Materials Research Bulletin, Vol.32, No.8, 983-992, 1997
Synthesis and Resistivity Properties of Sr1-Xlaxpbo3-Delta and Srpb1-Xbixo3-Delta
The solid solutions with the composition SrPb1-xBixO3-delta and Sr1-xLaxPbO3-delta 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-delta 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 greater than or equal to 0.05 d rho/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 in terms of quantum interference and a subsequent transition to localized electronic states.
Keywords:ELECTRONIC-STRUCTURE;SUPERCONDUCTING PROPERTIES;COMPOSITION DEPENDENCE;BAPB1-XBIXO3;SYSTEM;CONDUCTION;(BA