NASICON-STRUCTURED PHOSPHOR AND LIGHT EMITTING ELEMENT COMPRISING SAME LUMINESENT MATERIALS

Abstract

A phosphor of a chemically stable inorganic luminescent material having a NASICON structure and an application product including the phosphor, such as a light-emitting device. A phosphor having the formula of A.sub.1+xB.sub.xC.sub.2xD.sub.3X.sub.12:AE.sub.y where A is one or two types of elements of monovalent metal cations, B is one or two types of elements of trivalent cations, C is one or two types of elements of tetravalent cations, D is one or two types of elements of pentavalent cations, X is one or two types of elements of N, O, F, P, S, O, Cl, and Br, AE is one or two types of elements of Mn, Ce, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Th, U, and Bi, 0x2, and 0y0.1.

Claims

1: A phosphor having the following Chemical Formula 1:
A.sub.1+xB.sub.xC.sub.2xD.sub.3X.sub.12:AE.sub.y[Chemical Formula 1] where A is one type or two types of elements selected from a group consisting of monovalent metal cations; B is one type or two types of elements selected from a group consisting of trivalent cations; C is one type or two types of elements selected from a group consisting of tetravalent cations; D is one type or two types of elements selected from a group consisting of pentavalent cations; X is one type or two types of elements selected from a group consisting of N, O, F, P, S, O, Cl, and Br; AE is one type or two types of elements selected from a group consisting of Mn, Ce, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Th, U, and Bi; 0x2; and 0y0.1.

2: The phosphor of claim 1, wherein the phosphor is an inorganic compound having a same crystal structure as a crystal phase of Na.sub.3Sc.sub.2P.sub.3O.sub.12 or a Na.sub.3Sc.sub.2P.sub.3O.sub.12 solid solution.

3: The phosphor of claim 1, wherein A is any one among Li, Na, K, Rb, and Cs, B is any one among Sc, Cr, Fe, Y, La, Gd, and Lu, C is any one among C, Si, Ti, Ge, and Zr, and D is any one among N, P, and V.

4: The phosphor of claim 1, wherein the phosphor is changed in crystal structure and is imparted with an improved emission intensity by heating.

5: The phosphor of claim 4, wherein the phosphor has the same crystal structure as an -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase or a solid solution of the -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase at room temperature, has the same crystal structure as a -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase or a solid solution of the -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase when the phosphor is heated to 50 to 60 C., and has the same crystal structure as a -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase or a solid solution of the -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase when the phosphor is heated to 150 C. or higher.

6: The phosphor of claim 1, wherein the phosphor has the following Chemical Formula 2:
Na.sub.3xSc.sub.2P.sub.3O.sub.12:AE.sub.x[Chemical Formula 2] where AE is Eu.sup.2+ or Ce.sup.3+, and 0<x0.5.

7: The phosphor of claim 6, wherein when ultraviolet rays, visible rays, or electron rays having a wavelength in a range of 100 to 450 nm are radiated thereon as an excitation source, the phosphor exhibits emission of near-ultraviolet rays or blue rays having a wavelength in a range of 350 to 500 nm.

8: The phosphor of claim 6, wherein the phosphor emits color in the visible region during radiation of an excitation source, thereon to satisfy the condition of 0.01x0.3 with respect to (x, y) values of CIE chromaticity coordinates.

9: A phosphor composition, comprising: the phosphor according to claim 1, and a crystal phase or non-crystal phase compound different from the phosphor.

10: The phosphor composition of claim 9, wherein the phosphor is a powder having an average particle size in a range of 0.1 to 20 m.

11: The phosphor composition of claim 9, wherein the crystal phase or non-crystal phase compound is a conductive inorganic material, and is an oxide, an oxynitride, or a nitride including one type element or two types or more elements selected from among Zn, Al, Ga, In, and Sn.

12: The phosphor composition of claim 9, wherein the crystal phase or non-crystal phase compound is an inorganic luminescent material having a fluorescence which is different from a fluorescence of the phosphor.

13: A light-emitting device comprising: an excitation light source of 300 to 550 nm; and at least one of (i) the phosphor according to claim 1 and (ii) a phosphor composition comprising the phosphor and a crystal phase or non-crystal phase compound different from the phosphor.

14: An image display unit comprising: at least one of (i) the phosphor according to claim 1 and (ii) a phosphor composition comprising the phosphor and a crystal phase or non-crystal phase compound different from the phosphor.

15: A pigment comprising: at least one of (i) the phosphor according to claim 1 and (ii) a phosphor composition comprising the phosphor and a crystal phase or non-crystal phase compound different from the phosphor.

16: An ultraviolet-ray absorbent comprising: at least one of (i) the phosphor according to claim 1 and (ii) a phosphor composition comprising the phosphor and a crystal phase or non-crystal phase compound different from the phosphor.

17: A phosphor composition comprising: the phosphor according to claim 3 and a crystal phase or non-crystal phase compound different from the phosphor.

18: A phosphor composition comprising: the phosphor according to claim 6 and a crystal phase or non-crystal phase compound different from the phosphor.

19: A light-emitting device comprising: an excitation light source of 300 to 550 nm; and at least one of (i) the phosphor according to claim 3 and (ii) a phosphor composition comprising the phosphor and a crystal phase or non-crystal phase compound different from the phosphor.

20: A light-emitting device comprising: an excitation light source of 300 to 550 nm; and at least one of (i) the phosphor according to claim 6 and (ii) a phosphor composition comprising the phosphor and a crystal phase or non-crystal phase compound different from the phosphor.

21: An image display unit comprising: at least one of (i) the phosphor according to claim 3 and (ii) a phosphor composition comprising the phosphor and a crystal phase or non-crystal phase compound different from the phosphor.

22: A pigment comprising: at least one of (i) the phosphor according to claim 3 and (ii) a phosphor composition comprising the phosphor and a crystal phase or non-crystal phase compound different from the phosphor.

23: An ultraviolet-ray absorbent comprising: at least one of (i) the phosphor according to claim 3 and (ii) a phosphor composition comprising the phosphor and a crystal phase or non-crystal phase compound different from the phosphor.

Description

DESCRIPTION OF DRAWINGS

[0036] FIG. 1 shows an X-ray diffraction pattern of a phosphor (Example 1) according to an Example of the present invention;

[0037] FIG. 2 shows a crystal structure model of -Na.sub.3Sc.sub.2P.sub.3O.sub.12 to the phosphor of the X-ray diffraction pattern of FIG. 1;

[0038] FIG. 3 shows an X-ray diffraction pattern of a phosphor (Example 2) according to another Example of the present invention;

[0039] FIG. 4 shows a crystal structure model of -Na.sub.3Sc.sub.2P.sub.3O.sub.12 to the phosphor of the X-ray diffraction pattern of FIG. 2;

[0040] FIG. 5 is a graph showing a change in maximum wavelength and intensity of emission depending on substituted europium in the phosphor (Example 1) according to the Example of the present invention;

[0041] FIG. 6 shows excitation and emission spectra of the phosphor (Example 1) according to the Example of the present invention;

[0042] FIG. 7 is a graph showing a change in maximum wavelength and intensity of emission depending on substituted cerium in the phosphor (Example 2) according to another Example of the present invention;

[0043] FIG. 8 shows excitation and emission spectra of the phosphor (Example 2) according to another Example of the present invention;

[0044] FIG. 9 shows X-ray diffraction patterns depending on the temperature of the phosphor (Example 1) according to the Example of the present invention;

[0045] FIG. 10 shows the emission spectrum depending on the temperature of the phosphor (Example 1) according to the Example of the present invention;

[0046] FIG. 11 shows the emission spectrum depending on the temperature of the phosphor (Example 2) according to another Example of the present invention;

[0047] FIG. 12 shows the spectrum of an LED lighting apparatus (Example 3) according to still another Example of the present invention; and

[0048] FIG. 13 shows the CIE coordinates of the LED lighting apparatus (Example 3) according to still another Example of the present invention.

BEST MODE

[0049] While the present invention has been described using terms relating to what is presently considered to be the most practical and preferred embodiment, it is to be understood that these may vary depending on the intention of a person skilled in the art, precedents, and the emergence of new technology. Further, in certain cases, there may be a term arbitrarily selected by the applicant, in which case the meaning thereof will be described in detail in the description of the relevant invention. Accordingly, the terms used in the present invention should not be construed as merely descriptive terms, but should be interpreted based on the ordinary meanings of the terms and the contents described throughout the specification of the present invention.

[0050] Hereinafter, the technical structure of the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments.

[0051] However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Like reference numerals used to describe the present invention throughout the specification denote like elements.

[0052] The technical characteristics of the present invention include an inorganic fluorescent substance having the same crystal structure as a Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase, which is any one of a NASICONs [sodium (Na) super ionic conductor], or a solid solution of the Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase. The inorganic luminescent material has high emission efficiency, excellent thermal stability, and a novel composition.

[0053] That is, the present inventors have conducted a detailed study on a phosphor using a multi-membered inorganic crystal phase, including monovalent cations such as Na, trivalent cations such as Sc, tetravalent cations such as Zr, and pentavalent cations such as P, as a mother matrix. Thereby, it was found that when an optically active element is solid-solved in a phosphor having a specific composition or a specific crystal structure as a mother matrix, in particular, in the crystal structure of the Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase, to thus form a solid solution, an inorganic luminescent material having high emission efficiency and thermal stability, compared to a conventional phosphor, and a novel composition can be manufactured.

[0054] Therefore, the present invention provides a fluorescent substance having the following Chemical Formula 1.

A.sub.1+xB.sub.xC.sub.2xD.sub.3X.sub.12:AE.sub.y[Chemical Formula 1]

[0055] In Chemical Formula 1, A is one type or two types of elements selected from the group consisting of monovalent metal cations, B is one type or two types of elements selected from the group consisting of trivalent cations, C is one type or two types of elements selected from the group consisting of tetravalent cations, D is one type or two types of elements selected from the group consisting of pentavalent cations, X is one type or two types of elements selected from the group consisting of N, O, F, P, S, O, Cl, and Br, AE is one type or two types of elements selected from the group consisting of Mn, Ce, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Th, U, and Bi, 0x2, and 0y0.1.

[0056] A, which is a monovalent metal cation, may be any one among Li, Na, K, Rb, and Cs, B, which is a trivalent cation, may be any one among Sc, Cr, Fe, Y, La, Gd, and Lu, C, which is a tetravalent cation, may be any one among C, Si, Ti, Ge, and Zr, and D, which is a pentavalent cation, may be any one among N, P, and V.

[0057] Examples of the phosphor may include a phosphor in which A is Na, B is Sc, X is O, and AE is Eu, a phosphor in which A is Na, B is Sc, C is Zr, X is O, and AE is Ce, a phosphor in which A is Na, B is Sc, D is P, X is O, and AE is Eu, and a phosphor in which A is Na, B is Sc, C is Zr or a mixture of Zr and Si, D is P, X is O, and AE is Ce.

[0058] Further, the phosphor of the present invention is changed in crystal structure and is imparted with improved photoluminescence by heating.

[0059] For example, in the case where the crystal structure of the phosphor is the same as that of an -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase or a solid solution of the -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase at room temperature, the crystal structure of the phosphor may be changed so as to be the same as that of a -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase or a solid solution of the -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase when the phosphor is heated to 50 to 60 C., and may also be changed so as to be the same as that of a -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase or a solid solution of the -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase when the phosphor is heated to 150 C. or higher.

[0060] The crystal structure is changed by heating, which enables the emission to be changed. For example, in the case where the phosphor has the same crystal structure as the -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase and Eu is solid-solved in the crystal phase, emission light having a wavelength of 400 to 500 nm may be emitted during exposure to light having a wavelength of 100 to 450 nm. However, in the case where the phosphor has the same crystal structure as the -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase and Ce is solid-solved in the crystal phase, emission light having a wavelength of 350 to 450 nm may be emitted during exposure to light having a wavelength of 100 to 400 nm.

[0061] Further, the phosphor of the present invention may be represented by the following Chemical Formula 2.

Na.sub.3xSc.sub.2P.sub.3O.sub.12:AE.sub.x[Chemical Formula 2]

[0062] In Chemical Formula 2, AE is Eu.sup.2+ or Ce.sup.3+, and 0<x0.5.

[0063] Particularly, when ultraviolet rays, visible rays, or electron rays having a wavelength in the range of 100 to 450 nm are radiated as an excitation source on the phosphor having Chemical Formula 2, the phosphor exhibits emission of near-ultraviolet rays or blue rays having a wavelength in the range of 350 to 500 nm. The phosphor having Chemical Formula 2 emits color in the visible region during radiation of an excitation source, thereon to satisfy the condition of 0.01x0.3 with respect to (x, y) values of CIE chromaticity coordinates. Since the phosphor can emit near-ultraviolet rays having a wavelength of 400 nm or more or blue rays having a wavelength of 450 nm or more, it is possible to manufacture a white light-emitting diode having high emission efficiency and an excellent color rendering index using the above-mentioned light emission characteristics of the fluorescent substance.

[0064] The mixture of the metal compounds is calcined to obtain the phosphor of the present invention. For example, the raw material mixture, including raw materials that include Na, Sc, P, O, and AE (where AE is one type or two types of elements selected from the group consisting of Mn, Ce, Nd, Sm, Eu, Tb, Tb, Dy, Ho, Er, Tm, Yb, Th, U, and Bi) and which are mixed at the molar ratio shown in Chemical Formula 1 or 2, may be calcined in a reduction atmosphere at a temperature in the range of 1000 to 1600 C. under normal pressure, and then pulverized to thus obtain the phosphor. The calcining temperature may depend on the type of raw material. For example, when raw materials including Na, Zr, Si, P, O, and AE (where AE is one type or two types of elements selected from the group consisting of Mn, Ce, Nd, Sm, Eu, Tb, Tb, Dy, Ho, Er, Tm, Yb, Th, U, and Bi) are used, the raw materials may be calcined in a reduction atmosphere at a temperature in the range of 1200 to 1800 C. under normal pressure. The raw materials may be one or more among oxides, carbonates, nitrides, fluorides, or chlorides including constitutional elements.

[0065] Next, the present invention provides a phosphor composition including the phosphor and a crystal phase or non-crystal phase compound different from the phosphor. The phosphor is a powder having an average particle size in the range of 0.1 to 20 m. The powder includes single crystal particles or a single crystal aggregate, and the content of the phosphor in the phosphor composition may be 10 wt % or more based on the total weight of the composition. The crystal phase or non-crystal phase compound included in the phosphor composition may be a conductive inorganic material, and may be an oxide, an oxynitride, or a nitride including one type element or two types or more elements selected from among Zn, Al, Ga, In, and Sn. In some cases, the crystal phase or non-crystal phase compound may be an inorganic luminescent material having photoluminescence that is different from that of the phosphor.

[0066] Next, the present invention may provide a light-emitting device including an excitation light source of 300 to 550 nm and one or more of the phosphor or the phosphor composition. Further, the present invention may provide an image display unit, a pigment, and an ultraviolet-ray absorbent including one or more of the phosphor or the phosphor composition.

MODE FOR INVENTION

Example 1

[0067] Sodium phosphate (Na.sub.3PO.sub.4), scandium oxide (Sc.sub.2O.sub.3), ammonium phosphate (NH.sub.4H.sub.2PO.sub.4), and europium oxide (Eu.sub.2O.sub.3) were used as raw materials. Quantification of 0.3562 g of sodium phosphate, 0.3078 g of scandium oxide, 0.5135 g of ammonium phosphate, and 0.0157 g of europium oxide was performed so that a molar composition ratio of Na:Sc:P:O:Eu was 2.92:2:3:0.04, and mixing and pulverization were then performed in a dry state for 30 min using an agate mortar and a pestle. The mixture was placed into an alumina crucible. The crucible containing the mixture was heated to 350 C. in a box furnace, maintained for 1 hour, and naturally cooled. After the powder was again pulverized, the mixture was disposed in a horizontal alumina tube, heated to 1300 C. at a rate of 300 C./hr in a 5% hydrogen reduction atmosphere, serving as a calcination atmosphere, maintained at 1300 C. for 3 hours, and naturally cooled. After calcination, the calcined body was pulverized to manufacture a Na.sub.2.92Sc.sub.2P.sub.3O.sub.12:Eu.sup.2+.sub.0.04 phosphor.

Example 2

[0068] Sodium mono-phosphate (NaPO.sub.3), scandium oxide (Sc.sub.2O.sub.3), ammonium phosphate (NH.sub.4H.sub.2PO.sub.4), and cerium oxide (CeO.sub.2) were used as raw materials. Quantification of 0.6575 g of sodium mono-phosphate, 0.3088 g of scandium oxide, 0.0309 g of ammonium phosphate, and 0.0154 g of cerium oxide was performed so that the molar composition ratio of Na:Sc:P:O:Ce was 2.88:2:3:0.04, and mixing and pulverization were then performed in a dry state for 30 min using an agate mortar and pestle. The mixture was placed into an alumina crucible. The mixture powder was disposed in a horizontal alumina tube, heated to 1500 C. at a rate of 300 C./hr in a 5% hydrogen reduction atmosphere as a calcination atmosphere, maintained at 1500 C. for 3 hours, and naturally cooled. After calcination, the calcined body was pulverized to manufacture a Na.sub.0.88Sc.sub.2P.sub.3O.sub.12: Ce.sup.3+.sub.0.04 phosphor.

Experimental Example 1

[0069] 1. Preparation of Standard Material

[0070] In order to obtain pure -Na.sub.3Sc.sub.2P.sub.3O.sub.12 containing no AE element as a standard material, quantification of 0.3694 g of sodium phosphate, 0.3108 g of scandium oxide, and 0.5184 g of ammonium phosphate was performed, and mixing and pulverization were then performed in a dry state for 30 min using an agate mortar and pestle. The crucible containing the mixture was heated to 350 C. in a box furnace, maintained for 1 hour, and naturally cooled. After the powder was pulverized again, the mixture was placed in an alumina crucible. The mixture powder was disposed in a horizontal alumina tube, heated to 1300 C. at a rate of 300 C./hr, maintained at 1300 C. for 3 hours, and naturally cooled. After the cooling, the calcined body was pulverized to prepare an -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase which was the standard material.

[0071] 2. X-Ray Diffraction Measurement

[0072] X-ray diffraction measurement of the prepared standard material powder and the Na.sub.2.92Sc.sub.2P.sub.3O.sub.12:Eu.sup.2+.sub.0.04 phosphor obtained in Example 1 was performed using the K line of Cu. The resulting chart is shown in FIG. 1. Both compounds showed the patterns of FIG. 1, and were judged to be an -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase. The spatial group, determined according to a conventional document report [Inger S TOFTE and De-Chun Fu, Solid state Ionics 26 (1988) 307-310], was C2/c (spatial group #15).

Experimental Example 2

[0073] 1. Preparation of Standard Material

[0074] In order to obtain pure -Na.sub.3Sc.sub.2P.sub.3O.sub.12 containing no AE element as a standard material, quantification of 0.6892 g of sodium mono-phosphate and 0.3108 g of scandium oxide was performed, and mixing by dry grinding for 30 min using an agate mortar and pestle. The mixture was placed into an alumina crucible. The mixture powder was disposed in a horizontal alumina tube, heated to 1500 C. at a rate of 300 C./hr, maintained at 1500 C. for 3 hours, and naturally cooled. The calcined body was pulverized to manufacture a -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase which was the standard material.

[0075] 2. X-Ray Diffraction Measurement

[0076] The powder X-ray diffraction measurement of the prepared standard material powder and the Na.sub.0.88Sc.sub.2P.sub.3O.sub.12: Ce.sup.3+.sub.0.04 phosphor obtained in Example 2 was performed using the K line of Cu. The resulting chart is shown in FIG. 3. Both compounds showed the patterns of FIG. 3, and were judged to be a -Na.sub.3Sc.sub.2P.sub.3O.sub.12 crystal phase based on the index of Table 2. The spatial group, determined according to a conventional document report [M. de la Rochre et al., Solid State Ionics 9-10 (1983) 825-828], was R-3c (spatial group #167).

Experimental Example 3

[0077] As for the phosphor obtained in Example 1, the PL results (the relative emission intensity and the main wavelength of emission) depending on the content of substituted Eu were analyzed. The results are shown in FIG. 5.

[0078] From FIG. 5, it can be seen that the relative emission intensity of the phosphor of Example 1 depends on the content of substituted Eu. The emission intensity is increased as the amount of Eu, which is an activator, is increased. However, when the molar composition ratio is more than 0.03 mol, the drop in intensity due to the concentration quenching effect is increased. From the experimental results, it can be seen that the molar composition ratio of Eu contained in the phosphor is preferably 0.03 to 0.04 mol. Further, it can be seen that the best emission intensity is obtained when the molar composition ratio of Eu is 0.04 mol.

Experimental Example 4

[0079] As for the fluorescent substance obtained in Example 1, excitation and light emission spectra were observed, and the results are shown in FIG. 6.

[0080] From FIG. 6, it can be seen that the phosphor obtained in Example 1 emits blue light having a wavelength of 400 to 500 nm when an excitation source of ultraviolet rays, visible rays, or electron rays having a wavelength of 100 to 440 nm is radiated thereon.

Experimental Example 5

[0081] As for the phosphor obtained in Example 2, the PL results (the relative emission intensity and the main wavelength of emission) depending on the content of substituted Ce were analyzed. The results are shown in FIG. 7.

[0082] From FIG. 7, it can be seen that the relative emission intensity of the phosphor of Example 2 depends on the content of substituted Ce. The emission intensity is increased as the amount of Ce, which is an activator, is increased. However, when the molar composition ratio is more than 0.04 mol, the intensity drop due to the concentration quenching effect is increased. From the experimental results, it can be seen that the molar composition ratio of Ce contained in the phosphor is preferably 0.03 to 0.04 mol. Further, it can be seen that the best emission intensity is obtained when the molar composition ratio of Ce is 0.04 mol.

Experimental Example 6

[0083] As for the phosphor obtained in Example 2, excitation and emission spectra were observed, and the results are shown in FIG. 8.

[0084] From FIG. 8, it can be seen that the phosphor obtained in Example 2 emits near-ultraviolet rays having a wavelength of 350 to 450 nm when an excitation source of ultraviolet rays, visible rays, or electron rays having a wavelength of 100 to 360 nm is radiated thereon.

Experimental Example 7

[0085] The change in crystal phase depending on the temperature of the phosphor obtained in Example 1 was observed using X-ray diffraction measurement, and an experiment was performed in order to observe the change in emission intensity depending on the change in crystal phase. The X-ray diffraction pattern and the emission intensity variation graph obtained from the experimental results are shown in FIGS. 9 and 10, respectively.

[0086] From FIG. 9, it can be seen that an -Na.sub.3Sc.sub.2P.sub.3O.sub.12 structure is changed into a -Na.sub.3Sc.sub.2P.sub.3O.sub.12 structure when the temperature is increased and that the -Na.sub.3Sc.sub.2P.sub.3O.sub.12 structure is changed into the -Na.sub.3Sc.sub.2P.sub.3O.sub.12 structure when the temperature is reduced to room temperature. In addition, from FIG. 10, it can be seen that the emission intensity is maintained and then increased as the temperature is increased. From the above results, it can be seen that the crystal phase is changed depending on the temperature to thus improve photoluminescence. This is one of the most important characteristics of the phosphor of the present invention.

Experimental Example 8

[0087] The change in emission intensity depending on the temperature of the phosphor obtained in Example 2 is shown in FIG. 10.

[0088] From FIG. 11, it can be seen that the emission intensity of the phosphor having a -Na.sub.3Sc.sub.2P.sub.3O.sub.12 structure at room temperature is reduced as the temperature is increased due to the thermal quenching effect. Therefore, it can be seen that, in the structure having a characteristic exhibiting a change in phase when the temperature is changed from room temperature to a high temperature, photoluminescence at high temperatures is improved due to this characteristic.

Example 3

[0089] The blue phosphor obtained in Example 1 and commercial green and red phosphor were mixed with a silicon resin. The mixture was inserted into a surface-mount device (SMD)-type LED and cured at 150 C. for 1 hour, thereby manufacturing a WLED based on an LED having an excitation wavelength of 365 nm.

Experimental Example 9

[0090] The change in emission spectrum depending on the current mA applied to the WLED manufactured in Example 3 was measured, and the result is shown in FIG. 12.

[0091] From FIG. 12, it can be seen that the phosphor obtained in Example 1 of the present invention exhibits excellent light characteristics when excited at a wavelength of about 365 nm.

Experimental Example 10

[0092] A change in CIE coordinates depending on the current mA applied to the WLED manufactured in Example 3 was measured, and the results are shown in FIG. 13. The (x, y) values of the CIE color coordinates when the current of 100 mA was applied were obtained. The color temperature of the color rendering index (CRI) of 97 was 7253 K. Since the values (0.33, 0.33) correspond to an ideal white color in the CIE color coordinates and a commercial LED lamp has a CRI of about 85, the above results show that there is a possibility of application of the present invention to the WLED, although optimization needs to be performed using additional experiments.

[0093] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.