COPPER DEFICIENCY AND SUPERCONDUCTIVITY IN ND2-XCEXCUO4 OXIDES

The solid-state synthesis of Nd2-xCexCuO4 superconducting oxides is st udied. In this paper we investigate the importance of: (1) the duratio n of the reduction time, (2) the possibility to induce superconductivi ty by fast quenching from high temperature and the role of cationic st oichiometry on the superconducting properties. We have found that the typical synthesis conditions lead to some Cu deficiency in the samples . This result, together with the fact that Cu non-stoichiometry suppre sses superconductivity allows one to understand the role of CuO excess on the synthesis of superconducting materials.