High specific heat metals for use in superconducting composites

In an effort to enhance adiabatic stability, copper containing percentage amounts of Gd
2
O
3
powder was prepared. The specific heat (C
v
) of the resulting material was measured at temperatures from 2 to 12 K in zero and 2.4 T applied magnetic field. Below 5 K the C
y
is one to two orders of magnitude higher than that of ordinary copper. For example, at 3.7 K in zero field the C
v
of 2.4% GdAlO
3
is 1.5 mJ/g-K and for 7.2% Gd
2
O
3
C
v
is 3.7 mJ/g-K. These results are only weakly dependent on the magnetic field. Resistance ratios (room temperature to 4 K) of 99 to 46 are obtained, depending on the method of preparation. Mechanical properties of the copper seem good; photomicrographs of the material are shown. Additional cost for materials is $1.20 per pound for 3% oxide in copper. In superconducting applications a fault which reduces the magnetic field on the copper will actually lower the temperature through adiabatic demagnetization unless there is an appreciable heat imput. At 4 K, for example, a 3% oxide material could absorb the heat required to raise pure copper to 11 K, with no change in temperature. It is hoped that this "doped" copper will provide more adiabatic stability for composite superconductor-copper wires than pure copper alone.