Structural and physical properties of heavily doped yttrium vanadate: Y_0.6Cd_0.4VO₃

Structural properties of Y_0.6Cd_0.4VO₃ were investigated by electron diffraction and laboratory and synchrotron X-ray powder diffraction methods. Y_0.6Cd_0.4VO₃ crystallizes in space group Pnma (GdFeO₃type perovskite structure) between 12 and 300 K (a = 5.45887(3) Å, b = 7.57250(4) Å, and c = 5.27643(2) Å at 300 K). The lattice parameters showed anomalous behavior on temperature. The c parameter linearly decreased from 12 to 120 K, and then it lineally increased from 160 to 300 K. The b parameter was constant between 12 and 120 K, demonstrated a drop from 120 to 200 K, and then lineally increased from 200 to 300 K. The cla ratio had a rather sharp maximum at 150 K. In Y _0.6Cd_0.4VO₃ the V-O distances in the ac plane began to split to shorter and longer ones below 150 K, indicating that orbital fluctuations are involved. The phase transition near 150 K in Y _0.6Cd_0.4VO₃ is accompanied by a broad anomaly on the specific heat and change of the slope of the inverse magnetic susceptibility. Other members of the Y_1-xCd_xVO₃ solid solution with x = 0.3, 1/3, and 0.5 did not show this kind of phase transition. This kind of a phase transition has never been detected in other doped vanadates, R_1-xM_xVO₃ (R = Y and rare earths and M-Ca and Sr).