Hochdrucksynthese und Kristallstrukturen von TlInS2-II und TlInS2-III / High Pressure Synthesis and Crystal Structures of TlInS2-II and TlInS2-III

Abstract

Pressure treatment of TlInS2-I at 30 kbar, 300°C yielded the rhombohedral modification TlInS2-II (space group R3̄m, α = 3,83 Å, c= 22,23 Å, Z = 3). TlInS2-II has a-NaFeO2-structure and is metastable at all ρ, T-conditions investigated. At 30 kbar, 400°C, TlInS2-I and TlInS2-II transform to the hexagonal modification TlInS2-III, which was later found to be the normal pressure, low temperature modification of TlInS2. The crystal structure of Τ1Ιn2InS2-ΙΙΙ was solved from single-crystal data. The crystals are hexagonal, space group P63/mmc, with a = 3,83 Å, c = 14,88 Å and Z = 2. The structure consists of sulfur layers with a sequence ABBA ... All octahedral sites are occupied by In, and one half of the trigonal-prismatic sites by Tl. The arrangement is such as to separate Tl and In by the greatest possible distance.