Transport studies of perovskite oxide BaPb1-xZrxO3

We have synthesized perovskite oxide BaPb1-xZrxO3 by solid-stare reaction i n different atmospheres and performed x-ray diffraction (XRD) analyses, ele ctrical resistivity and thermoelectric power measurements on them. Nearly s ingle-phase samples with cubic symmetry were obtained in the range 0.0 < x less than or equal to 0.25. As x increased, a metal-insulator (MI) transiti on occurred at a critical doping level x(c), which depended on the sinterin g atmosphere of the samples. Meanwhile, a jump in resistivity was found. At low temperatures (13 K less than or equal to T less than or equal to 100 K ), the temperature dependence of resistivity followed the power law when 0 < x < x(c) and the hopping law when x greater than or equal to x(c). When p repared in oxygen and in air, the resistivity decreased linearly with the r ising temperature in the range between 100 and 300 K. However, the unusual linear behaviour was absent when the doped oxides were sintered in N-2. An anomalous broad peak was also observed in the thermoelectric power of the a ir-sintered samples. The results are discussed in terms of the effects of d isorder and electron-electron interactions, oxygen vacancies and the crysta l-held splitting of the 4d levels of transition metal Zr.