JPS608072B2 - luminescent material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a novel luminescent material for excitation by slow electron beams, more specifically, a luminescent material for excitation by slow electron beams, which is made by mixing appropriate amounts of antimony-doped tin oxide and zinc sulfide phosphor. It is related to.

In recent years, many crab photons using transition metal ions, rare earth element ions, etc. as activators have been developed.

It has long been known that these metal ions in various solids and liquids exhibit emission line-like emission spectra unique to each metal ion when irradiated with electron beams, ultraviolet rays, near-infrared light, etc. It has been attracting attention and research as a laser material. Among these studies, for example, YAO:Nd
While lasers were put into practical use, it was also discovered that cerium, eurobium, erbium, etc. can emit light with high efficiency when they are present in various matrixes, and since then, crab photons using rare element ions as activators have been developed. has been extensively researched. As a result, many products have been put into practical use, and among these, yttrium oxide activated with eurobium, yttrium oxysulfide, and yttrium vanadate are particularly important, and are used as red components in color televisions, high-pressure mercury lamps, etc. These crab photons emit light with high brightness when excited by a high number of electrons of several KV or more, ultraviolet rays, and the like. However, these crab phosphors hardly emit light when subjected to slow electron beam excitation of several tens of volts or less, so they cannot be used as crab phosphors for crab optical display tubes.
As a result, the applications of crab light display tubes that emit only green light are limited, and in order to expand the use of display tubes, there has been a strong demand for the development of luminescent materials that emit bright light other than green.
Conventionally, the self-activated zinc oxide crab photoreceptor (
Zn○:Zn) is known.

This phosphor emits green light when excited by slow electron beams,
It is used as a light display tube for calculators, various measuring instruments, etc. In the laboratory, Y2 is a luminescent material that emits colors other than green emitted by this self-activated zinc oxide crab photoform, such as red, yellow, and blue, when excited by slow electron beams.
It is known that 02S:Eu, ZnS:Ag, etc. are imparted with conductivity in one strand of 03, but they have not been put to practical use in display tubes because the conductivity is insufficient. The conductivity of low-resistance materials varies greatly depending on the amount of chemically adsorbed gas molecules.

For example, when oxygen, which is an electron acceptor, is adsorbed to a low-resistance n-type semiconductor material and ionized, a new surface level is formed within the forbidden band, and the energy band is changed because the surface satisfies the electrical neutrality condition. It bends to form a surface potential barrier. In other words, electrons move from the donor level to the adsorption layer due to chemical adsorption of oxygen molecules, oxygen becomes negatively charged adsorption state, a space charge layer is formed near the semiconductor surface, the Fermi level of the semiconductor decreases, and the electron energy of oxygen decreases. and the Fermi level of the semiconductor become equal and equilibrium is reached. In the case of powdered low-resistance materials, gas molecules are adsorbed at the interface of each particle, forming a potential barrier at the grain boundary and blocking the movement of conduction electrons, so the overall electrical conductivity is extremely reduced. shows.

Sufficient baking is necessary to prevent the conductivity from decreasing due to the adsorption of gas molecules and to obtain high brightness.

Generally, it is difficult to degas the powder, so baking at a high vacuum and high temperature is necessary. Baking at high temperatures deteriorates the properties of indium oxide, making it impossible to obtain sufficient brightness. Therefore, although a certain degree of brightness can be obtained by baking at a low temperature, degassing is insufficient, resulting in a short life as a practical display tube.
SUMMARY OF THE INVENTION In order to meet the above-mentioned needs, an object of the present invention is to obtain a luminescent material that exhibits a luminescent color other than green-white when exposed to a slow electron beam, and whose characteristics do not change even when gas is vented by sufficient baking soda.

That is, the present invention is a luminescent material in which a zinc sulfide halo activated at least one of gold, copper, aluminum, gallium, manganese, bismuth, and iron is mixed with antimony-doped tin oxide. When this is excited with a slow electron beam, it emits high-brightness red and green light that is characteristic of activated materials.
Unlike indium oxide, tin oxide doped with antimony does not change its properties when baked at temperatures up to about 500°C in the production of optical display tubes, and sufficient gas release can be performed, making it suitable for practical use. It is possible to produce a light display tube with a long lifespan.

The present invention will be explained in detail below using examples.

Zinc sulfide was precipitated by passing hydrogen sulfide into an aqueous solution of zinc salt, and gold salt and aluminum salt as activators and NaCe as a flux were added to the zinc sulfide, and the mixture was calcined at 90°C.

After firing, soluble by-products were removed by washing with water, and the surface was treated with an insoluble silicate to produce a gold- and aluminum-activated zinc sulfide crystal. The amounts of the activators gold and aluminum were both 0.028 atomic percent relative to the zinc in the host lattice. Also, after mixing tin oxalic acid powder and an aqueous hydrochloric acid solution in which antimony oxide was dissolved and drying it, the temperature was 1200? By firing at ○, antimony dolph tin oxide with low resistance was obtained.
After thoroughly mixing both, they were made into a paste using a POIJ vinyl alcohol aqueous solution and glycerin, and screen printed on the anode groups 3a to 3n shown in the figure. 500 in the air
A crab light display tube as shown in FIG. 1 was assembled, glass-sealed at 500 qo in nitrogen, and baked at 450 qo. In the figure, 1 is a transparent windshield, 2 is a glass substrate, 3a to 3n are an anode group coated with a luminescent material, 4 is a cathode filament, and 5a to 5n are control grit groups. When the crab photogen was excited to emit light, the brightness 15 hours after lighting was 170 foot lamberts at an anode voltage of 30V.

When experiments were conducted by changing the baking temperature, the highest brightness was obtained at 400 to 500 oo. Furthermore, the luminance after lighting changed gradually over time, and it took more than 5,000 hours for the luminance to drop to 50% of the maximum luminance, which was sufficient for practical use. On the other hand, in order to compare with the example, when indium oxide was mixed instead of antimony-doped tin oxide and the same experiment as above was conducted, the maximum brightness was 200 to 300 oo.
Obtained with. At this baking temperature, the grooved light material powder was not sufficiently degassed, and therefore, when it was made into a display tube, the brightness deteriorated quickly due to the influence of the residual adsorbed gas, and the brightness decreased to 50% of the maximum brightness after about 1000 hours. In this example, a zinc sulfide trunk light body activated with gold and aluminum was described, but copper,
The luminous material, which is a mixture of zinc sulfide phosphor activated with gallium, manganese, iron, bismuth, etc., and tin oxide doped with antimony, can withstand heat treatment temperatures of up to 50 psi and has a maximum brightness of 150 ft. It could be used for more than 500 hours before the brightness exceeded Lambert's and decreased to 50% of the maximum brightness.

5 As described above, the luminescent material of the present invention emits luminescent colors other than green and white, such as red and green, and can withstand high-temperature heat treatment, allowing for sufficient gas release. Obtainable.

The simple explanatory diagram in Figure 0 is a sectional view showing the typical basic structure of a crab optical display tube.

1 is a transparent windshield, 2 is a glass substrate, 3a to 3n
4 is an anode group coated with a luminescent material, 4 is a cathode filament,
5a to 5n represent control blit groups.

Claims (1)

[Claims] 1. A luminescent material comprising a mixture of a zinc sulfide phosphor activated with at least one of gold, copper, aluminum, gallium, manganese, bismuth, and iron and tin oxide doped with antimony.