JP2006036943A - Orange fluorescent material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new orange fluorescent material excited by ultraviolet to visible light of 200-500 nm wavelength to emit fluorescent light in high intensity. <P>SOLUTION: The orange fluorescent material is composed of a single-phase crystal and expressed by general formula (Sr<SB>1-x</SB>Eu<SB>x</SB>)<SB>3</SB>SiO<SB>5</SB>(0<x≤0.10). Quite different from a green fluorescent material (Sr<SB>3</SB>SiO<SB>5</SB>: Eu<SP>2+</SP>fluorescent material) baked at ≤1,250°C, the orange fluorescent material forms a single-phase crystal structure from the starting material or the formulation ratio of raw materials same as those of the green fluorescent material by changing the baking condition. The fluorescent material having the single-phase crystal structure is not a green light-emitting material but emits high-intensity orange fluorescent light having a peak near 580 nm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a novel phosphor exhibiting high-luminance orange light emission by photoexcitation in the ultraviolet to visible region.

  Phosphors that absorb light in the ultraviolet to visible range and emit light with high brightness are used in various illumination / display devices and the like.

A fluorescent lamp well known as general illumination uses a phosphor that emits light with high efficiency using ultraviolet light having a wavelength of 254 nm emitted by discharge in mercury vapor as a main excitation light source. BaMgAl ₁₀ O ₁₇ : Eu ²⁺ (BAM), Sr ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ (SCA) as a blue phosphor, LaPO ₄ : Ce ³⁺ , Tb ³⁺ (LAP), CeMgAl ₁₁ O as green phosphors ₁₉ : Tb ³⁺ (CAT), and red phosphors include Y ₂ O ₃ : Eu ³⁺ .

In order to improve color rendering properties, BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ (BAM: Mn), Sr ₂ Si ₃ O ₈ .2SrCl ₂ : Eu ²⁺ as blue-green phosphors, and (Sr, Mg) as orange phosphors ) ₃ (PO ₄ ) ₂ : Sn ²⁺ , and 3.5MgO · 0.5MgF ₂ · GeO ₂ : Mn ⁴⁺ are also used as a deep red phosphor (see, for example, Non-Patent Document 1).

  On the other hand, a phosphor that emits light with high efficiency by using a light emitting diode that emits visible light from near ultraviolet having a wavelength of 350 to 500 nm as an excitation light source has been very actively researched and developed in recent years. For example, in addition to yellow phosphors and red phosphors excited by blue light emitting diodes, many phosphors such as blue phosphors, green phosphors, red phosphors and pink phosphors excited by near ultraviolet light emitting diodes are reported. Has been done.

Typical examples of blue phosphors include BaMgAl ₁₀ O ₁₇ : Eu ²⁺ (BAM) and Sr ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ (SCA). As a green phosphor, BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ (BAM: Mn) is representative. Further, as a red phosphor, for example, Y ₂ O ₂ S: Eu ³⁺ is representative. As the yellow phosphor, for ^{_{example, Y 3 Al 5 O 12:}} Ce 3+ (YAG: Ce) is the representative (e.g., see Non-Patent Document 2). In addition, red phosphors La ₂ O ₂ S: Eu ³⁺ , Sm ³⁺ (see Patent Document 1) and LiEuW ₂ O ₈ (see Patent Document 2), and Y ₃ Al ₅ O ₁₂ : Ce ³⁺ , as a pink phosphor. Eu ³⁺ (see Patent Document 3) has also been reported.

Incidentally, as disclosed in Non-Patent Document 3, Non-Patent Document 4, and the like, the Sr ₃ SiO ₅ : Eu ²⁺ phosphor has been well known as a green phosphor for some time. The green phosphor has an emission peak wavelength in the vicinity of 545 nm and an emission spectrum having a shoulder in the vicinity of 470 nm is reported in these documents.

“Phosphor Handbook” edited by Phosphors Society, published by Ohm Company p. 192 (1987) Yoshino et al. “Development of phosphors for white LEDs” Japan Society for the Promotion of Science, Optoelectronic Interconversion 125th Committee (176th), Wide Gap Semiconductor Optoelectronic Device 162nd Committee (30th), Joint Study Group , P. 5 (2002) JP 2003-160785 A JP 2003-41252 A JP 2002-363555 A Journal of the Electrochemical Society 97, 415 (1950) Philips Research Reports 23, 189 (1968)

However, what has been reported so far as Sr ₃ SiO ₅ : Eu ²⁺ phosphor is actually composed of a multi-phase matrix such as SrO and Sr ₂ SiO _4, and such a multi-phase matrix and In this case, the present inventors have found that the emission becomes green.

Furthermore, a single phase crystal structure of Sr ₃ SiO ₅ can be generated by changing the firing conditions with the same starting material / raw material blending ratio as that of the green phosphor described above, and a phosphor having this single phase crystal structure The present inventors have made the present invention by discovering the world's first high-luminance emission of orange having a peak near 580 nm instead of green.

  An object of the present invention is to provide a novel orange phosphor that emits light with high luminance by being excited by light in the ultraviolet to visible region having a wavelength of 200 to 500 nm.

The orange phosphor according to the invention described in claim 1 has a general formula (Sr _1-x Eu _x ) ₃ SiO ₅ (where 0 <x ≦ 0.10).
It is comprised by the crystal | crystallization of a single phase shown by these.

The orange phosphor according to the invention described in claim 2 has a general formula (Sr _1-x Eu _x ) ₃ (Si _1-y Ge _y ) O ₅ (where 0 <x ≦ 0.10, 0 ≦ y ≦ 0.10)
It is comprised by the crystal | crystallization of a single phase shown by these.

The orange phosphor according to the invention described in claim 3 has a general formula (Sr _1-x Eu _x ) ₃ SiO ₅ (where 0 <x ≦ 0.10).
It has a single-phase crystal structure represented by the following formula, and exhibits orange high-luminance emission having a peak in the vicinity of 580 nm.

  As described above, the present invention has an effect that it is possible to obtain a novel orange phosphor that emits light with high luminance by being excited by light in the ultraviolet to visible region having a wavelength of 200 to 500 nm. The orange phosphor of the present invention is expected to improve color rendering in a light emitting diode, for example. Also, in combination with a lamp that excites with ultraviolet light or a light emitting diode that emits near ultraviolet or visible light, it emits light of various colors including white in combination with high-luminance amber light emitting / display elements or other phosphors.・ It is expected to obtain display elements.

In the present invention, the general formula (Sr _1-x Eu _x ) ₃ SiO ₅ (where 0 <x ≦ 0.10)
It is a novel orange phosphor composed of single-phase crystals.

As described above, the green phosphor (Sr ₃ SiO ₅ : Eu ²⁺ phosphor) that has been published in Non-Patent Document 3, Non-Patent Document 4 and the like is a multiphase such as SrO and Sr ₂ SiO ₄ by the present inventors. It was found to consist of More specifically, as shown in FIG. 2 described later, it was found that the one fired at 1250 ° C. or lower is a mixture of SrO and Sr ₂ SiO ₄ .

On the other hand, a single phase crystal structure of Sr ₃ SiO ₅ can be generated by changing the firing conditions even at the same starting material / raw material blending ratio as the green phosphor described above, and the phosphor having this single phase crystal structure is green. Instead, the inventors of the present invention have discovered for the first time in the world that high-luminance emission of orange having a peak near 580 nm is exhibited.

More specifically, when firing at a temperature of 1300 ° C. or higher and a temperature higher than 1300 ° C., the powder of Sr ₃ SiO ₅ registered in JCPDS (Joint Committee on Powder Diffraction Standards) card number 26-984 A phosphor having a single-phase crystal structure represented by an X-ray diffraction pattern is obtained, and this phosphor exhibits orange high-luminance emission having a peak near 580 nm.

This orange phosphor has a crystal structure of Sr ₃ SiO ₅ and has a structure in which a part of Sr is substituted with Eu as an activator. The substitution ratio of Eu is more than 0% and not more than 10% of the atomic weight of Sr. This is because if Eu is not substituted, no light is emitted, and if more than 10% is substituted, high emission luminance is not exhibited by photoexcitation in the ultraviolet to visible region due to concentration quenching, generation of a multiphase, or the like.

Further, in the present invention, as a result, it has a single-phase crystal structure indicated by the X-ray diffraction pattern of Sr ₃ SiO ₅ registered in JCPDS card number 26-984, and has a peak near 580 nm. As long as it exhibits orange high-luminance light emission, a part of the Sr atom may be replaced with another atom, or a part of the Si atom may be replaced with another atom.

For example, for a phosphor in which a part of Si atom is substituted with Ge atom, the single-phase crystal structure shown by the X-ray diffraction pattern of Sr ₃ SiO ₅ registered in JCPDS card number 26-984 as a result. In addition, it has been found to exhibit orange high-luminance emission having a peak at around 580 nm.

More specifically, it is an orange phosphor composed of single-phase crystals represented by the general formula (Sr _1-x Eu _x ) ₃ (Si _1-y Ge _y ) O ₅ . However, x and y are numerical values satisfying 0 <x ≦ 0.10 and 0 ≦ y ≦ 0.10, respectively. The reason why the Eu amount (x) and the Ge amount (y) in the above general formula are defined in the above ranges is that when they deviate from these ranges, high emission luminance is not exhibited by photoexcitation in the ultraviolet to visible region.

  In addition to Ge atoms in which a part of Si atoms are substituted, examples of atoms that can substitute a part of each atom include those having the same valence and a close atomic diameter. For example, Ba atom, Ca atom, etc. are mentioned as an atom which can substitute a Sr atom.

Experimental Examples 1-5
Experiments described below using SrCO ₃ (manufactured by Central Glass, purity 99.6%), Eu ₂ O ₃ (manufactured by Shin-Etsu Chemical, purity 99.99%), and SiO ₂ (manufactured by Nippon Aerosil, purity 99.99%) as raw materials Exactly weighed so that the stoichiometric ratio of the phosphors shown in Examples 1 to 5, and mixed for 1 to 2 hours by a ball mill. The mixed raw material was baked for 3 to 5 hours in a reducing atmosphere. The reducing gas was H ₂ : N ₂ = 5: 95.

As Experimental Examples 1 to 5, phosphors represented by the following general formula were fired at a predetermined temperature.
Experimental example 1: (Sr _0.99 Eu _0.01 ) ₃ SiO ₅ phosphor obtained at a firing temperature of 1100 ° C. Experimental example 2: a firing temperature obtained at 1200 ° C. (Sr _0.99 Eu _{0 .01} ) ₃ SiO ₅ phosphor / experimental example 3: obtained at a firing temperature of 1250 ° C. (Sr _0.99 Eu _0.01 ) ₃ SiO ₅ phosphor / experimental example 4: obtained at a firing temperature of 1300 ° C. (Sr _0.99 Eu _0.01 ) ₃ SiO ₅ phosphor / Experimental example 5: (Sr _0.99 Eu _0.01 ) ₃ SiO ₅ phosphor obtained at a firing temperature of 1400 ° C.

  The light from the mercury xenon lamp (L2483 manufactured by Hamamatsu Photonics) was split into light of a predetermined wavelength by a 10 cm spectrometer (H-10 manufactured by Jobin Yvon), and this was used as excitation light. This excitation light was irradiated to the samples of Experimental Examples 1 to 5 obtained by the above synthesis, and light emission from the sample was measured using an instantaneous multi-photometry system (MCPD-2000 manufactured by Otsuka Electronics Co., Ltd.) via an optical fiber.

The results are shown in Table 1. FIG. 1 is a graph showing the firing temperature dependence of the emission spectrum of the Sr ₃ SiO ₅ : Eu ²⁺ phosphor at an excitation wavelength of 254 nm. In the figure, each emission spectrum is normalized by each peak intensity.

  Table 1 shows the emission intensity and emission peak wavelength when excited by ultraviolet light at 254 nm, near ultraviolet light at 395 nm, and blue light at 470 nm. The emission intensity is a relative intensity when the emission peak intensity of a sample fired at 1400 ° C. is taken as 100%. The reason why the emission peak wavelength at 470 nm excitation was not written in Experimental Examples 1 and 2 was that the emission peak wavelength was not obtained because the emission intensity was weak.

As described above, the Sr ₃ SiO ₅ : Eu ²⁺ phosphor has been known as a green phosphor so far, and an emission spectrum having an emission peak wavelength near 545 nm and having a shoulder near 470 nm has the aforementioned non-patent document 3. And non-patent document 4. In Non-Patent Document 3, the firing temperature of this phosphor is 1100 ° C., and in Non-Patent Document 4, the exact firing temperature is unknown, but it is described that the phosphor is fired in a temperature range of 1100 to 1300 ° C.

As shown in Experimental Examples 1 to 3 in Table 1 and FIG. 1, when the present inventors measured samples fired at 1100 to 1250 ° C., Sr ₃ SiO ₅ : Eu ²⁺ phosphors reported in those documents It was confirmed that the light emission spectrum was almost the same as that of.

FIG. 2 is a diagram showing the firing temperature dependence of the powder X-ray diffraction pattern of Sr ₃ SiO ₅ : Eu ²⁺ phosphor. The uppermost graph is an X-ray diffraction pattern of Sr ₃ SiO ₅ registered in JCPDS card number 26-984. As shown in FIG. 2, the Sr ₃ SiO ₅ : Eu ²⁺ phosphor obtained by firing at 1100 to 1250 ° C. shows that the host crystal is SrO (JCPDS card number 6-520) or Sr based on the measurement result of powder X-ray diffraction. ₂ SiO ₄ (JCPDS card numbers 38-271, 39-1256) and the like were found to be composed of double phase crystals. In this case, the Sr ₃ SiO ₅ : Eu ²⁺ phosphor emits green light.

On the other hand, the Sr ₃ SiO ₅ : Eu ²⁺ phosphor obtained by the inventors at a firing temperature of 1300 ° C. or higher is completely different from the one fired at 1100 to 1250 ° C. as shown in the powder X-ray diffraction pattern of FIG. The host crystal is substantially composed of single-phase Sr ₃ SiO ₅ (JCPDS card number 26-984, see the top graph in FIG. 2). In this case, the emission spectrum exhibits high-luminance orange emission with a peak wavelength of around 580 nm as shown in Experimental Examples 4 and 5 in FIG. 1 and Table 1.

That is, the Sr ₃ SiO ₅ : Eu ²⁺ phosphor, which has been conventionally known as a phosphor that emits green light, is actually a phosphor composed of a multi-phase of SrO or Sr ₂ SiO ₄ . The discovered Sr ₃ SiO ₅ : Eu ²⁺ phosphor that emits orange light was found to be a phosphor composed of a single phase crystal of Sr ₃ SiO ₅ .

Experimental Examples 6-11
Experiments described below using SrCO ₃ (manufactured by Central Glass, purity 99.6%), Eu ₂ O ₃ (manufactured by Shin-Etsu Chemical, purity 99.99%), and SiO ₂ (manufactured by Nippon Aerosil, purity 99.99%) as raw materials The phosphors were accurately weighed to achieve the stoichiometric ratio of the phosphors shown in Examples 6 to 11, and mixed with a ball mill for 1-2 hours. The mixed raw material was baked for 3 to 5 hours in a reducing atmosphere. The reducing gas was H ₂ : N ₂ = 5: 95.

As Experimental Examples 6 to 11, phosphors represented by the following general formula were fired at a predetermined temperature.
Experimental Example 6: Obtained at a firing temperature of 1400 ° C. (Sr _0.9999 Eu _0.0001 ) ₃ SiO ₅ phosphor Experimental Example 7 Obtained at a firing temperature of 1400 ° C. (Sr _0.99 Eu _{0 .01} ) ₃ SiO ₅ phosphor / experimental example 8: obtained at a firing temperature of 1400 ° C. (Sr _0.95 Eu _0.05 ) ₃ SiO ₅ phosphor / experimental example 9: obtained at a firing temperature of 1400 ° C. (Sr _0.90 Eu _0.10 ) ₃ SiO ₅ phosphor.
Experimental Example 10: (Sr _0.99 Eu _0.01 ) ₃ (Si _0.95 Ge _0.05 ) O ₅ phosphor obtained at a firing temperature of 1400 ° C. Experimental Example 11: a firing temperature of 1400 ° C. Obtained (Sr _0.99 Eu _0.01 ) ₃ (Si _0.90 Ge _0.10 ) O ₅ phosphor

Further, as a comparative example, Y ₂ O ₂ S: Eu ³⁺ red phosphor conventionally used as a phosphor for light emitting diode excitation that emits light in the near ultraviolet to visible region is used as Comparative Example 1, Y ₃ A1. _{A 5} O ₁₂ : Ce ³⁺ (YAG; Ce) yellow phosphor was prepared as Comparative Example 2.

  The light from the mercury xenon lamp (L2483 manufactured by Hamamatsu Photonics) was split into light having a predetermined wavelength by a 10 cm spectroscope (H-10 manufactured by Jobin Yvon) and used as excitation light. The samples of Experimental Examples 6 to 11 and Comparative Examples 1 and 2 obtained by the above synthesis were irradiated with this excitation light, and light emission from the irradiated samples was instantaneous multiphotometric system via an optical fiber (MCPD-2000 manufactured by Otsuka Electronics). It measured using.

  The results are shown in Table 2. FIG. 3 is a diagram showing an emission spectrum of the orange phosphor of the present invention under 395 nm light excitation. FIG. 4 is a diagram showing an emission spectrum of the orange phosphor of the present invention under light excitation at 470 nm.

In Table 2, the emission intensity and emission peak wavelength of each sample when excited with 395 nm near ultraviolet light and 470 nm blue light are shown. The emission intensity is a relative intensity when the emission peak intensity of the Y ₂ O ₂ S: Eu ³⁺ red phosphor under 395 nm and 470 nm light excitation is 100%.

As shown in Table 2, when the Eu amount is increased in Sr ₃ SiO ₅ : Eu ³⁺ (Ge substitution amount: y = 0) (Experimental Examples 6 to 9), Sr is obtained in both cases where the excitation wavelength is 395 nm and 470 nm. When the molar ratio of the atoms is 1% (Eu substitution amount: x = 0.01), the emission intensity becomes the strongest. In particular, in the case of 470 nm light excitation, the brightness is extremely high, such as about 2 times that of Y ₂ O ₂ S: Eu ³⁺ red phosphor and about 1.5 times that of Y ₃ Al ₅ O ₁₂ : Ce ³⁺ (YAG: Ce) yellow phosphor. Light emission. When the Eu amount is further increased and the Eu amount exceeds 10% (x = 0.10) in terms of the molar ratio of Sr atoms, the emission intensity is reduced to 50% or less of Y ₂ O ₂ S: Eu ³⁺ red phosphor even at 470 nm photoexcitation. Therefore, it seems that it is not suitable for practical use.

On the other hand, even when Eu is 1% (x = 0.01) in terms of the molar ratio of Sr atoms, if the Ge is substituted more than 10% (y = 0.10) in terms of the molar ratio of Si atoms, the emission intensity becomes Y ₂ O. _{Since it} is 50% or less of ₂ S: Eu ³⁺ red phosphor, it seems that it is not suitable for practical use.

In the above embodiment, the production of an orange phosphor by a solid phase reaction using a powder raw material with a firing temperature of 1300 ° C. or higher and using no flux is taken as an example. Other manufacturing methods may be used. Specifically, a method of producing a single-phase Sr ₃ (Si, Ge) O ₅ : Eu ²⁺ phosphor at a low temperature of 1300 ° C. or lower by adding flux to a powder raw material or by a sol-gel method or a hydrothermal synthesis method. May be used.

  As described above, according to the present invention, an orange phosphor that exhibits high-luminance emission by photoexcitation in the ultraviolet to visible region can be provided. In particular, in combination with a lamp excited by ultraviolet light or a light emitting diode that emits near ultraviolet or visible light, it emits various colors including white in combination with a high-luminance amber light emitting / display element or other phosphor. -A display element etc. can be provided.

_Sr 3 _SiO 5 at the excitation wavelength of 254 nm: is a diagram showing the firing temperature dependence of the emission spectrum of ^{Eu 2+} phosphor. Each emission spectrum is normalized by each peak intensity. Sr ₃ SiO _5: Powder X-ray diffraction pattern of the ^{Eu 2+} phosphor - the emission is a diagram showing the firing temperature dependency. The uppermost graph is an X-ray diffraction pattern of Sr ₃ SiO ₅ registered in JCPDS card number 26-984. It is a figure which shows the emission spectrum under 395 nm light excitation of the orange fluorescent substance of this invention. It is a figure which shows the emission spectrum under 470 nm light excitation of the orange fluorescent substance of this invention.

Claims (3)

General formula (Sr _1-x Eu _x ) ₃ SiO ₅ (where 0 <x ≦ 0.10)
An orange phosphor characterized in that it is composed of single-phase crystals. General formula (Sr _1-x Eu _x ) ₃ (Si _1-y Ge _y ) O ₅ (where 0 <x ≦ 0.10, 0 ≦ y ≦ 0.10)
An orange phosphor characterized in that it is composed of single-phase crystals. General formula (Sr _1-x Eu _x ) ₃ SiO ₅ (where 0 <x ≦ 0.10)
An orange phosphor having a single-phase crystal structure represented by the formula (1) and exhibiting orange high-luminance emission having a peak near 580 nm.

Images