Influence of Ca2+ substitution on thermal, structural, and conductivity behavior of Bi1−xCaxFeO3−y (0.40 ≤ x ≤ 0.55)
Bi1−xCaxFeO3−y (0.40 ≤ x ≤ 0.55) perovskite oxides have been synthesized by solid-state reaction method to study their properties as a cathode material for intermediate temperature solid oxide fuel cells. The as prepared samples were characterized by X-ray diffraction, differential thermal analyzer/thermogravimetry, dilatometer, and impedance spectroscopy to study their structural, thermal, and electrical properties. The Rietveld refinement results confirmed that all the samples exhibit tetragonal structure with P4mm space group. In addition to this, sample x = 0.55 exhibits Ca2Fe2O5 as a secondary phase. It has been observed that lattice parameters decrease with increase in calcium content. The thermal expansion coefficient and ionic conductivity increases with increase in calcium content up to x = 0.50. The highest ionic conductivity is observed for Bi0.5Ca0.5FeO3−y i.e. 1.71 × 10−2 S cm−1.
KeywordsRietveld refinement Thermal properties Ac impedance spectroscopy Mixed ionic-electronic oxide
The authors are thankful to Defense Research and Development Organization (DRDO) for financial support vide letter no. ERIP/ER/1103976/M/01/1411. The authors are thankful to Dr. B. N. Chudasama for his help in thermal measurements and discussion.
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