Mechanical properties of La0.58Sr0.4Co0.2Fe0.8O3-δ membranes

In this paper, we report on the mechanical properties of a La0.58Sr0.4Co0.2Fe0.8O3-delta perovskite material. We use ring-on-ring bending tests with disk-shaped samples and depth-sensitive micro-indentation. In particular, the temperature dependency of fracture stress and elastic behavior are addressed. The fracture load is measured to be similar to 40% higher at room temperature (RT) than at 800 degrees C, which is due to the ferro-elasticity or material at RT. The stiffness shows an increase of about 50% above 600 degrees C and 700 degrees C in vacuum and air, respectively. The effect is attributed to a rhombohedral to cubic phase transition, which is not fully reversible upon cooling. The changes in phase composition with temperature are also confirmed by in-situ high temperature XRD. The transition appears to be associated with a change of heat capacity. (C) 2008 Elsevier B.V. All rights reserved.