JPS5821943B2 - Method for manufacturing phosphor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a powdered phosphor that is stimulated with a slow electron beam to emit light, and in particular, Zn, which is a material with high luminous efficiency in a fast electron beam-stimulated luminescent phosphor, is used.
The present invention relates to a method for producing a phosphor made of S and Zn5e compound powder that can emit light by low-speed electron beam stimulation.

Conventionally, ZnS and Zn5e compound powder phosphors were stimulated with high-speed or medium-speed electron beams to emit light, but most of the visible light-emitting phosphors are insulators and have low resistance. expensive.

Further, the first crossover voltage of the secondary electron emission characteristic is usually in the medium-speed electron beam energy range.

Mainly due to these two reasons, electronic stimulation in the low-speed electron beam energy range generates charges on the surface of the phosphor, and the stimulating electrons lose their energy, making it impossible to stimulate the phosphor to emit light.

On the other hand, in the case of a low-speed electron beam, the formation of a light-emitting inactive layer that occurs on the surface of the phosphor due to physicochemical adsorption of atmospheric gas, etc. It is thought that this will significantly impede the stimulation of

In contrast, the present invention has made it possible to reduce the resistance of the crystal at the same time as forming luminescent centers in the phosphor crystal, and to make the phosphor emit light by slow electron beam stimulation. This method can be implemented regardless of the influence of the surface condition of the phosphor or secondary electron emission characteristics on line-stimulated light emission.

Note that the slow electron beam here refers to an electron beam at an accelerating voltage equal to or lower than the first crossover voltage in the secondary electron emission characteristics of the material.

Therefore, lowering the resistance of nb-vib group compound materials is usually achieved by using Wb group (A/, Ga, In) or
By adding elements of groups (CI, Br, I) into the crystal and causing stoichiometric misalignment of the constituent elements of the compound, shallow impurity levels or lattices other than impurities are created in the forbidden band of the compound. This can be easily achieved by creating a defect level.

Among the nb-■b group compounds, ZnS and the like are impurities that once enter the crystal due to the thermal diffusion of impurities as described above, and are re-diffused during the heat treatment and cooling process and released outside the crystal. It has been impossible to achieve low resistance for many years.

Recently, nb-vib group compound materials have been attracting attention as materials for blue light emitting diodes, but since it is necessary to reduce the resistance of this material, research has been carried out on low resistance processing methods, and furthermore, ZnS single crystal Its low resistance was established.

Therefore, techniques for reducing the resistance of ZnS compound ICs are known.

The purpose of the present invention is to make ZnS and Zn5e compounds into phosphors that emit light by low-speed electron beam stimulation. At the same time, it is necessary to efficiently form luminescent centers in the crystal by low-speed electron beam stimulation.

The present invention is a method for synthesizing a powder phosphor that achieves low resistance of fine particle crystals and provides efficient light emission by low-speed electron beam stimulation.

The present invention will be described in detail below by showing two examples of a method for synthesizing ZnS and ZnSe compound powder crystals for low-resistance phosphors, and the luminescence characteristics of the synthesized phosphors when stimulated with slow electron beams.

[Example 1] Already, for example, Cu was used as an activator at approximately 10'A.
tom/mob, ZnS or Zn5e powder activated with a specified amount of impurities effective for forming luminescent centers using, for example, approximately 10 8 Atom/mol of Al as a co-activator, zinc vapor heat treated inside,
This is a manufacturing method that reduces resistance.

In a transparent quartz crucible 3 having the shape shown in FIG. It is vacuum sealed at a partial pressure of 10-'Torr and placed in a horizontal tube furnace having the temperature distribution shown in FIG.

The amount of zinc metal 2 used here may be sufficient to maintain the saturated vapor pressure in the sealed container at several atmospheres or less during heat treatment, and the amount does not need to be strictly determined.

During the heat treatment, the quartz rod 5 welded to the quartz crucible is connected to a rotating drive mechanism; it is rotated loosely about the axis so that the powder 1 is uniformly treated with zinc vapor.

The treatment temperature at this time is approximately 1000° C. at the powder insertion portion, the zinc metal vapor generating portion is maintained at the boiling point of zinc of 950° C. or higher, and the treatment time is 10 hours or more.

That is, the effect of the treatment according to the present invention increases as a function of the treatment time, but in order to fully achieve the effect of lowering resistance, it is desirable that the treatment time be 10 hours or more.

After such treatment, the quartz crucible is quickly removed from the furnace and placed in water, where it is rapidly cooled to a temperature of 15-25°C.

At that time, be sure to operate so that molten zinc does not mix with the powder.

[Example 2] Impurities necessary for forming luminescent centers, such as those shown in Example 1, are added to chemically synthesized ZnS or Zn5e luminescent grade raw material powder, and at the same time, in order to promote lower resistance. Add excess zinc metal to.

In other words, this is a method of simultaneously accomplishing the heat treatment for forming the luminescent center and the heat treatment in zinc vapor.

Into a quartz crucible 3 as shown in FIG. 1C, added impurities necessary for forming a luminescent center, such as aluminum and a large amount of zinc metal 2', are inserted together with raw powder 1 of ZnS or Zn5e compound having a particle size of 1 μm or less. .

Here, too, the amount of zinc metal 2' used is sufficient to maintain the saturated vapor pressure in the sealed container at several atmospheres or less during heat treatment, and the amount does not need to be strictly determined.

Those added impurities and a large amount of zinc metal 2' are directly
Since it comes into contact with the nS or Zn5e ([lS compound raw material powder 1), a highly pure powder is used, and particularly a surface cleaning chemical treatment is performed.

The amount of added impurity is much larger than the amount actually required in the ZnS or Zn5e compound crystal, for example, about 10% molar ratio, and the amount of zinc is 3 to 5 times that of the raw material powder of ZnS or Zn5e compound. into the molar ratio of

On the other hand, when ano-reminium is used as the additive impurity, a carbon film is deposited on the inner wall of the quartz tube to prevent corrosion of the quartz by aluminum.

The quartz crucible containing these raw materials is preheated to 300° C. under vacuum to sufficiently remove residual moisture, and the crucible is sealed when the degree of vacuum reaches 10-' Torr.

Next, a quartz crucible is placed in the soaking zone of a vertical tube furnace having the temperature distribution shown in FIG.

The firing temperature and time were the same as in Example 1,
After the firing process, the quartz crucible is dropped vertically into a water tank installed directly below the furnace for rapid cooling.

The above has described a method for synthesizing a low resistance powder phosphor that can be applied to ZnS or Zn5e compounds in general. By using the above-described synthesis method of the present invention, it is possible to reduce the resistance of a phosphor, create a highly efficient luminescent center near the surface of the phosphor, and obtain light emission by slow electron beam stimulation. Examples of its characteristics are as follows. Shown below.

FIG. 2 shows a typical ZnS produced by the above-described production method of the present invention: Zn, AJI! An example of the relationship between the luminance of a powder phosphor and the current flowing through the phosphor with respect to the electron beam acceleration voltage is shown.

As is clear from this figure, the acceleration voltage threshold (Uc) of the above-mentioned phosphor is slightly higher than the threshold Uc of about 2 volts for zinc oxide, but it is less than 10 volts, and the acceleration voltage of several tens of volts The brightness of light emitted by voltage is different from that of conventional Zn.
O: Comparable to the brightness of Zn.

Note that from the sample current shown in the figure, it is not possible to simply estimate the resistance value because the sample is a powder, but according to the data of a single crystal that has been subjected to the same treatment, it is 10 to 100 Ωα,
The resistance value of this powder crystal appears to be at least IKΩm or less.

FIG. 3 shows ZnS:Cu, AA powders produced by the same manufacturing method as the above-mentioned ZnS:Zn, AA powders.
This shows the emission spectrum of Zn mixed powder by slow electron beam stimulation, and the former is blue and has good monochromaticity, which also supports the fact that the luminescence center is the D-A pair, so it has good luminescence efficiency at room temperature. .

In addition, since the latter was zinc-treated with a small amount of copper, the light emission at the shoulder of arrow a on the characteristic curve is the pair light emission of Zn and AI, and furthermore, The peak of the spectrum is the paired luminescence between copper and Al, and the paired luminescence dominates the luminescent color of this phosphor, giving it a green color.

The luminance and current of the above-mentioned phosphor with respect to the electron beam accelerating voltage almost match those shown in FIG.

The above-mentioned phosphor materials emit blue and green light when stimulated with slow electron beams, but in order to practically obtain materials that emit light in the three primary colors, similar phosphor materials that emit light at longer wavelengths are used. It could be made using the manufacturing method.

Examples of typical phosphors are ZnS: Mn,
Zn and Zn5e: The emission spectra of Cu, AI, and Zn upon slow electron beam stimulation are shown in FIG.

As is clear from the above description, according to the present invention, it is possible to improve the luminous efficiency of a slow electron beam stimulated luminescent phosphor and obtain a phosphor that emits three primary colors with good monochromaticity. ) Multicolor display on display tubes, (2) color image display, (3) reduction in accelerating voltage for color picture tubes, and (4) energy savings in display devices.

[Brief explanation of the drawing]

Figures 1 a and b and C and d are layout diagrams and characteristic curve diagrams showing the characteristics of the embodiment and implementation of the phosphor manufacturing method of the present invention, respectively, and Figure 2 is an example of the luminescent characteristics of the phosphor produced by the inventive manufacturing method. FIGS. 3 and 4 are characteristic curve diagrams showing other examples of emission spectra. 1... Raw material powder crystal, 2... Zinc or cadmium powder, 2'... nb gold metal ib gold metal mixture, 3... Transparent quartz crucible , 4...
... Furnace body, 5 ... Crucible rotating shaft rod, 6 ...
...Carbon coating.

Claims (1)

[Claims] 1. When producing a phosphor made by adding an activator to zinc sulfide or selenide by firing, 1. 1. A method for producing a phosphor, characterized by providing a resistive process. 2. The phosphor according to claim 1, characterized in that a process of adding an activator to zinc sulfide or selenide and firing it once is performed before the process of lowering the resistance. manufacturing method. 3. The method for producing a phosphor according to claim 1, characterized in that the step of lowering the resistance is carried out subsequent to the step of adding an activator to zinc sulfide or selenide. .