Thermal Dependence of the Absorption Band Edge in Zincblende-type Cadmium Sulphide obtained in Pressure Experiments

Abstract

THE discontinuity in the optical absorption edge shift of wurtzite-type cadmium sulphide (CdS–W) under a pressure of 27,000 kg/cm², reported in Edwards–Drickamer's experiments¹, was assumed as a phase transition, essentially complete at about 40,000 kg/cm², perhaps² due to the zincblende phase (CdS–Z). The high-pressure X-ray experiments recently carried out by Rooymans³ in CdS–W under a pressure of 20,000 kg/cm² have shown indeed a rocksalt-type structure (CdS–R) with a lattice constant, measured under pressure, of a₀ = 5.30 Å and an X-ray density of 6.44 corresponding to ΔV/V = −25 per cent during the transition CdS–W→CdS–R.