Electronic transport properties of YBaCo2−xCuxO5+δ (0⩽x⩽1) at high temperature

YBaCo2−xCuxO5+δ (0⩽x⩽1) samples were synthesized and the effect of Cu doping on the oxygen desorption and electronic transport properties was investigated from room temperature (RT) to 800 °C. The samples begin to release oxygen when temperature is above approximately 300 °C, and the amount of oxygen desorption decreases with increasing Cu content. Transport properties measurements show that all samples behave as p-type semiconductor in the temperature range of RT–300 °C. When temperature is above approximately 300 °C, the resistivity and Seebeck coefficients of low Cu-doped samples increase with the increase of temperature due to oxygen desorption from the lattices, whereas high Cu-doped samples keep the semiconducting conduction in all temperature range measured because Cu doping suppresses the release of oxygen. Cu doping tends to increase the resistivity and Seebeck coefficients of YBaCo2−xCuxO5+δ. The reason can be explained by the drop of hole concentration resulting from the reordering of CoO5 pyramidal and CoO6 octahedral planes along a and b directions in YBaCo2−xCuxO5+δ.