Investigations on TlBa2Ca2Cu3Ox superconducting thin films formation on LaAlO3 substrate

Abstract Investigations on pure superconducting phase TlBa 2 Ca 2 Cu 3 O x (Tl-1223) thin films formation, of about 100–125 nm in thickness, on (001) LaAlO 3 single crystal substrate, were made using radio-frequency sputtering deposition of Ba 2 Ca 2 Cu 3 O x precursor films and ex-situ thallination in sealed quartz tube. The precursor films were thallinated under different conditions of partial oxygen pressure, temperature, time and y thallium source content using unreacted pellets of composition Tl y Ba 2 Ca 2 Cu 3 O x . In all cases, strongly c -oriented multiphase films were obtained. A correlation between the Tl-1223 phase purity and the precursor film conditions of thallination is established. Temperature and time of thallination as well as the thallium source content and the partial pressure of oxygen play a key role in the quality of the obtained film. The films' onset temperature of the superconducting transition ranges between 90 and 103 K. It is shown that the best samples can be obtained from a dense precursor film and relatively medium thallination time.