Phase equilibria and crystal structure of the complex oxides in the Ln–Ba–Co–O ( Ln=Nd, Sm) systems

• Published in: Journal of solid state chemistry 2011-08, Vol.184 (8), p.2083-2087
• Main Authors: Gavrilova, L.Ya, Aksenova, T.V., Volkova, N.E., Podzorova, A.S., Cherepanov, V.A.
• Format: Article
• Language: English
• Subjects: CHALCOGENIDES; Cobaltates; COHERENT SCATTERING; CRYSTAL LATTICES; CRYSTAL STRUCTURE; DIAGRAMS; DIFFRACTION; DISPERSIONS; ELEMENTS; EQUILIBRIUM; Homogeneity; HOMOGENEOUS MIXTURES; INFORMATION; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; MIXTURES; NONMETALS; ORTHORHOMBIC LATTICES; OXIDES; OXYGEN; OXYGEN COMPOUNDS; Oxygen content; PHASE DIAGRAMS; Phase equilibria; PHASES; QUENCHING MECHANISMS; SCATTERING; SOLID SOLUTIONS; SOLUTIONS; X-RAY DIFFRACTION; YTTRIUM OXIDE
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2011.06.006

The phase equilibria in the Ln–Ba–Co–O ( Ln=Nd, Sm) systems were systematically studied at 1100 °C in air. The homogeneity ranges and crystal structure of the solid solutions: Ln 2− x Ba x O 3−δ (0< x≤0.1 for Ln=Nd and 0< x≤0.3 for Ln=Sm), Nd 3− y Ba y Co 2O 7 (0.70≤ y≤0.80), BaCo 1− z Sm z O 3−δ (0.1≤ z≤0.2) were determined by X-ray diffraction of quenched samples. The values of oxygen content (5+δ) for slowly cooled LnBaCo 2O 5+δ ( Ln=Nd, Sm) samples were estimated as 5.73 for Ln=Nd, and 5.60 for Ln=Sm. The unit cell parameters were refined using Rietveld full-profile analysis. It was shown that NdBaCo 2O 5.73 possesses tetragonal structure and SmBaCo 2O 5.60 – orthorhombic structure. The projections of isothermal–isobaric phase diagrams for the Ln–Ba–Co–O ( Ln=Nd, Sm) systems to the compositional triangle of metallic components were presented. Projections of isobaric isothermal phase diagrams of the Nd–Ba–Co–O system and Sm–Ba–Co–O system. [Display omitted] ► Phase equilibria in the Ln–Ba–Co–O systems ( Ln=Nd, Sm). ► The homogeneity range for Nd 2− x Ba x O 3−δ solid solutions at studied conditions 0< x≤0.1. ► The homogeneity range for Sm 2− x Ba x O 3−δ solid solutions at studied conditions 0< x≤0.3. ► Nd 3− y Ba y Co 2O 7 solid solutions within the range 0.7≤ y≤0.8. ► BaCo 1− z Sm z O 3−δ solid solutions within the range 0.1≤ z≤0.2.