Materials of the Y-Ba-Cu-O (melt-textured YBa2Cu3O7-d-based materials orMT-YBCO) and Mg-B-O (MgB2-based materials) systems with high superconductingperformance, which can be attained due to the formation of regularlydistributed nanostructural defects and inhomogenities in their structure can beeffectively used in cryogenic technique, in particular in fault currentlimiters and electrical machines (electromotors, generators, pumps for liquidgases, etc.). The developed processes of high-temperature (900-800 oC)oxygenation under elevated pressure (16 MPa) of MT-YBCO and high-pressure (2GPa) synthesis of MgB2-based materials allowed us to attain high SC (criticalcurrent densities, upper critical fields, fields of irreversibility, trappedmagnetic fields) and mechanical (hardness, fracture toughness, Young modulus)characteristics. It has been shown that the effect of materials propertiesimprovement in the case of MT-YBCO was attained due to the formation of hightwin density (20-22 micron-1), prevention of macrockracking and reduction (by afactor of 4.5) of microcrack density, and in the case of MgB2-based materialsdue to the formation of oxygen-enriched as compared to the matrix phasefine-dispersed Mg-B-O inhomogenities as well as inclusions of higher borideswith near-MgB12 stoichiometry in the Mg-B-O matrix (with 15-37 nm average grainsizes). The possibility is shown to obtain the rather high Tc (37 K) andcritical current densities in materials with MgB12 matrix (with 95 percent ofshielding fraction as calculated from the resistant curve).
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