Synthesis and Structure Determination of Ferromagnetic Semiconductors LaAMnSnO6 (A = Sr Ba)

• Published in: Journal of materials chemistry Vol. 21
• Main Authors: T Yang, T Perkisas, J Hadermann, M Croft, A Ignatov, M Greenblatt
• Format: Journal Article
• Language: English
• Published: United States 31.12.2011
• Subjects: ABSORPTION SPECTROSCOPY; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; MATERIALS SCIENCE; PEROVSKITES; SPACE GROUPS; SYMMETRY; SYNTHESIS; TOLERANCE; TRANSMISSION ELECTRON MICROSCOPY; VALENCE; X-RAY DIFFRACTION
• ISSN: 0959-9428; 1364-5501
• DOI: 10.1039/C0JM02614J

LaAMnSnO{sub 6} (A = Sr, Ba) have been synthesized by high temperature solid-state reactions under dynamic 1% H{sub 2}/Ar flow. Rietveld refinements on room temperature powder X-ray diffraction data indicate that LaSrMnSnO{sub 6} crystallizes in the GdFeO{sub 3}-structure, with space group Pnma and, combined with transmission electron microscopy, LaBaMnSnO{sub 6} in Imma. Both space groups are common in disordered double-perovskites. The Mn{sup 3+} and Sn{sup 4+} ions whose valence states were confirmed by X-ray absorption spectroscopy, are completely disordered over the B-sites and the BO{sub 6} octahedra are slightly distorted. LaAMnSnO{sub 6} are ferromagnetic semiconductors with a T{sub C} = 83 K for the Sr- and 66 K for the Ba-compound. The title compounds, together with the previously reported LaCaMnSnO{sub 6} provide an interesting example of progression from Pnma to Imma as the tolerance factor increases. An analysis of the relationship between space group and tolerance factor for the series LaAMnMO{sub 6} (A = Ca, Sr, Ba; M = Sn, Ru) provides a better understanding of the symmetry determination for double perovskites.