文摘
The crystal structures of the series of ordered double perovskites Ba2鈥?i>xSrxYIrO6 (0 鈮?x 鈮?2) were refined using a combination of high-resolution synchrotron X-ray and high-intensity neutron diffraction data. The materials displayed a sequence of structures Fm3虆m(a0a0a0) I4/m(a0a0c鈥?/sup>) I2/m(a鈥?/sup>a鈥?/sup>c0) P21/n(a鈥?/sup>a鈥?/sup>c+) associated with increased tilting of the corner-sharing octahedra induced by increasing amount of the smaller Sr cation present. A similar sequence of transitions was induced by heating selected samples. Magnetic susceptibility measurements between 2 and 300 K showed no evidence for long-range magnetic ordering, an observation that was supported by neutron diffraction measurements, and rather strong spin鈥搊rbit coupling results in a Jeff = 0 ground state.