Experimental corroboration of the thermoelectric performance of Bi2PdO4 oxide and Pb-doped derivatives

Abstract

A theoretical study has recently revealed Bi₂PdO₄ to be a promising p-type oxide thermoelectric material, with excellent electrical properties and low thermal conductivity, due to its structural peculiarities. Polycrystalline samples of the pristine material and Pb-doped Bi_1.9Pb_0.1PdO₄ have been prepared by a conventional solid-state reaction, and an exhaustive structural characterization has been performed by high-energy synchrotron X-ray diffraction. Thermoelectric transport properties have been measured in the 300–800 K temperature range. The undoped compound displays p-type semiconductor behaviour and extremely high values of thermopower, up to 1458 μV K⁻¹ at 340 K, along with low lattice thermal conductivity, related to large vibrations of Bi and O atoms. In the Pb-doped derivative the electrical resistivity is greatly enhanced, which along with a reduction of the lattice thermal conductivity results in an improved thermoelectric performance by more than one order of magnitude. These features underline the promising further optimization of this material aiming at thermoelectric applications.