Ferroelastic deformation of La0.58Sr0.4Co0.2Fe0.8O3-δ under uniaxial compressive loading

The mechanical deformation of lanthanum strontium cobalt ferrite under uniaxial compression was investigated at various temperatures. The material revealed a rather complex mechanical behaviour related to its ferroelasticity and stress strain curves obtained in the 1st and 2nd loading cycles were completely different. A distinctive ferroelastic creep was observed at 293 K whilst typical ferroelastic stress strain curves were obtained in the temperature range from 473 K to 873 K. At 1073 K, high-temperature creep deformation was observed instead of the ferroelastic deformation. The apparent Young's modulus was evaluated in various ways; the modulus determined from the last unloading curve ranged between 85 and 120 GPa. The obtained critical stress monotonically decreases from about 80 MPa to zero with increasing temperature, corresponding to the behaviour of the remnant strain. The presented results indicate that the importance of an appropriate consideration of the loading history in the practical application of these ferroelastic materials. (C) 2012 Elsevier Ltd. All rights reserved.