Crystal structure and properties of novel oxide Sm0.9Ca1.1Fe0.7Co0.3O4-d

Abstract

Sm0.9Ca1.1Fe0.7Co0.3O4-δ oxide with the K2NiF4-type structure was prepared using a glycerin-nitrate technique. The XRD pattern of Sm0.9Ca1.1Fe0.7Co0.3O4-δ was refined by the Rietveld method within an orthorhombic structure (space group Bmab). The electrical conductivity, Seebeck coefficient, and thermal expansion of Sm0.9Ca1.1Fe0.7Co0.3O4-δ were measured depending on temperature in air. The change of oxygen nonstoichiometry determined by TGA in air does not exceed 0.01. The oxygen content in Sm0.9Ca1.1Fe0.7Co0.3O4-δ determined by the reduction in a hydrogen flux is equal to 3.96 ± 0.01. The positive value of Seebeck coefficient indicates that the predominant charge carriers in the oxide studied are electron holes.

Keywords

• complex oxide
• ruddlesden-popper phase
• crystal structure
• oxygen nonstoichiometry, electroconductivity
• thermal expansion