Plasticity and strength of metal oxide high-temperature superconductors (review)

The results on plasticity and strength of a wide class of metal oxide perovskite like compounds which are of high-temperature superconductivity (HTSC) or used as basic compounds to fabricate HTSCs are systematized and discussed from the unified viewpoint. The mechanical properties of materials of different morphology - single crystals, polycrystals, composites studied by various methods of mechanical testing in low, room and high temperature regions are treated. The defects typical of these compounds are considered, and the crystallography of two deformation modes - slip and twinning - are discussed. Rearrangement under mechanical stresses of the twin structure formed in high temperature phase transformation are considered too. The peculiarities of the plastic deformation and fracture of metal oxide materials caused by structural microdefects (dislocations, impurities, twin and grain boundaries) and macro defects (pores, cracks, heterophase inclusions) are observed. The role of heavy cations in the high temperature deformation kinetics is discussed. The influence of the structural phase transformations and superconducting transition on the mechanical properties of the metal oxides is viewed. This review is a continuation of the previous review on elastic and acoustic properties of HTSC s published by the authors: (Low Temp. Phys. 21, 367 (1995))