Darstellung und Kristallstruktur der Hochdruckphase AgAlS2-II / Preparation and Crystal Structure of the High-pressure Phase AgAlS2-II

Abstract

AgAlS2-I with chalcopyrite structure transforms at 25 kbar and 300°C to the new highpressure phase AgAlS2-II. The crystal structure of AgAlS2-II is trigonal, space group P3ml, with a= 3,50 Å, c = 6,84 Å and Z = 1. The structure is based on a hexagonally close packed arrangement of sulfur atoms with aluminium atoms in octahedral sites and silver atoms in tetrahedral sites. The AgS4-tetrahedra are considerably distorted, giving a coordination number 3 + 1 for the silver atoms.