EFFECT OF HIGH-PRESSURE ON THE CRYSTAL-STRUCTURE AND PROPERTIES OF THE LACU1-XNIXO2,5+DELTA PEROVSKITE

The oxygen-deficient perovskite LaCu1-xNixO2,5+delta was exposed to hi gh pressure (6 GPa) and high temperature (900 degrees C). As a result, the low-temperature orthorhombic modification of this compound charac terized by a high content of oxygen (delta=0,25) acquired a simple cub ic unit cell of the perovskite. The high-temperature modification of t he compound (orthorhombic structure of the La8-x,SrxCu8O20 type) under went no changes. The lanthanum cuprate La2Cu2O5 had a structure of the Ca2Mn2O5 type upon analogous treatment. Electrical resistivity measur ements of the obtained high-pressure phases LaCu1-xNixO2,5+delta show a semiconducting conductivity in the temperature range front 4,2 to 30 0 K.