Investigation of the effect of Al plasma treatment on the superconducting properties of YBa₂Cu₃O_7−δ

The effect of the partial substitution of Cu for Al on the structural, compositional, and magnetic properties of polycrystalline compounds YBa₂Cu₃O_7−δ was studied. All prepared samples turned out to be single-phase with a small fraction of Ba secondary phases. Substitution of more than 2% aluminum causes an increase in spurious phases. DC susceptibility measurements show that the superconducting transition temperature T _C decreases. Hysteresis loops show that magnetic irreversibility decreases with increasing Al content. The critical current density J _C obtained using the Bean formula does not follow the same change. Al compensates for a decrease in J _C and an increase in its content near the solubility limit gives a higher J _C than in an undissolved sample.