Cu doping and pressure effect on a layered palladium oxide: PbPdO 2

Abstract

Effects of Cu doping and pressures on the physical properties of PbPdO 2 have been investigated. Single-phase samples of PbPd 1− x Cu x O 2 (0 ≤ x ≤ 0.04) have been synthesized via solid-state reaction and their temperature-dependent electrical resistivity and thermoelectric properties have been characterized. The temperature-dependent electrical resistivity exhibits a metal–insulator transition around 90–140 K for all compositions. The sign of the thermoelectric power is positive for all compositions indicating that the majority of carriers in PbPd 1− x Cu x O 2 (0 ≤ x ≤ 0.04) are holes. Both the electrical resistivity and the thermoelectric power increase as the Cu content increases. The largest power factor in this system is 0.022 μW/K 2 cm at x = 0.03. The electrical resistivity of PbPdO 2 decreases as the applied pressure increases. In addition, the metal–insulator transition is suppressed as the applied pressure increases.