Transport properties and oxygen sublattice time relaxation of Nd2CuO4-delta

We report results of resistivity rho and thermopower S measurements of tetr agonal (T'-type) Nd2CuO4-delta polycrystalline samples. Both rho and S have shown strong dependence on the oxygen deficiency delta, which in principle reflects a semiconducting like electronic structure of the compound. We ha ve also found that for the sample with maximum oxygen deficiency of delta s imilar to 0.12, the rho and S values undergo a substantial variation versus time at room temperature, despite the constant oxygen content. These varia tions saturate after similar to 300 h. It is suggested that they are caused by a reordering of vacancies in oxygen deficient sublattice. (C) 1999 Else vier Science Ltd. All rights reserved.