Papers by Author: Vladimir S. Melnikov

Abstract: The critical current density, jc, of high-pressure synthesized MgB2-based balk materials correlates with the amount and distribution of higher borides (MgB12) and Mg-B-O inclusions, which in tern correlates with the synthesis temperature and presence of additions (Ti, Ta, SiC). High-pressure-synthesized materials with near MgB12 composition of matrix exhibited superconducting transition temperature, Tc, of about 37 K, rather high jc (5∙105 and 103 A/cm2 in 0 T and 3.5 T, respectively, at 20 K) and doubled matrix microhardness: 25±1.1 GPa at 4.9 N –load as compared to materials with MgB2).

Abstract: Addition of Ti and Zr to high-pressure (HP) synthesized MgB2 results in an increase of critical current density of the material due to the absorption of impurity hydrogen coming most likely from the materials of a high-pressure cell. The results of the studies of structure, critical current density, trapped field and mechanical characteristics are discussed. High-pressure synthesized MgB2 (with Ti additions) blocks were for the first time used in a SC electromotor at 20 K and demonstrated the efficiency similar to that of MT-YBCO bulk (at the same working temperature).