Thermal, micro-structural, and electrical properties of a La1-x Sr x Mn0.85Fe0.05Co0.05Ni0.05O3+[delta] (x = 0-0.4 mole) cathode system

• Published in: Metals and materials international 2009-12, Vol.15 (6), p.1055
• Main Authors: Gupta, Ravindra Kumar, Kim, Eun Yi, Kim, Yoo Hang, Whang, Chin Myung
• Format: Article
• Language: English
• Subjects: Alloys; Fuel cells
• ISSN: 1598-9623; 2005-4149
• DOI: 10.1007/s12540-009-1055-y

The oxygen stoichiometry, thermal expansion, morphology, and electrical conductivity of a co-doped perovskitetype cathode system, La^sub 1-x^Sr^sub x^ Mn^sub 0.85^Fe^sub 0.05^Co^sub 0.05^Ni^sub 0.05^O^sub 3+ä^ (x = 0-0.4 mole), are studied for intermediate-temperature solid oxide fuel cell applications. Sr^sup 2+^-doping led to a decrease in the unit cell volume, oxygen stoichiometry, particle size, and activation energy, and an increase in the coefficient of thermal expansion and electrical conductivity. The sample with x = 0.3 mole exhibited four to five fold weight loss with respect to La^sub 0.75^Sr^sub 0.25^MnO^sub 3+δ^ at an intermediate temperature range and suggested the availability of a large number of oxygen vacancies due to a co-doping effect. This sample also showed sufficiently high electrical conductivity (76 S cm^sup -1^) at 650 °C, a low activation energy (0.15 eV), and a coefficient of thermal expansion (12.1 × 10^sup -6^ °C^sup -1^) comparable to those of the adjacent components and submicron sized particles. The experimental results are explained using defect models.[PUBLICATION ABSTRACT]