Engineering of Superconducting Ba1−x K x BiO3 Thin Films: Novel Electrochemical Route

Abstract

A novel electrochemical processing technique was used to prepare thin films of Ba1−x K x BiO3−δ . The course of action consists of co-deposition of Ba, K, and Bi metals from single electrolytic bath at −2.1 VSCE followed by annealing at 175 °C in vacuum and air to control the quantity of K in the film. The desired metal stoichiometries were obtained by adjusting the electrolytic bath composition empirically. The nucleation and growth mechanism of the electro-deposit is found to be of progressive type. Well-connected and compact grain growth was observed after annealing. The crystallinity and purity of phase in the film annealed in vacuum is found be better than sample annealed in air. The superconductivity in the sample processed in vacuum and air is seen at 26 K with the width of 1.3 K and at 18.4 K with width 6 K. Electrodeposited thin films processed in vacuum exhibit current densities of the order to 6.1×104 A cm−2 at 5 K.