Superconducting thick films prepared via electrodeposition

Abstract

Electrodeposition techniques provide a way of synthesising oxide superconductor thick films in two steps: (a) electrodeposition of the cations and (b) oxidation of the deposit at high temperatures. This method is fast, economic and enjoys the benefits of a well known technology. We have performed the preparation of several copper containing superconductors (YBa ₂ Cu ₃ O _7–δ , Bi ₂ Sr ₂ CaCu ₂ O _8+δ ) and a copper-free one (Ba _1–x K _x BiO ₃ ) from electrolytes containing nitrate salts dissolved in dimethyl sulfoxide using chronoamperometric techniques. The quality of the films strongly depends on the experimental conditions such as substrate, bath composition and thermal annealing. Characterisation of the initial deposit and the final superconducting oxide was made by means of infrared spectroscopy, thermal analysis, X-ray diffraction and scanning electron microscopy. The best critical current (J _c ) values, in A cm ^–2 , for the different phases were: YBa ₂ Cu ₃ O _7–δ (13 000/5 K and 400/77 K), Bi ₂ Sr ₂ CaCu ₂ O _8+δ (12 000/77 K) and Ba _1–x K _x BiO ₃ (2 700/5 K).