Partial Anion Exchange in Ag23Te12X: The Solid Solutions Ag23Te12Cl1–xBrx, Ag23Te12Br1–yIy and Ag23Te12Cl1–zIz

Abstract

AbstractX‐ray powder diffraction, EDX and DSC measurements were performed in order to determine the structural and thermal properties of the solid solutions of Ag23Te12Cl1–xBrx, Ag23Te12Br1–yIy and Ag23Te12Cl1–zIz. A complete solid solution exists between the two ternary end members Ag23Te12Cl and Ag23Te12Br, whereas the substitution of bromine by iodine can only be observed up to y = 0.3 in Ag23Te12Br1–yIy under thermodynamically controlled synthesis conditions. Even chlorine can be partially substituted by small amounts of iodine up to a certain extend. Temperature dependent single crystal structure determinations of crystals with the nominal composition Ag23Te12Cl0.95I0.05 substantiated the significant influence of the iodine intake on the lattice parameters of the pseudo‐tetragonal orthorhombic system, especially at low temperatures. A systematic deviation from the 1:1 ratio of the a and b lattice parameter (pseudo‐tetragonal ratio) was observed upon cooling, which could not be detected in the case of the ternary compounds. X‐ray powder diffraction experiments gave a first hint on the non‐stoichiometry of this set of materials and all compounds show peritectic decomposition to binary phases at temperatures slightly above 680 K.