Crystal and magnetic structure of Pr/sub 0.7/Sr/sub 0.3-x/MnO/sub 3/ (0/spl les/x/spl les/0.2) compounds

摘要: The electronic and magnetic properties of the ABO/sub 3/ type manganites (A=rare earth, B=Mn) depend sensitively on ratio divalent trivalent atoms A sublattice. substitution rare-earth by Ca or Sr not only affects total valence, but also lattice spacing, which, in turn may affect structure ordering temperature. If these compounds are synthesized with less than stoichiometric amounts site constituents, (relative to Mn content), three possible outcomes be considered: (a) single phase materials vacancies sublattice formed, (b) two Mn/sub 3/O/sub 4/ result, (c) some combination B occur. We have carried out neutron diffraction (ND) studies samples Pr/sub 0.7/Sr/sub 0.3-x/MnO/sub nominal x=0.0, 0.1 0.2, at 300 K 10 K. ND data clearly show presence as a second x=0.1 0.2. Refinements manganite structure, based assumption that Pr is equal concentration, reveal can induced site. In x=0.2 sample, about 5.5% sites found vacant. refined moments z=0.0 nearly (3.4 /spl mu//sub B/). parallel With magnitude 0.27 B/ 0.33 B/, respectively, samples. sample more complex due an antiferromagnetic component.