A study of silver chloride containing gold

Measurements of optical absorption, dielectric loss, photoconductivity and photolysis have been used to investigate the properties of silver chloride containing gold. The gold enters the silver chloride lattice either substitutionaly or as a separate phase of aurous or auric chloride depending on the method of preparation. The most interesting properties are shown by the aurous chloride phase which is produced by annealing in chlorine or nitrogen at 673º K and quenching to room temperature. The temperature and concentration dependences of the optical absorption of the aurous chloride phase indicate that the energy for the formation of a separate phase of aurous chloride approaches a minimum near 673º K. The incorporation of gold sensitises silver chloride for colloid formation. The photolysis of silver chloride is determined by measuring the optical absorption during irradiation. In silver chloride containing substitutional Au or auric chloride as a separate phase, the photolysis occurs mainly on the. surface. The incorporation of a separate phase of aurous chloride results in strong volume sensitivity to both blue and red light. The volume sensitivity is explained in terms of the spectral sensitisation of silver chloride by the aurous chloride. At temperatures above 170ºK irradiation results in the formation of silver and gold colloid and the conversion of aurous chloride to auric chloride. The thermal development which occurs at 423°K is attributed to the thermal decomposition of the aurous chloride phase. The properties of the deep hole and electron traps in silver chloride sensitised with europium have been studied by measuring both the photoconductivity and the thermally stimulated conductivity at low temperatures. The slow growth in the photoconductivity which occurs' on blue irradiation at 130º K is shown to be due to the effects of deep hole trapping and the gradual filling of intrinsic electron traps. Dielectric loss measurements are used to determine the binding energy of cation vacancies to impurity ions and the activation energy for reorientation of cation vacancies about impurity ions in silver chloride and bromide containing chromium and in silver chloride containing europium. These measurements and those of photoconductivity and thermally stimulated conductivity are made on a spectrometer developed for the continuous measurement of complex permittivity