Thallium-based HTS thin films, processing, properties and applications

Abstract

Thin films of the Tl-based high-temperature superconducting (HTS) phases are beginning to find application in a number of practical devices, especially in the field of microwave communication systems. This review describes the issues surrounding the fabrication of thin films of the thallium-based HTS materials. The influence of thermodynamics and kinetics, the various potential thalliation techniques and the selection of an appropriate substrate material are all important considerations when designing a process for the fabrication of thin films of these highly reactive materials. The properties of the resulting films are critically dependent on the microstructures developed during thalliation. Microstructural evolution during thalliation, the effect of structural defects on the properties of such films and the importance of achieving biaxial grain alignment in optimizing the properties of the films are all discussed.

Influence of the reaction conditions on the formation of Tl(Re)-Ba-Ca-Cu-O superconducting thin films by thallination in open system

“…1b). It has been suggested that the Tl-1212 phase may be formed by annealing at low thallous oxide partial pressures [11]. The measured values of the critical temperatures of the prepared samples were comparable (Fig.…”

“…In open system, the formation path for the Tl-2223 phase implies Tl-2201 and Tl-2212 intermediates according to the sequence: precursor → Tl-2201 → Tl-2212 → Tl-2223 [11,12]. For the growth of the Tl-2223 phase annealing at higher temperatures and lower Tl content in the source pellet is necessary [11]. • C / 45 min using pellet B.…”

Stable fluoride based sputtering target for Tl-based cuprate superconducting thin film fabrication

“…The substrate plays a key role in the microstructural development of the grown film and hence in determining its superconducting properties [1]. Monocrystalline MgO and CeO 2 buffered R-plane sapphire were chosen for the fabrication of Tl-based superconducting thin films.…”

“…Especially thin films prepared on appropriate substrates can be used in applications ranging from passive microwave devices and active Josephson-effect devices to fundamental study of superconducting state [1]. Because of high toxicity and volatility of thallium at elevated temperatures, the synthesis of the thin films is realized in two steps.…”

Ultrafast sampling measurements using the photomodulated kinetic inductance in high-Tc superconductors

“…Further details of the film fabrication process are described elsewhere. 10 The films were patterned by a combination of photolithography ͑using Shipley S1805 resist͒ and etching in dilute acetic acid ͑0.05 M͒. Finer features ͑including the 10 m wide bridges used in the experiments͒ were defined by direct laser micromachining of the film.…”