Lanthanum metal oxides with a perovskite structure have attracted much attention because of their possible application as cathode and electrolyte materials for solid oxide fuel cells. These perovskites show anomalous mechanical behavior such as nonlinear elastic stress–strain curves, creep, hysteresis, remnant strain, and strain recovery. Previous studies on ferroelastic lanthanum metal oxides were performed under uniaxial compression tests which usually need bar specimens whose preparation processes are time consuming and costly. On the other hand, localized mechanical testing techniques which can provide the mechanical characteristics from small specimens have generated much interest in recent years.  Impression test as one of the well-known examples of these miniature mechanical testing methods has been applied to a wide range of materials for creep behavior characterizations. The impression test has significant advantages over conventional mechanical tests of compression including small specimen volume, constant stress at constant load, and the capability to characterize local mechanical properties of heterogeneous materials.

The current study attempts to investigate the possibility of gaining information on ferroelastic behavior of LaCoO₃ prepared by sol-gel method and the use of impression test utilizing high alumina cylindrical flat-end punches (diameters: 1 and 2 mm). A universal material testing machine (Zwick/Roell) with one kN load cell is used for applying impression loads (50-200 Mpa). Digital Image Correlation (DIC) technique is used for punch displacement measurements.