NEW OXYGEN-DEFICIENT PEROVSKITE LACU1-XNIXO2.5+DELTA WITH ANOMALOUS THERMAL, ELECTRICAL AND MAGNETIC-PROPERTIES

The recently synthesized perovskite LaCu1-xNixO2.5+delta (0.15 < x < 0.40; 0 < delta < 0.40) in which a discontinuous and reversible change of oxygen content occurs in air at about 500 degrees C which is accompanied by structural transformation and transition from the metallic to the semiconducting state has been studied. The results of TG and DTA investigations of this compound in the homogeneity region, as well as the lattice parameters and the data of specific electrical resistivity and magnetic susceptibility measurements are reported. The magnetic susceptibility of LaCu1-xNixO2.5+delta (delta=0.25) in the region of the transition increases abruptly by 1.4-1.6 times due to the reduction of CU3+ to CU2+ and transition to the nonconducting state.