Structural and Physical Properties of Heavily Doped Yttrium Vanadate: Y_0.6Cd_0.4VO₃

Structural properties of Y 0.6 Cd 0.4 VO 3 were investigated by electron diffraction and laboratory and synchrotron X-ray powder diffraction methods. Y 0.6 Cd 0.4 VO 3 crystallizes in space group Pnma (GdFeO 3 -type 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 c / a ratio had a rather sharp maximum at 150 K. In Y 0.6 Cd 0.4 VO 3 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 0.6 Cd 0.4 VO 3 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- x Cd x VO 3 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- x M x VO 3 (R = Y and rare earths and M = Ca and Sr).