Thermal and structural analysis of the effects of chlorine impurities on pressurized CdS

Abstract

Anomalous large diamagnetism (χv∼−0.25/4π cgs units) and large positive magnetism (χv∼+10−4 cgs units) have recently been reported in pressure-quenched CdS polycrystalline samples by Homan and MacCrone. These effects were shown to be sample material source dependent, and as a first step toward characterizing these samples, we compared the thermal and structural properties of various CdS samples before and after pressurization. Samples containing up to 6-wt. % Cl were prepared by precipitaion from a chloride containing aqueous bath. We find that (i) Cl impurities are probably present in the form of a complex which can decompose on heating to CdS+CdCl2, (ii) melting of a portion of the samples containing high levels of Cl occurs at 535 °C and is attributed to the eutectic temperature of the CdS+CdCl2 mixture, and (iii) heating beyond 535 °C produces complete volatization of the CdCl2 component. The results on samples prepared by mixing of CdS and CdCl2⋅H20 were examined and found to have similar thermal behavior. The cadmium sulfide used in the previous magnetization study was examined and, based on the similarities in the thermal and structural properties, we conclude that the samples which exhibit the anomalous magnetic effects were also prepared by precipitation. In agreement with earlier studies, metastable phases are observed after various pressurizations to above 4.0 GPa.