Synthesis and resistivity properties of Sr1 − xLaxPbO3-δ and SrPb1 − xBixO3 − δ

The solid solutions with the composition SrPb1 − xBixO3 − δ and Sr1 − xLaxPbO3 − δ were synthesized. It was found that the solubility limits do not exceed the values x = 0.2 and x = 0.1, respectively. It was shown by X-ray powder diffraction that the initial crystal symmetry (orthorhombic, space group Pnma) remains unchanged with the substitution, whereas unit cell parameters increase monotonically. The undoped SrPbO3 − δ exhibit positive and negative temperature coefficient of resistivity at high and low temperatures, respectively. La-doping leads to a drastical decrease of the absolute value of the resistivity and for the doped samples with x ≥ 0.05 dp/dT is positive in the entire temperature range. Bi-doping leads, first to a similar decrease of resistivity, but at higher substitutions, variable range hopping conduction is observed. The results were interpreted hi terms of quantum interference and a subsequent transition to localized electronic states,