Abstrakt

The crystal structure and electric transport properties of Pr1-xCaxBa2Cu3O7- delta (x= 0.0, 0.1, 0.2, 0.5) bulk ceramic samples, prepared by the standard solid-state reaction in air, were examined by X-ray power diffraction, resistivity measurements and room temperature thermoelectric power determination. Ca atoms introduce additional holes to the system as well as structural defects. The orthorhombic-to-tetragonal structural transition, observed for high calcium concentrations, indicates strong oxygen disorder occurring predominantly in the chain layers. Charge transport in Ca-doped samples is typical for materials with localized carriers and generally could be described in terms of three-dimensional variable range hopping. The applied hole doping was not sufficient to compensate suppression of superconductivity in PrBa2Cu3O7-delta.

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