The effect of iridium oxidation state on the electronic properties of perovskite-type solid solutions: Ba2–xLaxInIrO6 and BaLaIn1–yCayIrO6.

Two novel solid solution series, Ba 2- x La x InIrO 6 ( x =0–1.0) and BaLaIn 1- y Ca y IrO 6 ( y =0–1.0), were prepared and several changes in structure, moment and charge transport were observed. The Ba 2- x La x InIrO 6 series exhibits a transition from a 6M polytype to an orthorhombic perovskite structure with increased La content whereas the BaLaIn 1- y Ca y IrO 6 series transitioned from a disordered, orthorhombic perovskite to an ordered, cubic perovskite with increased Ca content. Seebeck measurements for both systems showed that Ir(IV)-rich compounds tended to have a n-type conduction mechanism while Ir(V)-rich compounds tended to be p-type. Both systems were found to be semiconducting and the magnitude of the resistivity is dependent on crystal structure and Ir environment. Magnetic measurements show that the μ eff values for both systems are significantly less than predicted for Ir(IV) (1.73 μ B ) and greater than predicted for Ir(V) (0 μ B ). These results are compared to other iridate compound families. [ABSTRACT FROM AUTHOR]