FORMATION OF A REAL STRUCTURE OF PEROVSKITES (LA1-X, SR-X)COO3-DELTA IN THE REGION OF THE MORPHOTROPIC PHASE-TRANSITION

Precision X-ray diffractometry with synchrotron radiation and transmis sion electron microscopy are used to show that the extent of hexagonal distortion of the perovskite cell of the (La1-x,Sr-x)CoO3-delta syste m decreases and the microstructure of the samples changes when La is s ubstituted by Sr; these changes are due to increased microstrains in t he structure and subsequent formation of microunits. The microunit str ucture of particles bt the region of the morphotropic transition 0.3 l ess than or equal to x less than or equal to 0.4 which is a consequenc e of the metastable state of the system, may be the reason for the hig h catalytic activity of the samples which we found previously.