化學法製備高溫超導體

The Chemical Copper-Oxide Processes for The Superconductors

陳殿豪(Dian-Hau Chen) ； 沈祥榮(Shyang-Roeng Sheen) ； 張昭鼎(Chau-Ting Chang)

《化學》 50卷2期 (1992/06) Pp. 158-167

https://doi.org/10.6623/chem.1992017

摘要

高溫超道體是一種金屬氧化物的燒結體，故其導電及機械等性質受製程的影響甚巨。除了超導特性外，良好的超導體必順對顆粒大小、均勻性及陽離子比例等有仔細的控制，方有益於進一步的應用。本篇論文主要介紹共沉、凝膠、噴霧乾燥、冷凍乾燥等四種常用於製備粉體的化學製程。起始物以原子級的均勻混合是化學法製備高溫超導體的主要優點。此外，在製程中可以藉對化學反應的控制，合成大小分佈均的超微細粉體，惟對製程中的物理化學反應需有較多的了解，才有最佳的效果。

並列摘要

The superconductive properties of the copper oxide compounds are quite sensitive to the method of preparation. Multiphase samples containing fractions with Tc above liquid nitrogen temperature can be synthesized using rather crude techniques, but really high-grade single phase speciments require careful attention to such factors as grain size, homogeneity and the ratio of cations in the final sample. Polycrystalline samples are the easiest to prepare, and much of the early works were carried out by those processes. Of great importance are the thin film and wires preparation which require more specialized techniques. In this paper four preparative methods are described, namely the coprecipitation, the sol-gel method, the spray-drying method and the freeze-drying technique. These chemical methods have the advantage of mixing the constituents at near atomic scale. In addition the products may form fine powders whose uniformity can be controlled, which can elimination some labor in the ensuing processes. The main disadvantage of these processes are the involvement of more skill and finer experimental controls.