Ordered vs. disordered perovskites; structural studies of Fe-doped SrIrO3 and SrRuO3

Sr2IrFeO6 and SrRu0.5Fe0.5O3 are shown, using a combination of synchrotron and neutron diffraction, to be monoclinic I2/m with cation ordering and tetragonal I4/mcm with disordered Fe and Ir, respectively. Both undergo phase transitions upon heating due to the loss of the octahedral tilts.