Synthesis of the Tl-based superconducting materials by the sol gel method iodine vapor pressure

Author: Daviti Surmanidze
Keywords: superconducting, materials
Annotation:

In superconducting materials, under cryogenic temperature resistance completely vanishes, and magnetic fields are expelled (Meissner effect), enabling the free movement of electrons. Generally, superconducting compounds do not conduct electricity at room temperature due to their low transition temperatures in the superconductivity state. Throughout the development of superconducting materials, various compounds, synthesis techniques, and physical parameters have been proposed. In recent years, particular attention has been given to high-temperature superconductors, which exhibit high critical temperatures (Tc) and critical current densities (Jc). Among these types of superconductors, mercury and thallium-based high-temperature superconductors, with critical temperatures ranging from 125 to 135 K, are of great importance. Superconducting materials have a wide range of diverse and promising applications. This master's thesis aims to synthesize superconducting samples using one of the most recent techniques, the sol-gel method. The research focuses on identifying the ideal chemical and physical conditions required for synthesis, examining the influence of dopants at various concentrations on superconducting parameters. The main advantage of the aforementioned synthesis method is the ability to easily control the composition of the produced substance. Furthermore, this method allows for the production of ideal homogeneous nanostructures and high yields of precursors with high reactivity. In the synthesis process, thallium oxide and iodine oxide was added to the synthesized Ba2Ca2Cu2Ox precursor, and their solid-phase reaction was conducted in a sealed quartz ampoule under various oxygen pressure conditions. The critical temperature and critical current density values was determined through physical measurements of the obtained superconducting samples. The use of iodine pentoxide in the research process was novel and resulted in the creation of iodine-doped superconducting samples. Additionally, the investigation of the impact of oxygen pressure on the development of superconducting phases and their physical characteristics was conducted for the first time. Throughout the synthesis process, the samples was undergone infrared spectrophotometric, X-ray phase, and electron microscopic analyses, enabling a comprehensive examination of all the research questions raised and facilitating significant conclusions.