Phase Equilibria in Thallium Based Superconducting Films

将测量铊超导系统中的相平衡。我们的目标是了解控制铊基超导体家族晶体生长的复杂的固-液-蒸汽平衡。这项研究将包括将已知成分的薄膜和粉末混合物暴露在高温(600-950摄氏度)的氧化亚锡和氧气蒸汽的受控超压下，然后淬火。将检查淬火样品的成分和微观结构，以确定平衡的高温相。通过这种方式，将在对薄膜和晶体生长重要的成分区域中确定液、固线温度、平衡超压和稳定相。有关相变的更多信息将通过差热分析(DTA)获得，该分析使用密封的金安瓶来控制铊的挥发性。

Phase equilibria in the thallium superconducting system will be measured. The goal is to understand the complex solid-liquid- vapor equilibria that govern crystal growth of the thallium based family of superconductors. This study will involve exposure of films and powder mixtures of known composition to controlled overpressures of thallous oxide and oxygen vapor at high temperature (600 - 950 C) followed by quenching. The composition and microstructure of quenched samples will be examined to identify the equilibrium high temperature phases. In this manner the liquidus and solidus temperatures, equilibrium overpressures, and stable phases will be determined in those regions of composition that are important for thin film and crystal growth. Additional information on phase changes will be gained by differential thermal analysis (DTA) using sealed gold ampoules to control thallium volatility.