Studies on Microhardness of Composition Materials of High-Temperature Superconductor YBCO–MoO₃ Nanofibers

Superconducting polycrystalline composites YBa₂Cu₃O_7–x + MoO₃ with MoO₃ nanofiber content of 1, 5, 10, and 15 wt % have been studied in the work. The temperature and width of transition into the superconducting state of samples with description of possible mechanisms for observable changes have been determined from measurements of electrical resistance. The elastic modulus, yield strength, fracture toughness, and fragility index have been determined from measurements of the Vickers microhardness. Five different models have been used during studies on the physical and mechanical properties of the MoO₃-containing bulk HTSC samples to interpret microindentation data and explain the results with consideration of the indentation size effect.