Structural Relations and Phase Transformations in the Rare-Earth Sesquisulfide Series at High Pressures and Temperatures

Abstract

The p-T diagrams of the heavy rare-earth sesquisulfides Ln₂S₃ (Ln=Dy to Lu) have been determined with a modified Belt-type apparatus. Structural characterization of the high-pressure phases was achieved by x-ray analysis of the quenched samples. Furthermore, the representation of the generalized phase relations in a master phase diagram has been tried. This clearly demonstrates the possible structure types expected with an arbitrary Ln³⁺ cation as a function of temperature and pressure. Problems met with the defect-Th₃P₄ phase are touched upon but cannot be solved without further investigation.