| 摘要 |
A photo-conductive material for use in photoelectric cells (see Group XXXVI) is made by mixing cadmium sulphide, selenide or sulphoselenide with a flux, firing above the melting point of the flux and washing out the crystals from the resulting product, firing the washed crystals to sinter them into a mass, breaking up the mass into powder without grinding and finally firing the powder in a third firing below the sintering temperature at least part of which is carried out under atmospheric pressure in the presence of sulphur. In a specific example 100 grams of cadmium sulphide or selenide or a mixture of the two is mixed with 10 grams of cadmium chloride, 1 gram of ammonium chloride 0.7 ml. of 0.1 mol. copper chloride and 25 ml. water and the mixture dried at 150 DEG C. for 15 hours, broken up and fired at 600 DEG C. for 20 minutes. The fired mass, consisting of CdS crystals impregnated with Cu and Cl is soaked and washed in water to remove most of the CdCl2, then moistened with a solution containing equal parts of 0.1 mol. CdCl2 and 1 mol. NH4Cl and passed through a 325-mesh sieve. It is then fired at 600 DEG C. for 20 minutes and the sintered mass resulting is grated through a 50-mesh sieve, and is fired in the presence of sulphur vapour for 10 minutes at 500 DEG C. and for a further 10 minutes in vacuo. After cooling it is passed through a 325-mesh sieve. Ag or another monovalent iron may replace Cu. In a further embodiment cadmium sulphide is crystallized from a mass comprising 10 per cent by weight of a molten flux containing a halide and the flux leached out. Cu is added and diffused into the CdS in a second firing.
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