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

Abstract

The results of research on the plasticity and strength of a wide class of metal oxide perovskite-like compounds which have the property of high-temperature superconductivity or which can be used as base compounds for making high-temperature superconductors (HTSCs) are systematized and presented from a unified point of view. The mechanical properties of materials with different morphology—single crystals, polycrystals, and composites,—measured by different methods of mechanical testing in the low-temperature, room-temperature, and high-temperature regions, are discussed. The characteristic defects of the crystal structure for these compounds are considered, the crystallography of two modes of plastic deformation—slip and twinning—is described, and the stress-induced structural rearrangement of the twin structure that appears at a high-temperature phase transformation is discussed. The features of plastic deformation and fracture of metal oxide materials due to structural microdefects (dislocations, impurities, twin and grain boundaries) and macrodefects (voids, cracks, heterophase inclusions) are noted, and the role of heavy-cation diffusion in the kinetics of high-temperature deformation is discussed. The influence of structural phase transformations and the superconducting transition on the mechanical properties of metal oxides is considered. This review is a continuation of a review of the elastic and acoustic properties of HTSCs published earlier by the authors in Fiz. Nizk. Temp. 21, 475 (1995) [Low Temp. Phys. 21, 367 (1995)].

Nanoindentation of Bridgman YBCO samples

“…This phase is highly anisotropic, being confined to the ab-plane. Lubenets et al [28] reported that strong covalent and ionic bonds create high Peierls barriers, which constrain dislocation mobility in YBaCuO single crystals. Indentation depth, h (nm) Fig.…”

Mechanical properties of Ag-doped top-seeded melt-grown YBCO pellets

“…Therefore, the study of mechanical properties of these compounds, such as of the hardness (H), elastic modulus (E) and fracture toughness (K IC ), is very crucial [1,2].…”

Plasticity of Fe-Oxypnictides Superconductor

“…Polycrystalline LaFeAsO 0.9 F 0.1 was synthesized by heating a mixture of lanthanum arsenide, iron arsenide, and dehydrated La 2 O 3 powders in silica tube filled with Ar gas at 1527 K for 40 h. F -ion doping was performed by adding mixture of LaF 3 and La at the ratio of 1:1 to the starting powder.…”

“…One of the important subfields of the high-T c superconductors is the study of the plasticity and strength for practical application as devising and for manufacturing high-quality objects. While metal oxide ceramics is brittle in the region of moderately low temperatures due to its high Peierls stress, a ceramic can manifest significant ductility 2,3) and even superplasticity, which is due to grain boundary diffusion, dislocation motion and grain boundary sliding, at elevated temperatures.…”