ELECTRONIC CONDUCTION IN LANIO3-DELTA - THE DEPENDENCE ON THE OXYGEN STOICHIOMETRY DELTA

We report a systematic study of the electronic transport properties of the metallic perovskite oxide LaNiO3-delta as a function of the oxyge n stoichiometry delta (delta less than or equal to 0.14). The electric al resistivity, magnetoresistance, susceptibility, Hall effect and the rmopower have been studied, All of the transport coefficients are depe ndent on the value of delta. The resistivity increases almost exponent ially as delta increases. We relate this increase in rho to the creati on of Ni2+ with square-planar coordination. We find that there is a di stinct T-1.5-contribution to the resistivity over the whole temperatur e range. The thermopower is negative, as expected for systems with ele ctrons as the carrier, but the Hall coefficient is positive. We have g iven a qualitative and quantitative explanation for the different quan tities observed and their systematic variation with the stoichiometry delta.