[PtIn6][CGaO4](2) - The first oxide containing [PtIn6] octahedra. Preparation, characterisation, and rietveld refinement with a remark to the solid solution series [PtIn6][GaO4](2-x)[InO4](x) (0 < x <= 1)

The novel oxides [PtIn6][GaO4](2-x)[InO4](x) (0 < x <less than or equal to> 1) are formed by heating intimate mixtures of Pt, In, In2O3, and Ga2O3 in the corresponding stoichiometric ratio in corundum crucibles under an atmos phere of argon (1220 K, 70 h). The compounds are black, stable in air at ro om temperature, reveal a semiconducting behaviour, and decompose only in ox idizing acids. X-ray powder diffraction patterns can be indexed by assuming a face centered cubic unit cell with lattice parameters ranging from a = 1 001.3(1) pm (x = 0) to a = 1009.3(1) pm (x = 1). According to a Rietveld re finement [PtIn6][GaO4](2) crystallizes isotypic to the mineral Pentlandite (Fm(3) over barm, Z = 4, R(profile) = 6.11%, R(intensity) = 3.95%). The cha racteristic building units are isolated [PtIn6](10+) octahedra which are li nked via [GaO4](5-) tetrahedra to a three dimensional framework. Starting f rom [PtIn6][GaO4](2) the substitution of Ga3+ ions by larger In3+ ions lead s to the formation of a solid solution series according to the general form ula [PtIn6][GaO4](2-x)[InO4](x) and becomes apparent in an increase of the lattice parameter.