GB1343200A - Process for producing photoconductive materials - Google Patents

Abstract

1343200 Photo-conductive material KONISHIROKU PHOTO INDUSTRY CO Ltd 23 Dec 1971 [26 Dec 1970] 59925/71 Headings G2C and C17E A photo-conductive CdS, CdSe or CdSeS is fired in the presence of an actiator, a co-activator, a flux and a dispersant, the firing temperature being such that the dispersant does not melt nor causes agglomeration or fusion of the powder. The activator is preferably a halide, sulphate or nitrate of Ag, Au or Cu. The co-activator is NH 4 Cl or a compound of Al, In or Ga while the flux may be CaCl 2 , ZnCl 2 , NaCI or KCl. The dispersant is preferably NaI, KI, NaBr, KBr, NaCl, KCI, Na 2 SO 4 , CaCO 3 , Na 2 CO 3 or CaO. In an embodiment a mixture of CdS, CdCl 2 , NH 4 Cl and CuCl 2 is ground in water and dried at 140‹C. The dried mixture is mixed with a mixture of NaCl in alcohol, ground, and dried at 120‹C. The dried mixture containing NaCI is ground and heated in air at 590‹C. The fired mixture is washed in water to remove all traces of chloride ions and dried to yield a uniformly fine spherical powder. The washed powder may be further treated if required by mixing with NH 4 Cl and CdCl 2 , drying and firing to 590‹C. The further fired particles are ground , fired in a mixture of H 2 S + N 2 at 500‹C. and then in vacuo at 500‹C. The powder is allowed to cool in vacuo to 100‹C. and then dried in a desiccator. The further treated powder is dispersed in an alkyol resin and either coated on aluminium comb electrodes on a polyester sheet or an aluminium plate to form an electro-photographic element. The powder may also be used in image converters or intensifiers or photo-cells.