KR20010111833A - A green emitting phosphor for low-voltage applications and a method of preparing the same - Google Patents

Abstract

The green phosphor of the present invention mixes the barium salt and titanium oxide (TiO ₂ ), and the mixture is first baked at a temperature of 1100 to 1400 ° C. for 1 to 6 hours in an air atmosphere, and then the first baked material is It is prepared by a process of secondary baking for 0.5 to 2 hours at a temperature of 1000 to 1300 ℃ in a reducing atmosphere. The low-voltage BaTiO ₃ green phosphor of the present invention may be used by adding a conductive material such as In ₂ O ₃ , V ₂ O ₅ , WO _3, and the like.

Description

Green phosphor for low voltage and its manufacturing method {A GREEN EMITTING PHOSPHOR FOR LOW-VOLTAGE APPLICATIONS AND A METHOD OF PREPARING THE SAME}

[Industrial use]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low voltage green phosphor and a method of manufacturing the same, and more particularly, to a low voltage driveable green phosphor that can be applied to a low voltage display device such as VFD or FED.

[Prior art]

Low voltage displays of less than 1 kV include vacuum fluorescent display (VFD) and field emission display (FED). VFD is mainly used for various display devices such as home appliances, AV, automobiles, etc., and FED is being actively researched as a next-generation small flat panel display device. These low voltage display devices have a structure in which electrons emitted from an electron emitter such as a hot wire emit light to emit a phosphor, thereby reproducing a desired image.

Phosphors for low voltage drive devices such as FED and VFD should have low resistance, low emission start voltage, high luminous efficiency at low speed voltage, no luminance saturation, less defects on the surface of phosphor particles, and low electron excitation emission state. It should be stable and not degrade.

Currently, sulfide phosphors are widely used as phosphors for low voltage driving devices. A sulfide-based phosphor used as a low voltage green phosphor is ZnS: Zn. This phosphor is excellent in luminous efficiency but has a disadvantage in that the sulfide is decomposed under high current and low voltage conditions, so that the phosphor itself is not stable and the life is short.

Since sulfide-based phosphors have high resistance of a host material and emit low-speed electron beam excitation light emission, a conductive material is added and used as a method for lowering resistance. However, the development of non-sulfide-based phosphors has been actively progressed due to the problem of sulfide-based gas emission and phosphor material decomposing and scattering the electron beams during the electron beam excitation, thereby degrading the cathode filament and reducing phosphor efficiency.

An object of the present invention is to provide a low-voltage green phosphor for chemical stability, long life and excellent conductivity, and a method of manufacturing the same.

Another object of the present invention is to provide an oxide-based green phosphor that does not contaminate the cathode filament.

In order to achieve the above object, the present invention provides a green phosphor for the low voltage of the general formula (1).

[Formula 1]

BaTiO ₃

In addition, the present invention is a step of mixing a barium salt and titanium oxide (TiO ₂ ); Firstly baking the mixture at an atmosphere of 1100 to 1400 ° C. for 1 to 6 hours; And it provides a method for producing a green phosphor for low voltage comprising the step of secondary firing the first calcined material at a temperature of 1000 ~ 1300 ℃ for 0.5 to 2 hours in a reducing atmosphere.

Hereinafter, the present invention will be described in more detail.

The green phosphor for low voltage of the present invention is a phosphor of Formula 1 below.

[Formula 1]

BaTiO ₃

Since the phosphor does not include sulfide, it is possible to prevent the problem of phosphor lifetime deterioration due to decomposition of sulfides generated in the conventional sulfide-based green phosphors such as ZnS: Zn. In addition, the phosphor is a self-activation phosphor that emits light even without using an activator.

In the method for preparing the green phosphor of Chemical Formula 1, a barium salt and titanium oxide (TiO ₂ ) are first mixed. BaCO ₃ or Ba (NO ₃ ) ₂ and the like may be used as the salt containing barium, the molar ratio of the barium salt and titanium oxide is preferably 0.6 to 1: 1, more preferably 0.8 to 1: 1 And most preferably 0.8: 1. When the molar ratio of barium salt and titanium oxide is out of the above range, there is a problem in that the luminance of the manufactured phosphor is lowered. In the mixing step, a flux may be further added. Li ₃ PO ₄ , Na ₃ PO ₄ , Li ₂ CO ₃ , K ₂ HPO ₄ or KF may be used as the flux. The flux increases the particle size or controls the shape. The use amount of flux is preferably 10 to 50 mol%, and if it exceeds this range, there is a problem in that the conductivity of the mother is inferior.

In the second step, the mixture is first calcined under an atmospheric atmosphere at a temperature of 1100-1400 ° C. for 1-6 hours. BaTiO after the first firing process₃The matrix is formed and in the case of using a flux, the flux is volatilized and removed in this process.

The primary fired material is subjected to secondary firing at a temperature of 1000 to 1300 ° C. for 0.5 to 2 hours under a reducing atmosphere. Through this secondary firing process, the crystallinity of the phosphor may be increased to improve luminance. When the first calcined material is secondarily calcined in a oxygen-deficient reducing atmosphere, the phosphor becomes conductive. The reducing atmosphere is a mixed atmosphere of 5% by volume of H ₂ , 95% by volume of N ₂ .

The secondary calcined material is classified using a sieve to produce a green phosphor for low voltage. The low-voltage BaTiO ₃ green phosphor of the present invention may be used by adding a conductive material such as In ₂ O ₃ , V ₂ O ₅ , WO _3, or the like to improve luminance. The conductive material is preferably added in an amount of 10 to 20% by weight based on the phosphor.

The following presents a preferred embodiment to aid the understanding of the present invention. However, the following examples are merely provided to more easily understand the present invention, and the present invention is not limited to the following examples.

Example 1-3

BaCO ₃ , TiO ₂ and Li ₃ PO ₄ were mixed in the amounts shown in Table 1 below. The mixture was first calcined in an atmosphere and then calcined in a reducing atmosphere to prepare BaTiO ₃ , which is a green phosphor. Primary firing conditions and secondary firing conditions are as shown in Table 1 below.

Example 4

A phosphor was prepared in the same manner as in Example 1, except that 15 wt% of In ₂ O ₃ was added to BaTiO ₃ , which is a green phosphor.

Example 5

A phosphor was prepared in the same manner as in Example 1, except that BaCO ₃ and TiO ₂ were mixed in the amounts shown in Table 1, and Li ₃ PO ₄ was not added.

Example 6

A phosphor was manufactured in the same manner as in Example 1, except that the secondary firing process was performed in an air atmosphere.

BaCO ₃ [g] TiO ₂ [g] BaCO ₃ / TiO ₂ molar ratio Li ₃ PO ₄ [% by weight] Primary firing condition Second firing condition Temperature [℃] Time [h] Temperature [℃] Time [h] Example One 197.35 79.8988 1: 1 1.5 1300 6 1100 One 2 197.35 63.91904 1: 0.8 1.5 1300 6 1100 One 3 197.35 47.93928 1: 0.6 1.5 1300 6 1100 One 4 197.35 79.8988 1: 1 1.5 1300 6 1100 One 5 197.35 79.8988 One ; One 1.5 1300 6 1100 One 6 197.35 63.91904 1: 0.8 1.5 1300 6 1100 One

The CIE color coordinates and relative luminance of the phosphors of Examples 1-6 were measured at a driving voltage of 27 V, and the results are shown in Table 2 below.

Color coordinates Relative luminance (%) x y Example One 0.101 0.701 100 2 0.097 0.719 120 3 0.098 0.717 70 4 0.099 0.718 200 5 0.106 0.714 120 6 0.097 0.719 140

As shown in Table 1, it can be seen that the phosphors of Examples 1 to 6 emit green light. In Table 2, the highest luminance of the phosphor of Example 4 in which the mixing ratio of barium salt and titanium salt is 1: 1 is considered to be due to the further use of a conductive material of In ₂ O ₃ .

The green phosphor for low voltage according to the present invention is a BaTiO ₃ phosphor, which does not contain sulfide, and thus is chemically stable and has a long lifetime. In addition, the low driving voltage can be applied to low voltage display devices such as VFD or FED.

Claims (7)

A green phosphor for low voltage of the formula (1). [Formula 1] BaTiO ₃ The low-voltage BaTiO ₃ green phosphor according to claim 1, further comprising a conductive material selected from the group consisting of In ₂ O ₃ , V ₂ O _5, and WO ₃ . Mixing a barium salt and titanium oxide (TiO ₂ ); Firstly baking the mixture at an atmosphere of 1100 to 1400 ° C. for 1 to 6 hours; And Secondly calcining the first calcined material at a temperature of 1000 to 1300 ° C. for 0.5 to 2 hours under a reducing atmosphere; The low voltage green phosphor manufacturing method comprising a. 4. The method for producing a green phosphor for low voltage according to claim 3, wherein the mixing molar ratio of barium salt to titanium oxide is in the range of 0.6 to 1: 1. 4. The method for producing a green phosphor for low voltage according to claim 3, wherein a flux is further used in the mixing step. The method of claim 5, wherein the flux is selected from the group consisting of Li ₃ PO ₄ , Na ₃ PO ₄ , Li ₂ CO ₃ , K ₂ HPO _4, and KF. The method for producing a green phosphor for low voltage according to claim 5, wherein the amount of the flux added is 10 to 50 mol%.