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

A P Galayda,V A Cherepanov,P D Battle,A I Dyagileva,L Ya Gavrilova,N E Volkova

doi:10.15826/chimtech.2018.5.4.01

A P Galayda, V A Cherepanov + Show 4 more

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https://doi.org/10.15826/chimtech.2018.5.4.01

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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.

Highlights

Complex oxides with the K2NiF4‐type structure based on rare earth, alkaline earth and 3d-transition metals are known as materials with high mixed electronic-ionic conductivity and oxygen mobility, and thermodynamic stability at high temperature under an oxidizing atmosphere [1,2,3,4]
The present study has focused on the structure and properties of the novel Sm0.9Ca1.1Fe0.7Co0.3O4–δ oxide with the K2NiF4‐type structure
A bar-shaped sample (3×4×25 mm) for thermal expansion coefficient (TEC) and conductivity measurements was obtained by pressing powder that was mixed with 2–3 drops of ethanol using a manually-operated press

Summary

Introduction

Complex oxides with the K2NiF4‐type structure based on rare earth, alkaline earth and 3d-transition metals are known as materials with high mixed electronic-ionic conductivity and oxygen mobility, and thermodynamic stability at high temperature under an oxidizing atmosphere [1,2,3,4]. The absolute values of oxygen content were determined by a reduction of the samples in a hydrogen flux inside the TGA cell at 1200 °C [15]. Thermal expansion measurements were carried out within the temperature range of 25–1100 °C in air using a dilatometer DIL 402C (Netzsch) at a heating / cooling rate of 5K / min.

Results

Conclusion