JPH01133938A - Method for reducing resistance of zink sulfide - Google Patents

Abstract

PURPOSE:To obtain ZnS having low resistance by adding a compd. of a group IV element and/or a compd. of a group V element to ZnS and calcining them. CONSTITUTION:One or more kinds of compds. selected among compds. of Si, Ge, Sn and Pb as group IV elements, e.g., SiO2 and compds. of P, As, Sb and Bi as group V elements, e.g., P2O5 are added to ZnS by 0.01-10 wt.% and 0.5-20wt.% S and 0.1-10wt.% flux such as NaI or KI are further added as required. They are uniformly mixed and calcined at 400-1,500 deg.C in an atmosphere of an oxidizing gas, reducing gas or inert gas to obtain ZnS having such low resistance as 10<5>-10<6>OMEGA.cm volume resistivity.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for reducing the resistance of zinc sulfide.

Zinc sulfide with reduced resistance is a useful substance that is expected to be applied in various fields.

(Prior Art) Zinc sulfide is originally an insulator, and various attempts have been made to lower the resistance of this material. For example, Apl 1
．． Phys, Lett, 2 units.

697 (1975), 10~10% of zinc sulfide single crystals were added to a molten mixture of metallic zinc and aluminum at 900°C.
A method for lowering the resistance of zinc sulfide by soaking it for 24 hours is described. However, this method requires expensive corrosion-resistant equipment that can withstand high temperatures and high pressures, requires a long processing time, and requires a very complicated post-processing process to remove metallic zinc and aluminum that adhere to the surface of the IT-based zinc after dipping. It cannot be said to be suitable as an industrial method as it requires treatment. Further, this method cannot be said to be suitable for zinc sulfide powder.

(Problems to be solved by the invention) Reducing the resistance of zinc sulfide, which is known as an insulator, is expected to be used in various fields such as electronic materials and luminescent material tubes, and is of great industrial significance. be.

The present inventors have conducted extensive research into reducing the resistance of zinc sulfide using various methods, and have arrived at the present invention.

That is, the present inventors added 0.01 to 10% by weight of one or more of a group 4 element compound and a group 5 element compound to zinc sulfide, and fired the mixture. We have discovered a method of lowering the resistance of zinc sulfide by doing this.

The method according to the present invention can easily and inexpensively reduce the resistance of zinc sulfide without requiring particularly expensive equipment or complicated operations.

(Means for Solving the Problems) The gist of the present invention is to add one or more of a group 4 element compound and a group 5 element compound to zinc sulfide at a concentration of 0.01 to zinc sulfide. This is a method for reducing the resistance of zinc sulfide, which is characterized by adding ~10% by weight and firing.

Here, during firing, better results are often obtained by adding sulfur and various chlorides, bromides, iodides, etc. known as so-called fluxing agents. Examples of fluxing agents include sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, ammonium chloride,
Examples include zinc chloride and magnesium chloride, but particularly preferred are iodides such as sodium iodide and potassium iodide.

It is believed that the addition of a flux allows the compounds of group 4 elements and compounds of group 5 elements to penetrate well into zinc sulfide during firing and quickly diffuse, giving good results.

Furthermore, the addition of sulfur is considered to be effective in suppressing the sulfur in zinc sulfide, which is volatile especially at high temperatures. In particular, when fired without adding any sulfur, the quality of zinc sulfide changes and the properties of zinc sulfide itself may be lost.

The amount of flux and sulfur added is not particularly limited, but if it is too small, there will be no effect, and if it is too large, the corresponding effect will not be achieved by 1q, making it uneconomical. The amount of sulfur is in the range of 0.1 to 10 weight percent relative to zinc sulfide, while the amount of sulfur is in the range of 0.5 to 20 ffl percent. However, if they are added, it is desirable to use both together.

In the present invention, compounds of Group 4 elements include compounds of silicon, germanium, tin, and lead, among which silicon oxide, silicic acid and its salts, germanium oxide, tin oxide, stannic acid, and Its salt, lead oxide, is preferred. More specifically, examples of these compounds include silicon dioxide, silicic acid, sodium silicate, potassium silicate, magnesium silicate, calcium silicate, zinc silicate, aluminum silicate, germanium dioxide, stannous oxide, Stannic oxide, stannic acid, sodium stannate, potassium stannate.

- Lead oxide, lead dioxide, lead dioxide, lead tetroxide, and the like.

On the other hand, compounds of Group 5 elements include phosphorus and arsenic.

Target compounds include antimony and bismuth, but especially phosphoric oxides, phosphoric acid and its salts, and arsenic oxides.

Arsenic acid and its salts, antimony oxide, antimonic acid and its salts, and bismuth oxide are preferred.

More specific examples of these compounds include phosphorus pentoxide, metaphosphoric acid, orthophosphoric acid, and pyrophosphoric acid.

Sodium phosphate, potassium phosphate, magnesium phosphate, calcium phosphate, zinc phosphate, aluminum phosphate, tin phosphate, diarsenic pentoxide, arsenic acid.

Examples include arsenite, sodium arsenate, antimony trioxide, antimonic acid, sodium antimonate, bismuth trioxide, and the like.

These may be used alone or in combination of two or more. This is selected depending on the purpose of reducing resistance and the type of additive.

Although these additives cannot be uniquely limited depending on the type, they are usually in the range of 0.01 to 10% by weight, preferably in the range of 0.05 to 5% by weight.

Less than 0.01 weight percent has no effect, while 10
If the weight percentage is exceeded, not only the corresponding effect cannot be obtained, but also the properties may be lost, so it should be avoided.

It is preferred that zinc sulfide and these additives, and in some cases flux and sulfur, be mixed as uniformly as possible. As a mixing method, dry mixing using a mortar or ball mill, or wet mixing using a suitable medium such as water can be advantageously used.

The order of mixing is not particularly limited, and all may be mixed together. These mixtures are subjected to the next firing step.

The firing process is performed in an oxidizing gas atmosphere, a reducing gas atmosphere, or an inert gas atmosphere. Oxidizing gases include air and oxygen, reducing gases include hydrogen and hydrogen sulfide, and inert gases include nitrogen and argon, all of which can be used. The atmosphere to be used for firing should be selected depending on the purpose and the type of additives.

The firing temperature ranges from 400 to 1500'C, preferably 5
A range of 00 to 1200°C is suitable.

If it is less than 400'C, sufficient calcination or sufficient diffusion of additives will not be carried out, while if it exceeds 1500'C, it will be uneconomical due to the high temperature, and on the contrary, the effect may be reduced.

The reason why zinc sulfide has low resistance according to the present invention is not fully understood at present, but
It is thought that this is because some of the group element compounds as they were or some of these chemically changed compounds were dissolved in the zinc sulfide crystal. Furthermore, according to the experiments of the present inventors, compounds of Group 2 elements such as magnesium oxide and calcium oxide, compounds of Group 3 elements such as aluminum oxide and indium oxide, and compounds of Group 8 elements such as iron oxide and cobalt oxide. Adding a compound of the element and firing it has no effect at all.

Furthermore, it is completely acceptable for elements of groups other than the above-mentioned Group 4 elements and Group 5 elements to be the bottom component of the composition of the Group 4 element compound and the Group 5 element compound of the present invention. do not have. In short, compounds other than Group 4 elements and Group 5 elements do not have a positive or negative effect when lowering the resistance, so there is no need to add them.

By the method of the invention, for example, a volume resistivity of 1010 to 10
Zinc sulfide with Ω・cm is 105 to 106 Ω・c
It becomes low resistance zinc sulfide with m. To measure the volume resistance, place 0.2 g of the sample into an alumina cylinder with an inner diameter of 10 m, and
Measure using a resistance meter under pressure of Kl/cri.

(Effects of the Invention) According to the present invention, low-resistivity zinc sulfide can be obtained industrially, and this product is expected to be applied to various fields of electronic materials and luminescent material tubes.

(Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 10 g of zinc sulfide powder, 0.2 y of silicon dioxide (manufactured by Silicic Anhydride/Precipitation), 0.2 g of potassium iodide as a flux, 5A
Yellow powder 17 was added, thoroughly mixed in a mortar, heated at a rate of 200'C/hour in a nitrogen atmosphere, and held at 900'C for 1 hour for firing. After cooling, wash with water and heat at 120'C under reduced pressure.
and dried to obtain low resistance zinc sulfide. The volume resistivity of this product was 8×10” Ω·cm. When zinc sulfide was treated in the same manner without adding silicon dioxide, the volume resistivity was 3×10 10 Ω·cm.

Example 2 Sodium dihydrogen phosphate dihydrate 0 in zinc sulfide powder 109
．． 19, mixed in a mortar and heated to 200'C/hr in air.
The temperature was raised at a rate of 200°C, and the temperature was maintained at 600°C for 1 hour for firing. A low resistance zinc sulfide was obtained by processing in the same manner as in Example 1.

The volume resistivity of this material was 9×10 6 Ω·cm.

Example 3 0.53 disodium hydrogen phosphate in 10 g of zinc sulfide powder
was added, thoroughly mixed, and held at 200° C. for 30 minutes in a nitrogen atmosphere, then brought to ambient temperature at a rate of 200° C./hour in a hydrogen sulfide atmosphere, and held at 1200° C. for 30 minutes for firing. The volume resistivity of low-resistivity zinc sulfide obtained by the same treatment is
It was 5×10”Ω·cm.

Examples 4 to 16 and Comparative Examples 1 to 2 10 g of zinc sulfide powder, 0.5 sodium iodide as a flux
g, 1 g of sulfur powder and a compound of a group 4 element or a compound of a group 5 element shown in Table 1 were thoroughly mixed, and 800 g of sulfur powder was mixed in a nitrogen atmosphere.
It was baked at 'C for 1 hour. A low resistance zinc sulfide was obtained by processing in the same manner as in Example 1. Table 1 shows the results of measuring volume resistance. Table 1 also shows comparative examples in which a Group 3 element compound was added in place of the Group 4 element compound and the Group 5 element compound.

(Lr) CD size the law of nature Real overwhelming Nα Compound name 12) Potassium phosphate 13) Zinc pyrophosphate 14) Aluminum phosphate 15) Three Awakening Bismuth Comparative example 1) Aluminum oxide 2) Indium oxide Added calorie volume volume resistance 0.29 1×106Ω・Cm O, 25x106 0.2　　　　　　X106 0.2 5 Xl07 0-1 3 X106 0.05 0.2 4×108 0.1 6 XIO10

Claims (5)

[Claims] (1) To zinc sulfide, one or more of the compounds of group 4 elements and compounds of group 5 elements are added to zinc sulfide.
．． 1. A method for reducing the resistance of zinc sulfide, which comprises adding 1 to 10 percent by weight of zinc sulfide and firing. (2) The method according to claim 1, wherein a flux and sulfur are added during firing. (3) The method according to claim 2, wherein the fluxing agent is sodium iodide or potassium iodide. (4) The compound of Group 4 element is silicon dioxide, silicic acid,
3. The method according to claim 1 or 2, wherein the silicate is sodium silicate, potassium silicate, magnesium silicate, calcium silicate, zinc silicate, or aluminum silicate. (5) The compound of Group 5 element is phosphorus pentoxide, metaphosphoric acid, orthophosphoric acid, pyrophosphoric acid, sodium phosphate, potassium phosphate, magnesium phosphate, calcium phosphate,
3. The method according to claim 1 or 2, wherein the phosphate is zinc phosphate or aluminum phosphate.