Ca. Hollin et al., THE MICROSTRUCTURE AND ELECTRICAL-PROPERTIES OF LOW-RESISTANCE CONTACTS TO YBA2CU3O7-DELTA CERAMICS, Superconductor science and technology, 8(1), 1995, pp. 6-14
Contacts with resistivities of 10(-8) Ohm cm(2) or less, at temperatur
es below the T-c of the underlying YBCO material, have been formed by
incorporating gold wires into silver contact pads in a single heat tre
atment. Voltage-current characteristics of these contacts show superco
nducting behaviour. Microstructural cross-sections show an Ag/Au alloy
with an Ag:Au atomic ratio of 3:1. Contacts made by applying wires af
ter the silver heat treatment, which do not form an Ag/Au alloy, show
residual resistances below T-c of around 0.5-50 m Ohm. Susceptibility
and resistivity measurements were not suitable for critically differen
tiating between contact methods or treatment temperatures.