STRUCTURAL ASPECTS, DENSITY-MEASUREMENTS AND SUSCEPTIBILITY BEHAVIOR OF THE DEFECT PEROVSKITE APPROXIMATE-TO-LAMNO3, WITH 0.8-LESS-THAN-OR-EQUAL-TO-LA MN-LESS-THAN-OR-EQUAL-TO-1 AND -THAN-OR-EQUAL-TO-O/MN-LESS-THAN-OR-EQUAL-TO-3.58/

X rays diffraction, Rietveld refinement investigations, chemical analy sis of cations and oxygen completed with density measurements have all owed us to propose a model of non-stoechiometry for approximate to LaM nO3 compounds. The anionic lattice can be considered as fully occupied while the concentration of both lanthanum and manganese vacancies inc reases as lanthanum content decreases. According to the non-stoechiome try model, it appears that the total sum of cations is closed to the p articular value 1.89 (1) over the whole range of experimental composit ions 0.8 less than or equal to La/Mn less than or equal to 1 and 2.87 less than or equal to O/Mn less than or equal to 3.19 at 1623K. Lattic e symmetry remains rhombohedral regardless of O/Mn value.