PREPARATION, CRYSTAL-STRUCTURE, AND VIBRATIONAL-SPECTRA OF PEROVSKITE-TYPE MIXED OXIDES LAM(Y)M'(1-Y)O(3) (M,M'=MN, FE, CO)

Three series of samples LaMnyCo1-yO3+/-lambda, LaFeyMn1-yO3+/-lambda, and LaFeyCo1-yO3+/-lambda (y = 0.0 to 1.0) with Perovskite structure w ere prepared by an explosion method different from the generally used ceramic techniques. The variation of crystal structure, the infrared s pectra, and the relationship between them were discussed in detail. Th e change of infrared absorption reflects the change of the crystal str ucture and the mixing of transition metals on B sites significantly in fluences the strength of the B-O bond. These influences are attributed to geometrical effects for LaFeyMn1-y O-3+/-lambda and LaFeyCo1-yO3+/ -lambda and to electronic effects for LaMnyCO1-yO3+/-lambda. (C) 1994 Academic Press, Inc.