JP2005060542A - Red light-emitting phosphor and luminous composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a red light-emitting phosphor and a luminous composition which are suitably applicable to a Vacuum Fluorescent Display (VFD), a Field Emission Display (FED) and the like which make no use of a toxic substance such as cadmium and which have the high luminance and little change of the luminance with time under the electron beam excitation by a low accelerating voltage, especially 10 KV or less. <P>SOLUTION: This red light-emitting phosphor has a composition expressed by the general formula: (In<SB>1-x</SB>Eu<SB>x</SB>)<SB>2</SB>O<SB>3</SB>-nGeO<SB>2</SB>, wherein n and x are each a number satisfying the condition of 0.9≤n≤2.7 and 0.0001≤x≤0.2, respectively. This luminous composition comprises a blend of this phosphor and an electrically conductive substance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is a novel red light emitting oxide phosphor, light emitting composition, and fluorescent display tube (VFD) that does not contain harmful elements such as Cd that emit red light when irradiated with an electron beam having a low acceleration voltage of 10 KV or less. The present invention relates to a phosphor film for low-speed electron beams that is applied to a display device that emits light by being excited by an electron beam having a low acceleration voltage of 10 KV or less, such as an electroluminescent display (FED).

Conventionally, as a practical phosphor that emits red light with high luminance by irradiating an electron beam with a low acceleration voltage of 10 KV or less (hereinafter referred to as a low-speed electron beam), cadmium (Cd) whose element element of the phosphor is harmful is used. For example, a (Zn, Cd) S: Ag phosphor or a luminescent composition in which a conductive material such as In ₂ O ₃ , ZnO, SnO ₂ is mixed or adhered to the phosphor is well known, It is used for practical use. However, it has become difficult to use a harmful substance such as Cd as a constituent element of the phosphor due to the problem of pollution to the environment, which has been regarded as important in recent years.
Therefore, it is desired to develop a red light-emitting phosphor for low-energy electron beam excitation that does not contain harmful substances such as Cd.

In response to such a demand, as a red light emitting phosphor containing no Cd, an oxide phosphor Y ₂ O ₃ : Eu using europium as an activator, and an oxysulfide phosphor Y using europium as an activator. ₂ O ₂ S: Eu (refer to Patent Document 1), SrTiO ₃ : Pr, Al (refer to Patent Document 2), and SnO ₂ : Eu (refer to Patent Document 3) in which the crystal base of the phosphor itself is conductive are proposed. Have been considered.
However, the phosphors described above are extremely difficult to put into practical use because their emission luminance is extremely low or the initial emission luminance cannot be maintained under long-time electron beam irradiation, and so-called deterioration with time occurs. Under such circumstances, it is desired to develop a phosphor having high emission luminance and little deterioration with time of emission luminance as a red light emitting phosphor for low-energy electron beam excitation that does not contain harmful substances such as Cd.
Japanese Patent Publication No. 52-23915 Japanese Patent Laid-Open No. 09-87618 Japanese Patent Publication No.54-238

  The present invention is a novel red light emission used as a fluorescent film for a fluorescent display tube (VFD), an electroluminescent display (FED), etc., which has high emission luminance and little deterioration of the emission luminance with time, particularly by low-energy electron beam excitation of 10 KV or less. It is intended to provide a phosphor and a luminescent composition.

In order to achieve the above-mentioned object, the present inventors diligently searched for various phosphors. As a result, a composite oxide composed of indium germanate, which is a conductive oxide, using Eu as an activator is configured as a phosphor matrix. The phosphor used as the element is suitable as a red light-emitting phosphor for low-energy electron beam excitation, and when a conductive substance is further added to the phosphor, a red light-emitting composition with higher emission luminance is found. It came to complete.
The configuration of the present invention will be described as follows.
(1) A red light emitting phosphor characterized in that a general formula is represented by (In _1-x Eu _x ) ₂ O ₃ .nGeO ₂ (where n and x are 0.9 ≦ n ≦ 2.7, respectively) And a number satisfying the condition of 0.0001 ≦ x ≦ 0.2.
(2) Red light-emitting phosphor represented by the general formula (In _1-x Eu _x ) ₂ O ₃ .nGeO ₂ (where n and x are 0.9 ≦ n ≦ 2.7 and 0.0001 ≦, respectively) a light-emitting composition comprising a mixture of a conductive substance and a conductive material.
(3) The light-emitting composition according to (2), wherein a mixing ratio of the phosphor and the conductive material is 30% by weight or less with respect to the phosphor.
(4) The light-emitting composition according to (2) or (3), wherein the conductive substance is at least one of In ₂ O ₃ , ZnO, SnO ₂ , WO ₃ and TiO ₂ .

  The red phosphor and the light emitting composition of the present invention are configured as described above, so that no harmful substances such as Cd are used as components, and particularly under excitation by a low-speed electron beam having an acceleration voltage of 10 KV or less. It has little luminance deterioration with time, exhibits high luminance red light emission, and is useful as a fluorescent film for low-speed electron beams such as VFD and FED.

Hereinafter, the present invention will be described in more detail.
The phosphor of the present invention is manufactured as follows.
(1) In compounds such as oxides of indium (In), nitrates, and chlorides, which are constituents of the matrix,
(2) Germanium (Ge) oxide or other Ge compound, which is one constituent of the matrix, and (3) activator component, europium (Eu) oxide, nitrate, carbonate, A phosphor raw material composed of three kinds of components of Eu compound such as chloride is stoichiometrically converted into (In _1-x Eu _x ) ₂ O ₃ .nGeO ₂ (where n and x are 0.9 ≦ n ≦ 2.7 and 0.0001 ≦ x ≦ 0.2. The same applies hereinafter.), and if necessary, further as a crystal growth accelerator, An alkali metal and / or alkaline earth metal barogenide or ammonium barogenide is blended and mixed thoroughly by wet or dry method to prepare the raw material mixture of the phosphor of the present invention, and then the above raw material mixture is added to the crucible. Filled into heat-resistant containers such as And baked at least once 1 to 12 hours at 1000 to 1600 ° C. or in the air in a neutral atmosphere or in an oxidizing atmosphere. After firing, the fired product is pulverized, washed with a thin aqueous mineral acid solution, washed with water, further dispersed with a ball mill, etc., and then removed unnecessary large particles by a wet classification method such as a water sieve. After the dehydration treatment is performed, drying and sieving are performed, so that the general formula (In _1-x Eu _x) exhibits high-luminance red light emission particularly under excitation of an electron beam with a low acceleration voltage of 10 KV or less. ) The phosphor of the present invention that is ₂ O ₃ .nGeO ₂ can be obtained.
In the present invention, the phosphor having a general formula of (In _1-x Eu _x ) ₂ O ₃ .nGeO ₂ means each of In, Ge, and Eu contained in the phosphor after firing the raw material mixture. A phosphor in which the composition ratio of metal elements satisfies the above general formula.

FIG. 1 shows the case where the phosphor represented by (In _0.95 Eu _0.05 ) ₂ O ₃ .nGeO ₂ obtained as described above is emitted when light is emitted under electron beam excitation at an acceleration voltage of 50V. It is the graph which showed the relationship between a value and light emission luminance. As can be seen from FIG. 1, the emission luminance is highest when the n value is approximately 1.5 to 2, and the emission luminance of the phosphor obtained decreases as the n value increases or decreases. This correlation is the same even when the Eu concentration (x value) as the activator is changed, and the n value is 0.9 ≦ n ≦ 2. 7 is preferable, and 1.5 ≦ n ≦ 2.0 is particularly preferable.
In the phosphor of the present invention represented by the composition formula (In _1-x Eu _x ) ₂ O ₃ .nGeO ₂ , it has been confirmed that the phosphor has an inherent basic crystal structure in the vicinity of n = 2. When the value is smaller than 2, the In ₂ O ₃ component in the composition becomes excessive and In ₂ O ₃ itself is non-luminous, but on the other hand, since it is a conductor, the conductivity increases in a certain excess region. Although it works favorably for light emission, if it is too much, the mixing ratio of non-light emitting substances increases, so that the light emission efficiency decreases. In general, when the proportion of the component having a conductive role in the crystal exceeds 30%, the influence of the non-light emitting substance becomes stronger and the light emission luminance becomes insufficient. In the phosphor of the present invention, where the n value is less than about 0.9, the light emission efficiency tends to decrease as described above, and the light emission luminance becomes insufficient. On the other hand, when the n value is larger than about 2.7, the GeO ₂ component which is not light-emitting itself and is not a conductor becomes excessive, so that the light-emitting performance and the conductivity are lowered, and the light emission luminance is remarkably lowered.

In the phosphor of the present invention, in order to obtain red light emission with high luminance and little change with time, the concentration of Eu added as an activator (x value) to the matrix having the above composition composed of In ₂ O ₃ and GeO _2. ) Is preferably in the range of 0.0001 ≦ x ≦ 0.2, and more preferably in the range of 0.005 ≦ x ≦ 0.1 in terms of practical color and brightness. No.

FIG. 2 shows one of the typical compositions of the phosphor of the present invention. The phosphor of the present invention represented by the general formula (In _0.95 Eu _0.05 ) ₂ Ge ₂ O ₇ (the above general formula) , When n = 2 and x = 0.05), the emission spectrum is illustrated under the excitation of electron beam at an acceleration voltage of 50 V, and has a peak wavelength of the emission spectrum at 613 nm. The chromaticity point (x / y) exhibits high luminance and preferable red light emission of 0.641 / 0.349. This emission characteristic is the same as that of Y ₂ O ₂ S: Eu phosphor and In ₂ O ₃ , which has been proposed as a red light-emitting phosphor for low-energy electron beam excitation that does not contain harmful substances such as cadmium. The luminescent composition thus obtained (wavelength peak of the emission spectrum is 626 nm, chromaticity coordinates x / y of the emission color is 0.649 / 0.343), shows no problem in terms of emission color, and acceleration voltage The emission luminance at 50 V was 1.5 times higher in the phosphor of the present invention, and it was confirmed that the phosphor had superior characteristics in practical use.

  On the other hand, the luminescent composition of the present invention can be obtained by adding and mixing the phosphor produced as described above and a certain amount of conductive material. When the light emitting composition of the present invention is produced, the conductive material added to and mixed with the phosphor of the present invention is not particularly limited as long as it has a small specific resistance and good solid conductivity. , Zn, Sn, W and Ti at least one kind of oxides are added, and are dry-mixed by a mixing means such as by a ball mill, or are stirred and mixed in water or an organic solvent and then wet-mixed It can be obtained by mixing thoroughly by the method. Further, as in the case of producing a pigmented phosphor in which pigment particles are attached to the surface of the phosphor particles, a conductive substance is charged together with a binder into the phosphor slurry in which the phosphor of the present invention is dispersed, The conductive substance may be attached to the phosphor surface of the present invention by solid-liquid separation after stirring and drying. The phosphor of the present invention described above exhibits red light emission under excitation by a low-energy electron beam. In particular, when excited by a low-energy electron beam of 100 V or less, a conductive substance is added thereto to add the light-emitting composition of the present invention. As a result, the emission luminance is further enhanced as compared with the case of the phosphor of the present invention alone.

In the light-emitting composition of the present invention, the amount of the conductive material mixed with the phosphor is 30% by weight or less, more preferably 0.5 to 10% by weight with respect to the phosphor in terms of light emission luminance of the light-emitting composition to be obtained. % to, but include _{(in 1-x Eu x)} 2 O 3 of · nGeO ₂ the phosphor conductive in the composition as a matrix component _in 2 _{O 3} of the present invention, n value in the basic crystal composition In the case where a phosphor having a composition smaller than 2 is used, excess In ₂ O ₃ remains as a mixed crystal on the phosphor side, so that the amount of the conductive material mixed therewith has an n value of 2 Is added depending on the composition of the phosphor of the present invention used (depending on the extent to which excess In ₂ O ₃ remains as a mixed crystal on the phosphor side). The amount of conductive material needs to be adjusted.
The thus obtained red light-emitting phosphor of the present invention and the light-emitting composition of the present invention containing this phosphor as a constituent component are mainly used to emit an image by causing the phosphor film to emit light with a low-energy electron beam such as VFD or FED. In addition, it can be used as a red component fluorescent film for display devices that display characters and the like with high luminance and little luminance deterioration. In addition, when used as a fluorescent film such as VFD and FED using the phosphor of the present invention, in addition to the phosphor and the light emitting composition of the present invention, the emission luminance and emission color of the phosphor film are finely adjusted, In order to improve the deterioration characteristics, Ln ₂ O ₃ : Eu, Ln ₂ O ₂ S: Eu, LnVO ₄ : Eu (Ln is at least one of Y, La, Gd, and Lu), SrTiO ₃ : Pr , Al, SnO ₂ : Eu, ZnS: Mn may be mixed and used.

  EXAMPLES Next, although an Example demonstrates this invention, this invention is not limited to the embodiment illustrated to the following example.

In ₂ O ₃ 26.3 g
Eu ₂ O ₃ 1.7 g
19.8 g of GeO ₂
LiF 0.5g
The above phosphor raw materials were sufficiently mixed, packed in an alumina crucible, and fired at 1400 ° C. for 2 hours in air. The obtained fired product was pulverized and washed with water, and dried to produce the phosphor of Example 1.
The phosphor thus produced was examined for its composition by X-ray diffraction analysis and chemical analysis. As a result, the phosphor was a germanate phosphor having a composition of (In _0.95 Eu _0.05 ) ₂ Ge ₂ O _7. there were.
10 wt% of indium oxide was added to the phosphor of Example 1 and mixed well to obtain the light emitting composition of Example 1. This luminous composition is suspended in water to prepare a water slurry, and a 2 cm × 2 cm glass plate piece is submerged in the bottom of the slurry container, stirred and allowed to stand, and then the supernatant liquid is removed. A phosphor film made of the light-emitting composition of Example 1 was prepared on one side of the glass plate by the method, and a low-speed electron beam with an acceleration voltage of 50 V was irradiated to the phosphor film on the glass plate using a low acceleration voltage demountable electron beam stimulator. As a result, the emission spectrum as shown in FIG. 1 was shown, the emission wavelength peak was 613 nm, and the emission chromaticity coordinate (x / y) was red emission with 0.641 / 0.349.
For comparison, a red phosphor Y ₂ O ₂ S: Eu, which is currently practically used for color television, is mixed well with 10 wt% indium oxide in the same manner as in the light-emitting composition of Example 1, Comparative Example 1 A luminescent composition was produced. When the emission luminance of the phosphor film made of the light emitting composition of Comparative Example 1 was measured under the same conditions, the peak wavelength of the emission spectrum was 626 nm, and the degree coordinate (x / y) of the emission color was (0.649 / The emission luminance of the phosphor film made of the luminescent composition of Example 1 at that time was 1.5 times that of the phosphor film made of the luminescent composition of Comparative Example 1.

In ₂ O ₃ 26.3 g
Eu ₂ O ₃ 1.7 g
19.8 g of GeO ₂
LiF 0.5g
The phosphor of Example 2 was manufactured in the same manner as the phosphor of Example 1 except that each of the above compounds was used as the phosphor material.
The composition of this phosphor was examined by X-ray diffraction analysis and chemical analysis. As a result, (In _0.95 Eu _0.05 ) ₂ Ge ₂ O ₇ and In ₂ O ₃ were mixed (In _{0. 95} Eu _0.05 ) ₂ Ge ₂ O ₇ germanate phosphor.
About the fluorescent substance of Example 2, when the light emission brightness | luminance was measured using the low acceleration voltage demountable electron beam stimulator like the case of the luminescent composition of Example 1, preparation of the luminescent composition of the said Comparative Example 1 was carried out. It is found that it has an emission luminance approximately twice that of the red phosphor Y ₂ O ₂ S: Eu currently used for color televisions, and is particularly excellent as a phosphor for low-energy electron beam excitation. It was.
In addition, almost no decrease in light emission luminance due to a deterioration phenomenon caused by continuous irradiation with a low-speed electron beam was observed. The phosphor of Example 2 also emitted red light having an emission spectrum similar to that shown in FIG.

It is a graph which shows the correlation with the host composition (n value) and light emission luminance in the fluorescent substance of this invention. Is a graph showing an emission spectrum when excited phosphors _{(In 0.95 Eu 0.05) 2 Ge} 2 O 7 of Example 1 with an electron beam of low acceleration voltage 50V of the present invention.

Claims (4)

A red light-emitting phosphor characterized in that the general formula is represented by (In _1-x Eu _x ) ₂ O ₃ .nGeO ₂ (where n and x are 0.9 ≦ n ≦ 2.7 and 0.7, respectively). Represents the number satisfying the condition of 0001 ≦ x ≦ 0.2). A red light-emitting phosphor represented by the general formula (In _1-x Eu _x ) ₂ O ₃ .nGeO ₂ (where n and x are 0.9 ≦ n ≦ 2.7 and 0.0001 ≦ x ≦ 0, respectively) .. A light-emitting composition comprising a mixture of a conductive material and a conductive material.   The luminescent composition according to claim 2, wherein a mixing ratio of the phosphor and the conductive material is 30% by weight or less with respect to the phosphor. The luminescent composition according to claim 2 or 3, wherein the conductive substance is at least one of In ₂ O ₃ , ZnO, SnO ₂ , WO ₃ and TiO ₂ .

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