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https://www.ias.ac.in/article/fulltext/boms/033/04/0407-0411

Coefficient of thermal expansion; perovskite; doped lanthanum gallate; solid oxide fuel cells.

Thermal expansion of several compositions of Sr and Mg-doped LaGaO₃ including an 𝐴-site deficient composition (La_0.9Sr_0.1)_0.98(Ga_0.8Mg_0.2)O_2.821 were measured in the temperature range from 298 to 1273 K. The effect of doping on thermal expansion was studied by varying the composition at one site of the perovskite structure (either 𝐴 or 𝐵), while keeping the composition at the other site invariant. Thermal expansion varied nonlinearly with temperature and exhibited an inflexion between 550 and 620 K, probably related to the change in crystal structure from orthorhombic to rhombohedral. The dependence of average thermal expansion coefficient (𝛼_av) on the dopant concentration on either 𝐴 or 𝐵 site of the perovskite structure was found to be linear, when the composition at the other site was kept constant. Mg doping on the 𝐵-site had a greater effect on the average thermal expansion coefficient than Sr doping on the 𝐴-site. Cation deficiency at the 𝐴-site decreases thermal expansion when compositions at both sites are held constant.

K T Jacob¹ S Jain¹ V S Saji¹ P V K Srikanth¹

1. Department of Materials Engineering, Indian Institute of Science, Bangalore 560 012, India

Published

August 2010

Manuscript received

15 January 2010