Reduction process of double perovskites Sr2B’UO6 where B’ = Mn, Fe, Co, Ni, Zn. Magnetic behavior of uranium cations

RUBEN M PINACCA; MARIA DEL C. VIOLA; JOSE C. PEDREGOSA; RAUL E. CARBONIO; MARIA J. MARITINEZ-LOPE; JOSE ANTONIO ALONSO

MATERIALS RESEARCH BULLETIN

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2011 vol. 46 p. 1755 - 1760

0025-5408

We describe the preparation of five perovskites obtained from reduction of Sr2B’UO6 (B’ = Mn, Fe, Co, Ni, Zn) and structural characterization by X-ray powder diffraction (XRPD). These compounds were synthesized by reduction with H2/N2 (5/95) at 900 ºC during 8 hours.  The structural refinements for the obtained reduced perovskites were carried out by XRPD data using Rietveld method from patterns of well crystallized samples. Elemental metal is segregated when B’ = Co, Ni, Fe and the corresponding oxide when B’ = Mn, Zn. The crystal structure of the phases obtained in all cases SrB0.5-xU0.5+xO3-δ  with x ≈ 0.3 are orthorhombic, space group Pnma (Nº 62), with cationic disorder in the B site, as intermediate between ordered double perovskite Sr2B’UO6 and simple perovskite SrUO3. The magnetic measurements were performed on the phase with B’ = Zn, ion diamagnetic, with U5+/U4+ as unique responsible of the magnetic behaviour. The other phase Sr3UO6 is always present as impurity.