JP2018087278A - Phosphor, method for producing the same, luminescent device thereof, and ultraviolet use device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phosphor that makes it possible to obtain efficiently ultraviolet emission without using mercury, in a fluorescent lamp using an excitation source and the phosphor in combination, a method for producing the same and a use therefor.SOLUTION: A phosphor includes at least A element (where A element is carbon and/or silicon) in hexagonal boron nitride crystals, and emits a fluorescence having a luminescence peak at the wavelengths of 290 nm or more and less than 350 nm when irradiated with an excitation source.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a phosphor that emits ultraviolet light by electron beam excitation, a method for producing the same, a light-emitting device, and an ultraviolet light utilization device.

  Ultraviolet light emission is used in various fields. The range of water, air, containers, food, medical instruments, etc., such as sterilization, film and glass surface modification, semiconductor cleaning, banknote and blood inspection, resin curing, and so on. A mercury lamp is used as an ultraviolet ray source. In a mercury lamp, mercury vapor is sealed in a vacuum tube, and mercury atoms are changed to an excited state with high energy by an electron beam emitted from an electron beam emitter. Ultraviolet light is emitted when returning from the excited state to the ground state.

  Ultraviolet light emission using mercury is widely used, but since mercury is toxic to the human body, regulation of use is planned, and clean ultraviolet light emission that does not use mercury is required. As such a light-emitting device, an ultraviolet LED has been developed, but there are problems in light emission intensity and efficiency due to problems such as difficulty in producing a high-quality crystal structure. Furthermore, the wavelength required for ultraviolet rays varies depending on the application, and a light source having a peak at 310 to 330 nm is required for phototherapy and ink curing.

  Fluorescent display tubes and field emission displays are known as ultraviolet light emitting devices that do not use mercury, and these are devices that emit visible light. On the other hand, as another ultraviolet light emitting device, a field emission lamp in which a field emission electron source and an ultraviolet light emitting phosphor are combined is known (see, for example, Patent Document 1). Patent Document 1 reports an ultraviolet lamp that emits light having a peak at 350 nm to 450 nm by using a ZnS-based phosphor.

  Further, it has been reported that boron nitride (BN) phosphors emit visible and ultraviolet light (see, for example, Patent Documents 2 to 5 and Non-Patent Document 1). According to Patent Document 2 and Patent Document 3, it is reported that the B—C—N—O phosphor emits white light by blue light excitation.

  According to Patent Document 4 and Non-Patent Document 1, it is reported that the BN crystal emits light at a wavelength in the range of 200 nm to 220 nm when excited by an electron beam, but there is little light emission at less than 290 nm, and 290 nm to 350 nm. A BN phosphor that emits fluorescence having an emission peak at a wavelength in the range below is not reported.

  According to Patent Document 5, a BN phosphor activated with Eu ions or the like has been reported, but light emission having a peak in the range of 290 nm to 350 nm has not been observed.

JP 2007-294698 A JP 2012-2111278 A JP2013-10878A JP 2007-9095 A JP 2006-316722 A

Kenji Watanabe et al., Diamond & Related Materials, 20, 849-852, 2011

  An object of the present invention is to provide a phosphor capable of efficiently obtaining ultraviolet light emission without using mercury in a fluorescent lamp in which an excitation source and a phosphor are combined, a manufacturing method thereof, and an application thereof.

  The present inventor has conducted research to solve the above-mentioned problems, and a phosphor having a specific composition having a BN-based specific crystal structure (BN phosphor) is excited by an electron beam in a vacuum, whereby efficient ultraviolet light emission is achieved. I found out what happened. Furthermore, when this BN phosphor is applied to a metal thin film plate and excited with an electron beam, ultraviolet rays are emitted, and it is found that an ultraviolet light source can be constructed by combining this phosphor and an electron beam source. It was. Thereby, it came to complete invention regarding a fluorescent substance, the manufacturing method of a fluorescent substance, a light-emitting fixture, and an ultraviolet-ray utilization apparatus. The configuration is as described below.

The phosphor of the present invention contains at least an A element (however, the A element is carbon and / or silicon) in a hexagonal boron nitride crystal, and has a wavelength in the range of 290 nm to less than 350 nm when irradiated with an excitation source. Fluorescent light having an emission peak is emitted, thereby solving the above problem.
The content of the element A may be 0.01% by mass or more.
The content of the element A may be 0.3% by mass or more and 15% by mass or less.
The element A may be carbon.
The content (mass%) of the element A may be larger than the content (mass%) of the oxygen.
The oxygen content may be not less than 0.1% by mass and not more than 0.3% by mass.
The maximum light emission intensity in the range from 200 nm to less than 290 nm may be 1/10 or less of the maximum light emission intensity in the range from 290 nm to less than 350 nm.
Fluorescence having an emission peak at a wavelength in the range of 310 nm to less than 330 nm may be emitted.
Fluorescence having an emission peak at a wavelength in the range of 315 nm or more and less than 325 nm and a peak half-value width of 10 nm or more and 50 nm or less may be emitted.
The excitation source may be an electron beam, an X-ray, or an ultraviolet ray having a wavelength of 150 nm or more and less than 290 nm.
Composition formula B _a O _b N _{C Ad} E _e (where B is a boron element, O is an oxygen element, N is a nitrogen element, A element is carbon and / or silicon, and E element is B, O, N, An element other than C or Si, wherein a, b, c, d, and e are parameters representing the ratio of the number of atoms, and a + b + c + d + e = 1).
0.39 ≦ a ≦ 0.5
0 ≦ b ≦ 0.01
0.39 ≦ c ≦ 0.55
0.0001 ≦ d ≦ 0.3
0 ≦ e ≦ 0.05
The above conditions may be satisfied. However, when the A element is two kinds, the d value is a total value of the respective elements, and when the E element is two or more kinds, the e value is a total value of the respective elements.
The parameters b and d may satisfy the condition b <d.
The parameter b may satisfy a condition of 0.0001 ≦ b ≦ 0.008.
The parameter d may satisfy a condition of 0.001 ≦ d ≦ 0.25.
The parameter e may be e = 0.
The element A is carbon, and the parameters a, b, c, d, e are
0.4 ≦ a ≦ 0.5
0.0001 ≦ b ≦ 0.008
0.45 ≦ c ≦ 0.499
0.001 ≦ d ≦ 0.03
b <d
e = 0
This condition may be satisfied.
The hexagonal boron nitride crystal may be particles having a particle size of 0.8 μm or more and 5 μm or less.
The hexagonal boron nitride crystal may be a particle having a particle size of 1 μm to 5 μm.
The light-emitting device according to the present invention includes at least an electron beam source and a phosphor, and the phosphor includes at least the above-described phosphor, and emits the phosphor by electron beam excitation by the electron beam source to 290 nm. This emits light having an emission peak at a wavelength in the range of less than 350 nm, thereby solving the above problem.
The electron beam source may be a field electron emission (field emission) electron source, and the light emission method may be a field emission lamp.
The electron beam source and the phosphor are housed in a vacuum vessel, and the electron beam source includes a cathode electrode having a field electron emission type electron source and a gate electrode having a positive potential with respect to the cathode electrode. And an anode electrode having a positive high potential with respect to the gate electrode, the phosphor is applied to the anode electrode, and electrons extracted from the cathode electrode are applied to the anode electrode. Further, light may be emitted by colliding with the phosphor.
An ultraviolet ray utilization apparatus according to the present invention includes the above-described light emitting device, and irradiates an object with ultraviolet light emitted from the light emitting device, thereby solving the above-described problem.
The method for producing the phosphor according to the present invention includes a step of adding a compound containing carbon and / or silicon to boron nitride or a compound that becomes boron nitride by heating and heating to a temperature of 1400 ° C. or higher and 2500 ° C. or lower. This solves the above problem.
The boron nitride or the compound that becomes boron nitride by heating may be a powder.

  The phosphor of the present invention emits ultraviolet rays having an emission peak at a wavelength in the range of 290 nm to less than 350 nm by containing at least an A element (A element is carbon and / or silicon) in a hexagonal boron nitride crystal. To do. Furthermore, the light emitting device includes an electron beam source and a phosphor, and emits ultraviolet light having a light emission peak at a wavelength in the range of 290 nm to less than 350 nm. Furthermore, an ultraviolet-ray utilization apparatus can be comprised by comprising a light-emitting device. By changing the composition of the phosphor, the emission intensity and the emission wavelength can be adjusted.

The figure which shows the excitation spectrum and emission spectrum by the photoexcitation of the compound of Example 1. The figure which shows the emission spectrum by the electron beam excitation of the compound of Example 1 The figure which shows the emission spectrum by the electron beam excitation of the BN raw material of the comparative example 1 The figure which shows the emission spectrum by the electron beam excitation of the compound of Example 2 The figure which shows the emission spectrum by the electron beam excitation of the compound of Example 3 The figure which shows the emission spectrum by the electron beam excitation of the compound of Example 4 The figure which shows the emission spectrum by the electron beam excitation of the compound of Example 5 The figure which shows the emission spectrum by the electron beam excitation of the compound of Example 6 The figure which shows the emission spectrum by the electron beam excitation of the compound of Example 7 The figure which shows the emission spectrum by the electron beam excitation of the compound of Example 8 Schematic diagram of ultraviolet light emitting device according to the present invention

  Hereinafter, embodiments of the present invention will be described in detail.

  The phosphor of the present invention contains at least an A element (however, the A element is carbon and / or silicon) in a hexagonal boron nitride crystal, and irradiates an excitation source to a wavelength in the range of 290 nm to less than 350 nm. Fluorescence with an emission peak is emitted. Conventional hexagonal boron nitride phosphors mainly emit light with a wavelength of less than 290 nm. However, by containing element A, they emit light with a wavelength of 290 nm or more.

  The phosphor of the present invention can be used as a mixture to which other substances are added in addition to being used alone. Examples of the other substance include a second phosphor, a conductive substance, and an environmental resistant substance. When other substances are included, the content of the phosphor is preferably 20% by mass or more from the viewpoint of luminous efficiency.

As the second phosphor, CaAlSiN ₃ : Eu red phosphor, Ca ₂ Si ₅ N ₈ : Eu red phosphor, α-sialon: Eu yellow phosphor, β-sialon: Eu green phosphor, BaSi ₇ N ₁₀ : Eu blue phosphor or the like can be used. These second phosphors are usually used for photoexcitation with blue light or violet light, but when combined with the phosphor of the present invention, the ultraviolet light emitted by the phosphor of the present invention excites the second phosphor. By doing so, the second phosphor can emit light.

  Examples of the conductive material include metals such as aluminum and silicon, and carbon. When a conductive material is added, the light emission efficiency of electron beam excitation may be improved.

  Examples of environmentally resistant substances include oxidation resistant films such as silicon oxide and aluminum oxide. When an environmentally resistant substance is added, deterioration of the phosphor can be reduced, and high-efficiency light emission can be maintained over a long period of time.

  The content of element A is preferably 0.01% by mass or more. Thereby, the emission peak intensity in the wavelength range of 290 nm or more and less than 350 nm is increased. Hexagonal boron nitride and graphite have similar crystal structures, and carbon and silicon are likely to dissolve in hexagonal boron nitride, which is considered to have an effect of adding a light emitting point to hexagonal boron nitride. As a result, fluorescence having a light emission peak at a wavelength in the range of 290 nm to less than 350 nm and having a small half-value width is emitted. If the A element is less than 0.01% by mass, there is a risk of emitting light at a wavelength shorter than 290 nm. In addition, since the half width increases, it is not suitable for an application using light having a sharp waveform of 290 nm or more and less than 350 nm.

  More preferably, the content of the element A is 0.3% by mass or more and 15% by mass or less. In this range, the emission intensity is particularly high at a wavelength of 290 nm or more, preferably 300 nm or more and less than 350 nm.

  Carbon is more preferable as the A element. Carbon is more easily dissolved in hexagonal boron nitride and has high emission intensity at a wavelength of 290 nm to less than 350 nm.

Furthermore, in some compositions in which the content of element A (mass%) is greater than the content of oxygen (mass%), the maximum emission intensity in the range of 200 nm or more and less than 290 nm is the maximum emission intensity in the range of 290 nm or more and less than 350 nm. Therefore, it is suitable for applications using wavelengths of 290 nm to 350 nm. Examples of some compositions include the composition formula B _a O _b N _{c Ad} E _e (where B is a boron element, O is an oxygen element, N is a nitrogen element, and A element is carbon and / or silicon, The element E is an element other than B, O, N, C, and Si, or a mixture thereof. In the formula, a, b, c, d, and e are parameters representing the ratio of the number of atoms, and a + b + c + d + e = 1) The parameters a, b, c, d, e are
0.4 ≦ a ≦ 0.5
0.0001 ≦ b ≦ 0.008
0.45 ≦ c ≦ 0.499
0.001 ≦ d ≦ 0.3
b <d
e = 0
Can be mentioned.

  In some compositions in which the content of element A (mass%) is greater than the content of oxygen (mass%), it has a light emission peak in the range of 310 nm or more and less than 330 nm, so it is suitable for applications using wavelengths in this range. Yes.

  Furthermore, in some compositions in which the oxygen content is 0.1% by mass or more and 0.3% by mass or less and the carbon content (% by mass) is greater than the oxygen content (% by mass), 315 nm or more and less than 325 nm This is suitable for applications using wavelengths in this range because it emits fluorescent light having a light emission peak at a wavelength in this range and a half-width of the peak in the range from 10 nm to 50 nm.

  The excitation source is not particularly defined, but it is preferable to use an electron beam, X-ray, or ultraviolet light having a wavelength of 150 nm or more and less than 290 nm because of high luminous efficiency.

Composition formula B _a O _b N _{C Ad} E _e (where B is a boron element, O is an oxygen element, N is a nitrogen element, A element is carbon and / or silicon, and E element is B, O, N, An element other than C or Si, wherein a, b, c, d, and e are parameters representing the ratio of the number of atoms, and a + b + c + d + e = 1).
0.39 ≦ a ≦ 0.5
0 ≦ b ≦ 0.01
0.39 ≦ c ≦ 0.55
0.0001 ≦ d ≦ 0.3
0 ≦ e ≦ 0.05
A phosphor satisfying the above conditions has high emission intensity. However, when the A element is two kinds, the d value is a total value of the respective elements, and when the E element is two or more kinds, the e value is a total value of the respective elements.

  Here, the parameter a indicating the amount of boron is preferably in the range of 0.39 ≦ a ≦ 0.5, and a high-luminance phosphor can be obtained. If the parameter a is outside this range, the impurity components other than BN increase, and the emission intensity of the phosphor may decrease. Among these, the range of 0.4 ≦ a ≦ 0.5 is preferable because the emission intensity is particularly high.

  The parameter b indicating the amount of oxygen is preferably in the range of 0 ≦ b ≦ 0.01, and a high-luminance phosphor can be obtained. If the parameter b is outside this range, the impurity components other than BN increase, and the emission intensity of the phosphor may decrease.

  The parameter c indicating the amount of nitrogen is preferably in the range of 0.39 ≦ c ≦ 0.55, and a high-luminance phosphor can be obtained. When the parameter c is outside this range, there are many impurity components other than BN, which may reduce the emission intensity of the phosphor. Among these, the range of 0.45 ≦ c ≦ 0.499 is preferable because the emission intensity is particularly high.

  The parameter d indicating the amount of carbon and silicon is preferably in the range of 0.0001 ≦ d ≦ 0.3, and a high-luminance phosphor can be obtained. When the parameter d is smaller than 0.0001, light emission with a wavelength of less than 290 nm is large, and light emission in the range of 290 nm to 350 nm is small, which is not preferable. When the parameter d is larger than 0.3, there are many impurity components other than BN, which may reduce the emission intensity of the phosphor. Preferably, the emission intensity is high in the range of 0.0001 ≦ d ≦ 0.25. More preferably, the emission intensity is high in the range of 0.0001 ≦ d ≦ 0.2. More preferably, the emission intensity is high in the range of 0.001 ≦ d ≦ 0.03.

  Other elements may not be included, but if included, the e value is preferably 0.05 or less. When the parameter e is outside this range, there are many impurity components other than BN, which may reduce the emission intensity of the phosphor.

Since the phosphor of the present invention can control the emission spectrum and the emission intensity by controlling the content ratio of oxygen and the A element, the parameters b and d are b <1.333 × d.
It is desirable to satisfy the following conditions. Above all,
b <d
A phosphor satisfying the above condition has particularly high emission intensity.

Parameter b is
0.0001 ≦ b ≦ 0.008
A phosphor satisfying the condition has high emission intensity.

Parameter d is
0.001 ≦ d ≦ 0.25
A phosphor satisfying the above condition has high emission intensity.

Changing the parameter e changes the emission wavelength.
e = 0
A phosphor satisfying the above condition has high emission intensity at a specific wavelength.

The element A is carbon, and the parameters a, b, c, d, e are
0.4 ≦ a ≦ 0.5
0.0001 ≦ b ≦ 0.008
0.45 ≦ c ≦ 0.499
0.001 ≦ d ≦ 0.03
b <d
e = 0
A phosphor satisfying the above condition has particularly high emission intensity.

  A phosphor in which the hexagonal boron nitride crystal is a particle having a particle size of 0.8 μm or more and 5 μm or less is preferable because it has high emission intensity due to electron beam excitation and excellent application characteristics to the anode electrode.

  In addition, a phosphor composed of particles having an average particle diameter of 1 μm or more is particularly preferable because of high emission intensity due to electron beam excitation. The average particle diameter is the volume-based median diameter (D50).

  Since the phosphor of the present invention emits light efficiently by electron beam excitation, it is suitable for a device using an electron beam.

  As one form of such a device, the device has an electron beam source and the phosphor of the present invention, and emits light having an emission peak at a wavelength in the range of 290 nm to less than 350 nm by emitting the phosphor by electron beam excitation. An instrument can be configured. Since this light-emitting device has many light components with wavelengths in the range of 290 nm to less than 350 nm, it is suitable for applications that use light in this range.

  Furthermore, a light-emitting instrument in which the electron beam source is a field electron emission type (field emission type) electron source and the light emission method is a field emission lamp has high luminous efficiency.

  The electron beam source and the phosphor are accommodated in a vacuum container. The electron beam source includes a cathode electrode having a field electron emission type electron source, a gate electrode having a positive potential with respect to the cathode electrode, and an anode electrode having a positive high potential, and the anode electrode has a phosphor. Is applied, and the light emitting device that emits light when the electrons drawn from the cathode electrode collide with the phosphor applied to the anode electrode has high luminous efficiency.

  An ultraviolet ray utilization apparatus that includes this light emitting device and irradiates an object with ultraviolet light emitted by the light emitting device can be configured. As one form of the ultraviolet ray utilization device, a phototherapy device or an ultraviolet ray irradiation device for ultraviolet curable ink can be configured.

  The method for producing the phosphor is not particularly defined, but as one method, a compound containing carbon and / or silicon is added to boron nitride or a compound that becomes boron nitride by heating (referred to as a boron nitride raw material) at 1400 ° C. There is a method of heating to a temperature of 2500 ° C. or lower. A boron nitride raw material containing 0.1% to 2% by mass of oxygen as an impurity is preferable for controlling the amount of oxygen in the phosphor. For example, examples of the compound containing carbon include carbon, graphite, boron carbide, and silicon carbide. If the calcination temperature is lower than 1400 ° C., there is a risk that sufficient reaction will not proceed. If it is higher than 2500 ° C., boron nitride may be thermally decomposed.

  In addition, in the case of using a phosphor such as a field emission lamp in a powder, a phosphor having a controlled particle size can be obtained by using a powder that is boron nitride as a starting material or boron nitride by heating. preferable.

  According to this production method, the added carbon-containing compound acts as a carbon source during heating, reduces oxygen in the boron nitride raw material and controls it to an appropriate oxygen content, and is incorporated into the crystal and boron nitride. It is considered that the carbon impurity level is formed therein, and light emission with a wavelength in the range of 290 nm to less than 350 nm is generated when irradiated with an electron beam.

[Example 1]
A BN phosphor was produced by the following method. As starting materials, Denka boron nitride powder grade SGP (purity 99%) and Mitsubishi Kasei (currently Mitsubishi Chemical) carbon black MA-600B grade were used.

  The amount of oxygen contained in the BN raw material powder was measured using a TC-436 oxygen-nitrogen analyzer manufactured by LECO. BN raw material powder was weighed into a tin capsule, heated in helium gas together with a nickel basket, and the amount of oxygen was measured by quantifying the generated carbon dioxide with an infrared detector. The amount of impurity oxygen contained in the BN raw material powder was 1.0 ± 0.1% by mass.

  The amount of carbon contained in the BN raw material powder was measured using a LE-CO CS-44LS carbon analyzer. The amount of carbon was measured by heating the BN raw material powder in oxygen gas and quantifying the generated carbon dioxide with an infrared detector. The amount of impurity carbon contained in the BN powder raw material was 0.17 ± 0.01 mass%.

  From the above, the material design was performed with the BN raw material powder as a mixture of 98.83 mass% BN, 1.0 mass% oxygen, and 0.17 mass% carbon.

BN raw material powder 98.1% by mass and carbon black 1.9% by mass were weighed and mixed for 20 minutes using a silicon nitride sintered pestle and mortar to obtain a mixed powder. In consideration of the amount of oxygen and the amount of carbon contained in the BN raw material powder, the parameters represented by B _a O _b N _c A _d E _e are a = 0.4855, b = 0.0076, c = 0.4855. , D = 0.0214, e = 0. Next, the obtained mixed powder was put into a crucible made of a boron nitride sintered body. The bulk density of the mixed powder (powder) was about 30%.

  Here, the bulk density is a ratio of a value (bulk density) obtained by dividing the mass of the powder filled in the container by the volume of the container and the true density of the substance of the powder. Unless otherwise specified, in the present invention, the relative bulk density is simply referred to as bulk density.

The crucible containing the mixed powder was set in a graphite resistance heating type electric furnace. In the firing operation, first, the firing atmosphere is set to a vacuum of 1 × 10 ⁻¹ Pa or less by a diffusion pump, heated from room temperature to 800 ° C. at a rate of 500 ° C. per hour, and the purity is 99.999% by volume at 800 ° C. Was introduced to raise the pressure in the furnace to 1 MPa, and the temperature was raised to 2000 ° C. at 500 ° C. per hour and held at that temperature for 2 hours.

  When the phase of the composite was measured by powder X-ray diffraction, a hexagonal boron nitride peak was confirmed. The production rate was 95% or more.

  As a result of analyzing the synthesized product, the oxygen content was 0.24 ± 0.01 mass% and the carbon content was 1.9 ± 0.1 mass%. From the above, it was confirmed that the synthesized product contained at least carbon and oxygen as element A in the hexagonal boron nitride crystal, and the carbon content was higher than the oxygen content. Moreover, it was shown that the oxygen in the BN raw material powder was reduced by adding a compound containing carbon and firing.

  The composite was ground with a mortar and pestle and then ground with a ball mill for 24 hours. Thereafter, a sieve having an opening of 60 μm was passed. The treated powder contained particles of 1 μm or more and 10 μm or less. The fluorescence spectrum of this powder was measured. The results are shown in FIG.

  FIG. 1 is a diagram showing an excitation spectrum and an emission spectrum of the synthesized product of Example 1 by photoexcitation.

  The emission spectrum of this powder by ultraviolet excitation is shown in FIG. According to FIG. 1, emission of 320 nm was observed with excitation of 285 nm. From this, the compound containing at least the A element (here, carbon element) and oxygen in the hexagonal boron nitride crystal of the present invention and having a carbon content higher than the oxygen content, It was confirmed to be a phosphor that emits light.

Next, 1.0 g of this phosphor was dispersed in ethanol using a stirrer, and then the stirrer was stopped and allowed to settle naturally on the aluminum substrate. The substrate covered with the phosphor was dried with a drier and pressed with a press. The sample substrate bonded with the phosphor was placed in a vacuum chamber, and a vacuum level of 1 × 10 ⁻⁶ Pa or less was set using a turbo molecular pump. A high voltage power source was applied between the emitter and the sample substrate, and the sample substrate was irradiated with an electron beam to obtain ultraviolet light emission. The results are shown in FIG.

  FIG. 2 is a diagram showing an emission spectrum of the synthesized product of Example 1 by electron beam excitation.

  Ultraviolet light having an emission peak at a wavelength in the range of 290 nm to less than 350 nm was observed under the conditions of a voltage of 1.5 kV to 4 kV and a current value of 0.5 μA to 57.8 μA. FIG. 2 shows the emission spectrum results at a voltage of 4 kV and a current value of 48 μA. From this, the compound containing at least element A (carbon element here) and oxygen in the hexagonal boron nitride crystal of the present invention, and having a carbon content higher than the oxygen content, It was confirmed that the phosphor emits light.

  In the observed light, the maximum emission intensity in the range of 200 nm or more and less than 290 nm was 1/10 or less of the maximum emission intensity in the range of 290 nm or more and less than 350 nm. Moreover, the maximum light emission intensity in the range of 350 nm or more and less than 780 nm was 1/10 or less of the maximum light emission intensity in the range of 290 nm or more and less than 350 nm.

[Comparative Example 1]
Using the BN raw material of Example 1 as it was, light emission by electron beam excitation was measured under the same conditions as in Example 1. The results are shown in FIG.

  FIG. 3 is a view showing an emission spectrum of the BN raw material of Comparative Example 1 by electron beam excitation.

  As described above, the BN raw material powder is a mixture of 98.83 mass% BN, 1.0 mass% oxygen, and 0.17 mass% carbon, and unlike the composite of Example 1, the oxygen content is carbon. More than the content of. As described above, the sample having a larger oxygen content than the carbon content had a maximum emission peak of 395 nm, which was outside the range of 290 nm to less than 350 nm. Moreover, the half width was as wide as 200 nm.

[Examples 2 to 8]
Starting materials: Denka boron nitride powder grade SGP (99% purity), Mitsubishi Kasei (current Mitsubishi Chemical) carbon black MA-600B grade, high purity chemical silicon carbide powder, Ube Industries silicon nitride powder SN- E10 grade (oxygen impurity 1.0 mass%), high purity chemical boron carbide powder was used. The raw material powder was weighed so as to have the composition shown in Table 1, and mixed for 20 minutes using a silicon nitride sintered body pestle and mortar. The element ratios of these compositions in consideration of impurities in BN are shown in Table 2 as parameters expressed by B _a O _b N _{c Ad} E _e . Next, the obtained mixed powder was put into a crucible made of a boron nitride sintered body. The bulk density of the mixed powder (powder) was about 30%. Tables 1 and 2 also show the conditions of Example 1 and Comparative Example 1.

The crucible containing the mixed powder was set in a graphite resistance heating type electric furnace. In the firing operation, first, the firing atmosphere is set to a vacuum of 1 × 10 ⁻¹ Pa or less by a diffusion pump, heated from room temperature to 800 ° C. at a rate of 500 ° C. per hour, and the purity is 99.999% by volume at 800 ° C. Was introduced to raise the pressure in the furnace to 1 MPa, the temperature was raised to 500 ° C. per hour to the temperature shown in Table 3, and the temperature was maintained for the time shown in Table 3.

  The composite was pulverized with a mortar and pestle and passed through a sieve having an opening of 60 μm. When the amount of oxygen and the amount of carbon in the powder after the treatment were quantified, as shown in Table 3, the amount of oxygen was smaller than the amount of carbon. Further, when the product phase was measured by powder X-ray diffraction, a hexagonal boron nitride peak was confirmed. The composites obtained in Examples 2 to 8 contain at least carbon and / or silicon and oxygen as the A element in the hexagonal boron nitride crystal, and the carbon content is larger than the oxygen content. Was confirmed.

  When these powders were irradiated with ultraviolet rays and their emission spectra were measured, as shown in Table 4, ultraviolet light having an emission peak at a wavelength in the range of 290 nm to less than 350 nm was observed. From this, the hexagonal boron nitride crystal of the present invention contains at least carbon and / or silicon and oxygen as the A element, and the compound having a carbon content higher than the oxygen content is caused by ultraviolet excitation. It was confirmed that the phosphor emits ultraviolet rays.

After dispersing 1.0 g of the phosphor in ethanol using a stirrer, the stirrer was stopped and allowed to settle naturally on the aluminum substrate. The substrate covered with the phosphor was observed with a dryer and pressed with a press. The sample substrate bonded with the phosphor was placed in a vacuum chamber, and a vacuum level of 1 × 10 ⁻⁶ Pa or less was set using a turbo molecular pump. When a high voltage power source was applied between the emitter and the sample substrate and the sample substrate was irradiated with an electron beam, ultraviolet light emission was obtained. The results are shown in Table 4 and FIGS.

FIG. 4 is a diagram showing an emission spectrum of the synthesized product of Example 2 by electron beam excitation.
FIG. 5 is a diagram showing an emission spectrum of the synthesized product of Example 3 by electron beam excitation.
6 is a diagram showing an emission spectrum of the synthesized product of Example 4 by electron beam excitation.
FIG. 7 is a graph showing an emission spectrum of the synthesized product of Example 5 by electron beam excitation.
FIG. 8 is a diagram showing an emission spectrum of the synthesized product of Example 6 by electron beam excitation.
FIG. 9 is a diagram showing an emission spectrum of the synthesized product of Example 7 by electron beam excitation.
10 is a diagram showing an emission spectrum of the synthesized product of Example 8 by electron beam excitation.

  4 to 10 show the results of emission spectra at a voltage of 4 kV and various current values. As shown in Table 4 and FIGS. 4 to 10, ultraviolet light having an emission peak at a wavelength in the range of 290 nm to less than 350 nm was observed. From this, the compound containing at least carbon and / or silicon and oxygen as the element A in the hexagonal boron nitride crystal of the present invention and having a carbon content higher than the oxygen content is excited by electron beam As a result, the phosphor was confirmed to emit ultraviolet light.

  In the observed light, the maximum emission intensity in the range of 200 nm or more and less than 290 nm was 1/10 or less of the maximum emission intensity in the range of 290 nm or more and less than 350 nm. Moreover, the maximum light emission intensity in the range of 350 nm or more and less than 780 nm was 1/10 or less of the maximum light emission intensity in the range of 290 nm or more and less than 350 nm.

[Examples 9 to 45]
As starting materials, Denka boron nitride powder grade SGP (purity 99%), Ube Industries silicon nitride powder grade E10, Mitsubishi Kasei (current Mitsubishi Chemical) carbon black MA-600B grade, high purity chemical silicon dioxide, Europium nitride prepared by nitriding silicon carbide, silicon, boron carbide, aluminum nitride, lithium nitride manufactured by Aldrich, barium nitride and metal europium with ammonia was used. The raw material powder was weighed so as to have the composition shown in Table 5, and mixed for 20 minutes using a silicon nitride sintered body pestle and mortar. Table 6 shows the design composition at this time. However, Table 6 does not consider impurities in the raw material. Next, the obtained mixed powder was put into a crucible made of a boron nitride sintered body. The bulk density of the mixed powder (powder) was about 30%.

The crucible containing the mixed powder was set in a graphite resistance heating type electric furnace. In the firing operation, first, the firing atmosphere is set to a vacuum of 1 × 10 ⁻¹ Pa or less by a diffusion pump, heated from room temperature to 800 ° C. at a rate of 500 ° C. per hour, and the purity is 99.999% by volume at 800 ° C. The pressure in the furnace was set to 1 MPa, the temperature was raised to 1900 ° C. at 500 ° C. per hour, and the temperature was maintained for 2 hours.

  The composite was pulverized with a mortar and pestle and passed through a sieve having an opening of 60 μm. When the amounts of oxygen and carbon in these powders were quantified, the amount of oxygen was less than the amount of carbon. When the product phase was measured by powder X-ray diffraction, a hexagonal boron nitride peak was confirmed. The composites obtained in Examples 9 to 45 contain at least carbon and / or silicon as the A element in the hexagonal boron nitride crystal, and, if necessary, oxygen and / or the E element (here, Al, Li, Ba, Eu) were contained, and it was confirmed that the carbon content was higher than the oxygen content.

After 1.0 g of each composite was dispersed in ethanol using a stirrer, the stirrer was stopped and allowed to settle naturally on an aluminum substrate. The substrate covered with the phosphor was observed with a dryer and pressed with a press. The sample substrate bonded with the phosphor was placed in a vacuum chamber, and a vacuum level of 1 × 10 ⁻⁶ Pa or less was set using a turbo molecular pump. When a high voltage power source was applied between the emitter and the sample substrate and the sample substrate was irradiated with an electron beam, ultraviolet light having an emission peak at a wavelength in the range of 290 nm to less than 350 nm was observed. From this, in the hexagonal boron nitride crystal of the present invention, at least carbon and / or silicon as an A element, and optionally oxygen and / or an E element (here, Al, Li, Ba, Eu). It was confirmed that the compound containing and having a carbon content higher than the oxygen content is a phosphor that emits ultraviolet rays by electron beam excitation.

[Example 46]
In Example 46, an ultraviolet light emitting device was constructed using the phosphor of the present invention.
FIG. 11 is a schematic view of an ultraviolet light emitting device according to the present invention.

  In FIG. 11, the ultraviolet light emitting device includes a phosphor film 1 made of the phosphor of the present invention and an electron beam emitter 2 as an electron beam source. These are accommodated in the vacuum vessel 4. The electron beam emitter 2 is a tube made of tungsten, lanthanum boride, diamond carbon, or the like. The phosphor film 1 is held on a conductive substrate. Here, the phosphor film 1 is the phosphor obtained in Example 1, and is held on an aluminum substrate as a conductive substrate by the above-described method.

  Electrons were emitted from the electron beam emitter 2 by applying a high voltage in a vacuum, and the phosphor film 1 was irradiated. The phosphor excited by the electron beam produced ultraviolet light emission 3. It was confirmed that the generated ultraviolet ray 3 went out through the glass. The phosphors obtained in other examples were also confirmed to emit ultraviolet light.

  The phosphor of the present invention obtains ultraviolet light emission mainly by irradiating an electron beam. Ultraviolet light emission has been applied in a wide range of fields, and the light emitting apparatus and the ultraviolet light utilization device of the present invention can be expected to contribute to the development of a wide range of industries as a new ultraviolet light emission source replacing the mercury lamp.

DESCRIPTION OF SYMBOLS 1 Phosphor film 2 Electron beam emitter 3 Ultraviolet light emission 4 Vacuum container

Claims (24)

  The hexagonal boron nitride crystal contains at least element A (provided that element A is carbon and / or silicon) and is irradiated with an excitation source to emit fluorescence having an emission peak at a wavelength in the range of 290 nm to less than 350 nm. A phosphor that emits light.   2. The phosphor according to claim 1, wherein the content of the element A is 0.01% by mass or more.   The phosphor according to claim 2, wherein the content of the element A is 0.3% by mass or more and 15% by mass or less.   The phosphor according to claim 1, wherein the element A is carbon.   The phosphor according to claim 1, wherein a content (mass%) of the element A is larger than a content (mass%) of the oxygen.   The phosphor according to claim 5, wherein the oxygen content is 0.1 mass% or more and 0.3 mass% or less.   2. The phosphor according to claim 1, wherein a maximum emission intensity in a range of 200 nm or more and less than 290 nm is 1/10 or less of a maximum emission intensity in a range of 290 nm or more and less than 350 nm.   The phosphor according to claim 1, which emits fluorescence having an emission peak at a wavelength in a range of 310 nm to less than 330 nm.   The phosphor according to claim 1, which emits fluorescence having an emission peak at a wavelength in a range of 315 nm to less than 325 nm, and a peak half-value width of 10 nm to 50 nm.   The phosphor according to claim 1, wherein the excitation source is an electron beam, an X-ray, or an ultraviolet ray having a wavelength of 150 nm or more and less than 290 nm. Composition formula B _a O _b N _{C Ad} E _e (where B is a boron element, O is an oxygen element, N is a nitrogen element, A element is carbon and / or silicon, and E element is B, O, N, An element other than C or Si, wherein a, b, c, d, and e are parameters representing the ratio of the number of atoms, and a + b + c + d + e = 1).
0.39 ≦ a ≦ 0.5
0 ≦ b ≦ 0.01
0.39 ≦ c ≦ 0.55
0.0001 ≦ d ≦ 0.3
0 ≦ e ≦ 0.05
The phosphor according to claim 1, which satisfies the above conditions. However, when the A element is two kinds, the d value is a total value of the respective elements, and when the E element is two or more kinds, the e value is a total value of the respective elements. The parameters b and d are b <d
The phosphor according to claim 11, which satisfies the following condition. The parameter b is
0.0001 ≦ b ≦ 0.008
The phosphor according to claim 11, which satisfies the following condition. The parameter d is
0.001 ≦ d ≦ 0.25
The phosphor according to claim 11, which satisfies the following condition. The parameter e is
e = 0
The phosphor according to claim 11, wherein The element A is carbon, and the parameters a, b, c, d, e are
0.4 ≦ a ≦ 0.5
0.0001 ≦ b ≦ 0.008
0.45 ≦ c ≦ 0.499
0.001 ≦ d ≦ 0.03
b <d
e = 0
The phosphor according to claim 11, which satisfies the following condition.   The phosphor according to claim 1, wherein the hexagonal boron nitride crystal is a particle having a particle diameter of 0.8 μm or more and 5 μm or less.   The phosphor according to claim 17, wherein the hexagonal boron nitride crystal is a particle having a particle diameter of 1 μm or more and 5 μm or less. Having at least an electron beam source and a phosphor,
The phosphor includes at least the phosphor according to claim 1,
A light-emitting device that emits light having an emission peak at a wavelength in a range of 290 nm to less than 350 nm by emitting the phosphor by electron beam excitation by the electron beam source.   The light emitting apparatus according to claim 19, wherein the electron beam source is a field electron emission type (field emission type) electron source, and a light emission method is a field emission lamp. The electron beam source and the phosphor are accommodated in a vacuum container,
The electron beam source is
A cathode electrode having a field emission electron source;
A gate electrode having a positive potential with respect to the cathode electrode;
An anode electrode having a higher positive potential than the gate electrode,
The light emitting device according to claim 19, wherein the phosphor is applied to the anode electrode, and electrons extracted from the cathode electrode emit light by colliding with the phosphor applied to the anode electrode.   An ultraviolet ray utilization device comprising the light emitting device according to claim 19 and irradiating an object with ultraviolet light emitted by the light emitting device.   The production of a phosphor according to claim 1, comprising a step of adding a compound containing carbon and / or silicon to boron nitride or a compound that becomes boron nitride by heating and heating to a temperature of 1400 ° C or higher and 2500 ° C or lower. Method.   The method according to claim 23, wherein the boron nitride or the compound that becomes boron nitride by heating is a powder.