Properties of La2-xSrxCuO4(x=0.0-0.25) oxidized by electrochemical method

Abstract

It is known that La2CuO4 changes from an insulator to a superconductor after oxidation under high oxygen pressure conditions. Recently it was reported that La2CuO4 was oxidized by electrochemical methods under normal pressure at room temperature. We attempted to control the oxygen contents in La2−xSrxCuO4+δ(x=0.0-0.25) by electrochemical methods and studied the properties of these samples systematically. Pellets of La2−xSrxCuO4 were used as the anode for electrolysis in 1N KOH solution. The electrolysis was carried out potentiostatically. Samples before and after electrochemical trearment were characterized by powder X-ray diffraction, resistivity, DC susceptibility, oxygen content and thermoelectric power. The x=0.0 sample which initially showed semiconductivity changed to a superconductor(Tc=40K) after electrochemical oxidation by this method. Our studies showed that underdoped samples were easy to oxidized, while overdoped samples were oxidezed with difficulty.