Preparation and characterization of TL-based superconducting thin films

Abstract

A simple method for growth of Tl-based superconducting thin films is described. In this method, the precursor was prepared in a vacuum chamber by deposition of Ba, Ca and Cu metals or a Ba-Ca alloy and Cu metal. The precursor was then oxidized at room temperature and in the atmosphere. Annealing and diffusion of thallium were carried out simultaneously at a temperature ranging from 920 C to 940 C in one atmosphere of oxygen for formation of the Tl-2212 phase. For the Tl-2223 phase, thermal processing was conducted at 820 C in 98% Ar + 2% 02 by volume flowing gas mixture. Representative samples were characterized by X-ray diffraction, electron microprobe analysis, microwave measurement and measurement of resistance versus temperature. The results show that highly oriented superconducting thin films can be prepared by this simple method. The problem of morphology of the thin films is discussed.