THERMOELECTRICITY FOR ELECTRICAL CONDUCTIVE REFRACTORY CERAMICS OF LaCrOィイD23ィエD2

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The new type of an instrument for measuring thermoelectricity and resistivity measurement was developed specially for this project. The samples were prepared by the solid-solid reaction method. X-ray analysis revealed that the samples in this project had perovskite-type structure and no impurity phase. The temperature dependence of electrical resistivity indicated a small polaron-type conducting mechanism and concentration dependence of the resistivity showed parcolation-type conductive mechanism. Thermoelectric measurement revealed that the fraction concentration of small polaron was 55% and 70% comparing to the expected values for the substituted ions by Ca and Sr, respectively. The analyses of the magnetic susceptibility of these samples agree well with the fraction concentration of small polaron obtained by the thermoelectric measurement. Consequently, it was made clrar that the total charge of the sample that substituted by divalent ion was compensated by formation of the CrィイD14+ィエD1 oxygen vacancies, and the mechanism of the conduction was revealed the hybrid of the parcolation type and small poralon type conduction mechanism.