention will be described.
The ultraviolet light emitting device of the present invention includes the ultraviolet light emitting phosphor of the present invention and the excitation light irradiation means for irradiating the ultraviolet light emitting phosphor with excitation light.

Further, in the ultraviolet emitting device of the present invention, the means for irradiating the excitation light may be one in which the ultraviolet light generated by the plasma discharge becomes the excitation light and is irradiated to the ultraviolet emitting phosphor of the present invention.

Further, in the ultraviolet emitting device of the present invention, the ultraviolet emitting phosphor of the present invention is a thin film, and the anode substrate having the thin film, the cathode substrate having the electric field electron emitting material, and the anode substrate and the cathode substrate facing each other. It has at least a spacer that is arranged and holds a gap between the substrates in a vacuum atmosphere, and a voltage circuit that applies an electric field between the anode substrate and the cathode substrate. Then, the gap between the anode substrate and the cathode substrate is set as a vacuum channel region, and electrons from the field electron emitting material are injected into the thin film of the ultraviolet emitting phosphor by applying an electric field between the substrates, and the ultraviolet emitting phosphor is used. It emits ultraviolet light.
When a voltage is applied to an electron emitting material such as a hot filament or a cold cathode material constituting a cathode electrode, electrons are generated by field emission and emitted into a vacuum. These electrons are attracted to the anode electrode and proceed, and collide with the thin film of the ultraviolet emitting phosphor constituting the anode electrode. When the electrons collide, the thin film of the ultraviolet emitting phosphor converts the electron energy into light energy and emits light.

Next, a method for producing an ultraviolet emitting phosphor in the present invention will be described.
The method for producing an ultraviolet emitting phosphor of the present invention is the above-mentioned method for producing an ultraviolet emitting phosphor of the present invention, and includes the following steps (S1) to (S6).
(S1) Step of determining the target emission center wavelength in the ultraviolet region in the range of 240 to 400 nm (S2) The emission center wavelength is controlled by adjusting the addition ratio of two or more transition element ions forming the emission center. Step (S3) A step (S4) of controlling the brightness by adjusting the total addition amount of each addition amount of two or more kinds of transition element ions forming the emission center to be equal to or more than the limit concentration due to the concentration extinction of each ion. Step of controlling emission center wavelength and brightness by preparing at least one of parameters x and y (S5) Two or more transition element ions for which the addition ratio and total addition amount have been prepared are coexisted with respect to the rare earth aluminum garnet crystal. Step of addition (S6) Step of firing and annealing

In particular, the rare earth aluminum garnet crystal is (Lu _x Y _1-x ) ₃ Al ₅ O ₁₂ (where 0 <x <1), and the two transition element ions forming the emission center are lanthanum (La). A method for producing an ultraviolet emitting phosphor having a structure of an ion and a scandium (Sc) ion includes the following steps (S1a) to (S6a).
(S1a) Step of determining the target emission center wavelength in the ultraviolet region in the range of 240 to 400 nm (S2a) The addition ratio of the lanthanum (La) ion and the scandium (Sc) ion forming the emission center is adjusted to determine the emission center. Step to control the wavelength (S3a) Step to control the brightness by adjusting the total addition amount of each addition amount of lanthanum (La) ion and scandium (Sc) ion to be equal to or more than the limit concentration due to the concentration quenching of each ion. (S4a) Parameter x is prepared, the amount of yttrium (Y) ion added is adjusted, and the emission center wavelength and the brightness are controlled. (S5a) The addition ratio and the total amount added are prepared for the rare earth aluminum garnet crystal. Step of co-adding lanthanum (La) ion and scandium (Sc) ion (S6a) Step of quenching and annealing

According to another viewpoint, the method for producing an ultraviolet emitting phosphor of the present invention is the above-mentioned method for producing an ultraviolet emitting phosphor of the present invention, which comprises the following steps (S1b) to (S6b).
(S1b) Step of determining the target emission center wavelength in the ultraviolet region in the range of 240 to 400 nm (S2b) The amount of one or more transition element ions forming the emission center is equal to or greater than the limit concentration due to ion concentration extinction. Step of controlling the emission center wavelength (S3b) The added transition element ion is replaced with at least one of the rare earth site of Lu or Y and the 13th group element site of Al or Z. (S4b) A step of controlling the content of the rare earth ion of Lu or Y and the content of Al or Z (S4b) A step of adjusting at least one of the parameters x and y to control the emission center wavelength and the brightness (S5b). ) Step of adding one or more transition element ions whose addition amount has been adjusted to rare earth aluminum garnet crystals (S6b) Step of firing and annealing

In particular, the rare earth aluminum garnet crystal is (Lu _x Y _1-x ) ₃ Al ₅ O ₁₂ (where x = 0 or 1), and the transition element ion forming the emission center is La ion or Sc ion. The method for producing an ultraviolet emitting phosphor comprising the following steps (S1c) to (S6c).
(S1c) Step of determining the target emission center wavelength in the ultraviolet region in the range of 240 to 400 nm (S2c) The amount of La ion or Sc ion forming the emission center becomes equal to or more than the limit concentration due to the ion concentration quenching. (S3c) The added La ion or Sc ion is replaced with at least one of the rare earth site of Lu or Y and the group 13 element site of Al or Z. Step (S4c) to control the content of rare earth ions of Lu or Y and the content of Al or Z (S4c) Step to control the quenching center wavelength and brightness (S5c) Rare earth aluminum garnet crystal. (S6c) A step of adding La ions or Sc ions whose addition amount has been prepared (S6c) A step of quenching and annealing.

According to the present invention, high brightness and controllability of the emission center wavelength can be realized at the same time by using an ultraviolet emitting phosphor based on a rare earth aluminum garnet crystal.

Processing flow of a method for producing an ultraviolet emitting phosphor in an ultraviolet emitting device (1) Processing flow of a method for producing an ultraviolet emitting phosphor in an ultraviolet emitting device (2) Sample preparation flow for ultraviolet luminescent phosphor Photoluminescence measurement result (emission spectrum) of the ultraviolet emitting phosphor of Example 1 Photoluminescence measurement result (integral intensity) of the ultraviolet emitting phosphor of Example 1 Photoluminescence measurement result (emission spectrum) of the ultraviolet emitting phosphor of Comparative Example 1 Photoluminescence measurement result (integral intensity) of the ultraviolet emitting phosphor of Comparative Example 1 Photoluminescence measurement result (emission spectrum) of the ultraviolet emitting phosphor of Comparative Example 2 Photoluminescence measurement result (integral intensity) of the ultraviolet emitting phosphor of Comparative Example 2 Comparison graph of emission spectra of ultraviolet-emitting phosphors of Example 1, Comparative Example 1, and Comparative Example 2. Photoluminescence measurement results (emission spectrum) of the ultraviolet-emitting phosphors of Examples 1, 2 and 3. Photoluminescence measurement results (integral intensity) of the ultraviolet emitting phosphors of Examples 1, 2 and 3. Photoluminescence measurement result (emission spectrum) of the ultraviolet emitting phosphor of Comparative Example 3 Photoluminescence measurement result (integral intensity) of the ultraviolet emitting phosphor of Comparative Example 3 Photoluminescence measurement result (emission spectrum) of the ultraviolet emitting phosphor of Comparative Example 4 Photoluminescence measurement result (integral intensity) of the ultraviolet emitting phosphor of Comparative Example 5 Results of X-ray diffraction measurement of the ultraviolet-emitting phosphors of Examples 1, 2 and 3 (X-ray diffraction spectrum) X-ray diffraction measurement results (diffraction peak shift) of the ultraviolet emitting phosphors of Examples 1, 2 and 3. Results of X-ray diffraction measurement of the ultraviolet-emitting phosphors of Comparative Examples 1 and 2 (X-ray diffraction spectrum) X-ray diffraction measurement results (diffraction peak shift) of the ultraviolet emitting phosphors of Comparative Examples 1 and 2. Results of X-ray diffraction measurement of the ultraviolet-emitting phosphors of Comparative Examples 1, 3 and 5 (X-ray diffraction spectrum) X-ray diffraction measurement results (diffraction peak shift) of the ultraviolet emitting phosphors of Comparative Examples 1, 3 and 5 Results of X-ray diffraction measurement of the ultraviolet-emitting phosphors of Comparative Examples 2, 4 and 6 (X-ray diffraction spectrum) X-ray diffraction measurement results (diffraction peak shift) of the ultraviolet emitting phosphors of Comparative Examples 2, 4 and 6 Schematic diagram of the structure of the ultraviolet light emitting device (1) Schematic diagram of the structure of the ultraviolet light emitting device (2) Photoluminescence measurement result of the ultraviolet emitting phosphor of Example 8 Photoluminescence measurement result of the ultraviolet emitting phosphor of Comparative Example 8a Photoluminescence measurement results of the ultraviolet emitting phosphor of Comparative Example 8b Photoluminescence measurement result of the ultraviolet emitting phosphor of Example 9 Photoluminescence measurement result of the ultraviolet emitting phosphor of Comparative Example 9a Photoluminescence measurement of the ultraviolet luminescent phosphor of Comparative Example 9b Photoluminescence measurement result of the ultraviolet emitting phosphor of Example 11 Photoluminescence measurement result of the ultraviolet emitting phosphor of Comparative Example 11a Photoluminescence measurement result of the ultraviolet emitting phosphor of Comparative Example 11b Photoluminescence measurement result of the ultraviolet emitting phosphor of Example 12 Photoluminescence measurement result of the ultraviolet emitting phosphor of Comparative Example 12a Photoluminescence measurement result of the ultraviolet emitting phosphor of Comparative Example 12b It is a graph of the PLE measurement result of Example 10, and shows (1) the change of a parent crystal, (2) the change of a substitution site, and (3) the change of a substitution element.

Hereinafter, an example of the embodiment of the present invention will be described in detail with reference to the drawings. The scope of the present invention is not limited to the following examples and illustrated examples, and many modifications and modifications can be made.

(Method for producing ultraviolet luminescent phosphor)
A method for producing an ultraviolet emitting phosphor in the ultraviolet emitting device of the present invention will be described. FIG. 1 shows a rare earth aluminum garnet crystal (Lu _x Y _1-x ) ₃ (Al _y Z _1-y ) ₅ O ₁₂ (where 0 ≦ x ≦ 1, 0 <y ≦ 1, Z is B, Ga, In. , Tl) is used as a base, and the processing flow of a method for producing an ultraviolet emitting phosphor to which at least two or more rare earth ions other than Lu and Y forming a light emitting center are co-added is shown.

First, the target emission center wavelength is determined in the ultraviolet region in the range of 240 to 400 nm (step S01). For example, in the case of applications of devices used for skin treatment applications, it is generally known to use ultraviolet UVB in the wavelength range of 280 to 320 nm, but tentatively, ultraviolet light of 305 nm is the most effective for healing skin damage. If so, the emission center wavelength is determined to be 305 nm. Then, the emission center wavelength is controlled by adjusting the addition ratio of at least two kinds of rare earth ions to be co-added other than Lu and Y contained in the base rare earth aluminum garnet crystal (step S02). For example, co-adding from Gd, Eu, Dy, La, Ce, Sm, Nd, Tb, Pr, Er, Tm, Yb, Sc, Pm, and Ho so that the emission center wavelength becomes 305 nm 2 Select rare earth ions above the species and adjust their addition ratio.

Next, the brightness is controlled by adjusting the total addition amount of each of at least two rare earth ions to be co-added to be near the limit at which concentration quenching occurs (step S03). At this time, the amount of addition, which is the limit concentration due to the concentration quenching of each rare earth ion, is obtained in advance. The total addition amount of each addition amount is adjusted so as to exceed the addition amount which is the limit concentration of each ion. As a result, a high content of rare earth ions is doped to realize high brightness. Further, the _{parameters x or y in (Lu x} Y _1-x ) ₃ (Al _y Z _1-y ) ₅ O ₁₂ or the parameters x and y are prepared to control the emission center wavelength and the brightness (step S04). ). Then, at least two kinds of rare earth ions prepared in the addition ratio and the total addition amount are co-added to the base rare earth aluminum garnet crystal (step S05). Then, it is calcined and annealed at 1400 to 1700 ° C. for about 10 hours to obtain an ultraviolet emitting phosphor crystal (step S06).
As a result, an ultraviolet luminescent phosphor crystal obtained by co-adding at least two kinds of rare earth ions based on the rare earth aluminum garnet crystal can be obtained.

In particular, there are two types of rare earth aluminum garnet crystals (Lu _x Y _1-x ) ₃ Al ₅ O ₁₂ (however, based on 0 <x <1), lanthanum (La) and scandium (Sc) that form a light emitting center. An ultraviolet emitting phosphor crystal to which rare earth ions are co-added will be described with reference to the flow of FIG.
FIG. 2 shows a processing flow of a method for producing an ultraviolet emitting phosphor in an ultraviolet emitting device. Similar to the flow of FIG. 1, the target emission center wavelength is determined in the ultraviolet region (step S11), and the addition ratio of La and Sc ions is adjusted to control the emission center wavelength (step S12). Further, the brightness is controlled by adjusting the total addition amount of each of La and Sc ions to be an addition amount near the limit at which concentration quenching occurs (step S13). Then, the parameter x is prepared, the amount of Y ion added is adjusted, and the brightness is controlled (step S14). La and Sc ions prepared in the addition ratio and the total addition amount are co-added to the rare earth aluminum garnet crystal containing the adjusted addition amount of Y ion and Lu ion (step S15). Then, it is calcined and annealed at 1400 to 1700 ° C. for about 10 hours to obtain an ultraviolet emitting phosphor crystal (step S16).

In this example, _{an ultraviolet emitting device using an ultraviolet emitting phosphor based on a Lu 3} Al ₅ O ₁₂ (LuAG) crystal and co-added with La ion and Sc ion will be described.
FIG. 3 shows a sample preparation flow of an ultraviolet emitting phosphor. To prepare a sample of an ultraviolet luminescent phosphor _{, each raw material powder of Lu 2} O ₃ , Al ₂ O ₃ , La ₂ O ₃ , and Sc ₂ O ₃ is weighed based on a chemical ratio (step S31), and an alumina mortar is prepared. The powder was mixed using the above (step S32), and then an annealing treatment was performed (step S33). The annealing treatment was carried out in the air using an electric furnace, the annealing temperature was 1600 ° C., and the annealing time was 10 hours. Since La ₂ O ₃ is deliquescent, it was measured after being annealed in an electric furnace using an alumina crucible for 1 hour.

The optical characteristics of the ultraviolet-emitting phosphor sample were evaluated by photoluminescence (hereinafter referred to as PL) measurement. In the PL measurement, a xenon excimer lamp was used as the excitation light source, the excitation wavelength was 172 nm (7.2 eV), and the measurement temperature was room temperature.

Table 1 below shows the sample preparation conditions for the ultraviolet luminescent phosphor of Example 1. The amount of La ion and Sc ion to be co-added is adjusted to be 0.6, 0.8, 1.0, and 1.2 (atomic%), respectively, and the ultraviolet luminescent phosphor Lu _{3-a is produced. -B} La _a Sc _b Al ₅ O ₁₂ (however, 0 <a, b <3) is 10 g, and each raw material of _{Lu 2} O ₃ , Al ₂ O ₃ , La ₂ O ₃ , Sc ₂ O ₃ The powder was weighed based on the chemical ratio.

Table 2 below shows the sample preparation conditions for the ultraviolet luminescent phosphor of Comparative Example 1. As the ultraviolet luminescent phosphor of Comparative Example 1, an ultraviolet luminescent phosphor based on a Lu ₃ Al ₅ O ₁₂ (LuAG) crystal to which only La ions were added was used. The amount of La ions to be added was adjusted to be 0.8, 1.0, 1.2, 1.4 (atomic%), and the ultraviolet luminescent phosphor Lu _3-a La _a Al of Comparative Example 1 was added. _{The raw material powders of Lu 2} O ₃ , Al ₂ O ₃ , and La ₂ O ₃ were weighed based on the ratio of chemical quantities so that 5 O ₁₂ (where 0 <a <3) was 10 g.

Table 3 below shows the sample preparation conditions for the ultraviolet luminescent phosphor of Comparative Example 2. As the ultraviolet luminescent phosphor of Comparative Example 2, an ultraviolet luminescent phosphor _{added with Sc ions based on a Lu 3} Al ₅ O ₁₂ (LuAG) crystal was used. The amount of Sc ions to be added was adjusted to be 1.1, 1.3, 1.5, 1.7 (atomic%), and the ultraviolet emitting phosphor Lu _3-b Sc _b Al of Comparative Example 2 was added. _{The raw material powders of Lu 2} O ₃ , Al ₂ O ₃ , and Sc ₂ O ₃ were weighed based on the stoichiometric ratio so that 5 O ₁₂ (where 0 <b <3) was 10 g.

As the conditions for the annealing treatment of Comparative Example 1 and Comparative Example 2, the annealing temperature was 1500 ° C., the annealing time was 10 hours, and the annealing treatment was carried out in the atmosphere using an electric furnace.

4 and 5 show the PL measurement results of the ultraviolet emitting phosphor of Example 1, FIG. 4 shows the PL spectrum, and FIG. 5 shows the integrated intensity thereof. 6 and 7 show the PL measurement results of the ultraviolet emitting phosphor of Comparative Example 1, FIG. 6 shows the PL spectrum, and FIG. 7 shows the integrated intensity thereof. 8 and 9 show the PL measurement results of the ultraviolet emitting phosphor of Comparative Example 2, FIG. 8 shows the PL spectrum, and FIG. 9 shows the integrated intensity thereof.

From the PL measurement result of the ultraviolet emitting phosphor of Comparative Example 1, the dependence of La added concentration on LuAG can be understood. The integrated intensity is maximum at 1.2 (atomic%) (see FIG. 7). When the addition amount is 1.4 (atomic%), the emission intensity decreases, which is presumed to be due to the concentration quenching. Although the crystal structure deteriorates as the amount of La added increases, the maximum emission intensity when La = 1.2 (atomic%) is due to the decrease in emission due to the deterioration of the crystal structure. It is presumed that this is because the rate of increase was higher.

Further, from the PL spectrum, the peak wavelength was 280 nm regardless of the amount of addition, and no shift could be confirmed (see FIG. 6). In all of the PL spectra in FIG. 6, the spectrum shape is disturbed around 330 nm, but this disturbance is due to the measuring device, and the spectrum changes smoothly around 330 nm due to the change in the spectrum before and after. I guess. Further, in the PL spectrum of FIG. 7, the PL intensity is not standardized. The same applies to the PL spectra in the other figures.

Further, from the PL measurement result of the ultraviolet emitting phosphor of Comparative Example 2, the dependence of Sc on LuAG on the addition concentration can be seen. The integrated intensity is maximum at 1.5 (atomic%) (see FIG. 9). When the addition amount reaches 1.7 (atomic%), the emission intensity decreases slightly, but it is presumed that this is also due to the concentration quenching. Although the crystal structure deteriorates as the amount of Sc added increases, the maximum emission intensity when Sc = 1.5 (atomic%) is due to the decrease in emission due to the deterioration of the crystal structure. It is presumed that this is because the rate of increase was higher.

Further, from the PL spectrum, it can be seen that as the addition amount increases, the peak shifts from 290 nm to 300 nm, and the spectrum width increases (see FIG. 8). Since the outermost shell of Sc is 3d, it is presumed that it is easily affected by surrounding atoms. On the other hand, in the case of La of Comparative Example 1, since the 5d orbital is the outermost shell, it is presumed that the influence of the surroundings is not so much, the spectrum width is relatively small, and the dependence due to the addition concentration does not appear.

The ionic radii of Lu, La, and Sc are in the order of La (0.116 nm)> Lu (0.097 nm)> Sc (0.087 nm), and Sc has the smallest ionic radius among the three types of ions. When the concentration of Sc having a small ionic radius increases, it becomes more susceptible to the influence of Lu having a large ionic radius, and Sc ions are pulled by Lu ions to reduce the transition energy. That is, the emission center wavelength shifts to the low energy side (long wavelength side).

From the PL measurement results of the ultraviolet luminescent phosphor of Example 1, the dependence of the co-addition concentration of La and Sc with respect to LuAG can be seen. The integrated intensity is maximized when the total addition concentration of La1.0 (atomic%) and Sc1.0 (atomic%) is 2.0 (atomic%) with respect to LuAG (see FIG. 5). As described above, in the case of Comparative Example 1 (only La added), the maximum integrated intensity is La added concentration of 1.2 (atomic%), and in the case of Comparative Example 2 (only Sc added), the maximum integrated intensity is Sc added. The concentration was 1.5 (atomic%). On the other hand, in the case of Example 1, the co-addition concentration of La and Sc was the maximum at 2.0 (atomic%) in total. That is, in the case of co-addition of La and Sc, it can be seen that the addition amount of the maximum integrated strength is larger than that of the addition of only La or only Sc. The maximum integrated intensity (see FIG. 5) of Example 1 (co-addition of La and Sc) is larger than the maximum integrated intensity of Comparative Example 1 (added only La) (see FIG. 7). From this, it can be seen that the addition concentration limit indicating concentration quenching is improved by co-addition.

The maximum integrated intensity (see FIG. 9) of Comparative Example 2 (added only Sc) is larger than the maximum integrated intensity (see FIG. 5) of Example 1 (co-added La and Sc). It is presumed that this is because the absolute value of the emission intensity of the PL spectrum has some error depending on the measurement method (the measurement using the integrating sphere was not performed in the measurement of the emission intensity this time). The vertical axis of the graph regarding integrated strength should be interpreted as the position of relative strength. Further, it can be confirmed that when only Sc is added, the emission center wavelength is shifted to the longer wavelength side and the PL spectrum is expanded to the longer wavelength side where there is no bactericidal effect, as compared with the case where La and Sc are co-added. (See FIGS. 4 and 8), it is presumed that this is also the cause of the large integral strength.

Further, the PL spectrum is about halfway between the spectrum widths of Comparative Example 1 (added only La) and Comparative Example 2 (added only Sc), and the amount of addition increases and the spectrum shifts from 280 nm to 290 nm. Was found (see FIG. 4). From this, it can be seen that the emission center wavelength of the ultraviolet emitting phosphor can be controlled by adjusting the addition amounts of La and Sc ions. Further, by co-adding La and Sc as in Example 1, the total addition amount can be increased as compared with the case where La or Sc are added alone as in Comparative Example 1 and Comparative Example 2. The emission intensity can be increased. That is, it is possible to realize controllability of the emission center wavelength at the same time as increasing the brightness.

FIG. 10 shows a comparison of the PL spectra of Example 1 (co-addition of La and Sc), Comparative Example 1 (addition of La only), and Comparative Example 2 (addition of Sc only). The shift of the peak wavelength and the change of the spectrum width can be clearly confirmed.

In this embodiment, (Lu _x Y _1-x ) ₃ Al ₅ O ₁₂ (however, 0 <x <1) (hereinafter referred to as LuYAG) crystal is used as a base, and La ion and Sc ion are co-added to ultraviolet rays. An ultraviolet light emitting device using a light emitting phosphor will be described.

Table 4 below shows the sample preparation conditions for the ultraviolet luminescent phosphor of Example 2. The amount of La ion and Sc ion to be co-added is adjusted to 1.0 (atomic%), respectively, and the ultraviolet luminescent phosphor (Lu _x Y _1-x ) _3-ab La _a Sc is produced. _b Al ₅ O ₁₂ (however, 0 <x <1, 0 <a, b <3) is 10 g, and each of Lu ₂ O ₃ , Al ₂ O ₃ , La ₂ O ₃ , and Sc ₂ O ₃ . The raw material powder was weighed based on the chemical ratio.

Table 5 below shows the sample preparation conditions for the ultraviolet luminescent phosphor of Comparative Example 3. As the ultraviolet luminescent phosphor of Comparative Example 3, an ultraviolet luminescent phosphor based on a (Lu _x Y _1-x ) ₃ Al ₅ O ₁₂ (Lu YAG) crystal to which only La ions were added by 1.2 (atomic%). Using. Here, as shown in the data of Comparative Example 1 described above, when 1.2 (atomic%) of La ions are added, it is the addition amount of La showing the maximum integrated intensity in Comparative Example 1.
The parameter x is prepared, the amount of Y ions to be added, and prepared so that the 0,2,5,8,11,13.8 (atomic%), ultraviolet-emitting phosphor of Comparative Example 3 (Lu _x Y _1-x ) _3-a La _a Al ₅ O ₁₂ (However, so that 0 <a <3) becomes 10 g, Lu ₂ O ₃ , Al ₂ O ₃ , La ₂ O ₃ , Y ₂ O ₃ Each raw material powder was weighed based on the chemical ratio.

Table 6 below shows the sample preparation conditions for the ultraviolet luminescent phosphor of Comparative Example 4. As the ultraviolet luminescent phosphor of Comparative Example 4, an ultraviolet luminescent phosphor based on a (Lu _x Y _1-x ) ₃ Al ₅ O ₁₂ (Lu YAG) crystal to which only 1.5 (atomic%) of Sc ions was added. Using. Here, as shown in the data of Comparative Example 2 described above, when 1.5 (atomic%) of Sc ions are added, it is the amount of Sc added showing the maximum integrated intensity in Comparative Example 2.
The parameter x was prepared, and the amount of Y ion to be added was adjusted to be 0,2,5,8,11,13.5 (atomic%), and the ultraviolet luminescent phosphor (Lu _{x) of Comparative Example 4 was prepared.} Y _1-x ) _3-b Sc _b Al ₅ O _{12 (However, Lu 2} O ₃ , Al ₂ O ₃ , La ₂ O ₃ , Y ₂ O ₃ so that 0 <b <3) becomes 10 g. Each raw material powder was weighed based on the chemical ratio.

As the conditions for the annealing treatment of Example 2, Comparative Example 3 and Comparative Example 4, the annealing temperature was 1600 ° C. and the annealing time was 10 hours, and the annealing treatment was carried out in the atmosphere using an electric furnace.

11 and 12 show the PL measurement results of the ultraviolet emitting phosphor of Example 2, FIG. 11 shows the PL spectrum, and FIG. 12 shows the integrated intensity thereof. 13 and 14 show the PL measurement results of the ultraviolet emitting phosphor of Comparative Example 3, FIG. 13 shows the PL spectrum, and FIG. 14 shows the integrated intensity thereof. 15 and 16 show the PL measurement results of the ultraviolet emitting phosphor of Comparative Example 4, FIG. 15 shows the PL spectrum, and FIG. 16 shows the integrated intensity thereof.

From the PL measurement results of the ultraviolet-emitting phosphor of Comparative Example 3, the dependence of Y on LuYAG on the addition concentration can be seen. The integrated intensity is maximized at an added concentration of Y of 11 (atomic%) (see FIG. 14). Further, it can be seen that the integrated intensity decreases when the Y addition concentration reaches 13.8 (atomic%).
Further, from the PL spectrum, even if the Y addition concentration changed, the peak wavelength was 280 nm and no shift could be confirmed (see FIG. 13).

Further, from the PL measurement result of the ultraviolet emitting phosphor of Comparative Example 4, the dependence of the addition concentration of Y on LuYAG can be understood. The integrated intensity is minimized at an added concentration of Y of 0.5 (atomic%) and maximized at an added concentration of Y of 13.5 (atomic%) (see FIG. 16).
Further, from the PL spectrum, it can be seen that as the addition concentration of Y increases, the peak shifts from 290 nm to 300 nm, and the spectrum width also increases (see FIG. 15).
The ionic radii of Lu, Y, and Sc are in the order of Y (0.102 nm)> Lu (0.097 nm)> Sc (0.087 nm) (reference database: NIMS National Institute for Materials Science http://mits.nims). .go.jp/) Of the three types of ions, Y has the largest ionic radius. When the concentration of Y having a large ionic radius increases due to the addition of Y, Sc having a small ionic radius becomes easily affected, and Sc ions are pulled by Y ions to reduce the transition energy. That is, the emission center wavelength shifts to the low energy side (long wavelength side).

From the PL measurement results of the ultraviolet-emitting phosphor of Example 2, the dependence of Y on LuYAG on the addition concentration can be seen (see FIG. 11). With the addition of Y, the peak shifted from 285 nm to 305 nm, and the intensity became stronger.
From this, it can be seen that the emission center wavelength of the ultraviolet emitting phosphor can be controlled by adjusting the amount of Y added. Further, as in Example 1, by co-adding La and Sc, the total addition amount can be increased as compared with the case where La or Sc are added alone as in Comparative Example 3 and Comparative Example 4. The emission intensity can be increased. Similar to Example 1, the ultraviolet-emitting phosphor of Example 2 can realize controllability of the emission center wavelength at the same time as increasing the brightness.

In Examples 1 and 2 above, the Lu ₃ Al ₅ O ₁₂ (LuAG) crystal and the (Lu _x Y _1-x ) ₃ Al ₅ O ₁₂ (where 0 <x <1) (LuYAG) crystal are used as the base. Although the ultraviolet luminescent phosphor to which La ion and Sc ion are co-added has been described, an ultraviolet luminescent phosphor to which La ion and Sc ion are co-added is used based on a Y ₃ Al ₅ O ₁₂ (YAG) crystal. Can be done.
As an example, FIGS. 11 and 12 show PL measurement results of an ultraviolet luminescent phosphor to which 1.0 (atomic%) La ion and Sc ion are added, respectively, based on a YAG crystal. As described above, FIG. 11 shows the PL spectrum, and FIG. 12 shows the integrated intensity.

The crystal structure evaluation of the samples of the ultraviolet-emitting phosphors of Examples 1, 2 and 3 described above was carried out by X-ray diffraction (hereinafter referred to as XRD) measurement. The XRD measurement was θ-2θ measurement, and CuKα ray (0.1541 nm) was used.
The XRD measurement results of the UV-emitting phosphor samples of Examples 1, 2 and 3 are shown in FIGS. 17 and 18. FIG. 17 shows the XRD spectrum, and FIG. 18 shows the shift of the diffraction peak with respect to LuAG (Example 1). In addition, the XRD measurement results of the UV-emitting phosphor samples of Comparative Examples 1 and 2 are shown in FIGS. 19 and 20. In addition, the XRD measurement results of the UV-emitting phosphor samples of Comparative Examples 1, 3 and 5 are shown in FIGS. 21 and 22. In addition, the XRD measurement results of the UV-emitting phosphor samples of Comparative Examples 2, 4 and 6 are shown in FIGS. 23 and 24. Here, Comparative Example 5 is a sample in which only La ions are added by 1.2 (atomic%) based on YAG crystals, and Comparative Example 6 is a sample in which only Sc ions are added by 1.5 (atomic%) based on YAG crystals. This is a sample. 19 and 21 and 23 show the XRD spectrum, and FIGS. 20, 22 and 24 show the shift of the diffraction peak with respect to LuAG. Note that FIGS. 18, 20, 22, and 24 compare the angle shifts with the JCPDS (Joint Committee on Powder Diffraction Standards) data.

As shown in Table 7 below, the ionic radii of La, Y, Lu, Sc and Al are La (0.116 nm)> Y (0.102 nm)> Lu (0.097 nm)> Sc (0.087 nm)> Al ( 0.054 nm) (Reference database: NIMS Materials and Materials Database http://mits.nims.go.jp/).
Comparing Example 1 (based on LuAG), Example 2 (based on LuYAG), and Example 3 (based on YAG), the addition of Y is large. In Examples 2 and 3, the lattice spacing is increased with the addition of Y. It can be confirmed from the graph of FIG. 18 that the diffraction peak is widened and the diffraction peak is shifted to the low angle side. It is inferred that this is due to the distortion of the dodecahedron site. It can be said that the shift of the diffraction peak is caused by the difference in ionic radius and impurities.
Further, from the XRD measurement results of Example 2 (based on LuYAG), it can be seen that the host crystal changes from LuAG to YAG as the amount of Y added increases.

Comparing the XRD measurement results of the ultraviolet emitting phosphor samples of Comparative Example 1 (only La was added based on LuAG) and Comparative Example 2 (only Sc was added based on LuAG), from the graph of FIG. 20, the lattice was added when La was added. It can be seen that the surface spacing is widened and the diffraction peak is shifted to the low angle side, while when Sc is added, the lattice plane spacing is narrowed and the diffraction peak is shifted to the high angle side.

The XRD measurement results of the ultraviolet emitting phosphor samples of Comparative Example 1 (only La added based on LuAG), Comparative Example 3 (only La added based on LuYAG), and Comparative Example 5 (only La added based on YAG) are shown. By comparison, it can be confirmed from the graph of FIG. 22 that the lattice spacing increases with the addition of Y and the diffraction peak shifts to the low angle side.

The XRD measurement results of the ultraviolet emitting phosphor samples of Comparative Example 2 (only Sc added based on LuAG), Comparative Example 4 (only Sc added based on LuYAG), and Comparative Example 6 (only Sc added based on YAG) are shown. By comparison, it can be confirmed from the graph of FIG. 24 that the lattice spacing increases with the addition of Y and the diffraction peak shifts to the low angle side.

As described in Examples 1 and 2 above, La ions and Sc ions are coexisting based on the rare earth aluminum garnet crystal (Lu _x Y _1-x ) ₃ Al ₅ O _{12 (where 0 ≦ x ≦ 1).} In the added ultraviolet emitting phosphor, the emission center wavelength is controlled by the addition ratio of La and Sc ions, and the total amount of both ions exceeds the addition amount of the concentration limit in the case of each single ion of La and Sc ions. It can be seen that the brightness is controlled by increasing the addition amount. Further, by preparing the parameter x and adjusting the amount of Y added, the emission center wavelength of the ultraviolet emitting phosphor can be controlled.
Furthermore, the composition of aluminum (Al) of rare earth aluminum garnet crystal (Lu _x Y _1-x ) ₃ Al ₅ O ₁₂ is partially replaced with B, Ga, In, or Tl to partially replace the emission center wavelength and brightness. Can be prepared. That is, in (Lu _x Y _1-x ) ₃ (Al _y Z _1-y ) ₅ O ₁₂ (where 0 ≦ x ≦ 1, 0 <y ≦ 1, Z is B, Ga, In, Tl). The emission center wavelength and the brightness are adjusted by controlling the selection of the substitution composition Z and the parameter y, and the target emission center wavelength and the brightness are realized.

FIG. 25 shows an example of a schematic structural diagram of the ultraviolet light emitting device. The excitation light source 2 is a light source that generates excitation light that excites the ultraviolet emitting phosphor 1 shown in the above-described embodiment. The excitation light source 2 is a radiation source of α-rays, β-rays, γ-rays, X-rays, ultraviolet rays, visible light or electromagnetic waves. Various radiation generating means, discharge light generating means, solid-state light emitting element, etc. are applicable, and for example, a laser light generating device including a plasma discharge device, a light emitting diode (LED), an electroluminescence (EL) element, and a semiconductor laser is preferably used. be able to.
In FIG. 25, the output light 4 is fluorescence emitted by exciting the ultraviolet emitting phosphor 1 by the excitation light 3 emitted by the excitation light source 2.
In FIG. 25, the irradiation direction of the output light 4 of the ultraviolet emitting phosphor 1 is the same direction as the direction in which the excitation light 3 irradiates the ultraviolet emitting phosphor 1, but the ultraviolet emitting device has a structure other than that. However, the structure may be such that the output light 4 of the ultraviolet emitting phosphor 1 is emitted in the direction opposite to the direction in which the excitation light 3 irradiates the ultraviolet emitting phosphor 1.

FIG. 26 shows an example of a schematic structural diagram of the ultraviolet light emitting device. The ultraviolet light emitting device of this embodiment includes a silicon (Si) substrate 18, a Si-doped aluminum nitride (AlN) thin film 17 grown on the Si substrate 18 at a low temperature, a quartz glass substrate 12, and the ultraviolet light emitting device of the above-described embodiment. It is composed of a thin film 11 of a phosphor, a spacer 15, and a voltage circuit 16. The Si-doped AlN thin film 17 serves as a field electron emitting material.

Here, the Si-doped AlN thin film 17 grown at a low temperature on the Si substrate 18 forms an emitter. Further, the Si substrate 18 and the Si-doped AIN thin film 17 form a cathode electrode 19 (cathode), and the quartz glass substrate 12 and the ultraviolet emitting phosphor thin film 11 form an anode electrode 13 (anode) and face each other with the spacer 15 interposed therebetween. do. The gap between the cathode electrode 19 and the anode electrode 13 is maintained in a high vacuum atmosphere.
The void between the anode electrode 13 and the cathode electrode 19 is used as a vacuum channel region, and an electric field is applied between the electrodes to inject electrons from the Si-doped AlN thin film 17, which is an electron emitting material, into the ultraviolet emitting phosphor thin film 11. Make it emit light.
It is also possible to control the emission current by inserting a grid between the cathode electrode 19 and the anode electrode 13. A three-pole system in which a grid is inserted between the cathode electrode 19 and the anode electrode 13 may be adopted.

In this embodiment, the rare earth aluminum garnet crystal (Lu _x Y _1-x ) ₃ (Al _y Z _1-y ) ₅ O ₁₂ (where x = 1, y = 1), that is, Lu ₃ Al ₅ O ₁₂ is used. As a base, it is a phosphor to which Sc ion of a transition element ion other than Lu forming a light emitting center is added, and the added Sc ion is both a rare earth site of Lu and a group 13 element site of Al. The emission characteristics of the ultraviolet emitting phosphor (Example 8) substituted with will be described.
Further, as a comparative example, _{it is a phosphor to which Sc ion is added based on Lu 3} Al ₅ O ₁₂ , and the added Sc ion is an ultraviolet emitting phosphor in which only the rare earth site of Lu is substituted (Comparative example). 8a) emission characteristics and _{a phosphor to which Sc ions have been added based on Lu 3} Al ₅ O ₁₂ , and the added Sc ions are ultraviolet emission fluorescence in which only the Group 13 element sites of Al are substituted. The emission characteristics of the body (Comparative Example 8b) will be described.

First, a procedure for preparing a sample of an ultraviolet emitting phosphor will be described. As shown in the flow of FIG. 3, in the preparation of the ultraviolet luminescent phosphor sample _{, each raw material powder of Lu 2} O ₃ , Al ₂ O ₃ , and Sc ₂ O ₃ is weighed based on the stoichiometric ratio (step S31). ), The powder was mixed using an alumina mortar (step S32), and then the mixed powder was annealed (step S33). The annealing treatment was carried out in the atmosphere using an electric furnace under the conditions of an annealing temperature of 1600 ° C., an annealing time of 10 hours, and a temperature rise temperature of 4 hours.

The sample preparation conditions for the ultraviolet luminescent phosphor will be described.
The sample of the ultraviolet luminescent phosphor of Example 8 was prepared so that the amount of Sc ions added was 2.6, 2.8, 3.0, 3.2, 3.4 (atomic%). _{Further, the raw material powders of Lu 2} O ₃ , Al ₂ O ₃ , and Sc ₂ O ₃ were weighed based on the stoichiometric ratio so as to be replaced by both the Lu side site and the Al side site. Here, Sc is substituted by 1.5 (atomic%) at the Al side site to be substituted, and 1.1, 1.3, 1.5, 1.7, 1.9 (atom) is substituted at the Lu side site. %) It was made to be replaced. That is, Al is reduced by 1.5 (atomic%), Lu is reduced by 1.1, 1.3, 1.5, 1.7, 1.9 (atomic%), and Sc is 2. Sc ions are replaced with both Lu-side and Al-side sites by weighing each raw material powder so as to increase by 6, 2.8, 3.0, 3.2, 3.4 (atomic%). I let you.

The sample of the ultraviolet luminescent phosphor of Comparative Example 8a was prepared so that the amount of Sc ions to be added was 1.1, 1.3, 1.5, 1.7 (atomic%), and the Lu side site. _{The raw material powders of Lu 2} O ₃ , Al ₂ O ₃ , and Sc ₂ O ₃ were weighed based on stoichiometric ratios so that they were replaced only by. Here, Lu is 1.1, 1.3, 1.5, 1.7 so that only the Lu side site is replaced by 1.1, 1.3, 1.5, 1.7 (atomic%). Each raw material powder was weighed to reduce by (atomic%) and increase Sc by 1.1, 1.3, 1.5, 1.7 (atomic%).

The sample of the ultraviolet luminescent phosphor of Comparative Example 8b was prepared so that the amount of Sc ions to be added was 1.1, 1.3, 1.5, 1.7, 1.9 (atomic%). _{Further, the raw material powders of Lu 2} O ₃ , Al ₂ O ₃ , and Sc ₂ O ₃ were weighed based on the stoichiometric ratio so as to be substituted only at the Al side site. Here, Al is 1.1, 1.3, 1.5 so that only the site on the Al side is substituted with 1.1, 1.3, 1.5, 1.7, 1.9 (atomic%). Each raw material is reduced by 1.7, 1.9 (atomic%) and increased by 1.1, 1.3, 1.5, 1.7, 1.9 (atom%) of Sc. The powder was weighed.

The samples of the ultraviolet luminescent phosphors of Example 8 and Comparative Examples 8a and 8b are summarized below.
8-1) Sample of the ultraviolet luminescent phosphor of Example 8 ... (LuSc) (AlSc) G The added Sc (replaced with both the Lu-side site and the Al-side site) is
5 types of 2.6, 2.8, 3.0, 3.2, 3.4 (atomic%) However, weighed so that Sc is replaced by 1.5 (atomic%) at the Al side site.
8-2) Sample of the ultraviolet luminescent phosphor of Comparative Example 8a ... (LuSc) Notated as AlG The added Sc (replaced only at the Lu side site) is
Four types of 1.1, 1.3, 1.5, 1.7 (atomic%) 8-3) Sample of ultraviolet luminescent phosphor of Comparative Example 8b ... Notated as Lu (AlSc) Added Sc (Al) Replace only on the side site)
Five types of 1.1, 1.3, 1.5, 1.7, 1.9 (atomic%)

Here, the ionic radii of each of Lu, Sc, and Al are Lu (0.097 nm)> Sc (0.087 nm)> Al (0.054 nm).

The emission characteristics of the samples of the ultraviolet-emitting phosphors of Example 8 and Comparative Examples 8a and 8b will be described.
The PL measurement result of the ultraviolet luminescent phosphor of Example 8 is shown in FIG. 27, the PL measurement result of the ultraviolet luminescent phosphor of Comparative Example 8a is shown in FIG. 28, and the PL measurement result of the ultraviolet luminescent phosphor of Comparative Example 8b is shown in FIG. 29. show. In each PL measurement result, (1) shows the PL spectrum, (2) shows the PL peak wavelength, (3) shows the (420) plane X-ray diffraction peak shift, and (4) shows the integrated intensity.
The XRD measurement was θ-2θ measurement, and CuKα ray (0.1541 nm) was used. For photoluminescence (PL) measurement, a xenon excimer lamp was used as an excitation light source, the excitation wavelength was 172 nm (7.2 eV), and the measurement temperature was room temperature.

From the measurement results of FIG. 27, particularly from the graph of FIG. 27 (2), in the sample of the ultraviolet emitting phosphor of Example 8, the PL peak wavelength shifts substantially linearly to the long wavelength side as the amount of Sc added increases. You can see that there is. When the amount of Sc added is 2.8 (atomic%), the PL peak is 321 (nm), and when the amount of Sc added is 3.4 (atomic%), the PL peak is 328 (nm). )Met. Further, from the graph of FIG. 27 (4), when the addition amount of Sc is 2.8 to 3.0 (atomic%), it was confirmed integrated intensity is 4.1 × 10 ⁶ or more.

On the other hand, in the sample of the ultraviolet emitting phosphor of Comparative Example 8a, from the measurement result of FIG. 28, the PL peak wavelength was substantially linearly shifted to the long wavelength side according to the amount of Sc added, as in the sample of Example 8. However, when the amount of Sc added is 1.1 (atomic%), the PL peak is 297 (nm), and when the amount of Sc added is 1.7 (atomic%), the PL peak is. Was 303 (nm). Further, from the graph of FIG. 28 (4), when the addition amount of Sc is 1.1 to 1.5 (atomic%), the integrated intensity increases, and when it is 1.5 (atomic%), the peak value ( 4.0 × 10 than ^6), and was confirmed to be decreased in 1.7 (atomic%). It can be seen that the integrated intensity decreases at 1.7 (atomic%) because the emission intensity decreases due to concentration quenching, and the limit concentration is reached.

Further, in the sample of the ultraviolet emitting phosphor of Comparative Example 8b, from the measurement result of FIG. 29, the PL peak wavelength is shifted to the long wavelength side according to the amount of Sc added, as in the sample of Example 8. , When the addition amount of Sc is 1.1 (atomic%), the PL peak is 308 (nm), and when the addition amount of Sc is 1.9 (atomic%), the PL peak is 313 (Atomic%). nm). Further, from the graph of FIG. 28 (4), when the addition amount of Sc is 1.1 to 1.7 (atomic%), the integrated intensity is increased or constant, and when it is 1.7 (atomic%). peak values (4.0 × 10 than ^6), and to be decreased in 1.9 (atomic%) was confirmed. It can be seen that the integrated intensity decreases at 1.9 (atomic%) because the emission intensity decreases due to concentration quenching, and the limit concentration is reached.

From the above, in the case of the sample of the ultraviolet luminescent phosphor of Example 8, by substituting Sc in both the Lu side site and the Al side site, it was replaced with a single site of the Lu side site or the Al side site. Compared with the case, it was possible to increase the integrated intensity (emission intensity) by adding Sc at a concentration equal to or higher than the limit concentration of concentration quenching. From the viewpoint of the PL peak wavelength, the PL peak is 297 (nm) to 303 (nm) when the Lu side site is replaced alone, and the PL peak is 308 (the PL peak) when the Al side site is replaced alone. It was nm) to 313 (nm), and the PL peak could be shifted from 321 (nm) to 328 (nm) by substituting Sc at both the Lu side site and the Al side site. That is, by controlling the Sc ion substitution site, the PL peak wavelength could be shifted by 297 (nm) to 328 (nm), or about 30 nm.

In this embodiment, the rare earth aluminum garnet crystal (Lu _x Y _1-x ) ₃ (Al _y Z _1-y ) ₅ O ₁₂ (where x = 0, y = 1), that is, Y ₃ Al ₅ O ₁₂ is used. As a base, it is a phosphor to which Sc ion of a transition element ion other than Y forming a light emitting center is added, and the added Sc ion is both a rare earth site of Y and a group 13 element site of Al. The emission characteristics of the ultraviolet emitting phosphor (Example 9) substituted with will be described.
Further, as a comparative example, _{it is a phosphor to which Sc ion is added based on Y 3} Al ₅ O ₁₂ , and the added Sc ion is an ultraviolet emitting phosphor in which only the rare earth site of Y is substituted (Comparative example). 9a) emission characteristics and _{a phosphor to which Sc ions have been added based on Y 3} Al ₅ O ₁₂ , and the added Sc ions are ultraviolet emission fluorescence in which only the Group 13 element sites of Al are substituted. The emission characteristics of the body (Comparative Example 9b) will be described.

First, a procedure for preparing a sample of an ultraviolet emitting phosphor will be described. As shown in the flow of FIG. 3, in the preparation of the ultraviolet luminescent phosphor sample _{, each raw material powder of Y 2} O ₃ , Al ₂ O ₃ , and Sc ₂ O ₃ is weighed based on the stoichiometric ratio (step S31). ), The powder was mixed using an alumina mortar (step S32), and then the mixed powder was annealed (step S33). The annealing treatment was carried out in the atmosphere using an electric furnace under the conditions of an annealing temperature of 1600 ° C., an annealing time of 10 hours, and a temperature rise temperature of 4 hours.

The sample preparation conditions for the ultraviolet luminescent phosphor will be described.
The sample of the ultraviolet luminescent phosphor of Example 9 was prepared so that the amount of Sc ions added was 2.6, 2.8, 3.0, 3.2 (atomic%), and the Y-side site. _{The raw material powders of Y 2} O ₃ , Al ₂ O ₃ , and Sc ₂ O ₃ were weighed based on the stoichiometric ratio so as to be replaced by both the sites on the Al side and the site on the Al side. Here, Sc is substituted by 1.5 (atomic%) at the Al-side site to be substituted, and 1.1, 1.3, 1.5, 1.7 (atomic%) is substituted at the Y-side site. It was to so. That is, Al is reduced by 1.5 (atomic%), Y is reduced by 1.1, 1.3, 1.5, 1.7 (atomic%), and Sc is 2.6, 2. Sc ions were substituted at both the Y-side site and the Al-side site by weighing each raw material powder so as to increase by 8, 3.0, 3.2 (atomic%).

The sample of the ultraviolet luminescent phosphor of Comparative Example 9a was prepared so that the amount of Sc ions to be added was 1.3, 1.5, 1.7 (atomic%), and was substituted only at the Y-side site. As described above, the _{raw material powders of Y 2} O ₃ , Al ₂ O ₃ , and Sc ₂ O ₃ were weighed based on the stoichiometric ratio. Here, Y is reduced by 1.3, 1.5, 1.7 (atomic%) so that only the Y-side site is replaced by 1.3, 1.5, 1.7 (atomic%). Then, each raw material powder was weighed so that Sc increased by 1.3, 1.5, 1.7 (atomic%).

The sample of the ultraviolet luminescent phosphor of Comparative Example 9b was prepared so that the amount of Sc ions added was 1.3, 1.5, 1.7, 1.9 (atomic%), and the site on the Al side. _{The raw material powders of Y 2} O ₃ , Al ₂ O ₃ , and Sc ₂ O ₃ were weighed based on the stoichiometric ratio so that they were replaced only with. Here, Al is 1.1, 1.3, 1.5, 1.7 so that only the site on the Al side is replaced by 1.3, 1.5, 1.7, 1.9 (atomic%). Each raw material powder was weighed to reduce by 1.9 (atomic%) and increase Sc by 1.3, 1.5, 1.7, 1.9 (atom%).

The samples of the ultraviolet luminescent phosphors of Example 9 and Comparative Examples 9a and 9b are summarized below.
9-1) Sample of the ultraviolet luminescent phosphor of Example 9 ... (YSc) (AlSc) G The added Sc (replaced with both the Y-side site and the Al-side site) is
4 types of 2.6, 2.8, 3.0, 3.2 (atomic%) However, weighed so that Sc is replaced by 1.5 (atomic%) at the Al side site.
9-2) Sample of the ultraviolet luminescent phosphor of Comparative Example 9a ... (YSc) Notated as AlG The added Sc (replaced only at the Y side site) is
Three types of 1.3, 1.5, 1.7 (atomic%) 9-3) Sample of ultraviolet luminescent phosphor of Comparative Example 9b ... Notated as Y (AlSc) Added Sc (only on Al side site) Replacement)
4 types of 1.3, 1.5, 1.7, 1.9 (atomic%)

Here, the ionic radii of Y, Sc, and Al are Y (0.102 nm)> Sc (0.087 nm)> Al (0.054 nm).

The emission characteristics of the samples of the ultraviolet-emitting phosphors of Example 9 and Comparative Examples 9a and 9b will be described.
The PL measurement result of the ultraviolet luminescent phosphor of Example 9 is shown in FIG. 30, the PL measurement result of the ultraviolet luminescent phosphor of Comparative Example 9a is shown in FIG. 31, and the PL measurement result of the ultraviolet luminescent phosphor of Comparative Example 9b is shown in FIG. show. In each PL measurement result, (1) shows the PL spectrum, (2) shows the PL peak wavelength, (3) shows the (420) plane X-ray diffraction peak shift, and (4) shows the integrated intensity. The measuring method is the same as in Example 8.

From the measurement results of FIG. 30, especially from the graph of FIG. 30 (2), in the sample of the ultraviolet emitting phosphor of Example 9, the PL peak wavelength shifts substantially linearly to the long wavelength side as the amount of Sc added increases. You can see that there is. When the amount of Sc added is 2.6 (atomic%), the PL peak is 329 (nm), and when the amount of Sc added is 3.2 (atomic%), the PL peak is 333 (nm). )Met. Further, from the graph of FIG. 27 (4), the addition amount of Sc is in all 2.6 to 3.2 (atomic%), integrated intensity was confirmed to be at approximately 4.7 × 10 ⁶ or more.

On the other hand, in the sample of the ultraviolet emitting phosphor of Comparative Example 9a, the PL peak wavelength was substantially linearly shifted to the long wavelength side according to the amount of Sc added, as in the sample of Example 9, from the measurement result of FIG. However, when the amount of Sc added is 1.3 (atomic%), the PL peak is 314 (nm), and when the amount of Sc added is 1.7 (atomic%), the PL peak is. Was 319 (nm). Further, from the graph of FIG. 31 (4), when the addition amount of Sc is 1.3 to 1.5 (atomic%), the integrated intensity increases, and when it is 1.5 (atomic%), the peak value ( to take a 4.1 × 10 less than ⁶⁾ it was confirmed.

Further, in the sample of the ultraviolet emitting phosphor of Comparative Example 9b, from the measurement result of FIG. 32, the PL peak wavelength is shifted to the long wavelength side according to the amount of Sc added, as in the sample of Example 9. , When the addition amount of Sc is 1.3 (atomic%), the PL peak is 314 (nm), and when the addition amount of Sc is 1.9 (atomic%), the PL peak is 318 (Atomic%). nm). Further, from the graph of FIG. 32 (4), when the addition amount of Sc is 1.3 to 1.9 (atomic%), the integrated intensity is increased and peaks at 1.9 (atomic%). it was confirmed that the a value (less than 3.7 × 10 ^6).

From the above, in the case of the sample of the ultraviolet luminescent phosphor of Example 9, by substituting Sc in both the Y-side site and the Al-side site, it was replaced with a single site of the Y-side site or the Al-side site. Compared with the case, it was possible to increase the integrated intensity (emission intensity) by adding Sc at a concentration equal to or higher than the limit concentration of concentration quenching. From the viewpoint of the PL peak wavelength, the PL peak is 314 (nm) to 319 (nm) when the Y-side site is replaced alone, and the PL peak is 314 (nm) when the Al-side site is replaced alone. It was nm) to 318 (nm), and the PL peak could be shifted from 329 (nm) to 333 (nm) by substituting Sc for both the Lu side site and the Al side site. That is, by controlling the Sc ion substitution site, the PL peak wavelength could be shifted by 314 (nm) to 333 (nm), or about 20 nm.

In this embodiment, the rare earth aluminum garnet crystal (Lu _x Y _1-x ) ₃ (Al _y Z _1-y ) ₅ O ₁₂ (where x = 1, y = 1) is the base, that is, Lu ₃ Al ₅ O. It is a phosphor to which La ion of a transition element ion other than Lu forming a light emitting center is added based on _{12, and the added La ion is a rare earth site of Lu and a group 13 element site of Al.} The emission characteristics of the ultraviolet emitting phosphor (Example 10) substituted with both sites will be described.
Further, as a comparative example, _{it is a phosphor to which La ion is added based on Lu 3} Al ₅ O ₁₂ , and the added La ion is an ultraviolet emitting phosphor in which only the rare earth site of Lu is substituted (Comparative example). A phosphor to which La ion is added based on the emission characteristics of 10a) and Lu ₃ Al ₅ O ₁₂ , and the added La ion is an ultraviolet emission phosphor in which only the Group 13 element site of Al is substituted. The emission characteristics of (Comparative Example 10b) will be described.

First, a procedure for preparing a sample of an ultraviolet emitting phosphor will be described. As shown in the flow of FIG. 3, in the preparation of the ultraviolet luminescent phosphor sample _{, each raw material powder of Lu 2} O ₃ , Al ₂ O ₃ , and La ₂ O ₃ is weighed based on the stoichiometric ratio (step S31). ), The powder was mixed using an alumina mortar (step S32), and then the mixed powder was annealed (step S33). The annealing treatment was carried out in the atmosphere using an electric furnace under the conditions of an annealing temperature of 1600 ° C., an annealing time of 10 hours, and a temperature rise temperature of 4 hours.

The sample preparation conditions for the ultraviolet luminescent phosphor will be described.
The sample of the ultraviolet luminescent phosphor of Example 10 was prepared so that the amount of La ions added was 2.4, 2.6, 2.8, and 3.0 (atomic%), and the Lu side site. _{The raw material powders of Lu 2} O ₃ , Al ₂ O ₃ , and La ₂ O ₃ were weighed based on the stoichiometric ratio so as to be replaced by both the sites on the Al side and the sites on the Al side. Here, La is substituted 1.3 (atomic%) at the Al-side site to be substituted, and 1.1, 1.3, 1.5, 1.7 (atomic%) is substituted at the Lu-side site. It was to so. That is, Al is reduced by 1.3 (atomic%), Lu is reduced by 1.1, 1.3, 1.5, 1.7 (atomic%), and La is 2.4, 2. La ions were replaced with both Lu-side sites and Al-side sites by weighing each raw material powder so as to increase by 6, 2.8 and 3.0 (atomic%).

The sample of the ultraviolet luminescent phosphor of Comparative Example 10a is prepared and prepared so that the amount of La ions added is 1.1, 1.3, 1.5, 1.7 (atomic%). Chemical quantity theory of each raw material powder of _{Lu 2} O ₃ , Al ₂ O ₃ , and La ₂ O ₃ so that the phosphor Lu ₃ Al ₅ O ₁₂ has the same amount and is replaced only at the Lu side site. Weighed based on the ratio. Here, Lu is 1.1, 1.3, 1.5, 1.7 so that only the Lu side site is replaced by 1.1, 1.3, 1.5, 1.7 (atomic%). Each raw material powder was weighed to reduce by (atomic%) and increase La by 1.1, 1.3, 1.5, 1.7 (atomic%).

The sample of the ultraviolet luminescent phosphor of Comparative Example 10b was prepared so that the amount of La ion added was 1.1, 1.3, 1.5, 1.7 (atomic%), and the site on the Al side. _{The raw material powders of Lu 2} O ₃ , Al ₂ O ₃ , and La ₂ O ₃ were weighed based on stoichiometric ratios so that they were replaced only by. Here, Al is 1.1, 1.3, 1.5, 1.7 so that only the site on the Al side is substituted with 1.1, 1.3, 1.5, 1.7 (atomic%). Each raw material powder was weighed to reduce by (atomic%) and increase La by 1.1, 1.3, 1.5, 1.7 (atomic%).

The samples of the ultraviolet luminescent phosphors of Example 10 and Comparative Examples 10a and 10b are summarized below.
10-1) Sample of the ultraviolet luminescent phosphor of Example 10 ... (LuSc) (AlLa) G The added La (replaced with both the Lu-side site and the Al-side site) is
4 types of 2.4, 2.6, 2.8 and 3.0 (atomic%) However, weighed so that La is replaced by 1.3 (atomic%) at the Al side site.
10-2) Sample of the ultraviolet luminescent phosphor of Comparative Example 10a ... (LuLa) Notated as AlG The added La (replaced only at the Lu side site) is
Four types of 1.1, 1.3, 1.5, 1.7 (atomic%) 10-3) Sample of ultraviolet luminescent phosphor of Comparative Example 10b ... Notated as Lu (AlLa) Added La (Al) Replace only on the side site)
4 types of 1.1, 1.3, 1.5, 1.7 (atomic%)

Here, the ionic radii of each of La, Lu, and Al are La (0.116 nm)> Lu (0.097 nm)> Al (0.054 nm).

The emission characteristics of the samples of the ultraviolet-emitting phosphors of Example 10 and Comparative Examples 10a and 10b will be described.
The PL measurement result of the ultraviolet luminescent phosphor of Example 10 is shown in FIG. 33, the PL measurement result of the ultraviolet luminescent phosphor of Comparative Example 10a is shown in FIG. 34, and the PL measurement result of the ultraviolet luminescent phosphor of Comparative Example 10b is shown in FIG. 35. show. In each PL measurement result, (1) shows the PL spectrum and (2) shows the integrated intensity. The measuring method is the same as in Example 8. Unlike Example 8, the difference between the PL peak wavelength and the (420) plane X-ray diffraction peak shift was small, so it was omitted.

From the graph of the measurement result of FIG. 33, in the sample of the ultraviolet emitting phosphor of Example 10, the PL peak wavelength was around 295 nm even if the amount of La added was increased. Further, from the graph of FIG. 33 (2), the addition amount of La is in the case of 2.8, the integrated intensity was confirmed to become 1.56 × 10 ⁶ and peak.

On the other hand, in the sample of the ultraviolet emitting phosphor of Comparative Example 10a, the PL peak wavelength was around 285 nm even if the amount of La added increased, from the measurement result of FIG. 34. Further, from the graph of FIG. 34 (4), the amount of La is in the case of 1.5, the integrated intensity was confirmed to become 1.42 × 10 ⁶ and peak. It can be seen that the reason why the integrated intensity decreases when the amount of La added is 1.7 (atomic%) is that the emission intensity decreases due to the concentration quenching, and the limit concentration is reached.

Further, in the sample of the ultraviolet emitting phosphor of Comparative Example 10b, from the measurement result of FIG. 35, the PL peak wavelength was around 300 nm even if the amount of La added was increased. Further, from the graph of FIG. 36 (4), the amount of La is in the case of 1.3 to 1.5, the integrated intensity was confirmed to become 2.8 × 10 ⁶ and peak. It can be seen that the reason why the integrated intensity decreases when the amount of La added is 1.7 (atomic%) is that the emission intensity decreases due to the concentration quenching, and the limit concentration is reached.

From the above, in the case of the sample of the ultraviolet luminescent phosphor of Example 10, by substituting La for both the Lu side site and the Al side site, it was replaced with a single site of the Lu side site or the Al side site. Compared with the case, it was possible to increase the integrated intensity (emission intensity) by adding La having a concentration equal to or higher than the limit concentration of concentration quenching. From the viewpoint of the PL peak wavelength, the PL peak is 285 nm when the Lu side site is replaced alone, and the PL peak is 300 n when the Al side site is replaced alone, and the Lu side site and the Al side are replaced. By substituting La for both sites, the PL peak could be shifted to 295 nm. That is, by controlling the substitution site of La ion, the PL peak wavelength could be shifted by 285 (nm) to 300 (nm), or about 15 nm.

In this embodiment, the rare earth aluminum garnet crystal (Lu _x Y _1-x ) ₃ (Al _y Z _1-y ) ₅ O ₁₂ (where x = 0, y = 1) is used as a base, that is, Y ₃ Al ₅ It is a phosphor to which La ion of a transition element ion other than Y forming a light emitting center is added based on O _{12, and the added La ion is a rare earth site of Y and a group 13 element site of Al.} The luminescence characteristics of the ultraviolet luminescent phosphor (Example 11) substituted with both of these sites will be described.
Further, as a comparative example, _{it is a phosphor to which La ion is added based on Y 3} Al ₅ O ₁₂ , and the added La ion is an ultraviolet emitting phosphor in which only the rare earth site of Y is substituted (Comparative example). 11a) emission characteristics and _{a phosphor to which La ions are added based on Y 3} Al ₅ O ₁₂ , and the added La ions are ultraviolet emission fluorescence in which only the Group 13 element sites of Al are substituted. The emission characteristics of the body (Comparative Example 10b) will be described.

First, a procedure for preparing a sample of an ultraviolet emitting phosphor will be described. As shown in the flow of FIG. 3, in the preparation of the ultraviolet luminescent phosphor sample, the _{raw material powders of Y 2} O ₃ , Al ₂ O ₃ , and La ₂ O ₃ are weighed based on the stoichiometric ratio (step S31). ), The powder was mixed using an alumina mortar (step S32), and then the mixed powder was annealed (step S33). The annealing treatment was carried out in the atmosphere using an electric furnace under the conditions of an annealing temperature of 1600 ° C., an annealing time of 10 hours, and a temperature rise temperature of 4 hours.

The sample preparation conditions for the ultraviolet luminescent phosphor will be described.
The sample of the ultraviolet luminescent phosphor of Example 11 was prepared so that the amount of La ions added was 2.4, 2.6, 2.8, and 3.0 (atomic%), and the Y-side site was also added. _{The raw material powders of Y 2} O ₃ , Al ₂ O ₃ , and La ₂ O ₃ were weighed based on the stoichiometric ratio so as to be replaced by both the sites on the Al side and the sites on the Al side. Here, La is substituted 1.3 (atomic%) at the Al-side site to be substituted, and 1.1, 1.3, 1.5, 1.7 (atomic%) is substituted at the Y-side site. It was to so. That is, Al is reduced by 1.3 (atomic%), Y is reduced by 1.1, 1.3, 1.5, 1.7 (atomic%), and La is 2.4, 2. La ions were replaced with both Y-side sites and Al-side sites by weighing each raw material powder so as to increase by 6, 2.8 and 3.0 (atomic%).

The sample of the ultraviolet luminescent phosphor of Comparative Example 11a was prepared so that the amount of La ion added was 1.1, 1.3, 1.5, 1.7 (atoichiometry), and the Y-side site was also added. _{Raw material powders of Y 2} O ₃ , Al ₂ O ₃ , and La ₂ O ₃ were weighed based on stoichiometric ratios so that they were replaced only by. Here, Y is 1.1, 1.3, 1.5, 1.7 so that only the Y-side site is replaced by 1.1, 1.3, 1.5, 1.7 (atomic%). Each raw material powder was weighed to reduce by (atomic%) and increase La by 1.1, 1.3, 1.5, 1.7 (atomic%).

The sample of the ultraviolet luminescent phosphor of Comparative Example 11b was prepared so that the amount of La ion added was 1.1, 1.3, 1.5, 1.7 (atomic%), and the site on the Al side. _{The raw material powders of Y 2} O ₃ , Al ₂ O ₃ , and La ₂ O ₃ were weighed based on the stoichiometric ratio so that they were replaced only with. Here, Al is 1.1, 1.3, 1.5, 1.7 so that only the site on the Al side is substituted with 1.1, 1.3, 1.5, 1.7 (atomic%). Each raw material powder was weighed to reduce by (atomic%) and increase La by 1.1, 1.3, 1.5, 1.7 (atomic%).

The samples of the ultraviolet luminescent phosphors of Example 11 and Comparative Examples 11a and 11b are summarized below.
11-1) Sample of the ultraviolet luminescent phosphor of Example 11 ... (YSc) (AlLa) G The added La (replaced with both the Y-side site and the Al-side site) is
4 types of 2.4, 2.6, 2.8 and 3.0 (atomic%) However, weighed so that La is replaced by 1.3 (atomic%) at the Al side site.
11-2) Sample of the ultraviolet luminescent phosphor of Comparative Example 11a ... (YLa) Notated as AlG The added La (replaced only at the Y side site) is
Four types of 1.1, 1.3, 1.5, 1.7 (atomic%) 11-3) Sample of ultraviolet luminescent phosphor of Comparative Example 11b ... Notated as Y (AlLa) Added La (Al) Replace only on the side site)
4 types of 1.1, 1.3, 1.5, 1.7 (atomic%)

Here, the ionic radii of each of La, Y, and Al are La (0.116 nm)> Y (0.102 nm)> Al (0.054 nm).

The PL measurement result of the ultraviolet luminescent phosphor of Example 11 is shown in FIG. 36, the PL measurement result of the ultraviolet luminescent phosphor of Comparative Example 11a is shown in FIG. 37, and the PL measurement result of the ultraviolet luminescent phosphor of Comparative Example 11b is shown in FIG. 38. show. In each PL measurement result, (1) shows the PL spectrum and (2) shows the integrated intensity. The measuring method is the same as in Example 8. Unlike Example 9, the difference between the PL peak wavelength and the (420) plane X-ray diffraction peak shift was small, so it was omitted.

From the graph of the measurement result of FIG. 36, in the sample of the ultraviolet emitting phosphor of Example 11, the PL peak wavelength was around 287 nm even if the amount of La added was increased. Further, from the graph of FIG. 36 (2), integrated intensity is ^{1.50 × 10 6 ~1.60 × 10 6} , the integrated intensity as the added amount of La is increased from 2.4 (atomic%) is reduced I was able to confirm that. It is inferred that this is because the peak of the integrated intensity exists below 2.4 (atomic%).

On the other hand, in the sample of the ultraviolet emitting phosphor of Comparative Example 11a, the PL peak wavelength was around 287 nm even if the amount of La added increased, from the measurement result of FIG. 37. Further, from the graph of FIG. 37 (4), the amount of La is the case of the 1.5 (atomic%), integrated intensity was confirmed to become 1.80 × 10 ⁶ and peak. It can be seen that the reason why the integrated intensity decreases when the amount of La added is 1.7 (atomic%) is that the emission intensity decreases due to the concentration quenching, and the limit concentration is reached.

Further, in the sample of the ultraviolet emitting phosphor of Comparative Example 11b, from the measurement result of FIG. 38, the PL peak wavelength was around 287 nm even if the amount of La added was increased. Further, from the graph of FIG. 38 (4), the amount of La is 1.1 integrated intensity (atomic%) as high as 1.80 × 10 ^6, the integrated intensity at 1.3 (atomic%) or more is 1. It was 65 × ¹⁰⁶ , and it was confirmed that the emission intensity decreased and the integrated intensity decreased. When La is added to YAG, the ionic radius of La is more than twice the ionic radius of Al. Therefore, in the case of Y (AlLa) G in which La replaces the Al side site, the emission intensity immediately increases when La is added. It will be attenuated. It is presumed that this is because the ionic radius of La is too large than the ionic radius of Al at the substitution site, and excessive addition of La creates a non-radiative center.

Even in the case of the sample of the ultraviolet luminescent phosphor of Example 11, by substituting La for both the Y-side site and the Al-side site, it is compared with the case where it is replaced with a single site of the Y-side site or the Al-side site. Therefore, the integrated intensity (emission intensity) can be increased by adding La above the limit concentration of concentration quenching, but since La is replaced by 1.3 (atomic%) at the Al side site, the Al side site. (It is presumed that the optimum concentration for substituting La on the Al side site is 1.1 (atomic%) or less), and the result of increasing the integrated intensity (emission intensity) was not reached.

FIG. 39 is a graph of the PLE measurement result, and in the PLE measurement, the PL spectrum is measured while changing the excitation light wavelength (excitation energy). In FIG. 39, the horizontal axis represents the excitation wavelength and the vertical axis represents the PL intensity.
The graph of FIG. 39 (1) shows the Sc ion of the transition element ion forming the emission center using LuAG of Example 1, LuYAG of Example 2, and YAG of Example 3 as the base rare earth aluminum garnet crystal. The results of PLE measurement of phosphors to which 1.5 (atomic%) have been added are shown. In the graph of FIG. 39 (1), the absorption end of “(LuSc) AlG, Sc = 1.5 at%” obtained by adding Sc ion 1.5 (atomic%) to LuAG is on the short wavelength side, and Sc in YAG. The absorption end of "(YSc) AlG, Sc = 1.5 at%" to which ion 1.5 (atomic%) is added is on the long wavelength side, and Sc ion 1.5 (atom%) is added to LuYAG. It can be seen that the absorption ends of "(LuYSc) AlG, Sc = 1.5 at%" exist on the short wavelength side and the long wavelength side, respectively. This confirms that as Y is added to LuAG, the absorption end becomes longer in wavelength, and the one in which Lu is completely replaced with Y has the absorption end on the longest wavelength side, and the long wavelength excitation efficiency is improved. It means that.

The graph of FIG. 39 (2) shows the PLE of the phosphor to which Sc ion 1.5 (atomic%) was added in (LuSc) AlG of Comparative Example 8a and Lu (AlSc) of Comparative Example 8b described above. The measurement result is shown. The (LuSc) AlG of Comparative Example 8a and the Lu (AlSc) of Comparative Example 8b are obtained by changing the substitution sites (Lu or Al) of Sc, respectively.
From the graph of FIG. 39 (2), when Sc having a small ionic radius enters the Lu site having a large ionic radius, the LuAG host crystal receives compressive stress and the absorption end has a shorter wavelength. It is clear from the X-ray diffraction peak shift of FIG. 28 (3) that the LuAG host crystal is subjected to compressive stress. On the other hand, when entering the Al site having an ionic radius smaller than Sc, it is shown that the average lattice constant expands from the X-ray diffraction peak shift in FIG. The wavelength has been shortened to. LuAG is a garnet crystal, which is an aggregate of an oxygen basket containing Lu and an oxygen basket containing Al, and it is the oxygen basket containing Sc that emits light. When Sc enters the smaller Al site, the basket containing Sc expands, so it is speculated that the basket containing Lu next to it is compressed and compressed (a person is trapped in a small room and a balloon inflates in the gap). Similar to the feeling). Since the wavelength of the band end became shorter when Sc replaced Al, it can be concluded that the basket containing Lu determines the absorption end energy. That is, it can be concluded that the replacement of rare earth sites is important for the control of the absorption edge. Therefore, if Lu is replaced with Y, the band end will move effectively as shown in the graph of FIG. 39 (1).

The graph of FIG. 39 (3) shows Sc ions 1.5 (atomic%) and 1 in (LuSc) AlG of Comparative Example 8a of Example 8 and (LuLa) AlG of Comparative Example 10a of Example 10 described above, respectively. The PLE measurement result of the phosphor to which .2 (atomic%) was added is shown. The (LuSc) AlG of Comparative Example 8a and the (LuLa) AlG of Comparative Example 10a are obtained by changing the substitution elements (Sc, La) of the substitution site Lu.
From the graph of FIG. 39 (3), when replacing the same rare earth site, when Sc having a small ionic radius enters the Lu site having a large ionic radius, the LuAG host crystal receives compressive stress (FIG. 28 (3)). (Clear from X-ray diffraction peak shift) The absorption end has a shorter wavelength, whereas when La with an ionic radius larger than Lu enters the Lu site, the LuAG host crystal receives tensile stress and the absorption end has a longer wavelength. It was confirmed that it became.

The ultraviolet-emitting phosphor of the present invention and an ultraviolet-emitting device using the same have potential for use in current industrial equipment and analyzers for which mercury-free operation is urgently needed. In addition, it can be expected to be widely used in an extremely wide range of application fields such as sterilization / sterilization equipment in the environment / medical field, cell selection by dye, surface analysis, fluorescence analysis, decomposition / removal equipment for environmental pollutants, and water quality management system.

1 Ultraviolet emitting phosphor 2 Excitation light source 3 Excitation light 4 Output light 11 Extraviolet emitting phosphor thin film 12 Quartz glass substrate 13 Anode electrode 15 Spacer 16 Voltage circuit 17 Si-doped AlN thin film 18 Si substrate 19 Cathode electrode

Claims (5)

Rare earth aluminum garnet crystal (Lu _x Y _1-x ) ₃ (Al _y Z _1-y ) ₅ O ₁₂ (However, 0 < x ≦ 1, 0 <y ≦ 1, Z is B, Ga, In, Tl) As a base, it is a phosphor to which La ion and Sc ion forming a light emitting center are co-added.
Each addition amount is an addition ratio that reaches the target emission center wavelength in the ultraviolet region in the range of 280 to 320 nm, and is an addition amount near the limit at which concentration quenching occurs.
The total amount of La ion and Sc ion added is larger than the amount of La ion or Sc ion added alone.
UV-emitting phosphor, characterized in that is excited by irradiation of the excitation light to emit ultraviolet light. Said rare earth aluminum garnet crystal, a _Lu 3 _Al 5 _{O 12,}
The ultraviolet luminescent phosphor according to claim 1 , wherein the co- added La ion and Sc ion are substituted with both Lu site and Al site. The ultraviolet luminescent phosphor according to claim 1 or 2,
Excitation light irradiation means for irradiating the ultraviolet emitting phosphor with excitation light,
With
The ultraviolet light emitting device is characterized in that the ultraviolet light generated by plasma discharge becomes excitation light and is irradiated to the ultraviolet emitting phosphor. The ultraviolet emitting phosphor of claim 1 or 2 is a thin film, and the ultraviolet emitting phosphor is a thin film.
With the anode substrate having the above thin film,
A cathode substrate having a field electron emission material and
A spacer in which the anode substrate and the cathode substrate are arranged so as to face each other and the gap between the substrates is maintained in a vacuum atmosphere.
It has at least a voltage circuit for applying an electric field between the anode substrate and the cathode substrate.
The gap between the anode substrate and the cathode substrate is set as a vacuum channel region, and electrons from the electric field electron emitting material are injected into the thin film of the ultraviolet emitting phosphor by applying an electric field between the substrates, and the ultraviolet emitting light is emitted. An ultraviolet light emitting device characterized by emitting ultraviolet light from a phosphor. The method for producing an ultraviolet luminescent phosphor according to claim 1.
1) Steps to determine the target emission center wavelength in the ultraviolet region in the range of 240 to 400 nm, and
2) A step of adjusting the addition ratio of La ion and Sc ion forming the emission center to control the emission center wavelength, and
3) Prepare so that the total addition amount of each of La ion and Sc ion is larger than the addition amount of La ion or Sc ion added alone, and is equal to or more than the limit concentration due to the concentration quenching of each ion. the method comprising the steps of,
4) A step of preparing the parameter x to control the emission center wavelength and the brightness.
5) To the rare earth aluminum garnet crystal, the step of co-adding La ion and Sc ion for which the above addition ratio and total addition amount have been prepared, and
6) Baking and annealing steps,
A method for producing an ultraviolet-emitting phosphor, which comprises the above.

Images