JP2014118421A - Fluorescent material, production method thereof and light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescent material that has high luminance, high efficiency and high chemical stability, and a production method thereof.SOLUTION: The fluorescent material is represented by the general formula (1) defined by (LnRE)(SiS), where Ln is one or more selected from the group consisting of Sc, Y, Gd and Lu; RE is one or more selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Bi and Mn; and x satisfies 0.001≤x≤0.6.

Description

  The present invention relates to a phosphor, a manufacturing method thereof, and a light emitting device.

  Phosphors are widely used in image display devices such as display devices, lighting devices such as fluorescent lamps and white LEDs. Examples of the display device include CRT (cathode ray tube), PDP (plasma display panel), FED (field emission display) and the like. A phosphor can also be used for a white light source for backlight of LCD (liquid crystal display). Furthermore, application of inorganic EL elements using phosphor electroluminescence (EL) to them has also been studied.

In particular, in recent years, white LEDs have been actively developed. In a conventional white LED, a phosphor in which Ce is activated in a YAG-based oxide known by a composition formula of (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ is dispersed in a blue LED sealing resin. The thing is widely used (patent documents 1-3). However, since this white LED emits less light in the red region, color reproducibility and color rendering are insufficient, and further improvements are required.

  On the other hand, a combination of a near-ultraviolet LED and red, green and blue phosphors (Patent Document 4) and a combination of a blue LED and green and red phosphors (Patent Document 5) have been reported. . White LEDs are used not only for illumination but also as backlights for LCDs, and phosphors of various emission colors have been developed.

  Many phosphors have been reported in which a luminescent ion called a luminescent center is activated in a crystal called a host crystal. Examples of the substitution position when the emission center is activated in the host crystal include an alkali metal position, an alkaline earth metal position, and a rare earth position. Oxides, nitrides, and oxynitrides containing these in their compositions are well studied as host crystals and are widely put into practical use.

  However, these basically require synthesis by high-temperature firing, and in particular, oxynitride phosphors require a reaction under high pressure in addition to high-temperature firing, and there is a problem that the synthesis is expensive.

On the other hand, sulfide phosphors have been reported as phosphors that can be synthesized at relatively low temperatures. Specifically, it is a phosphor having an alkaline earth sulfide or AZ ₂ S ₄ (where A is an alkaline earth metal, Z is a trivalent cation such as Ga, Al, In, and Y) as a base crystal, Application to an electroluminescence element has been made (Patent Document 6). In addition, among sulfide phosphors that can be excited by light having wavelengths of near ultraviolet to blue, phosphors having alkaline earth thiosilicate as a base crystal have been reported as a group of materials that exhibit various emission colors in the visible light range. (Patent Documents 7 to 10). In Non-Patent Document 1, blue phosphors: Ba ₂ SiS ₄ : Ce ³⁺ , green phosphors: Ba ₂ SiS ₄ : Eu ²⁺ , yellow and red phosphors: Ca ₂ SiS ₄ : Eu ^{2+ in} a near-ultraviolet LED having an emission wavelength of 380 nm. A white LED combining the above has been reported.

Mg ₂ SiS ₄ , Sr ₂ SiS ₄ , and Ca ₂ SiS ₄ have been reported as parent crystals of a thiosilicate phosphor having an emission peak in the yellow to red range (Non-patent Document 2). However, there is a problem of low stability and hydrolysis in the atmosphere. This is also a problem of the above-described sulfide phosphor as a whole.

  As a method of applying a thiosilicate phosphor for practical application of LED lighting, there is a method of applying moisture resistance and water resistance by coating phosphor particles (Patent Document 11). However, it is expected to improve the stability of the original phosphor itself, and development of a new host crystal is desired.

  As a desirable characteristic for the host crystal, it is of course highly stable, but a material with a large light absorption edge (bandgap) is generally used to prevent energy dissipation from the activated emission center to the host crystal. Is.

Non-Patent Documents 3 to 5 report Eu ₂ SiS ₄ having europium, which is a rare earth ion, as a constituent element among thiosilicates as a phosphor emitting yellow light. Although this phosphor is relatively stable, there is a problem that the emission intensity of the single substance is low due to a phenomenon called concentration quenching that causes a decrease in the luminous efficiency of the phosphor when a large amount of Eu as the emission center is contained. There is.

Non-Patent Document 6 reports Gd ₄ (SiS ₄ ) ₃ as a magnetic material, and Non-Patent Document 7 reports Ce ₆ Si ₄ S ₁₇ as an industrial pigment. None of them has been found to be a phosphor.

Japanese Patent No. 2900928 Japanese Patent No. 2927279 Japanese Patent No. 2998696 JP 2000-509912 A JP 2000-244021 A Japanese Patent Laid-Open No. 2005-520924 JP 2006-265501 A JP 2010-215729 A JP 2010-215728 A JP 2011-157484 A JP 2012-7082 A

P. F. Smet, K. Korthout, J. E. Van Haecke and D. Poelman, Mater. Sci. Eng. B 146 (2008) 264-8. A. B. Parmentier, P. F. Smet and D. Poelman, Opt. Mater. 33 (2010) 141-4. M. Nishimura, Y. Nanai, T. Bohda, T. Okuno, Jpn. J. Appl. Phys. 48 (2009) 072301-1-4. M. Sugiyama, Y. Nanai, Y. Okada, T. Okuno, J. Phys. D: Appl. Phys. 44 (2011) 09404-1-5. Y. Nanai, C. Sasaki, Y. Sakamoto, T. Okuno, J. Phys. D: Appl. Phys. 44 (2011) 405402-1-6. Stephan T. Hatscher and Werner Urland, J. Solid State Chem. 172 (2003) 417-423. G. Gauthier, S. Jobic, M. Evain, H.‐J. Koo, M.‐H Whangbo, C. Fouassier, and R. Brec, Chem. Mater. 15 (2003) 828-837.

  An object of the present invention is to provide a phosphor having high luminance and high efficiency and high chemical stability, and a method for producing the same.

One aspect of the present invention is represented by the general formula (1): (Ln _1-x RE _x ) ₄ (SiS ₄ ) ₃ , wherein Ln is one or more selected from the group consisting of Sc, Y, Gd and Lu. RE is at least one selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Bi, and Mn, and x is 0.001 ≦ x The phosphor is ≦ 0.6.

Another aspect of the present invention is represented by the general formula (2): (R _1-y RE _y ) ₆ Si ₄ S ₁₇ , R is La, RE is Sc, Y, Ce, Pr, Nd, A phosphor that is at least one selected from the group consisting of Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, and Mn, and y is 0.001 ≦ y ≦ 0.1 It is.

  Still another aspect of the present invention is a phosphor including the phosphor according to the one aspect and the phosphor according to the other aspect.

  In still another aspect of the present invention, one or more compounds selected from the group consisting of Sc, Y, La, Gd and Lu, and Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Mixing one or more compounds selected from the group consisting of Tm, Yb, Bi, and Mn, a raw material containing Si and / or Si compound, and S and / or S compound; Including at least one compound selected from the group consisting of Sc, Y, La, Gd, and Lu, and Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Production of phosphor having a stoichiometric ratio of 0.999: 0.001 to 0.4: 0.6 in a mixture with one or more compounds selected from the group consisting of Tm, Yb, Bi and Mn Is the method.

  Yet another aspect of the present invention is a light emitting device having the above-described phosphor.

  According to the present invention, it is possible to provide a phosphor having high luminance and high efficiency and high chemical stability, and a method for producing the same.

FIG. 1 is a graph showing the powder X-ray diffraction results of (Y _0.99 Ce _0.01 ) ₄ (SiS ₄ ) ₃ and (Y _0.98 Ce _0.02 ) ₄ (SiS ₄ ) ₃ . FIG. 2 is a graph showing powder X-ray diffraction results of (Gd _0.99 Ce _0.01 ) ₄ (SiS ₄ ) ₃ and (Gd _0.98 Ce _0.02 ) ₄ (SiS ₄ ) ₃ . FIG. 3 is a graph showing an emission spectrum and an emission excitation spectrum of (Y _0.99 Ce _0.01 ) ₄ (SiS ₄ ) ₃ and (Y _0.98 Ce _0.02 ) ₄ (SiS ₄ ) ₃ by light excitation. is there. FIG. 4 is a graph showing an emission spectrum and an emission excitation spectrum of (Gd _0.99 Ce _0.01 ) ₄ (SiS ₄ ) ₃ and (Gd _0.98 Ce _0.02 ) ₄ (SiS ₄ ) ₃ by light excitation. is there. FIG. 5 is a graph showing powder X-ray diffraction results of (La _0.99 Ce _0.01 ) ₆ Si ₄ S ₁₇ and (La _0.98 Ce _0.02 ) ₆ Si ₄ S ₁₇ . FIG. 6 is a graph showing an emission spectrum and an emission excitation spectrum of (La _0.99 Ce _0.01 ) ₆ Si ₄ S ₁₇ and (La _0.98 Ce _0.02 ) ₆ Si ₄ S ₁₇ by light excitation. FIG. 7 shows (Y _0.495 Gd _0.495 Ce _0.01 ) ₄ (SiS ₄ ) ₃ and (Y _0.495 La _0.495 Ce _0.01 ) ₄ (SiS ₄ ) ₃ + (Y _{0. 495} is a graph showing a powder X-ray diffraction results of _{La 0.495 Ce 0.01) 6 Si 4} S 17. FIG. 8 shows (Y _0.495 Gd _0.495 Ce _0.01 ) ₄ (SiS ₄ ) ₃ and (Y _0.495 La _0.495 Ce _0.01 ) ₄ (SiS ₄ ) ₃ + (Y _{0. 495} is a graph showing the emission spectrum and the emission excitation spectrum by photoexcitation of _{La 0.495 Ce 0.01) 6 Si 4} S 17. FIG. 9 is a graph showing a powder X-ray diffraction result of (Ln _0.99 Tb _0.01 ) ₄ (SiS ₄ ) ₃ (where Ln = Y or Gd). FIG. 10 is a graph showing an emission spectrum and an emission excitation spectrum of (Ln _0.99 Tb _0.01 ) ₄ (SiS ₄ ) ₃ (where Ln = Y or Gd) by light excitation. FIG. 11 is a graph showing the powder X-ray diffraction results immediately after preparation of (Y _0.99 Ce _0.01 ) ₄ (SiS ₄ ) ₃ and after storage in the atmosphere for 4 months. FIG. 12 is a graph showing powder X-ray diffraction results immediately after the production of (Gd _0.99 Ce _0.01 ) ₄ (SiS ₄ ) ₃ and after storage in the atmosphere for 4 months. Figure 13 _is a graph showing the _{(La 0.99 Ce 0.01) 6 Si} 4 powder X-ray diffraction results after the stored 4 months in the air immediately after the production of S _17. FIG. 14 is a graph showing powder X-ray diffraction results immediately after the production of (Ca _0.99 Eu _0.01 ) ₂ SiS ₄ and after storage in the atmosphere for 4 months. FIG. 15 is a schematic cross-sectional view of an example of the light emitting device according to the present embodiment.

  Hereinafter, although the embodiment concerning the present invention is described, the illustration in this embodiment does not limit the present invention.

Among thiosilicates, Eu ₂ SiS ₄ having europium, which is a rare earth ion, as a constituent element is a phosphor that has been reported to emit yellow light (Non-Patent Documents 3 to 5). This phosphor has a low emission intensity due to a phenomenon called concentration quenching in which the emission efficiency of the phosphor is reduced when a large amount of Eu, which is the emission center, is contained. Have In the present invention, in view of this characteristic, if a rare earth thiosilicate having no absorption edge in the visible light region can be used as a base crystal, the base crystal has high stability and does not inhibit light emission at the luminescent center. The knowledge that it is highly possible was obtained.

In the present invention, Gd ₄ (SiS ₄ ) ₃ reported as a magnetic material in Non-Patent Document 6 and Non-Patent Document as a result of earnest research on the thiosilicate crystal listed as a candidate for a base crystal with the above knowledge. It was found that Ce ₆ Si ₄ S ₁₇ reported as an industrial pigment in No. 7 is useful.

Since Gd ₄ (SiS ₄ ) ₃ is reported as a white crystal, it is considered that at least the band gap has an energy higher than the visible light region, and functions as a phosphor host crystal. Gd ³⁺ can also be a light emission center, but since it does not absorb in the visible light region, it is considered that light emission from the activated light emission center is not inhibited. Further, it is considered that a host crystal can be obtained when gadolinium (Gd) is substituted with a trivalent cation such as scandium (Sc), yttrium (Y), or lutetium (Lu), which are other rare earths. Sc, Y, and Lu can be preferably replaced because their ion radii are close to those of Gd.

Further, Ce ₆ Si ₄ S ₁₇ has been studied as a pigment, but is reported to emit yellowish green light weakly by photoexcitation. The weak light emission is considered to be due to the concentration quenching of the light-emitting ions, and it is highly possible that strong light emission is obtained by substituting with non-light-emitting ions in the same manner as Eu ₂ SiS ₄ . If substitution with other ions is desired without changing the space group to which the crystal belongs, this can be achieved by using one having a close ion radius. Therefore, Ce can be substituted with the same rare earth element to obtain a parent crystal, and preferably, the ionic radius is close, and the parent crystal is substituted with lanthanum (La), which is a rare earth element having no 4f orbital electrons. The knowledge that it was possible was obtained.

  As an element used as an activator serving as a luminescent center, rare earth, Mn, Bi, and the like are practically used, and it is suitable to use at least one of these in view of luminescent characteristics. Examples of the rare earth include Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Yb in addition to the above-described Sc, Y, Gd, Lu, and La.

  As a result of earnest research by obtaining the above knowledge, the present inventors found a rare earth thiosilicate base crystal and succeeded in functioning as a phosphor by adding an activator thereto, thereby completing the present invention. I came to let you. The detailed composition of the phosphor is as follows.

<Phosphor of formula (1)>
A phosphor according to an embodiment of the present invention (hereinafter, also referred to as a phosphor of formula (1)) may be represented by general formula (1): (Ln _1-x RE _x ) ₄ (SiS ₄ ) ₃ . Ln is at least one selected from the group consisting of Sc, Y, Gd and Lu, and RE is La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Bi And at least one selected from the group consisting of Mn, and x is 0.001 ≦ x ≦ 0.6.

  In the general formula (1), Ln is one or more selected from the group consisting of Sc, Y, Gd, and Lu, and these elements may be used alone or in combination at any ratio. Ln preferably contains Y and / or Gd, more preferably at least Y.

  From the viewpoint of storage stability, Ln preferably contains at least Gd, and more preferably contains Y together with Gd.

  When Ln contains Y, Ln can contain one or more selected from the group consisting of Sc, Gd and Lu together with Y. In this case, the composition ratio of Y in Ln is preferably 0.5 or more, and more preferably 0.8 or more.

  RE is at least one selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Bi, and Mn, and these elements can be used alone or arbitrarily. You may use combining in the ratio of. The RE preferably contains at least Ce.

  When RE contains Ce, it can contain at least one selected from the group consisting of La, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Bi, and Mn together with Ce. . In this case, the composition ratio of Ce in RE is preferably 0.001 or more, and more preferably 0.01 or more.

  Examples of the combination of Ln and RE include those in which Ln contains at least Y and / or Gd and RE contains at least Ce. With such a combination, high luminous efficiency can be obtained.

In addition, examples of the combination of Ln and RE include those in which Ln includes at least Y and / or Gd, and RE includes at least Tb. In such a combination, light is absorbed by Ln ₄ (SiS ₄ ) ₃ (just Ln is Y and / or Gd), and Tb ³⁺ is indirectly excited, and Tb ³⁺ is directly excited. It is possible to emit light by absorbing excitation light with higher efficiency.

  x is 0.001 ≦ x ≦ 0.6 and represents the number of moles of RE. Preferably x is 0.005 or more, more preferably x is 0.01 or more. Further, x is preferably 0.5 or less, more preferably 0.1 or less, and still more preferably 0.05 or less. By setting it as this range, excitation efficiency and luminous efficiency can be improved.

  In particular, when RE contains at least Tb, even if x is set to 0.1 or more, further 0.5 or more, the emission intensity can be further prevented from decreasing and the emission efficiency can be further increased.

The crystal structure of the phosphor of formula (1) is preferably monoclinic (space group P2 _{1 /} n, _No. 14). Thereby, the luminous efficiency can be increased. Since the phosphor of formula (1) is a monoclinic crystal, absorption in the visible light region is reduced, and light emission at the added emission center is not inhibited, so that the light emission efficiency can be increased.

<Phosphor of formula (2)>
The phosphor according to another embodiment of the present invention (hereinafter sometimes referred to as the phosphor of the formula (2)) is represented by the general formula (2): (R _1-y RE _y ) ₆ Si ₄ S ₁₇ . R is La and RE is selected from the group consisting of Sc, Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, and Mn. It is one or more types, and y is 0.001 ≦ y ≦ 0.1.

  RE is at least one selected from the group consisting of Sc, Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, and Mn, and these elements May be used alone or in combination at any ratio. The RE preferably contains at least Ce.

  When RE contains Ce, it is one type selected from the group consisting of Sc, Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, and Mn together with Ce. The above can be included. In this case, the composition ratio of Ce in RE is preferably 0.001 or more, and more preferably 0.01 or more.

  As a combination of R and RE, those in which R is La and RE contains at least Ce are preferable. With such a combination, high luminous efficiency can be obtained.

  y is 0.001 ≦ y ≦ 0.1 and represents the number of moles of RE. Preferably y is 0.005 or more, more preferably y is 0.01 or more. Moreover, y is preferably 0.05 or less, more preferably 0.03 or less. By setting it as this range, excitation efficiency and luminous efficiency can be improved.

  The crystal structure of the phosphor of formula (2) is preferably triclinic (space group P-1, No. 2). Thereby, the luminous efficiency can be increased. Since the phosphor of the formula (2) is triclinic, absorption in the visible light region is reduced, and light emission at the added emission center is not inhibited, so that the light emission efficiency can be increased.

  The phosphors of the above formulas (1) and (2) may be used in combination. The phosphor of formula (1) and the phosphor of formula (2) are in a mass ratio of, for example, 1:90 to 90: 1, preferably 20:80 to 80:20, more preferably 40: 60-60: 40. This mixture may be adjusted by mixing the phosphor of the formula (1) and the phosphor of the formula (2), and the phosphor and the formula of the formula (1) by adjusting the raw material ratio in the manufacturing method described later. The phosphor mixed with the phosphor of (2) may be directly adjusted.

  The phosphors of the above formulas (1) and (2) may contain other components as long as the effects of the present invention are not impaired. For example, the reaction residue may contain Si compounds, optional additives, other phosphors, and the like.

<Characteristics of phosphor>
The phosphors of the above formulas (1) and (2) can have the following characteristics.

  The emission peak wavelength of the phosphor of the formula (1) is not particularly limited because the emission spectrum differs depending on the selection of the elements of Ln and RE. For example, when excited with light having a wavelength of 300 to 500 nm, the emission peak wavelength is 450 nm or more, preferably 500 nm or more, more preferably 530 nm or more, and 650 nm or less, preferably 600 nm or less, more preferably 580 nm or less. is there.

  The emission peak wavelength of the phosphor of the formula (2) is not particularly limited because the emission spectrum differs depending on the selection of R and RE elements. For example, when excited with light having a wavelength of 300 to 500 nm, the emission peak wavelength is 400 nm or more, preferably 450 nm or more, more preferably 480 nm or more, and 650 nm or less, preferably 600 nm or less, more preferably 570 nm or less. is there.

  When the emission peak wavelength is in the above-described range, a phosphor suitable for a white LED can be provided, and color rendering can be improved.

  The full width at half maximum of the emission peak of the phosphors of the formulas (1) and (2) varies depending on the selection of the elements Ln, R, and RE, and is not particularly limited. Usually, the full width at half maximum is about 1 to 300 nm, for example, 50 to 150 nm.

  The excitation peak wavelengths of the phosphors of the formulas (1) and (2) are not particularly limited because the emission excitation spectrum differs depending on the selection of the elements Ln, R and RE, respectively. For example, the excitation peak wavelength is 300 nm or more, preferably 350 nm or more, and 500 nm or less, preferably 480 nm or less.

  When the excitation peak wavelength is in the above-described range, it is possible to provide a phosphor that can be efficiently excited with a blue LED from near ultraviolet. Since this near-ultraviolet to blue LED can be used as an excitation light source for a white LED, a phosphor suitable for the white LED can be provided.

  For example, in the formula (1), when Ln is Y and / or Gd and RE is Ce, the emission peak wavelength is about 450 to 600 nm, particularly about 550 to 600 nm, and the full width at half maximum is about 100 to 150 nm. The peak wavelength is preferably about 350 to 450 nm.

  In the formula (1), when Ln is Y and / or Gd and RE is Tb, a plurality of emission peak wavelengths are generated. For example, the main peak is preferably about 530 to 570 nm, particularly preferably about 530 to 550 nm. The other peaks are preferably 480 to 500 nm, 580 to 600 nm, and 610 to 630 nm. The full width at half maximum is about 1 to 50 nm, particularly 5 to 20 nm, and the excitation peak wavelength is preferably about 330 to 400 nm. Although Tb is not highly light-absorbing, the host crystal containing Y absorbs light, so that the light emission efficiency can be increased.

  In the formula (2), when R is La and RE is Ce, the emission peak wavelength is about 470 to 530 nm, the full width at half maximum is about 80 to 120 nm, and the excitation peak wavelength is preferably about 350 to 450 nm. .

<Method for producing phosphor>
Although it does not specifically limit as a manufacturing method of the fluorescent substance by this embodiment, A preferable example is demonstrated below.

  As a method for producing a phosphor according to an embodiment of the present invention, a compound containing at least one selected from the group consisting of Sc, Y, La, Gd, and Lu (hereinafter sometimes referred to as Compound A), and Ce. , Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Bi, and a compound containing at least one selected from the group consisting of Bi and Mn (hereinafter sometimes referred to as compound B), and Si. And / or a step of mixing a raw material containing a Si compound (hereinafter sometimes referred to as Si source) and S and / or a S compound (hereinafter sometimes referred to as S source), and this raw material. Including a step of firing at 1000 ° C. to 1150 ° C., including compound A and at least one selected from the group consisting of Sc, Y, La, Gd and Lu, and Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm The stoichiometric ratio in the mixture with compound B containing one or more selected from the group consisting of Yb, Bi and Mn is 0.999: 0.001 to 0.4: 0.6. .

  According to such a manufacturing method, a phosphor having the above composition and crystal structure can be obtained, and a phosphor having high luminance, high efficiency, and high stability can be obtained.

  Examples of the compound A include sulfides, oxides, hydroxides, carbonates, nitrates, sulfates, oxalates, carboxylates and halides of Sc, Y, La, Gd, and Lu.

  Further, as compound B, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Bi, Mn sulfide, oxide, hydroxide, carbonate, nitrate, sulfate , Oxalate, carboxylate, halide and the like.

Specific examples of the Sc source include Sc ₂ S ₃ , Sc ₂ O ₃ , Sc (OH) ₃ , ScCl ₃ , Sc (NO ₃ ) ₃ .nH ₂ O, Sc ₂ (SO ₄ ) ₃ .nH ₂ O, Sc ₂ (C ₂ O ₄ ) ₃ · nH ₂ O can be exemplified.

Specific examples of the Y source include Y ₂ S ₃ , Y ₂ (CO ₃ ) ₃ , Y ₂ O ₃ , Y (OH) ₃ , YCl ₃ , YBr ₃ , Y ₂ (CO ₃ ) ₃ .3H ₂ O, Y (NO ₃ ) ₃ · 6H ₂ O, Y ₂ (SO ₄ ) ₃ , Y ₂ (C ₂ O ₄ ) ₃ · 9H ₂ O and the like can be mentioned.

Specific examples of the La source include La ₂ S ₃ , La ₂ O ₃ , La (OH) ₃ , LaCl ₃ , LaBr ₃ , La ₂ (CO ₃ ) ₃ .H ₂ O, La (NO ₃ ) ₃ · 6H. _{2 O, La 2 (SO 4} ) 3, La 2 (C 2 O 4) can be cited 3 · 9H ₂ O and the like.

Specific examples of the Gd source include Gd ₂ S ₃ , Gd ₂ O ₃ , Gd (OH) ₃ , GdCl ₃ , Gd (NO ₃ ) ₃ · 5H ₂ O, Gd ₂ (C ₂ O ₄ ) ₃ · 10H _2. O etc. can be mentioned.

Specific examples of the Lu source include Lu ₂ S ₃ , Lu ₂ O ₃ , LuCl ₃ , Lu (NO ₃ ) ₃ .8H ₂ O, Lu ₂ (OCO) ₃ .6H ₂ O, and the like.

Specific examples of the Ce source include Ce ₂ S ₃ , CeCl ₃ , Ce ₂ (CO ₃ ) ₃ .5H ₂ O, CeO ₂ , Ce ₂ (SO ₄ ) ₃ , Ce (NO ₃ ) ₃ · 6H ₂ O, _{Ce 2 (C 2 O 4)} 3 · 9H 2 O, mention may be made of Ce _{(OH) 3} and the like.

Specific examples of the Pr source include Pr ₂ S ₃ , PrCl ₃ , Pr ₂ O ₃ , Pr ₆ O ₁₁ , PrCl ₃ · 7H ₂ O, Pr (CO ₃ ) ₃ · 8H ₂ O, Pr (NO ₃ ) ₃ · _6H 2 _O, mention may be made of _{Pr (SO 4) 3, Pr} (SO 4) 3 · 8H 2 O, Pr 2 (C 2 O 4) 3 · 10H 2 O and the like.

Specific examples of the Nd source include Nd ₂ S ₃ , NdCl ₃ , NdBr ₃ , Nd ₂ O ₃ , NdCl ₃ · 6H ₂ O, Nd (CO ₃ ) ₃ · 6H ₂ O, Nd (NO ₃ ) ₃ · nH ₂ O, Nd (SO ₄ ) ₃ · 8H ₂ O, Nd ₂ (C ₂ O ₄ ) ₃ · 10H ₂ O, and the like.

Specific examples of the Sm source include Sm ₂ S ₃ , SmCl ₃ , Sm ₂ O ₃ , SmCl ₃ · nH ₂ O, Sm (NO ₃ ) ₃ · nH ₂ O, Sm (SO ₄ ) ₃ · nH ₂ O, sm _{2 (C 2 O 4)} can be cited 3 · nH ₂ O and the like.

Specific examples of the Eu source include EuS, EuCl ₃ , EuCl ₃ .nH ₂ O, Eu (NO ₃ ) ₃ .nH ₂ O, Eu (SO ₄ ) ₃ .nH ₂ O, Eu ₂ (C ₂ O ₄ ). ₃ , nH ₂ O and the like.

Specific examples of the Tb source include Tb ₄ S ₇ , Tb ₄ O ₇ , Tb ₂ (SO ₄ ) ₃ , Tb (NO ₃ ) ₃ .nH ₂ O, Tb ₂ (C ₂ O ₄ ) ₃ · 10H ₂ O , TbCl _{3 and the} like.

Specific examples of the Dy source include Dy ₂ S ₃ , DyCl ₃ , Dy ₂ O ₃ , DyCl ₃ .nH ₂ O, Dy (CO ₃ ) ₃ , Dy (NO ₃ ) ₃ .5H ₂ O, Dy (SO ₄ ) ₃ · 8H ₂ O, Dy ₂ (C ₂ O ₄ ) ₃ · 10H ₂ O, and the like.

Specific examples of the Ho source include Ho ₂ S ₃ , HoCl ₃ , Ho ₂ O ₃ , HoCl ₃ · 6H ₂ O, Ho (CO ₃ ) ₃ · nH ₂ O, Ho (NO ₃ ) ₃ · 5H ₂ O, Examples include Pr (SO ₄ ) ₃ · 8H ₂ O, Ho ₂ (C ₂ O ₄ ) ₃ · 10H ₂ O, and the like.

Specific examples of the Er source include Er ₂ S ₃ , ErCl ₃ , Er ₂ O ₃ , ErCl ₃ · 6H ₂ O, Er (NO ₃ ) ₃ · 5H ₂ O, Er (SO ₄ ) ₃ · nH ₂ O, Er ₂ (C ₂ O ₄ ) ₃ · 10H ₂ O and the like can be mentioned.

Specific examples of the Tm source include Tm ₂ S ₃ , TmCl ₃ , Tm ₂ O ₃ , TmCl ₃ · 6H ₂ O, Tm (NO ₃ ) ₃ · 5H ₂ O, Tm (SO ₄ ) ₃ · 8H ₂ O, tm _{2 (C 2 O 4)} can be cited 3 · 6H ₂ O and the like.

Examples of Yb _source, mention may be made of _{Yb 2 S 3, YbCl 3,} YbBr 3, YbI 3, Yb 2 O 3, YbCl 3 · 6H 2 O, Pr (NO 3) 3 · 6H 2 O , etc. .

Specific examples of the Bi source include Bi ₂ S ₃ , BiCl ₃ , BiBr ₃ , BiI ₃ , Bi (NO ₃ ) ₃ .nH ₂ O, and the like.

Specific examples of the Mn source include MnS, MnCl ₂ , MnCl ₂ .4H ₂ O, MnCO ₃ , Mn (NO ₃ ) ₂ .6H ₂ O, MnSO ₄ .4-5H ₂ O, MnC ₂ O _{4 and the} like. be able to.

  Examples of the Si source include Si alone, Si sulfide, oxide, hydroxide, carbonate, nitrate, sulfate, oxalate, carboxylate, and halide.

Specific examples of the Si source include Si, SiS ₂ and SiS.

  Examples of the S source include S alone, S oxides, hydroxides, carbonates, nitrates, sulfates, oxalates, carboxylates and halides. Moreover, sulfide can be used as the S source among the compounds A, B and Si source compounds described above.

Further, if a gas component such as hydrogen sulfide to the sintering atmosphere in the firing step (H 2 _S) and carbon disulfide (CS _2), also a S source these compounds.

  These raw materials may be used alone or in combination.

  The stoichiometric ratio in the mixture of Compound A and Compound B is 0.999: 0.001 to 0.4: 0.6. Thereby, the phosphor of the formula (1) and / or the formula (2) can be obtained. This ratio can be adjusted according to the composition of the target phosphor. In the firing step, each element contained in Compound A and Compound B does not volatilize and remains almost in its entirety, so it may be blended with an accurate composition.

In order to obtain the phosphor of the formula (1): (Ln _1-x RE _x ) ₄ (SiS ₄ ) ₃ , Sc, Y, Gd, Lu or a combination thereof can be used.

  In order to obtain the phosphor of formula (1), the stoichiometric ratio is preferably 0.999: 0.001 to 0.4: 0.6, more preferably 0.995: 0.005. To 0.5: 0.5, more preferably 0.99: 0.01 to 0.9: 0.1, and even more preferably 0.99: 0.01 to 0.95: 0.05. It is.

In order to obtain the phosphor of formula (2): (R _1-y RE _y ) ₆ Si ₄ S ₁₇ , La can be used as a rare earth element contained in compound A having a large ionic radius.

  In order to obtain the phosphor of formula (2), the stoichiometric ratio is preferably 0.999: 0.001 to 0.9: 0.1, more preferably 0.995: 0.005. It is -0.95: 0.05, More preferably, it is 0.99: 0.01-0.97: 0.03.

  As the compound A, a compound containing Sc, Y, Gd, Lu or a combination thereof and a compound containing La can be mixed and used. In this case, since the ionic radii of Sc, Y, Gd, Lu, and La are greatly different, Sc, Y, Gd, and Lu are synthesized as phosphors of formula (1), and La is a phosphor of formula (2). May be synthesized. In this case, the stoichiometric ratio between the compound containing Sc, Y, Gd, Lu, or a combination thereof and the compound containing La is 0.475: 0.525-0.99: 0.01. preferable. That is, two types of phosphors represented by the following formula (3) can be synthesized simultaneously.

Equation _{(3) :( Ln 1-x} (R 1-x-a RE) x) 4 (SiS 4) 3 + (R 1-y (Ln (1-y-b) RE) y) 6 Si 4 S ₁₇
In the formula (3), Ln is at least one selected from the group consisting of Sc, Y, Gd and Lu, R is La, RE is Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, It is one or more selected from the group consisting of Er, Tm, Yb, Bi and Mn.

  x is preferably 0.001 ≦ x ≦ 0.6, and y is preferably 0.001 ≦ y ≦ 0.1. a is 0.475 × (1-x) ≦ a ≦ 0.99 × (1-x), and b is 0.475 × (1-y) ≦ b ≦ 0.99 × (1-y). Preferably there is.

By using the Si source and S source in excess of the stoichiometric ratio, the raw materials can react without excess and deficiency, and a phosphor having the desired chemical composition can be obtained. Since the Si source and the S source are volatilized to some extent in the firing step, it is preferable to mix them at a ratio equal to or higher than the stoichiometric ratio. Excess S source is removed as a gas component such as H ₂ S or CS _{2 in} the firing step. The Si source adheres to gas components such as H ₂ S and CS ₂ and is removed. As a result, the phosphor can be obtained with the Si source and the S source finally having an appropriate composition range.

  For example, the addition amount of the Si source and the S source varies depending on the firing conditions, but the Si and S are added in an amount in the range of 1 to 20 mol%, respectively, from the theoretically calculated composition. More preferably, the amount is increased by 5 to 15 mol%, more preferably about 10 mol%.

  Thus, even when Si source and S source are blended excessively, the composition of the obtained phosphor shows the composition of formula (1) or formula (2). It should be noted that even if the Si source remains, the light emission characteristics are not affected. Since the S source is removed as a gas component, it often does not remain.

  The method for mixing the compound A, the compound B, the Si source and the S source is not particularly limited, and examples thereof include a dry mixing method and a wet mixing method. As a dry mixing method, there is a method in which raw materials are batched or divided, and are charged into a mixing apparatus and mixed. As the wet mixing method, there is a method in which a raw material is added to a medium such as water, is batched or divided, is introduced into a mixing apparatus and mixed, and then the medium is removed. As the mixing device, a ball mill, a V-type mixer, a stirrer, a jet mill or the like can be used.

  In addition, when using S source as a gas component in a baking process, after mixing the compound A, compound B, and Si source, the gas component used as S source in a baking process is added, and the raw material containing S source is added. Will be mixed.

  In the step of firing the mixture, the firing temperature is 1000 ° C. to 1150 ° C., preferably 1020 ° C. or higher, more preferably 1040 ° C. or higher, and preferably 1100 ° C. or lower, more preferably It is 1080 degrees C or less.

  When the firing temperature is 1000 ° C. or higher, the crystal structure can be monoclinic in the phosphor of formula (1) and triclinic in the phosphor of formula (2). Moreover, particle growth can be promoted. In addition, the firing time required for sufficient firing can be set short.

  When the crystal structure is as described above, the absorption of the phosphor in the visible light region can be reduced, the light emission of the added fluorescence center can be prevented, and the light emission efficiency can be increased. On the other hand, if the firing temperature is less than 1000 ° C., hexagonal crystals may be generated. This hexagonal crystal has the same element types as those in the formulas (1) and (2), but the element ratio, that is, the composition is different. This hexagonal crystal becomes a host crystal having an absorption band in the visible light region, and may inhibit light emission from the added emission center, which may reduce the light emission efficiency.

  It can prevent that a raw material fuse | melts and becomes glassy because a calcination temperature is 1150 degrees C or less. In particular, it is possible to prevent Sc, Y, La, Gd and Lu from melting among the raw materials. It is also desirable from the viewpoint of durability of the firing furnace.

  The pressure at the time of baking is not particularly limited, and is usually not less than normal pressure.

  The firing time varies depending on the firing temperature, pressure, etc., but is usually 1 to 48 hours, preferably 12 to 24 hours.

  The atmosphere during firing is not particularly limited, and examples thereof include air, nitrogen, argon, carbon monoxide, hydrogen, and the like, or a combination thereof. An inert gas atmosphere is preferable, and for example, nitrogen, argon, or the like is more preferable.

As an atmosphere at the time of baking, gas components such as H ₂ S and CS ₂ can be used and used as an S source. In this case, the above-described inert gas such as nitrogen or argon may be mixed with the S source gas. Moreover, you may mix | blend the raw material of another powder together as S source. It is also possible to use only a gas component as the S source. Further, gas components such as H 2 _S and CS ₂ also has the effect of suppressing the decomposition of the product.

Further, in the case of using a powder such as S and / or SiS ₂ as S source, the calcination is vacuum, it is preferably carried out in filled in a closed tube with an inert gas or a reducing atmosphere. As the reducing atmosphere, H ₂ S or CS ₂ described above may be used, or CO, H ₂ , HCHO (formaldehyde), or the like may be used.

  The cooling step after firing is not particularly limited, and may be gradually cooled in a furnace or rapidly cooled in the atmosphere. Preferably, cooling is performed at a cooling rate of 100 ° C./min or more. More preferably, it is 150 degreeC / min or more, More preferably, it is 180 degreeC / min or more. Such rapid cooling can prevent the product from decomposing.

  The cooling can be performed at a time from a firing temperature of 1000 to 1150 ° C. to room temperature. Further, in order to prevent damage to the filter medium or the like, it may be cooled after being annealed to some extent and annealed. In this case, it is preferable to gradually cool to 500 to 800 ° C. and then cool to room temperature at 100 ° C./min or more.

  Moreover, in order to prevent decomposition | disassembly of a product, it is preferable to perform a cooling process in a vacuum or inert gas atmosphere.

  After the above-described firing and cooling, washing, dispersion treatment, drying, classification, and the like can be performed as necessary.

<Light emitting device>
A light emitting device according to an embodiment of the present invention includes the above-described phosphor.

  The above-mentioned phosphors include light-emitting devices using ultraviolet excitation such as liquid crystal backlights and fluorescent lamps, light-emitting devices using vacuum ultraviolet excitation such as PDP (plasma display panel) and rare gas lamps, CRTs (cathode ray tubes) and FEDs (fields). It can be used for a light emitting device such as an emission display) such as a light emitting device by electron beam excitation, a light emitting device by X ray excitation such as an X-ray imaging device, and a light emitting device by electric field excitation such as an inorganic EL display.

  This light emitting device can be used as a light source for an image display device such as a display device or a lighting device such as a white LED. In the display device, a light emitting device can be used as a backlight of an LCD (liquid crystal display) or the like.

  FIG. 15 is a schematic cross-sectional view of an example of the light emitting device according to the present embodiment. In FIG. 15, the light emitting device 1 includes a light emitting element 2 and a light emitting layer 3 formed on the light emitting element 2. The light emitting layer 3 includes the above-described phosphor. When light is received from the light emitting element 2, the phosphor is excited to emit light. When the light emitting layer 3 includes the phosphor described above, white light can be emitted, and the light emitting device can be used as a white LED.

The phosphor included in the light emitting layer 3 may be only the above-described phosphor, or may further include other phosphors. Specific examples of other phosphors include BaMgAl ₁₀ O ₁₇ : Eu, (Ba, Sr, Ca) (Al, Ga) ₂ S ₄ : Eu, BaMgAl ₁₀ O ₁₇ : (Eu, Mn), BaAl ₁₂ O ₁₉ : (Eu, Mn), (Ba, Sr, Ca) S: (Eu, Mn), YBO ₃ : (Ce, Tb), Y ₂ O ₃ : Eu, Y ₂ O ₂ S: Eu, YVO ₄ : Eu (Ca, Sr) S: Eu, SrY ₂ O ₄ : Eu, Ca—Al—Si—O—N: Eu, (Ba, Sr, Ca) Si ₂ O ₂ N ₂ : Eu, β-sialon, or CaSc ₂ O ₄ : Ce, Li— (Ca, Mg) —Ln—Al—O—N: Eu (where Ln represents a rare earth metal element other than Eu), etc. Or a combination of two or more That.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

(Example _{1: (Y 0.99 Ce 0.01)} 4 (SiS 4) 3)
Y ₂ S ₃ , Ce ₂ S ₃ , Si, S are used as raw materials, and the raw material ratio is Y ₂ S ₃ : Ce ₂ S ₃ : Si: S = 1.98: 0.02: 3.3: 6 in molar ratio. Weighed out to a .6. At this time, Si and S were added in an amount of 10 mol% in addition to those determined stoichiometrically.

After the raw materials were dry mixed for 15 minutes using a mortar and pestle, the raw material mixture was vacuum sealed at 10 ⁻² Pa in a quartz tube having an inner diameter of 9 mm and a length of about 150 mm. A quartz tube ampule in which the raw material mixture was vacuum-sealed was heated in an electric furnace, and the raw material mixture was reacted under the conditions of a firing temperature of 1050 ° C. and a firing time of 24 hours.

After firing, the product is taken out from the electric furnace, rapidly cooled to room temperature over 5 minutes (cooling rate: about 200 ° C./minute), and the fluorescence represented by the formula (Y _0.99 Ce _0.01 ) ₄ (SiS ₄ ) ₃ Body 1 was obtained.

When a powder X-ray diffraction pattern of the phosphor 1 was measured, a crystal structure (monoclinic (space group P2 ₁ / n) similar to that of the monoclinic Gd ₄ (SiS ₄ ) ₃ reported in Non-Patent Document 6 was obtained. No. 14), the same applies hereinafter), and no compounds including raw materials other than the target product were detected. The obtained results are shown in FIG. In FIG. 1, a diffraction pattern simulated from Non-Patent Document 6 is shown at the bottom.

  The light emission characteristics of the phosphor 1 were evaluated by an emission spectrum and an emission excitation spectrum. A He—Cd laser (325 nm) was used as the excitation light for the measurement of the emission spectrum, and a xenon arc lamp was used as the excitation light for the measurement of the emission excitation spectrum. It has been found that the phosphor 1 is excited by light having a wavelength of 350 nm or more and 480 nm or less and emits light having a maximum emission intensity at a wavelength of 545 nm. The results are shown in FIG.

(Example 2: (Y _0.98 Ce _0.02 ) ₄ (SiS ₄ ) ₃ )
Y ₂ S ₃ , Ce ₂ S ₃ , Si, S are used as raw materials, and the raw material ratio is Y ₂ S ₃ : Ce ₂ S ₃ : Si: S = 1.96: 0.04: 3.3: 6 in molar ratio. Weighed out to a .6. At this time, Si and S were added in an amount of 10 mol% in addition to those determined stoichiometrically.

In the same manner as in Example 1, mixing, firing, and rapid cooling were performed to obtain a phosphor 2 represented by the formula (Y _0.98 Ce _0.02 ) ₄ (SiS ₄ ) ₃ .

When the powder X-ray diffraction pattern of the phosphor 2 was measured, it was found that it had the same crystal structure as the monoclinic Gd ₄ (SiS ₄ ) ₃ reported in Non-Patent Document 6, and the desired production Compounds containing raw materials other than the product were not detected. The obtained results are also shown in FIG.

  The light emission characteristics of the phosphor 2 were evaluated in the same manner as in Example 1 above. It was found that the phosphor 2 was excited by light having a wavelength of 350 nm or more and 480 nm or less and emitted light having a maximum emission intensity at a wavelength of 560 nm. The results are shown in FIG.

(Example 3: (Gd _0.99 Ce _0.01 ) ₄ (SiS ₄ ) ₃ )
Gd ₂ S ₃ , Ce ₂ S ₃ , Si, and S are used as raw materials, and the raw material ratio in terms of molar ratio is Gd ₂ S ₃ : Ce ₂ S ₃ : Si: S = 1.98: 0.02: 3.3: 6 Weighed out to a .6. At this time, Si and S were added in an amount of 10 mol% in addition to those determined stoichiometrically.

In the same manner as in Example 1, mixing, firing and rapid cooling were performed to obtain a phosphor 3 represented by the formula (Gd _0.99 Ce _0.01 ) ₄ (SiS ₄ ) ₃ .

When the powder X-ray diffraction pattern of the phosphor 3 was measured, it was found that it had a crystal structure similar to that of the monoclinic Gd ₄ (SiS ₄ ) ₃ reported in Non-Patent Document 6, and the desired production Compounds containing raw materials other than the product were not detected. The obtained results are shown in FIG.

  The light emission characteristics of the phosphor 3 were evaluated in the same manner as in Example 1 above. It has been found that the phosphor 3 is excited by light having a wavelength of 350 nm or more and 480 nm or less and emits light having a maximum emission intensity at a wavelength of 570 nm. The results are shown in FIG.

(Example 4: (Gd _0.98 Ce _0.02 ) ₄ (SiS ₄ ) ₃ )
Gd ₂ S ₃ , Ce ₂ S ₃ , Si, and S are used as raw materials, and the raw material ratio in terms of molar ratio is Gd ₂ S ₃ : Ce ₂ S ₃ : Si: S = 1.96: 0.04: 3.3: 6 Weighed out to a .6. At this time, Si and S were added in an amount of 10 mol% in addition to those determined stoichiometrically.

In the same manner as in Example 1, mixing, firing, and rapid cooling were performed to obtain a phosphor 4 represented by the formula (Gd _0.98 Ce _0.02 ) ₄ (SiS ₄ ) ₃ .

When the powder X-ray diffraction pattern of the phosphor 4 was measured, it was found that it had a crystal structure similar to that of the monoclinic Gd ₄ (SiS ₄ ) ₃ reported in Non-Patent Document 6, and the desired production Compounds containing raw materials other than the product were not detected. The obtained results are shown in FIG.

  The light emission characteristics of the phosphor 4 were evaluated in the same manner as in Example 1 above. It has been found that the phosphor 4 is excited by light having a wavelength of 350 nm or more and 480 nm or less and emits light having a maximum emission intensity at a wavelength of 570 nm. The results are shown in FIG.

(Example _{5: (La 0.99 Ce 0.01)} 6 Si 4 S 17)
La ₂ S ₃ , Ce ₂ S ₃ , Si, S are used as raw materials, and the raw material ratio in terms of molar ratio is La ₂ S ₃ : Ce ₂ S ₃ : Si: S = 2.97: 0.03: 4.4: 8 .8 to weigh. At this time, Si and S were added in an amount of 10 mol% in addition to those determined stoichiometrically.

In the same manner as in Example 1, mixing, firing, and rapid cooling were performed to obtain a phosphor 5 represented by the formula (La _0.99 Ce _0.01 ) ₆ Si ₄ S ₁₇ .

When the powder X-ray diffraction pattern of the phosphor 5 was measured, the crystal structure (triclinic (space group P-1, No. 1) of triclinic Ce ₆ Si ₄ S ₁₇ reported in Non-Patent Document 7 was measured. 2), the same applies hereinafter). Diffraction lines from some by-products were observed, but the remaining diffraction pattern was from the same crystal structure as Ce ₆ Si ₄ S ₁₇ reported in Non-Patent Document 7 showing the simulation results at the bottom. Consistent with diffraction lines. Diffraction lines from some by-products are derived from La (indicated by arrows in the figure). The obtained results are shown in FIG.

  The light emission characteristics of the phosphor 5 were evaluated in the same manner as in Example 1. It has been found that the phosphor 5 is excited by light having a wavelength of 350 nm or more and 470 nm or less and emits light having a maximum emission intensity at a wavelength of 500 nm. The results are shown in FIG.

(Example 6: (La _0.98 Ce _0.02 ) ₆ Si ₄ S ₁₇ )
La ₂ S ₃ , Ce ₂ S ₃ , Si, S are used as raw materials, and the raw material ratio is La ₂ S ₃ : Ce ₂ S ₃ : Si: S = 2.94: 0.06: 4.4: 8. .8 to weigh. At this time, Si and S were added in an amount of 10 mol% in addition to those determined stoichiometrically.

In the same manner as in Example 1, mixing, firing, and rapid cooling were performed to obtain phosphor 6 represented by the formula (La _0.98 Ce _0.02 ) ₆ Si ₄ S ₁₇ .

When the powder X-ray diffraction pattern of the phosphor 6 was measured, it was found that it had the same crystal structure as that of the triclinic Ce ₆ Si ₄ S ₁₇ reported in Non-Patent Document 7. Diffraction lines from some by-products were observed, but the remaining diffraction pattern was from the same crystal structure as Ce ₆ Si ₄ S ₁₇ reported in Non-Patent Document 7 showing the simulation results at the bottom. Consistent with diffraction lines. Diffraction lines from some by-products are derived from La (indicated by arrows in the figure). The obtained results are shown in FIG. In FIG. 5, a diffraction pattern simulated from Non-Patent Document 7 is shown at the bottom.

  The light emission characteristics of the phosphor 5 were evaluated in the same manner as in Example 1. It has been found that the phosphor 5 is excited by light having a wavelength of 350 nm or more and 470 nm or less and emits light having a maximum emission intensity at a wavelength of 500 nm. The results are shown in FIG.

(Example 7: (Y _0.495 Gd _0.495 Ce _0.01 ) ₄ (SiS ₄ ) ₃ )
In order to obtain a phosphor composed of a solid solution of phosphor 1 and phosphor 3, Y ₂ S ₃ , Gd ₂ S ₃ , Ce ₂ S ₃ , Si, and S are used as raw materials, and the raw material ratio is Y _{2 in} molar ratio. _{S 3: Gd 2 S 3:} Ce 2 S 3: Si: S = 0.99: 0.99: 0.02: 3.3: were weighed so as to 6.6. At this time, Si and S were added in an amount of 10 mol% in addition to those determined stoichiometrically.

In the same manner as in Example 1, mixing, firing and rapid cooling were performed to obtain a phosphor 7 represented by the formula (Y _0.495 Gd _0.495 Ce _0.01 ) ₄ (SiS ₄ ) ₃ .

When a powder X-ray diffraction pattern was measured for phosphor 7, it was found that it had the same crystal structure as phosphors 1 to 4 described above, and no compounds including raw materials other than the target product were detected. . The obtained results are shown in FIG. In FIG. 7, the diffraction pattern of phosphor 1 (Y _0.99 Ce _0.01 ) ₄ (SiS ₄ ) ₃ is shown at the bottom.

  The light emission characteristics of the phosphor 7 were evaluated in the same manner as in Example 1 above. It was found that the phosphor 2 was excited by light having a wavelength of 350 nm or more and 480 nm or less and emitted light having a maximum emission intensity at a wavelength of 560 nm. The results are shown in FIG.

(Example 8: ((Y _0.495 La _0.495 Ce _0.01 ) ₄ (SiS ₄ ) ₃ + Y _0.495 La _0.495 Ce _0.01 ) ₆ Si ₄ S ₁₇ )
In order to obtain a phosphor composed of a solid solution of phosphor 1 and phosphor 5, Y ₂ S ₃ , La ₂ S ₃ , Ce ₂ S ₃ , Si, and S are used as raw materials, and the raw material ratio is Y _{2 in} molar ratio. _{S 3: La 2 S 3:} Ce 2 S 3: Si: S = 1.485: 1.485: 0.03: 4.4: were weighed so as to 8.8. At this time, Si and S were added in an amount of 10 mol% in addition to those determined stoichiometrically.

In the same manner as in Example 1 above, mixing, firing and quenching were performed to obtain the formulas (Y _0.495 La _0.495 Ce _0.01 ) ₄ (SiS ₄ ) ₃ and (Y _0.495 La _0.495 Ce _{0. .01} ) A phosphor 8 represented by ₆ Si ₄ S ₁₇ was obtained.

When the powder X-ray diffraction pattern of the phosphor 8 was measured, it was found that it had the same crystal structure as the phosphors 1 to 4 described above and the crystal structure similar to the phosphors 5 and 6 described above. Compounds containing raw materials other than the product were not detected. The obtained results are shown in FIG. In FIG. 7, the diffraction pattern of phosphor 1 (Y _0.99 Ce _0.01 ) ₄ (SiS ₄ ) ₃ is shown at the bottom, and phosphor 5 (La _0.99 Ce _0.01 ) is shown at the top. The diffraction pattern of ₆ Si ₄ S ₁₇ is shown.

  The light emission characteristics of the phosphor 8 were evaluated in the same manner as in Example 1 above. It has been found that the phosphor 8 is excited by light having a wavelength of 350 nm or more and 480 nm or less and emits light having a maximum emission intensity at a wavelength of 545 nm. The results are shown in FIG.

(Example 9: (Y _0.99 Tb _0.01 ) ₄ (SiS ₄ ) ₃ )
Y ₂ S ₃ , Tb ₂ S ₃ , Si, S are used as raw materials, and the raw material ratio is Y ₂ S ₃ : Tb ₂ S ₃ : Si: S = 1.98: 0.02: 3.3: 6 in molar ratio. Weighed out to a .6. At this time, Si and S were added in an amount of 10 mol% in addition to those determined stoichiometrically.

In the same manner as in Example 1, mixing, firing and rapid cooling were performed to obtain a phosphor 8 represented by the formula (Y _0.99 Tb _0.01 ) ₄ (SiS ₄ ) ₃ .

When the powder X-ray diffraction pattern of the phosphor 9 was measured, it was found that it had the same crystal structure as that of the monoclinic Gd ₄ (SiS ₄ ) ₃ reported in Non-Patent Document 6, and the desired production Compounds containing raw materials other than the product were not detected. The obtained results are shown in FIG. In FIG. 9, the diffraction pattern simulated from Non-Patent Document 6 is shown at the bottom.

  The light emission characteristics of the phosphor 9 were evaluated in the same manner as in Example 1. It was found that the phosphor 9 was excited by light having a wavelength of 350 nm or more and 390 nm or less, and the emission intensity was maximized at wavelengths 491, 546, 587, and 622 nm. The results are shown in FIG.

The emission excitation spectrum of the phosphor 9 shown in FIG. 10 is not absorption by Tb ³⁺ but absorption by the host crystal Y ₄ (SiS ₄ ) ₃ and indirectly excites Tb ³⁺ . Since the Tb ³⁺ absorption band is not found in the emission excitation spectrum, it can be seen that Tb ³⁺ absorbs the excitation light and emits light more efficiently than the direct excitation.

(Example 10: (Gd _0.99 Tb _0.01 ) ₄ (SiS ₄ ) ₃ )
Gd ₂ S ₃ , Tb ₂ S ₃ , Si, and S are used as raw materials, and the raw material ratio in terms of molar ratio is Gd ₂ S ₃ : Tb ₂ S ₃ : Si: S = 1.98: 0.02: 3.3: 6 Weighed out to a .6. At this time, Si and S were added in an amount of 10 mol% in addition to those determined stoichiometrically.

In the same manner as in Example 1, mixing, firing and rapid cooling were performed to obtain a phosphor 10 represented by the formula (Gd _0.99 Tb _0.01 ) ₄ (SiS ₄ ) ₃ .

When the powder X-ray diffraction pattern of the phosphor 10 was measured, it was found that it had the same crystal structure as that of the monoclinic Gd ₄ (SiS ₄ ) ₃ reported in Non-Patent Document 6, and the desired production Compounds containing raw materials other than the product were not detected. The obtained results are shown in FIG.

  The light emission characteristics of the phosphor 9 were evaluated in the same manner as in Example 1. It was found that the phosphor 9 was excited by light having a wavelength of 350 nm or more and 400 nm or less, and the emission intensity was maximized at wavelengths 491, 546, 587, and 622 nm. The results are shown in FIG.

The emission excitation spectrum of the phosphor 10 shown in FIG. 10 is not absorption by Tb ³⁺ but absorption by the host crystal Gd ₄ (SiS ₄ ) ₃ as in the case of the phosphor 9, and indirectly Tb ^3+. Excited. Since the Tb ³⁺ absorption band is not found in the emission excitation spectrum, it can be seen that Tb ³⁺ absorbs the excitation light and emits light more efficiently than the direct excitation.

<Evaluation of water resistance>
The following samples were evaluated for water resistance.
Phosphors 1, 3, 5, 7, and 8 produced in Examples 1, 3, 5, 7, and 8 above.
As Comparative Example 1, Eu ₂ SiS ₄ which is an existing sulfide phosphor.
As Comparative Example 2, (Ca _0.99 Eu _0.01 ) ₂ SiS _4, which is an existing sulfide phosphor.
As Comparative Example 3, (Ba _0.99 Eu _0.01 ) ₂ SiS _4, which is an existing sulfide phosphor.
As Comparative Example 4, (Ba _0.99 Eu _0.01 ) Si ₂ S _5, which is an existing sulfide phosphor.

In the water resistance evaluation method, phosphor particles were immersed in distilled water, and the change rate of internal quantum efficiency (internal quantum efficiency after immersion: Φ / internal quantum efficiency before immersion: Φ ₀ ) was determined and evaluated. When the phosphor particles are inferior in water resistance, the phosphor component is eluted in water, so that the phosphor base crystal is decomposed or deteriorated, and the internal quantum efficiency is lowered with the immersion time.

  The internal quantum efficiency was measured for 20 mg of the phosphor particles. Thereafter, 20 mg of phosphor particles and 5 ml of distilled water were placed in a glass bottle having a bottom diameter of 24 mm × height of 45 mm and a capacity of 10 ml, and the particles were allowed to settle for 24 hours. Next, the supernatant was removed, and the whole glass bottle was dried for 1 hour using an air constant temperature incubator set at 50 ° C. (“DN-43” manufactured by Yamato Scientific Co., Ltd.). The dried phosphor particles were collected and the internal quantum efficiency was measured again.

  The internal quantum efficiency was measured using an absolute PL quantum yield measuring device “C11347-01” manufactured by Hamamatsu Photonics Co., Ltd. The wavelength of the excitation light was set to a value suitable for each phosphor between 360 nm and 440 nm.

The water resistance was evaluated according to the following criteria from the rate of change in internal quantum efficiency (Φ / Φ ₀ ).
A: Φ / Φ ₀ is 0.70 or more.
B: Φ / Φ ₀ is less than 0.70.

As shown in Table 2, the phosphors of each example had a rate of change of internal quantum efficiency (Φ / Φ ₀ ) of at least 0.750 times before and after immersion in water, and water resistance was remarkably excellent. I found out.

The sulfide phosphor of Comparative Example 1 has a high rate of change in internal quantum efficiency (Φ / Φ ₀ ) and excellent water resistance, but the internal quantum efficiency before immersion is about 1%. On the other hand, in each Example, the internal quantum efficiency before immersion was about 30%, and it was excellent in water resistance while improving the internal quantum efficiency about 30 times that of the sulfided body of Comparative Example 1.

In the sulfide phosphors of Comparative Examples 2 to 4, the rate of change in internal quantum efficiency (Φ / Φ ₀ ) decreased to about 0.006 to 0.01 times.

<Evaluation of storage stability>
The storage stability of the phosphors 1, 3 and 5 obtained in Examples 1, 3 and 5 was evaluated.

  About 0.3 g of each of phosphors 1, 3 and 5 was weighed and placed in a container having a capacity of 10 ml. The sample was left in the atmosphere (temperature: about 28 ° C., humidity: about 50%) for 4 months without a lid. The powder X-ray diffraction pattern was measured for each phosphor immediately after production and after standing. The results are shown in FIGS.

As shown in FIG. 11, in the phosphor 1, after standing for 4 months, oxidation progressed to some extent, and a gentle peak due to SiO ₂ was observed at 20 to 30 deg. However, the decomposition of the phosphor 1 does not proceed completely, and the composition of the phosphor 1 is maintained to some extent. Therefore, the light emission characteristics are maintained to some extent.

  As shown in FIGS. 12 and 13, it was confirmed that the phosphors 2 and 3 were maintained in composition after being left for 4 months. As a result, the storage stability is high and it is possible to prevent the light emission characteristics from being deteriorated.

As Comparative Example 5, the storage stability of Ca ₂ SiS ₄ : Eu ²⁺ that emits yellow to red light was evaluated in the same manner as described above. The results are shown in FIG. As shown in FIG. 14, after being left for 4 months, peaks due to CaS and S were conspicuous, and the decomposition of Ca ₂ SiS ₄ : Eu ²⁺ progressed considerably.

1 Light-emitting device 2 Light-emitting element 3 Light-emitting layer

Claims (13)

General formula (1): (Ln _1-x RE _x ) ₄ (SiS ₄ ) ₃
Ln is one or more selected from the group consisting of Sc, Y, Gd and Lu,
RE is at least one selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Bi, and Mn.
x is a phosphor in which 0.001 ≦ x ≦ 0.6. The phosphor according to claim _1, wherein the crystal structure is monoclinic (space group P2 _{1 /} n, _No. 14).   In the general formula (1), when the Ln contains Y and / or Gd, the RE contains Ce, and is excited by light having a peak at a wavelength of 300 nm to 500 nm, it has an emission peak at a wavelength of 450 nm to 650 nm. Item 3. The phosphor according to item 1 or 2.   In the general formula (1), when the Ln contains Y and / or Gd and the RE contains Tb and is excited by light having a peak at a wavelength of 300 nm to 500 nm, the full width at half maximum is 1 to 50 nm at a wavelength of 530 nm to 550 nm. The phosphor according to any one of claims 1 to 3, which has an emission peak. Represented by the general formula (2): (R _1-y RE _y ) ₆ Si ₄ S ₁₇ ,
R is La,
RE is at least one selected from the group consisting of Sc, Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi and Mn.
y is a phosphor in which 0.001 ≦ y ≦ 0.1.   The phosphor according to claim 5, wherein the crystal structure is triclinic (space group P-1, No. 2).   The phosphor according to claim 5 or 6, which has an emission peak at a wavelength of 400 nm to 650 nm when the RE in the general formula (2) contains Ce and is excited by light having a peak at a wavelength of 300 nm to 500 nm.   A phosphor comprising the phosphor according to any one of claims 1 to 4 and the phosphor according to any one of claims 5 to 7. One or more compounds selected from the group consisting of Sc, Y, La, Gd and Lu;
One or more compounds selected from the group consisting of Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Bi, and Mn;
Si and / or Si compounds;
A step of mixing a raw material containing S and / or an S compound, and a step of firing the raw material at 1000 ° C. to 1150 ° C.,
One or more compounds selected from the group consisting of Sc, Y, La, Gd, and Lu, and Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Bi, and Mn. The manufacturing method of fluorescent substance whose stoichiometric ratio in a mixture with the 1 or more types of compound chosen from a group is 0.999: 0.001-0.4: 0.6.   The method for producing a phosphor according to claim 9, further comprising a step of cooling at a cooling rate of 150 ° C./min or more after the firing.   The method for producing a phosphor according to claim 9 or 10, wherein the S and / or S compound is S powder and / or silicon sulfide powder, and the firing is performed in a closed tube of vacuum, inert gas atmosphere or reducing atmosphere. .   The method for producing a phosphor according to any one of claims 9 to 11, wherein the S and / or S compound contains one or more gases selected from the group consisting of hydrogen sulfide and carbon disulfide.   The light-emitting device which has the fluorescent substance of any one of Claim 1 to 8.

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