JP2016176017A - Fluophor and light emitting device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide fluophor capable of being exited by a short-wavelength visible light, emitting light component of bright-line green color and/or red color and having improved temperature extinction and a light emitting device using the same.SOLUTION: The fluophor contains Ceand Tbas luminescent centers and consists of an inorganic compound having a calcium ferrite type crystal structure. An excitation spectrum of the fluophor has a broad excitation band by Ceand the excitation band has a peak in a range of 400 nm to 470 nm. Also emission spectrum of the phosphor has a bright-line fluorescent component by Tbwith emission peak wavelength of 535 nm or more and less than 560 nm. The luminescence peak in the range of 535 nm or more and less than 560 nm in the bright-line fluorescent component by Tbbecomes strength maximum value of the emission spectrum of the fluophor.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a phosphor and a light emitting device using the phosphor. More specifically, the present invention relates to a phosphor that can be excited by a solid-state light emitting element such as a light emitting diode (LED) and emits bright line-like green and / or red light components and a light emitting device using the same.

Conventionally, the phosphor of Patent Document 1 is known as an inorganic phosphor that can be excited by light from a light-emitting diode and emits bright-line green and / or red light components. In Patent Document 1, for example, phosphors of inorganic compounds having a garnet-type crystal structure such as Ca ₂ TbZr ₂ (AlO ₄ ) ₃ : Ce ³⁺ and Ca ₂ TbZr ₂ (AlO ₄ ) ₃ : Ce ³⁺ , Eu ³⁺ are disclosed. It is disclosed.

Conventionally, a phosphor disclosed in Patent Document 2 is known as an inorganic phosphor that can be excited by light from a light emitting diode and emits a broad blue-green or green light component. In Patent Document 2, for example, an inorganic phosphor having a calcium ferrite type crystal structure such as CaSc ₂ O ₄ : Ce ³⁺ is disclosed.

  Such phosphors have been studied for use in lighting devices such as LED lighting, or light emitting devices such as liquid crystal displays with backlight functions and display devices such as laser projectors, and some of them are actually used. ing.

International Publication No. 2014/097527 Japanese Patent No. 4148298

  However, a conventional inorganic phosphor that can be excited by LED light and emits bright line-like green and / or red light components has a large temperature quenching. For this reason, there is a problem that not only high-efficiency light emission cannot be obtained at room temperature, but also the light emission efficiency is further lowered due to an increase in phosphor temperature.

  On the other hand, conventional phosphors having a calcium ferrite type crystal structure were excited with high efficiency by LED light, and could not emit bright-line green and / or red light components. For this reason, it has been difficult to provide a high-power light-emitting device that uses a solid light-emitting element that emits violet or blue short-wavelength visible light as an excitation source and emits bright-line green and / or red light components.

  The present invention has been made in view of such problems of the prior art. An object of the present invention is a phosphor that can be excited with short-wavelength visible light, emits bright line-like green and / or red light components, and further has improved temperature quenching, and a light emitting device using the same Is to provide.

In order to solve the above problem, the phosphor according to the first aspect of the present invention includes a phosphor containing Ce ³⁺ and Tb ³⁺ as emission centers and made of an inorganic compound having a calcium ferrite type crystal structure. It is. The excitation spectrum of the phosphor has a broad excitation band due to Ce ³⁺ , and the excitation band has a peak in the range of 400 nm to 470 nm. Further, the emission spectrum of the phosphor has an emission line-like fluorescent component of Tb ³⁺ having an emission peak wavelength of 535 nm or more and less than 560 nm. And the emission peak in the range of 535 nm or more and less than 560 nm in the fluorescent component by Tb ³⁺ becomes the maximum intensity value of the emission spectrum.

The phosphor according to the second aspect of the present invention is a phosphor made of an inorganic compound containing Ce ³⁺ , Tb ³⁺ and Eu ³⁺ as emission centers and having a calcium ferrite type crystal structure. The excitation spectrum of the phosphor has a broad excitation band due to Ce ³⁺ , and the excitation band has a peak in the range of 400 nm to 470 nm. The emission spectrum of the phosphor has at least one of an emission line-like fluorescence component due to Tb ³⁺ having an emission peak wavelength of 535 nm to less than 560 nm and an emission line-like fluorescence component due to Eu ³⁺ having an emission peak wavelength of 580 nm to less than 650 nm. . The emission peak within the range of 535 nm to less than 560 nm in the fluorescent component due to Tb ³⁺ or the emission peak within the range from 580 nm to less than 650 nm in the fluorescent component due to Eu ³⁺ is the maximum intensity of the emission spectrum.

  The phosphor of the present invention can be excited with high efficiency by short wavelength visible light of 380 nm or more and less than 470 nm, and has low temperature quenching. Further, in the phosphor, light emitting components are concentrated in a range of 535 nm or more and less than 560 nm having high visibility and / or in a range of 580 nm or more and less than 650 nm having high visibility in red light. Therefore, when the phosphor is used for a light emitting device, the light emission efficiency of the device can be improved.

It is the schematic for demonstrating the light-emitting device which concerns on embodiment of this invention. 1 is a perspective view schematically showing an example of a semiconductor light emitting device according to an embodiment of the present invention. (A) is the sectional view on the AA line in FIG. 2, (b) is the sectional view on the BB line in FIG. It is a figure for demonstrating the formation method of the sealing member in a semiconductor light-emitting device. It is a figure which shows the XRD pattern of the fluorescent substance of Example 1 and 2. It is a figure which shows the excitation spectrum and emission spectrum of the fluorescent substance of Example 1. It is a figure which shows the excitation spectrum and emission spectrum of the fluorescent substance of Example 2. It is a graph which shows the relationship between the temperature of the fluorescent substance of Example 1 and 2, and the maintenance rate (%) of internal quantum efficiency when the internal quantum efficiency at the time of room temperature is 100%. It is a figure which shows the excitation spectrum and emission spectrum of the fluorescent substance of the reference example 1. It is a graph which shows the relationship between the temperature of the fluorescent substance of Example 1 and Reference Example 1, and the maintenance rate (%) of internal quantum efficiency when the internal quantum efficiency at room temperature is 100%. It is a figure which shows the XRD pattern of the fluorescent substance of the reference examples 2-5. It is a figure which shows the excitation spectrum and emission spectrum of the fluorescent substance of Reference Examples 2-5. It is a graph which shows the relationship between the temperature of the fluorescent substance of the reference example 1 and the reference example 3, and the maintenance rate (%) of the internal quantum efficiency when the internal quantum efficiency at room temperature is 100%. It is a figure which shows the XRD pattern of the fluorescent substance of the reference examples 6-11. It is a figure which shows the excitation spectrum and emission spectrum of the fluorescent substance of Reference Examples 6-11. It is a graph which shows the relationship between the temperature of the fluorescent substance of the reference example 6 and the reference example 11, and the maintenance rate (%) of internal quantum efficiency when the internal quantum efficiency at the time of room temperature is 100%.

  Hereinafter, the phosphor according to the present embodiment and a light emitting device using the phosphor will be described in detail. In addition, the dimension ratio of drawing is exaggerated on account of description, and may differ from an actual ratio.

[Phosphor]
In general, a phosphor refers to a compound in which part of an element constituting a crystalline compound is partially substituted with an element that can become a fluorescent ion. Ions having such characteristics are usually called “emission centers”. In the phosphor of the present embodiment, ions serving as the emission center are introduced into the matrix as the crystalline compound. Thereby, the phosphor is easily excited by external stimulation, for example, irradiation with particle beams (α rays, β rays, electron beams) or electromagnetic waves (γ rays, X rays, vacuum ultraviolet rays, ultraviolet rays, visible rays), etc. It becomes possible to emit fluorescence.

The first phosphor according to the present embodiment is a phosphor made of an inorganic compound containing Ce ³⁺ and Tb ³⁺ as emission centers and having a calcium ferrite type crystal structure. The excitation spectrum of the phosphor has a broad excitation band due to Ce ³⁺ , and the excitation band has a peak in the range of 400 nm to 470 nm. Further, the emission spectrum of the phosphor has an emission line-like fluorescent component of Tb ³⁺ having an emission peak wavelength of 535 nm or more and less than 560 nm. And the emission peak in the range of 535 nm or more and less than 560 nm in the fluorescent component by Tb ³⁺ becomes the maximum intensity value of the emission spectrum.

The second phosphor according to the present embodiment is a phosphor made of an inorganic compound containing Ce ³⁺ , Tb ³⁺ and Eu ³⁺ as emission centers and having a calcium ferrite type crystal structure. The excitation spectrum of the phosphor has a broad excitation band due to Ce ³⁺ , and the excitation band has a peak in the range of 400 nm to 470 nm. The emission spectrum of the phosphor has at least one of an emission line-like fluorescence component due to Tb ³⁺ having an emission peak wavelength of 535 nm to less than 560 nm and an emission line-like fluorescence component due to Eu ³⁺ having an emission peak wavelength of 580 nm to less than 650 nm. . The emission peak within the range of 535 nm to less than 560 nm in the fluorescent component due to Tb ³⁺ or the emission peak within the range from 580 nm to less than 650 nm in the fluorescent component due to Eu ³⁺ is the maximum intensity of the emission spectrum.

  In the present specification, “broad excitation band” means that the half width (FWHM) of the excitation spectrum corresponding to the excitation band is 25 nm to 150 nm. Similarly, “broad fluorescent component” means that the half-value width (FWHM) of the emission spectrum corresponding to the fluorescent component is 50 nm to 150 nm. Further, the “luminescent line-like fluorescent component” means that the half width (FWHM) of the emission spectrum corresponding to the fluorescent component is 3 nm to 30 nm.

As described above, the first phosphor contains at least cerium ions (Ce ³⁺ ) and terbium ions (Tb ³⁺ ) as emission centers. The second phosphor contains europium ions (Eu ³⁺ ) in addition to cerium ions (Ce ³⁺ ) and terbium ions (Tb ³⁺ ) as emission centers. The emission spectrum of the phosphor has a characteristic shape shown in FIGS. First, the mechanism in which the phosphor of this embodiment exhibits the characteristic spectrum shown in FIGS. 6 and 7 will be described.

In general, it is known that the Ce ³⁺ activated phosphor converts absorbed light into light having a longer wavelength, and the converted light has a broad spectral distribution. In contrast, the Tb ³⁺ activated phosphor converts absorbed light into light having a longer wavelength than that, but the converted light has a maximum intensity at 535 nm or more and less than 560 nm, and further comprises a plurality of bright lines. It has been known. Eu ³⁺ activated phosphor also converts absorbed light into light having a longer wavelength than that, but the converted light has a maximum intensity at 580 nm or more and less than 650 nm, and it is known that it consists of a plurality of bright lines. It has been.

Further, it is also known that in a phosphor activated by both Ce ³⁺ and Tb ³⁺ , at least a part of the energy absorbed by Ce ³⁺ moves to Tb ³⁺ by a mechanism called energy transfer. In order for energy transfer due to energy transfer to occur, it is usually necessary that the emission spectrum of Ce ³⁺ and the absorption spectrum of Tb ³⁺ overlap.

Furthermore, it is also known that even in a phosphor in which both Tb ³⁺ and Eu ³⁺ are activated, at least a part of the energy absorbed by Tb ³⁺ is transferred to Eu ³⁺ by a mechanism called energy transfer. This is because the emission spectrum of Tb ³⁺ and the absorption spectrum of Eu ³⁺ are slightly overlapped.

It is also known that in phosphors activated with three types of ions, Ce ³⁺ , Tb ³⁺ and Eu ³⁺ , energy transfer from Ce ³⁺ to Tb ³⁺ and energy transfer from Tb ³⁺ to Eu ³⁺ occur simultaneously. It has been. This, at least a portion of the ^{energy Ce 3+} is absorbed moves to ^{Tb 3+,} further through the ^{Tb 3+,} at least a portion of the ^{energy Tb 3+} is absorbed in order to move to ^{Eu 3+.}

Because the energy transfer to ^{Tb 3+} from Ce ^3+, even ^{when Ce 3+} is emitting 490nm following violet or blue light or a wavelength 400 nm, the overlap of the absorption spectrum of the emission spectrum and ^{Tb 3+} of ^{Ce 3+} is larger, It is also known that transmission probability is high. That is, when Tb ³⁺ is co-activated in a Ce ³⁺ activated phosphor having an emission peak in the range of 400 nm or more and 490 nm or less, the overlap between the Ce ³⁺ emission spectrum and the Tb ³⁺ absorption spectrum is large, so that Ce ³⁺ to Tb ^The probability of transferring energy to ³⁺ is high. Furthermore, when the concentration of ^{Tb 3+} is high, the ion distance between ^{Tb 3+} and ^{Ce 3+} are close, bright line shape almost all of the ^{energy Ce 3+} is absorbed moves to ^{Tb 3+,} due to ^{Tb 3+} Appears as the main component. Even when the concentration of Tb ³⁺ is low, much of the energy absorbed by Ce ³⁺ moves to Tb ³⁺ . Therefore, a broad light-emitting component having a peak at 400 nm or more and 490 nm due to Ce ³⁺ and an emission line-like light-emitting component having a peak of 535 nm or more and less than 560 nm due to Tb ³⁺ are recognized.

On the other hand, regarding the energy transfer from Tb ³⁺ to Eu ³⁺ , since the overlap between the emission spectrum of Tb ³⁺ and the absorption spectrum of Eu ³⁺ is small, it is necessary to increase the concentration of at least one of the ions. Thereby, the distance between ions between Tb ³⁺ and Eu ³⁺ is reduced, and the transmission probability can be increased. As a result, bright line-like light emission caused by Eu ³⁺ appears mainly.

Energy transfer to ^{Eu 3+,} which via a ^{Tb 3+} from Ce ^3+, since those containing two energy transfer to ^{Eu 3+} from energy transfer and ^{Tb 3+} to ^{Tb 3+} from ^{Ce 3+} described above, combines the advantages of both Yes. As a result, the excitation spectrum of the first phosphor has a broad excitation band due to Ce ^3+, the emission spectrum has bright lines shaped fluorescent component by Tb ^3+, the emission peak is the emission spectrum further from Tb ³⁺ It shows the maximum intensity value. The excitation spectrum of the second phosphor has a broad excitation band due to Ce ³⁺ , and the emission spectrum has at least one of an emission line-like fluorescence component due to Tb ^{3+ and} an emission line-like fluorescence component due to Eu ³⁺ . A light emission peak derived from Tb ³⁺ or a light emission peak derived from Eu ³⁺ shows the maximum intensity of the light emission spectrum.

In addition, Ce ³⁺ shows light absorption and emission based on the electron energy transition of 4f ¹ ⇔5d ¹ which is a parity-allowed transition. Therefore, normally, the long wavelength end of the excitation spectrum and the short wavelength end of the emission spectrum of Ce ³⁺ Has a slight overlap. For this reason, in the case of a phosphor that emits light of 450 nm to less than 500 nm when Ce ³⁺ is activated alone, a broad excitation band due to Ce ³⁺ having a peak in the range of 400 nm to 470 nm is observed.

Note that the coexistence of Ce ³⁺ and Eu ³⁺ promotes non-emission relaxation of excitation energy and causes a decrease in light emission efficiency, so that the content of these in the crystal of the inorganic compound is preferably small. That is, Ce ³⁺ has the property of easily emitting electrons to become Ce ⁴⁺ , whereas Eu ³⁺ has the property of easily receiving electrons and becoming Eu ²⁺ . Then, during the inorganic compound ^crystals, Ce 3+ ^{-Eu 3+} pair stably likely present as ^Ce 4+ ^{-Eu 2+} pair. Therefore, co-addition of Ce ³⁺ and Eu ³⁺ induces a functional decline of Ce ³⁺ or Eu ³⁺ .

Thus, the 1st and 2nd fluorescent substance of this embodiment utilizes the above-mentioned light emission mechanism. Therefore, in the first and second phosphors, the number of Tb atoms in the inorganic compound is preferably larger than the number of Ce atoms in the inorganic compound. Thereby, since the inter-ion distance between Tb ³⁺ and Ce ³⁺ is reduced, it is possible to easily obtain a phosphor mainly composed of a bright line-like light-emitting component derived from Tb ³⁺ .

When the inorganic compound further contains Eu as in the second phosphor, the number of Tb atoms in the inorganic compound is preferably larger than the number of Eu atoms in the inorganic compound. Thereby, a relatively high concentration of Tb has a structure that separates Ce and Eu. ^Therefore, the distance between Ce 3+ ^{-Eu 3+} becomes longer, it becomes possible to suppress a decrease in luminous efficiency due to the co-addition of ^{Ce 3+} and ^{Eu 3+.}

The inorganic compound constituting the first and second phosphors preferably contains at least an alkaline earth metal and a rare earth element. Alkaline earth metals and rare earth elements have both approximate ionic radii of around 1 、, and the Group 2 alkaline earth metals and Group 3 rare earth elements are adjacent to each other in the periodic table. The chemical properties are similar. Therefore, it is possible to obtain an inorganic compound that can be easily replaced with Ce ³⁺ ions that function as light-absorbing ions, or Tb ³⁺ or Eu ³⁺ ions that function as emission centers.

  The inorganic compound constituting the first and second phosphors preferably contains at least strontium (Sr) as the above-mentioned alkaline earth metal. As a result, an inorganic phosphor that can be excited with short-wavelength visible light with high efficiency, emits bright-line green and / or red light components, and has improved temperature quenching, although the reason is unknown at this time. Can be obtained.

When the inorganic compound constituting the first and second phosphors contains Sr as an alkaline earth metal, it is preferable to further contain calcium (Ca) as the alkaline earth metal. Thereby, a phosphor having further improved temperature quenching can be obtained. The reason why the temperature quenching is improved by containing Ca is considered as follows. That is, the lattice positions of ^{Sr 2+,} ionic radii by substituting ^Sr 2+ ^(1.12Å) small ^Ca 2+ than (0.99Å), ionic-bonding inorganic compound crystal is increased. This is considered to be caused by a decrease in the probability of non-light-emitting transition that relaxes energy accompanied by lattice vibration.

As described above, the inorganic compound constituting the first and second phosphors preferably contains an alkaline earth metal and a rare earth element. In this case, it is preferable to contain cerium (Ce), terbium (Tb), and lutetium (Lu) as the rare earth element. By containing Lu, a phosphor having an emission peak in the range of 450 to 500 nm can be obtained when Ce ³⁺ is activated alone without adding Tb ³⁺ . Further, when Tb ³⁺ is further co-activated in the phosphor, energy transfer from Ce ³⁺ to Tb ³⁺ is likely to occur. Since Tb ³⁺ is an ion having a function of emitting a bright line-like green component, a phosphor mainly composed of bright line-like light emission derived from Tb ³⁺ can be easily obtained.

In the case where the inorganic compound constituting the first and second phosphors contains an alkaline earth metal and a rare earth element, it is also preferable that the rare earth element further contains europium (Eu) in addition to Ce, Tb and Lu. The inclusion of Eu, through the ^{Tb 3+,} the energy transmitted from ^{Ce 3+} to ^{Tb 3+,} can be transmitted to further ^{Eu 3+.} As described above, Eu ³⁺ is an ion having a function of emitting a red component. Therefore, it is possible to obtain a phosphor that emits a bright red component derived from Eu ³⁺ and a fluorescent material mainly composed of a bright red component.

When the inorganic compound constituting the first and second phosphors contains an alkaline earth metal and a rare earth element, it is preferable that the rare earth element further contains scandium (Sc) in addition to Ce, Tb, and Lu. Sc is contained in the crystal as Sc ³⁺ (0.81Å) having the smallest ionic radius among the rare earth elements. An ion having a small ion radius has a small distance between the outermost shell electron and the nucleus, and the binding force of the outermost shell electron by the nucleus is strong, so that the ion binding property of the crystal is enhanced. Therefore, by including Sc, the ion binding property in the crystal | crystallization of an inorganic compound increases, and thereby the probability of the non-light-emission transition which carries out energy relaxation with a lattice vibration can be made small. The temperature quenching of the phosphor correlates with the probability of a non-light-emitting transition that relaxes energy accompanied by lattice vibration. This makes it possible to further suppress the temperature quenching.

The inorganic compound constituting the first phosphor has a general formula:
MX ₂ O ₄
It is preferable that a part of the elements constituting the matrix is substituted with Ce and Tb. In the formula, M contains at least one of Sr and Ca, and X contains at least one of Lu and Sc.

The inorganic compound constituting the second phosphor has the general formula:
MX ₂ O ₄
It is preferable that a part of the elements constituting the matrix is substituted with Ce, Tb and Eu. In the formula, M contains at least one of Sr and Ca, and X contains at least one of Lu and Sc.

  By using such a compound as the matrix of the inorganic compound constituting the first and second phosphors, it can be excited with high efficiency with short-wavelength visible light, and bright line-like green and / or red light components can be excited. It is possible to easily obtain an inorganic phosphor with improved temperature quenching.

The element M of the compound represented by the general formula: MX ₂ O ₄ preferably contains at least strontium (Sr) and further contains calcium (Ca). Strontium and calcium can be partially substituted with other elements that can be divalent ions. Therefore, the element M in the general formula: MX ₂ O ₄ is at least selected from the group consisting of Sr, an alkaline earth metal, magnesium (Mg), and zinc (Zn) as long as the calcium ferrite type crystal structure is not impaired. It may contain one element.

In the compound represented by the general formula: MX ₂ O ₄ , the majority of the element M is preferably occupied by Sr. Here, occupying the majority of the element M with Sr means that the Sr atom occupies the majority of the atomic group occupying the element M. By setting it as such a composition, it can function as a more efficient fluorescent substance. The element M may be occupied only by strontium.

The element X of the compound represented by the general formula: MX ₂ O ₄ preferably contains at least lutetium (Lu). Note that lutetium can be partially substituted with an element that can be a trivalent ion other than lutetium. Therefore, the element X in the general formula: MX ₂ O ₄ is Lu, scandium (Sc), yttrium (Y), lanthanum (La), gadolinium (Gd), aluminum in a range that does not impair the calcium ferrite type crystal structure. It may contain at least one element selected from the group consisting of (Al), gallium (Ga) and indium (In).

In the compound represented by the general formula: MX ₂ O ₄ , the majority of the element X is preferably occupied by Lu. Here, the fact that the majority of the element X is occupied by Lu means that the Lu atom occupies the majority of the atomic group occupying the element X. By setting it as such a composition, it can function as a more efficient fluorescent substance. The element X may be occupied only by lutetium.

  The phosphor of the present embodiment can be produced by a known method and can be synthesized using a general solid phase reaction.

  Specifically, first, rare earth oxides, alkaline earth metal carbonates and the like, which are universal ceramic raw material powders, are prepared. Next, the raw material powder is prepared so as to have a stoichiometric composition of the desired compound or a composition close thereto, and sufficiently mixed using a mortar, a ball mill, or the like. Then, the phosphor of the present embodiment can be prepared by firing the mixed raw material with an electric furnace or the like using a firing container such as an alumina crucible. In addition, when baking a mixed raw material, it is preferable to heat for several hours at the baking temperature of 1300-1700 degreeC in air | atmosphere or a weak reducing atmosphere.

  The phosphor of the present embodiment can be used as a slurry, paste, sol, or gel by appropriately mixing with a solvent such as water, an organic solvent, a resin, or water glass.

Thus, in the phosphor of the present embodiment, the excitation spectrum has a broad excitation band due to Ce ³⁺ , and the excitation band has a peak in the range of 400 nm to 470 nm. Therefore, short wavelength visible light (wavelength of 380 nm or more and less than 470 nm) can be efficiently absorbed and wavelength conversion can be performed.

Furthermore, the emission spectrum of the first phosphor has an emission line-like fluorescent component of Tb ³⁺ having an emission peak wavelength of 535 nm or more and less than 560 nm. And the emission peak in the range of 535 nm or more and less than 560 nm in the fluorescent component by Tb ³⁺ becomes the maximum intensity value of the emission spectrum of the phosphor. In addition, the emission spectrum of the second phosphor includes at least an emission line-like fluorescence component due to Tb ³⁺ having an emission peak wavelength of 535 nm or more and less than 560 nm, and an emission line-like fluorescence component due to Eu ^{3+ having} an emission peak wavelength of 580 nm or more and less than 650 nm. Have one. The emission peak in the range of 535 nm to less than 560 nm in the fluorescent component due to Tb ³⁺ or the emission peak in the range of 580 nm to less than 650 nm in the fluorescent component due to Eu ³⁺ is the maximum intensity value of the emission spectrum of the phosphor. Become. Therefore, the first and second phosphors can emit green light or red light with good visibility. In addition, light emitting components are concentrated in a range of 535 nm to less than 560 nm with high visibility, or in a range of 580 nm to less than 650 nm with high visibility. Therefore, when the phosphor is used for a light emitting device, the light emission efficiency of the device can be improved.

Note that the phosphor according to the present embodiment is not a mixture obtained by simply mixing a phosphor having an emission center of Ce ^{3+ and} a phosphor having Tb ³⁺ or a mixture obtained by simply mixing a phosphor having an emission center of Eu ³⁺ . That is, in the phosphor according to the present embodiment, Ce ³⁺ and Tb ³⁺ , or Ce ³⁺ , Tb ³⁺ and Eu ³⁺ coexist in a single compound. Therefore, Ce ³⁺ absorbs short-wavelength visible light, and energy transfer from Ce ³⁺ to Tb ³⁺ and energy transfer from Ce ³⁺ to Eu ³⁺ via Tb ³⁺ occur. It is possible to obtain an emission spectrum of

[Light emitting device]
Next, the light emitting device according to this embodiment will be described. The light emitting device of this embodiment includes the phosphor. As described above, the phosphor of this embodiment emits fluorescence having a special spectral shape and color tone control. For this reason, in the light emitting device according to the present embodiment, it is possible to output fluorescence whose color tone is effectively controlled by combining the phosphor and an excitation source that excites the phosphor.

  Note that the light emitting device of the present embodiment widely includes electronic devices having a function of emitting light, and is not particularly limited as long as it is an electronic device that emits some light. That is, the light-emitting device of the present embodiment is a light-emitting device that uses at least the phosphor of the present embodiment and further uses the fluorescence emitted by the phosphor as at least output light.

  More specifically, the light-emitting device of this embodiment combines the above-described phosphor and an excitation source that excites the phosphor. The phosphor absorbs the energy emitted by the excitation source and converts the absorbed energy into color-controlled fluorescence. The excitation source may be appropriately selected from a discharge device, an electron gun, a solid light emitting element, etc. according to the excitation characteristics of the phosphor.

  Conventionally, there are many light-emitting devices that use phosphors, such as fluorescent lamps, electron tubes, plasma display panels (PDP), white LEDs, and detection devices that use phosphors. In a broad sense, an illumination light source and an illumination device using a phosphor, a display device, and the like are light-emitting devices, and a projector including a laser diode, a liquid crystal display including an LED backlight, and the like are also considered as light-emitting devices. Here, since the light-emitting device of this embodiment can be classified according to the type of fluorescence emitted by the phosphor, this classification will be described.

  Fluorescence phenomena used in electronic devices are academically divided into several categories, and are distinguished by terms such as photoluminescence, cathodoluminescence, and electroluminescence. “Photoluminescence” refers to fluorescence emitted by a phosphor when the phosphor is irradiated with an electromagnetic wave. Note that the term “electromagnetic wave” collectively refers to X-rays, ultraviolet rays, visible light, infrared rays, and the like. “Cathodeluminescence” refers to fluorescence emitted by a phosphor when the phosphor is irradiated with an electron beam. Electroluminescence refers to fluorescence emitted when electrons are injected into a phosphor or an electric field is applied. In principle, there is also a term of thermoluminescence as fluorescence close to photoluminescence, which means fluorescence emitted by the phosphor when heat is applied to the phosphor. In addition, there is a term of radioluminescence (radioluminescence) in principle as fluorescence close to cathodoluminescence, which means fluorescence emitted by the phosphor when the phosphor is irradiated with radiation.

  As described above, the light-emitting device of this embodiment uses at least the fluorescence emitted by the above-described phosphor as output light. Since the fluorescence here can be classified at least as described above, the fluorescence can be replaced with at least one fluorescence phenomenon selected from the luminescence.

  Typical examples of the light emitting device that uses the photoluminescence of the phosphor as output light include an X-ray image intensifier, a fluorescent lamp, a white LED, a semiconductor laser projector using a phosphor and a laser diode, and a PDP. . Typical examples of a light emitting device that uses cathodoluminescence as output light include an electron tube, a fluorescent display tube, and a field emission display (FED). Furthermore, typical examples of a light-emitting device that uses electroluminescence as output light include inorganic electroluminescence displays (inorganic EL), light-emitting diodes (LED), semiconductor lasers (LD), and organic electroluminescence elements (OLED).

  Hereinafter, the light emitting device of this embodiment will be described with reference to the drawings. FIG. 1 schematically shows a light emitting device according to this embodiment. 1A and 1B, an excitation source 1 is a light source that generates primary light for exciting the phosphor 2 of the present embodiment. The excitation source 1 emits electromagnetic waves such as particle beams such as α rays, β rays, electron beams, γ rays, X rays, vacuum ultraviolet rays, ultraviolet rays, visible light (especially short wavelength visible light such as violet light and blue light). A radiating device can be used. As the excitation source 1, various radiation generators, electron beam emitters, discharge light generators, solid state light emitting elements, solid state light emitters, and the like can be used. Typical examples of the excitation source 1 include an electron gun, an X-ray tube, a rare gas discharge device, a mercury discharge device, a light emitting diode, a laser light generator including a semiconductor laser, and an inorganic or organic electroluminescence element. It is done.

  1A and 1B, the output light 4 is excitation light emitted from the excitation source 1 or fluorescence emitted from the phosphor 2 excited by the excitation light 3. FIG. The output light 4 is used as illumination light or display light in the light emitting device.

  FIG. 1A shows a light emitting device having a structure in which output light 4 from the phosphor 2 is emitted in a direction in which the phosphor 2 is irradiated with excitation rays or excitation light 3. In addition, as a light-emitting device shown to Fig.1 (a), a white LED light source, a fluorescent lamp, an electron tube, etc. are mentioned. On the other hand, FIG. 1B shows a light emitting device having a structure in which the output light 4 from the phosphor 2 is emitted in a direction opposite to the direction in which the phosphor 2 is irradiated with excitation lines or excitation light 3. Examples of the light emitting device shown in FIG. 1B include a plasma display device, a light source device using a phosphor wheel with a reflector, and a projector.

  Preferable specific examples of the light emitting device of the present embodiment include a semiconductor light emitting device, an illumination light source, an illumination device, a liquid crystal panel with an LED backlight, an LED projector, a laser projector and the like configured using a phosphor.

As described above, in the phosphor of the present embodiment, the excitation spectrum has a broad excitation band due to Ce ³⁺ , and the excitation band has a peak in the range of 400 nm to 470 nm. Therefore, the phosphor can efficiently absorb short-wavelength visible light and perform wavelength conversion. Therefore, the light emitting device of this embodiment preferably has a structure in which the phosphor is excited by short-wavelength visible light having a peak in the range of 380 nm or more and less than 470 nm. Furthermore, it is preferable that the light-emitting device further includes a solid light-emitting element that emits short-wavelength visible light.

  Next, a specific example of the semiconductor light emitting device according to this embodiment will be described in detail. As shown in FIG. 2, the semiconductor light emitting device 100 according to the present embodiment includes a substrate 110, a plurality of LEDs (light emitting elements) 120, and a plurality of sealing members 130. The substrate 110 has, for example, a two-layer structure of an insulating layer made of a ceramic substrate or a heat conductive resin and a metal layer made of an aluminum plate. The substrate 110 has a substantially square plate shape, and the width W1 in the short side direction (X-axis direction) of the substrate 110 is, for example, 12 to 30 mm, and the width W2 in the longitudinal direction (Y-axis direction) is, for example, 12 to 30 mm. is there.

  As shown in FIGS. 3A and 3B, the LED 120 is, for example, a GaN-based LED and has a substantially rectangular shape in plan view. The LED 120 has a width W3 in the short side direction (X-axis direction) of, for example, 0.3 to 1.0 mm, a width W4 in the long side direction (Y-axis direction) of, for example, 0.3 to 1.0 mm, and a thickness (Z-axis direction). For example) is 0.08 to 0.30 mm.

  The LEDs 120 are arranged such that the longitudinal direction (Y-axis direction) of the substrate 110 coincides with the arrangement direction of the element rows of the LEDs 120. The LED 120 constitutes an element row for each of the plurality of LEDs 120 arranged in a row, and these element rows are mounted side by side along the short side direction (X-axis direction) of the substrate 110. Specifically, for example, 25 LEDs 120 are mounted in a matrix with 5 columns and 5 rows. That is, one element row is composed of five LEDs, and five such element rows are mounted side by side.

  In each element row, the LEDs 120 are linearly arranged in the longitudinal direction (Y-axis direction). Thus, by arranging the LEDs 120 in a straight line, the sealing member 130 for sealing the LEDs 120 can also be formed in a straight line.

  As shown in FIG. 3B, each element row is individually sealed by a long sealing member 130. One light emitting unit 101 is configured by one element row and one sealing member 130 that seals the element row. Therefore, the semiconductor light emitting device 100 includes five light emitting units 101.

The sealing member 130 is made of a translucent resin material containing a phosphor. As the resin material, for example, a silicone resin, a fluororesin, a silicone / epoxy hybrid resin, a urea resin, or the like can be used. Further, the phosphor of the present embodiment can be used as the phosphor. However, as the phosphor, not only the phosphor of the present embodiment, but also oxide-based fluorescence such as oxide activated by at least one of Eu ²⁺ , Ce ³⁺ , Tb ³⁺ , and Mn ²⁺ , and acid halides, for example. The body can also be used. In addition, as phosphors, nitride phosphors such as nitrides and oxynitrides activated by at least one of Eu ²⁺ , Ce ³⁺ , Tb ³⁺ and Mn ²⁺ , or sulfides such as sulfides and oxysulfides are used. Physical phosphors can also be used.

Specifically, as the blue phosphor, BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , CaMgSi ₂ O ₆ : Eu ²⁺ , Ba ₃ MgSi ₂ O ₈ : Eu ²⁺ , Sr ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ^{2+ and the} like. Can be mentioned. Examples of the green-blue or blue-green phosphor include Sr ₄ Si ₃ O ₈ Cl ₄ : Eu ²⁺ , Sr ₄ Al ₁₄ O ₂₄ : Eu ²⁺ , BaAl ₈ O ₁₃ : Eu ²⁺ , and Ba ₂ SiO ₄ : Eu ²⁺ . Furthermore, BaZrSi ₃ O ₉ : Eu ²⁺ , Ca ₂ YZr ₂ (AlO ₄ ) ₃ : Ce ³⁺ , Ca ₂ YHf ₂ (AlO ₄ ) ₃ : Ce ³⁺ , Ca ₂ YZr ₂ (AlO ₄₎ ) ₃ : Ce ³⁺ , Tb ³⁺ Examples of the green phosphor include (Ba, Sr) ₂ SiO ₄ : Eu ²⁺ , Ca ₈ Mg (SiO ₄ ) ₄ Cl ₂ : Eu ²⁺ , and Ca ₈ Mg (SiO ₄ ) ₄ Cl ₂ : Eu ²⁺ , Mn ^2+. . Further, as a green phosphor, BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ , CeMgAl ₁₁ O ₁₉ : Mn ²⁺ , Y ₃ Al ₂ (AlO ₄ ) ₃ : Ce ³⁺ , Lu ₃ Al ₂ (AlO ₄ ) ₃ : Ce ³⁺ Is mentioned. Also, as the green _{phosphor, Y 3 Ga 2 (AlO 4} ) 3: Ce 3+, Ca 3 Sc 2 Si 3 O 12: Ce 3+, CaSc 2 O 4: Ce 3+, β-Si 3 N 4: Eu 2+, SrSi ₂ O ₂ N ₂ : Eu ²⁺ may be mentioned. Examples of the green phosphor include Ba ₃ Si ₆ O ₁₂ N ₂ : Eu ²⁺ , Sr ₃ Si ₁₃ Al ₃ O ₂ N ₂₁ : Eu ²⁺ , YTbSi ₄ N ₆ C: Ce ³⁺ , and SrGa ₂ S ₄ : Eu ^2+. . Examples of the green phosphor include Ca ₂ LaZr ₂ (AlO ₄ ) ₃ : Ce ³⁺ , Ca ₂ TbZr ₂ (AlO ₄ ) ₃ : Ce ³⁺ , Ca ₂ TbZr ₂ (AlO ₄ ) ₃ : Ce ³⁺ , and Pr ³⁺ . Examples of the green phosphor include Zn ₂ SiO ₄ : Mn ²⁺ and MgGa ₂ O ₄ : Mn ²⁺ . Examples of the green phosphor include LaPO ₄ : Ce ³⁺ , Tb ³⁺ , Y ₂ SiO ₄ : Ce ³⁺ , CeMgAl ₁₁ O ₁₉ : Tb ³⁺ , and GdMgB ₅ O ₁₀ : Ce ³⁺ , Tb ³⁺ . Examples of yellow or orange phosphors include (Sr, Ba) ₂ SiO ₄ : Eu ²⁺ , (Y, Gd) ₃ Al ₅ O ₁₂ : Ce ³⁺ , and α-Ca-SiAlON: Eu ²⁺ . Examples of the yellow or orange phosphor include Y ₂ Si ₄ N ₆ C: Ce ³⁺ , La ₃ Si ₆ N ₁₁ : Ce ³⁺ , Y ₃ MgAl (AlO ₄ ) ₂ (SiO ₄ ): Ce ³⁺ . As red phosphors, Sr ₂ Si ₅ N ₈ : Eu ²⁺ , CaAlSiN ₃ : Eu ²⁺ , SrAlSi ₄ N ₇ : Eu ²⁺ , CaS: Eu ²⁺ , La ₂ O ₂ S: Eu ³⁺ , Y ₃ Mg ₂ (AlO ₄ ) (SiO ₄ ) ₂ : Ce ³⁺ . Further, as the red ^{_{phosphor, Y 2 O 3: Eu 3+}} , Y 2 O 2 S: Eu 3+, Y (P, V) O 4: Eu 3+, YVO 4: Eu 3+ and the like. Examples of the red phosphor include 3.5MgO.0.5MgF ₂ .GeO ₂ : Mn ⁴⁺ , K ₂ SiF ₆ : Mn ⁴⁺ , GdMgB ₅ O ₁₀ : Ce ³⁺ , and Mn ²⁺ .

  As shown in FIG. 3, the sealing member 130 has a width W5 in the short side direction (X-axis direction) of, for example, 0.8 to 3.0 mm, and a width W6 in the longitudinal direction (Y-axis direction) of, for example, 3.0 to 3.0. It is preferably 40.0 mm. The maximum thickness (width in the Z-axis direction) T1 including the LED 120 is preferably 0.4 to 1.5 mm, for example, and the maximum thickness T2 not including the LED 120 is preferably 0.2 to 1.3 mm, for example. In order to ensure sealing reliability, the width W5 of the sealing member 130 is preferably 2 to 7 times the width W3 of the LED 120.

  The shape of the cross section of the sealing member 130 along the short direction is substantially semi-elliptical as shown in FIG. Further, both end portions 131 and 132 in the longitudinal direction of the sealing member 130 have an R shape. Specifically, as shown in FIG. 2, the shape of both end portions 131 and 132 is a substantially semicircular shape in plan view, and the cross-sectional shape along the longitudinal direction as shown in FIG. Is substantially fan-shaped with a central angle of about 90 °. When both end portions 131 and 132 of the sealing member 130 are formed in an R shape in this way, stress concentration is unlikely to occur at the both end portions 131 and 132, and the emitted light from the LED 120 is taken out of the sealing member 130. easy.

  Each LED 120 is mounted face up on the substrate 110. The wiring pattern 140 formed on the substrate 110 is electrically connected to a lighting circuit unit (not shown) that supplies power to the LED 120. The wiring pattern 140 includes a pair of power feeding lands 141 and 142 and a plurality of bonding lands 143 arranged at positions corresponding to the respective LEDs 120.

  As shown in FIG. 3, the LED 120 is electrically connected to the land 143 via a wire (for example, a gold wire) 150 by wire bonding, for example. One end 151 of the wire 150 is bonded to the LED 120, and the other end 152 is bonded to the land 143. Each wire 150 is arranged along an element row to which a light emitting element to be connected belongs. Furthermore, both end portions 151 and 152 of each wire 150 are also arranged along the element row. Since each wire 150 is sealed by the sealing member 130 together with the LED 120 and the land 143, the wire 150 is hardly deteriorated, and is insulated and highly safe. In addition, the mounting method of LED120 to the board | substrate 110 is not limited to the above face-up mounting, Flip chip mounting may be sufficient.

  As shown in FIG. 2, the LED 120 includes five LEDs 120 belonging to the same element row connected in series, and five element rows connected in parallel. In addition, the connection form of LED120 is not limited to this, You may connect how regardless of an element row | line | column. A pair of lead wires of a lighting circuit unit (not shown) is connected to the lands 141 and 142, and power is supplied from the lighting circuit unit to the LEDs 120 via the lead wires, whereby each LED 120 emits light.

  The sealing member 130 can be formed by the following procedure. First, as illustrated in FIG. 2, a substrate 110 is prepared on which a plurality of element arrays each including a plurality of LEDs 120 arranged in a line are arranged in the X-axis direction. Next, as shown in FIG. 4, a resin paste 135 is applied to the substrate 110 in a line shape along the element rows using, for example, a dispenser 160. Thereafter, the sealing member 130 is individually formed for each element row by solidifying the resin paste 135 after application.

  The semiconductor light emitting device of this embodiment can be widely used for illumination light sources, backlights for liquid crystal displays, light sources for display devices, and the like. That is, as described above, the phosphor of the present embodiment can emit light with good visibility. Therefore, when the phosphor is used as an illumination light source or the like, it is possible to provide an illumination light source with high color rendering properties and high efficiency, and a display device capable of displaying a wide color gamut on a high luminance screen.

  Such an illumination light source can be configured by combining the semiconductor light-emitting device of the present embodiment, a lighting circuit that operates the semiconductor light-emitting device, and a connection component for a lighting fixture such as a base. Moreover, if a lighting fixture is combined as needed, it will also comprise an illuminating device and an illumination system.

  Thus, since the light emitting device of this embodiment has favorable characteristics in terms of visibility and visibility, it can be widely used in addition to the semiconductor light emitting device and the light source device described above.

  Hereinafter, the present embodiment will be described in more detail with reference to examples, comparative examples, and reference examples, but the present embodiment is not limited to these examples.

  The phosphors according to Examples, Comparative Examples, and Reference Examples were synthesized using a preparation method utilizing a solid phase reaction, and their characteristics were evaluated. In the examples, comparative examples and reference examples, the following compound powders were used as raw materials.

Strontium carbonate (SrCO ₃ ): purity 3N, manufactured by Kanto Chemical Co., Ltd. Lutetium oxide (Lu ₂ O ₃ ): purity 3N, manufactured by Shin-Etsu Chemical Co., Ltd. Cerium oxide (CeO ₂ ): purity 4N, manufactured by Shin-Etsu Chemical Co., Ltd. Terbium (Tb ₄ O ₇ ): Purity 3N, manufactured by Shin-Etsu Chemical Co., Ltd. Europium oxide (Eu ₂ O ₃ ): Purity 3N, manufactured by Shin-Etsu Chemical Co., Ltd. Calcium carbonate (CaCO ₃ ): Purity 2N5, manufactured by Kanto Chemical Co., Inc. Zirconium oxide (ZrO ₂ ): purity 3N, manufactured by Kanto Chemical Co., Ltd. Aluminum oxide (θ-Al ₂ O ₃ ): purity 4N5, manufactured by Sumitomo Chemical Co., Ltd. scandium oxide (Sc ₂ O ₃ ): purity 3N, Shin-Etsu Chemical Co., Ltd. Made by company

Moreover, in the comparative example, the following was used as a reaction accelerator.
Aluminum fluoride (AlF ₃ ): Purity 3N, manufactured by Kojundo Chemical Laboratory Co., Ltd. Potassium carbonate (K ₂ CO ₃ ): Purity 2N5, manufactured by Kanto Chemical Co., Inc.

[Examples 1 and 2]
In Example 1, the target phosphor was Sr (Lu _0.899 Ce _0.001 Tb _0.1 ) ₂ O ₄ . In Example 2, the target phosphor was Sr (Lu _0.889 Ce _0.001 Tb _0.1 Eu _0.01 ) ₂ O ₄ . And the fluorescent substance of Example 1 and 2 was prepared as follows.

  First, each raw material was weighed at a ratio shown in Table 1. Next, these raw materials were sufficiently wet mixed with an appropriate amount of pure water. And the raw material after mixing was moved to the container, and was dried at 150 degreeC for 3 hours using the dryer. The mixed raw material after drying was pulverized using a mortar and pestle to obtain a baking raw material.

  Thereafter, the firing raw material was transferred to an alumina crucible with a lid and subjected to main firing for 2 hours in an atmosphere of 1500 to 1600 ° C. using a box-type electric furnace.

  The fired product after the main firing was crushed for several minutes using a mortar and pestle, then transferred to an alumina crucible, and fired in a weak reducing atmosphere at 1500 to 1600 ° C. for 2 hours using a tubular electric furnace. The weak reducing atmosphere was a mixed gas atmosphere of 96% argon and 4% hydrogen, and the mixed gas flow rate was 100 ml / min. In this way, the phosphors of Examples 1 and 2 were prepared.

[Comparative Example 1]
In Comparative Example 1, a phosphor (Ca ₂ (Tb _0.98 Ce _0.02 ) Zr ₂ (AlO ₄ ) ₃ ) having a conventional garnet-type crystal structure was prepared.

  First, each raw material and reaction accelerator were weighed at the ratio shown in Table 2. Next, using a ball mill, these raw materials and reaction accelerator were sufficiently wet mixed with an appropriate amount of pure water. And the raw material after mixing was moved to the container, and was dried at 120 degreeC overnight using the dryer. The mixed raw material after drying was pulverized using a mortar and pestle to obtain a baking raw material.

  Thereafter, the firing raw material was transferred to an alumina crucible with a lid and subjected to main firing for 4 hours in an atmosphere at 1600 ° C. using a box-type electric furnace.

  The fired product after the main firing was crushed for several minutes using a mortar and pestle, then transferred to an alumina crucible, and fired in a weak reducing atmosphere at 1600 ° C. for 2 hours using a tubular electric furnace. The weak reducing atmosphere was a mixed gas atmosphere of 96% argon and 4% hydrogen, and the mixed gas flow rate was 100 ml / min. In this way, the phosphor of Comparative Example 1 was prepared.

  The following evaluations were performed on the phosphors obtained in Examples 1 and 2.

First, the crystal structure analysis of the phosphors of Examples 1 and 2 was performed using an X-ray diffractometer (product name: MultiFlex, manufactured by Rigaku Corporation). The measurement results are shown in FIG. In FIG. 5, the XRD pattern of Example 1 is shown as (a), and the XRD pattern of Example 2 is shown as (b). Further, a pattern (PDF No. 32-1242) of SrLu ₂ O ₄ having a calcium ferrite type crystal structure registered in PDF (Power Diffraction Files) is shown as (c).

As can be seen by comparing (a), (b) and (c) in FIG. 5, the XRD patterns of the phosphors of Examples 1 and 2 are those of SrLu ₂ O ₄ having a calcium ferrite type crystal structure. It almost coincided with the pattern. This indicates that at least the phosphors of Examples 1 and 2 are mainly composed of a compound having a calcium ferrite type structure.

Next, the excitation characteristics and emission characteristics of the phosphors of Examples 1 and 2 were measured using a spectrofluorometer (FP-6500, manufactured by JASCO Corporation). FIG. 6 shows an emission spectrum 1a and an excitation spectrum 2a in the phosphor of Example 1 (Sr (Lu _0.899 Ce _0.001 Tb _0.1 ) ₂ O ₄ ). FIG. 7 shows the emission spectrum 1b and the excitation spectrum 2b of the phosphor of Example 2 (Sr (Lu _0.889 Ce _0.001 Tb _0.1 Eu _0.01 ) ₂ O ₄ ). The excitation wavelengths when measuring the emission spectra in the phosphors of Examples 1 and 2 were 407 nm and 406 nm, respectively, and the monitor wavelengths when measuring the excitation spectra were the emission peak wavelengths. 6 and 7, the emission spectrum and the excitation spectrum are both normalized with the maximum intensity being 100.

As can be seen from FIG. 6, the excitation spectrum of the phosphor of Example 1 has a broad excitation band due to Ce ³⁺ , and the excitation band has a maximum value of excitation intensity in the violet to blue wavelength region. Specifically, the broad excitation band due to Ce ³⁺ in the phosphor of Example 1 has a maximum excitation intensity at 407 nm. Therefore, the phosphor of Example 1 has a feature that it absorbs excitation light within a range of 400 nm to 470 nm and emits light.

From FIG. 6, the emission spectrum of the phosphor of Example 1 has an emission line-like fluorescent component with Tb ³⁺ having an emission peak wavelength of 535 nm or more and less than 560 nm. Furthermore, it can be seen that the emission peak in the range of 535 nm or more and less than 560 nm in the fluorescent component due to Tb ³⁺ is the maximum intensity value of the emission spectrum.

Further, as can be seen from FIG. 7, the excitation spectrum of the phosphor of Example 2 has a broad excitation band due to Ce ³⁺ , as in Example 1, and the excitation band is excited in the wavelength range of purple to blue. Has a maximum value of intensity. Specifically, the broad excitation band due to Ce ³⁺ in the phosphor of Example 2 has a maximum excitation intensity at 406 nm. Therefore, the phosphor of Example 2 has a feature that it emits light by absorbing excitation light within a range of 400 nm to 470 nm.

From FIG. 7, the emission spectrum of the phosphor of Example 2 has an emission line-like fluorescent component with Tb ³⁺ having an emission peak wavelength of 535 nm or more and less than 560 nm. Furthermore, it also has an emission line-like fluorescent component with Eu ³⁺ having an emission peak wavelength of 580 nm or more and less than 650 nm. And it turns out that the emission peak in the range of 580 nm or more and less than 650 nm in the fluorescence component by Eu ³⁺ is the intensity maximum value of the emission spectrum.

  As described above, it can be seen that the phosphors of Examples 1 and 2 are inorganic compounds having a calcium ferrite type crystal structure and have the above-described characteristic excitation spectrum and emission spectrum.

  Next, temperature quenching of the phosphors of Example 1 and Comparative Example 1 was performed using an instantaneous multi-photometry system (MPCD-9800, manufactured by Otsuka Electronics Co., Ltd.) and a quantum efficiency measurement system (QE-1100, Otsuka Electronics Co., Ltd.) equipped with a heating mechanism. And manufactured by the same company).

  First, an evaluation procedure of temperature quenching in the phosphors of Example 1 and Comparative Example 1 is shown. First, each phosphor was excited by irradiation with light having an excitation peak wavelength, and the internal quantum efficiency at room temperature (30 ° C.) was measured. Thereafter, the phosphor was heated in increments of 10 ° C. up to 200 ° C., and the internal quantum efficiency was measured each time. Thus, the temperature quenching of Example 1 and Comparative Example 1 was evaluated. The evaluation results are shown in FIG. FIG. 8 shows the relationship between the temperature of the phosphor and the maintenance rate (%) of the internal quantum efficiency when the internal quantum efficiency at room temperature is 100%. (A) shows the result of the phosphor of Example 1. (B) is the result of the phosphor of Comparative Example 1.

As can be seen by comparing (A) and (B) of FIG. 8, the internal quantum efficiency retention rate of the phosphor of Example 1 is higher than that of Comparative Example 1. In addition, although the measurement result of the temperature quenching of Example 2 was abbreviate | omitted, the characteristic similar to Example 1 was shown. The reason for this is that the temperature quenching of the phosphor of the example is generally determined by the temperature quenching of the phosphor activated by Ce ³⁺ alone. This will be described later using a reference example.

  As described above, an inorganic compound phosphor having a conventional garnet-type crystal structure that can be excited by LED light and emits bright line-like green and / or red light components has a large problem of temperature quenching. It was. However, it can be seen that the phosphor of this embodiment can improve temperature quenching.

[Reference Example 1]
In general, the temperature quenching of a phosphor having a light emission mechanism using energy transfer is the temperature quenching of a phosphor before using energy transfer, that is, the phosphor of the present embodiment in which Ce ³⁺ is independently activated. The same tendency is shown. Therefore, the result of investigating the temperature quenching of the phosphor using a Ce ³⁺ single activation phosphor that can be easily synthesized will be described.

In Reference Example 1, the target phosphor was Sr (Lu _0.9995 Ce _0.0005 ) ₂ O ₄ . Then, the phosphor of Reference Example 1 was prepared as follows. First, each raw material was weighed at a ratio shown in Table 3. Next, the phosphors of Reference Example 1 were prepared by mixing and firing these raw materials in the same manner as in Examples 1 and 2.

Next, in the same manner as in Examples 1 and 2, the crystal structure analysis of the phosphor of Reference Example 1 was performed. As a result, the compound of Reference Example 1 showed the same XRD pattern as in Examples 1 and 2. Therefore, it was found that Reference Example 1 was a compound represented by Sr (Lu _0.9995 Ce _0.0005 ) ₂ O ₄ and having a calcium ferrite type crystal structure.

Furthermore, the excitation characteristics and emission characteristics of the phosphor of Reference Example 1 were measured in the same manner as in Examples 1 and 2. FIG. 9 shows an emission spectrum 1c and an excitation spectrum 2c of the phosphor of Reference Example 1 (Sr (Lu _0.9995 Ce _0.0005 ) ₂ O ₄ ). The excitation wavelength when measuring the emission spectrum of the phosphor of Reference Example 1 was 405 nm, and the monitoring wavelength when measuring the excitation spectrum was the emission peak wavelength. In FIG. 9, the emission spectrum and the excitation spectrum are both normalized with the maximum intensity being 100.

As can be seen from FIG. 9, the excitation spectrum of the phosphor of Reference Example 1 has a broad excitation band due to Ce ³⁺ , and the excitation band has a maximum value of excitation intensity in the violet to blue wavelength region. Specifically, the broad excitation band due to Ce ³⁺ in the phosphor of Reference Example 1 has a maximum excitation intensity at 405 nm. Therefore, the phosphor of Reference Example 1 has a feature that it absorbs excitation light within a range of 400 nm to 470 nm and emits light.

From FIG. 9, the emission spectrum of the phosphor of Reference Example 1 has a broad fluorescent component due to Ce ³⁺ , and the fluorescent component has a maximum emission intensity in the wavelength region of blue to green blue light. Specifically, the broad fluorescent component due to Ce ³⁺ of the phosphor of Reference Example 1 is a phosphor having a maximum emission intensity at 455 nm and emitting blue to patina in the wavelength range of 450 nm to less than 500 nm. is there.

  Next, the temperature quenching of the phosphor of Reference Example 1 was measured in the same manner as in Example 1. In FIG. 10, the temperature quenching (A) of the phosphor of Example 1 is compared with the temperature quenching (C) of the phosphor of Reference Example 1. As shown in FIG. 10, the temperature quenching of the phosphor of Example 1 has the same tendency as the temperature quenching of the phosphor of Reference Example 1. Therefore, temperature quenching of a phosphor having a light emission mechanism that uses energy transfer can generally be determined by temperature quenching of the phosphor before using energy transfer.

[Reference Examples 2 to 5]
In the phosphors of Reference Examples 2 to 5, the target phosphor is (Sr _1-x Ca _x ) (Lu _0.9995 Ce _0.0005 ) ₂ O ₄ (where 0.1 ≦ x ≦ 0.7) It was set as the compound represented by these. And the fluorescent substance of Reference Examples 2-5 was prepared as follows. First, each raw material was weighed at a ratio shown in Table 4. Next, the phosphors of Reference Examples 2 to 5 were prepared by mixing and firing these raw materials in the same manner as in Examples 1 and 2.

Next, similarly to Examples 1 and 2, the crystal structure analysis of the phosphors of Reference Examples 2 to 5 was performed. The measurement results are shown in FIG. In FIG. 11, the XRD pattern of Reference Example 2 is shown as (d), the XRD pattern of Reference Example 3 is shown as (e), the XRD pattern of Reference Example 4 is shown as (f), and the XRD pattern of Reference Example 5 is shown as (g). In addition, a pattern of SrLu ₂ O ₄ having a calcium ferrite type crystal structure registered in PDF is shown as (c).

As can be seen by comparing (d) to (g) and (c) in FIG. 11, the XRD patterns of the phosphors of Reference Examples 2 to 5 are those of SrLu ₂ O ₄ having a calcium ferrite type crystal structure. It almost coincided with the pattern. This means that at least the phosphors of Reference Examples 2 to 5 are compounds represented by (Sr _1-x Ca _x ) (Lu _0.9995 Ce _0.0005 ) ₂ O ₄ and having a calcium ferrite type structure. Is shown.

  Next, the excitation characteristics and emission characteristics of the phosphors of Reference Examples 2 to 5 were measured in the same manner as in Examples 1 and 2. 12 shows the emission spectrum 1d and the excitation spectrum 2d of Reference Example 2, the emission spectrum 1e and the excitation spectrum 2e of Reference Example 3, the emission spectrum 1f and the excitation spectrum 2f of Reference Example 4, and the emission spectrum 1g and the excitation spectrum of Reference Example 5. The spectrum 2g is shown. The excitation wavelength at the time of emission spectrum measurement was the excitation peak wavelength, and the monitor wavelength at the time of excitation spectrum measurement was the emission peak wavelength. In FIG. 12, the emission spectrum and the excitation spectrum are both normalized with the maximum intensity being 100.

  As can be seen from FIG. 12, as the substitution amount (x) of Ca increases, both the emission spectrum and the excitation spectrum are relatively shifted to the longer wavelength side. Specifically, the peaks of the emission spectrum and the excitation spectrum were, for example, 460 nm and 407 nm in Reference Example 2 where the numerical value of x was 0.1, but in Reference Example 3 where the numerical value of x was 0.3, respectively. , Shifted to 467 nm and 410 nm, respectively. In Reference Example 4 where the value of x was 0.5, the shift was made to 478 nm and 412 nm, respectively, and in Reference Example 5 where the value of x was 0.7, the shift was made to 481 nm and 414 nm, respectively. With the long wavelength shift of the emission spectrum, the light color emitted by the phosphor having a calcium ferrite type crystal structure changed from blue to blue-green.

The reason why the wavelength shifts as the Ca substitution amount increases is considered as follows. That is, the lattice positions of ^{Sr 2+,} by substituting a small ^Ca 2+ than the ionic radius of ^{Sr 2+ (1.12Å) (0.99Å)} , the lattice volume of the crystal is ^decreased, Ce 3+ ^{-O 2-distance} This is thought to be due to the shrinkage of. In general, when the Ce ³⁺ —O ²⁻ distance is reduced, the Ce ³⁺ −O ²⁻ interaction increases, and the emission level of Ce ³⁺ decreases. Thereby, it is considered that the energy difference between the emission level and the ground state is reduced, and the excitation spectrum and emission spectrum of Ce ³⁺ are shifted to the long wavelength side where energy is low.

  The above results indicate that the phosphors of Reference Examples 2 to 5 can efficiently absorb purple to blue light in the vicinity of a wavelength of 405 to 415 nm and convert the wavelength to blue to blue green light.

Next, the temperature quenching of the phosphor of Reference Example 3 was measured in the same manner as in Example 1. In FIG. 13, the temperature quenching (D) of the phosphor of Reference Example 3 and the temperature quenching (C) of the phosphor of Reference Example 1 are shown in comparison. As shown in FIG. 13, the internal quantum efficiency maintenance rate of the phosphor of Reference Example 3 ((Sr _0.7 Ca _0.3 ) (Lu _0.9995 Ce _0.0005 ) ₂ O ₄ ) is Higher than the phosphor (Sr (Lu _0.9995 Ce _0.0005 ) ₂ O ₄ ). This result shows that the temperature quenching is further improved when the phosphor having the calcium ferrite type structure according to the present embodiment contains Ca.

[Reference Examples 6 to 11]
The phosphor of Example 6 to 11, the phosphor as a target _{(Sr 0.7 Ca 0.3) (Lu} 0.997-y Sc y Ce 0.003) 2 O 4 ( where, 0 ≦ y ≦ 0.997). And the fluorescent substance of Reference Examples 6-11 was prepared as follows. First, each raw material was weighed at a ratio shown in Table 5. Next, the phosphors of Reference Examples 6 to 11 were prepared by mixing and firing these raw materials in the same manner as in Examples 1 and 2.

First, in the same manner as in Examples 1 and 2, the crystal structures of the phosphors of Reference Examples 6 to 11 were analyzed. In FIG. 14, XRD pattern of Reference Example 6 is (h), XRD pattern of Reference Example 7 is (i), XRD pattern of Reference Example 8 is (j), XRD pattern of Reference Example 9 is (k), Reference Example The XRD pattern of 10 is shown as (l), and the XRD pattern of Reference Example 11 is shown as (m). In addition, a pattern of SrLu ₂ O ₄ having a calcium ferrite type crystal structure registered in PDF is shown as (c).

As can be seen by comparing (h) to (l) and (c) in FIG. 14, the XRD patterns of the phosphors of Reference Examples 6 to 10 are those of SrLu ₂ O ₄ having a calcium ferrite type crystal structure. It almost coincided with the pattern. This phosphor least reference example 6 to _10, represented by _{(Sr 0.7 Ca 0.3) (Lu} 0.997-y Sc y Ce 0.003) 2 O 4, calcium ferrite structure It is shown that it is a compound which has this.

Note that the XRD pattern of the phosphor of Reference Example 11 shown in (m) of FIG. 14 is different from Reference Examples 6 to 10. However, the position of the diffraction peak of Reference Example 11 is simply shifted by 2 to 3 ° on the high angle side with respect to the peak position of SrLu ₂ O ₄ having a calcium ferrite type crystal structure. Such coincidence of XRD patterns is substantially the case where the phosphor of Reference Example 11 is represented by (Sr _0.7 Ca _0.3 ) (Sc _0.997 Ce _0.003 ) ₂ O ₄ and is of calcium ferrite type It shows that it is a compound having the crystal structure of

  Next, the excitation characteristics and emission characteristics of the phosphors of Reference Examples 6 to 11 were measured in the same manner as in Examples 1 and 2. FIG. 15 shows the emission spectrum 1h and excitation spectrum 2h of Reference Example 6, the emission spectrum 1i and excitation spectrum 2i of Reference Example 7, and the emission spectrum 1j and excitation spectrum 2j of Reference Example 8. FIG. 15 shows the emission spectrum 1k and excitation spectrum 2k of Reference Example 9, the emission spectrum 1l and excitation spectrum 21 of Reference Example 10, and the emission spectrum 1m and excitation spectrum 2m of Reference Example 11. The excitation wavelength at the time of emission spectrum measurement was the excitation peak wavelength, and the monitor wavelength at the time of excitation spectrum measurement was the emission peak wavelength. In FIG. 15, the emission spectrum and the excitation spectrum are both normalized with the maximum intensity being 100.

  As can be seen from FIG. 15, both the emission spectrum and the excitation spectrum relatively shifted to the longer wavelength side as the Sc substitution amount (y) increased. Specifically, the peaks of the emission spectrum and the excitation spectrum were, for example, 467 nm and 410 nm in Reference Example 6 where y is 0, but in Reference Example 7 where y is 0.1, respectively. Shifted to 476 nm and 410 nm. Further, in Reference Example 8 where the numerical value of y was 0.3, the values shifted to 490 nm and 414 nm, respectively, and in Reference Example 9 where the numerical value of y was 0.5, they shifted to 490 nm and 421 nm, respectively. Furthermore, in Reference Example 10 where the numerical value of y was 0.7, the values shifted to 492 nm and 433 nm, respectively, and in Reference Example 11 where the numerical value of y was 0.997, they shifted to 496 nm and 440 nm, respectively. And the light color which a fluorescent substance emits changed from blue to blue-green with the long wavelength shift of the emission spectrum.

The reason why the wavelength shifts as the Sc substitution amount increases is considered as follows. That is, the lattice positions of the ^{Lu 3+,} by ionic radius substituted with ^Lu 3+ (0.86 Å) smaller ^Sc 3+ than (0.75Å), decreased cell volume of the crystal ^further, Ce 3+ ^{-O 2-} This is thought to be due to the reduction in distance. In general, when the Ce ³⁺ —O ²⁻ distance is reduced, the Ce ³⁺ −O ²⁻ interaction increases, and the emission level of Ce ³⁺ decreases. Thereby, it is considered that the energy difference between the emission level and the ground state is reduced, and the excitation spectrum and emission spectrum of Ce ³⁺ are shifted to the long wavelength side where energy is low.

  The above results indicate that the phosphors of Reference Examples 6 to 11 can efficiently absorb purple to blue light in the vicinity of a wavelength of 410 to 440 nm and convert the wavelength to blue to blue green light.

Next, the temperature quenching of the phosphors of Reference Example 6 and Reference Example 11 was measured in the same manner as in Example 1. In FIG. 16, the temperature quenching (E) of the phosphor of Reference Example 6 and the temperature quenching (F) of the phosphor of Reference Example 11 are shown in comparison. As shown in FIG. 16, the internal quantum efficiency retention rate of the phosphor of Reference Example 11 ((Sr _0.7 Ca _0.3 ) (Sc _0.997 Ce _0.003 ) ₂ O ₄ ) is Higher than the phosphor ((Sr _0.7 Ca _0.3 ) (Lu _0.997 Ce _0.003 ) ₂ O ₄ ). This result indicates that the phosphor having the calcium ferrite type crystal structure according to the present embodiment further improves the temperature quenching by containing Sc.

The reason why temperature quenching is improved by including Sc is considered as follows. That is, the lattice positions of the ^{Lu 3+,} ionic radii by substituting ^Lu 3+ (0.86 Å) smaller ^Sc 3+ than (0.75Å), ionic-bonding inorganic compound crystal is increased. This is considered to be caused by a decrease in the probability of non-light-emitting transition that relaxes energy accompanied by lattice vibration.

  As mentioned above, although this embodiment was described by the Example, this embodiment is not limited to these, A various deformation | transformation is possible within the range of the summary of this embodiment.

  2 Phosphor

Claims (14)

A phosphor comprising an inorganic compound containing Ce ³⁺ and Tb ³⁺ as an emission center and having a calcium ferrite type crystal structure,
The excitation spectrum of the phosphor has a broad excitation band due to Ce ³⁺ , and the excitation band has a peak within a range of 400 nm to 470 nm,
The emission spectrum of the phosphor has an emission line-like fluorescent component of Tb ³⁺ having an emission peak wavelength of 535 nm or more and less than 560 nm,
A phosphor in which an emission peak in a range of 535 nm or more and less than 560 nm in the fluorescent component due to Tb ³⁺ is the maximum intensity of the emission spectrum. A phosphor comprising an inorganic compound containing Ce ³⁺ , Tb ³⁺ and Eu ³⁺ as an emission center and having a calcium ferrite type crystal structure,
The excitation spectrum of the phosphor has a broad excitation band due to Ce ³⁺ , and the excitation band has a peak within a range of 400 nm to 470 nm,
The emission spectrum of the phosphor has at least one of an emission line-like fluorescence component due to Tb ³⁺ having an emission peak wavelength of 535 nm or more and less than 560 nm and an emission line-like fluorescence component due to Eu ^{3+ having} an emission peak wavelength of 580 nm or more and less than 650 nm ,
The phosphor in which the emission peak in the range of 535 nm to less than 560 nm in the fluorescent component due to Tb ³⁺ or the emission peak in the range of from 580 nm to less than 650 nm in the fluorescent component due to Eu ³⁺ becomes the maximum intensity of the emission spectrum.   The phosphor according to claim 1 or 2, wherein the inorganic compound contains an alkaline earth metal and a rare earth element.   The phosphor according to claim 3, wherein the inorganic compound contains Sr as the alkaline earth metal.   The phosphor according to claim 4, wherein the inorganic compound further contains Ca as the alkaline earth metal.   The phosphor according to claim 3, wherein the inorganic compound contains Ce, Tb, and Lu as the rare earth element.   The phosphor according to claim 6, wherein the inorganic compound further contains Eu as the rare earth element.   The phosphor according to claim 6, wherein the inorganic compound further contains Sc as the rare earth element.   The phosphor according to claim 1, wherein the number of atoms of Tb in the inorganic compound is larger than the number of atoms of Ce in the inorganic compound. The inorganic compound has the general formula:
MX ₂ O ₄
(Wherein M contains at least one of Sr and Ca, X contains at least one of Lu and Sc), and a part of the elements constituting the host is Ce and Tb. The phosphor according to claim 1, which is substituted. The inorganic compound has the general formula:
MX ₂ O ₄
(Wherein M contains at least one of Sr and Ca, X contains at least one of Lu and Sc), and a part of the elements constituting the host is Ce, Tb and The phosphor according to claim 2 substituted with Eu.   A light emitting device comprising the phosphor according to any one of claims 1 to 11.   The light emitting device according to claim 12, wherein the phosphor is excited by short wavelength visible light having a peak in a range of 380 nm or more and less than 470 nm.   The light-emitting device according to claim 13, further comprising a solid-state light-emitting element that emits the short-wavelength visible light.

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