Effects of third-element additions on the superconducting properties of bronze-processed V3Ga wires

The effect of In, Zn, and Mn additions to the bronze matrix on formation rate, critical current density, and critical temperature of V3Ga layers in bronze-processed V3Ga wires has been investigated. The V3Ga layers were produced by heat treatment at 600...650 °C within a period of 20... 200 h. For a given heat treatment condition the critical current density (jc) of the V3Ga phase and the critical current (Ic) of In-containing conductors with a suitable composition of bronze (e.g. 16 at.% Ga, 1.2 at.% In) are considerably higher (by the factor ≥ 1.7) than those of conductors with a usually applied, binary Cu-Ga alloy containing 19 at.% Ga. The critical temperature of In-containing samples is relatively high and approaches values up to 15.4 K (for which the specimens showed half its normal-state resistance). Too high Ga and In contents of the matrix are unfavourably for obtaining high critical parameters. An addition of Mn (0.6 at.%) to the bronze leads to considerably thicker V3Ga layers, however jcand Tc(down to 13 K) are decreased and thus, depending on theat treatment conditions and Ga content of bronze, unchanged or reduced Icvalues were obtained. Substitution of Zn for 2 at.% Ga in the matrix causes a reduction of V3Ga layer thickness and an increase of jc.