Expedited Award for Novel Research: Preparation of High Tc Superconductors Through Chemical Processing Involving Microemulsions

一种生产均匀、超细、 （~100），致密，单分散的超导陶瓷是 在这个快速的奖项。 此方法利用了 单室油包水微乳液形成微乳液的能力 在其外部和内部之间高度选择性屏障，因此 在乳液微滴空间中产生微体积反应器。 通过适当的处理，混合金属的共沉淀 氢氧化物（超导体、陶瓷的前体）可以是 仅在这些微乳液的内部区域中诱导。 混合 金属氯化物溶液由预先计算的Cu++， Cu+、Ba++和Y+离子沿着~ 1% w/w二棕榈酰 磷脂酰胆碱将在略高于脂质 凝胶-液相转变温度，以包封一些 金属和氯离子的油包水微乳液内。 这个与罗得岛大学的合作项目 代表首次尝试使用单隔室囊泡 金属氢氧化物的共沉淀，所述金属氢氧化物是 最近发现的高温超导陶瓷 的 临界转变温度和临界磁场 强度与化学计量和组成密切相关 陶瓷阶段。 这些可以很容易地改变在建议的 技术通过改变原材料中阳离子的比例， 溶液 然而，相反，临界电流密度取决于 在用于获得最终产品的加工步骤上。 通过 生产超细、致密和均匀的颗粒，预期 将获得比目前更高的临界电流密度 可用于烧结超导陶瓷。

A novel technique for the production of uniform, ultrafine (~100), dense, monodispersed superconducting ceramics is undertaken in this expedited award. This method exploits the ability of single compartment water-in-oil microemulsions to form a highly selective barrier between its exterior and interior, thus creating a microvolume reactor in the emulsion microdroplets space. By appropriate processing, coprecipitation of the mixed metal hydroxides (precursors of the superconducting, ceramics) can be induced in the internal region of these microemulsions only. A mixed metal chloride solution consisting of precalculated ratios of Cu++, Cu+, Ba++, and Y+++ ions along with ~1 percent w/w dipalmitoyl phosphatidylcholine will be sonicated at slightly above the lipid gel-liquid phase transition temperature to encapsulate some of the metal and chloride ions inside the water-in-oil microemulsion. This collaborative project with the University of Rhode Island represents the first attempt at using single compartment vesicles for coprecipitation of metal hydroxides which are precursors for the recently discovered high temperature superconducting ceramics. The critical transition temperature as well as the critical magnetic field strength are intimately related to the stoichiometry and composition of the ceramic phase. These can be varied easily in the proposed technique by changing the ratio of the cations in the original solution. In contrast, however, the critical current density depends upon the processing steps used to obtain the final product. By producing ultrafine, dense and uniform particles, it is expected that higher critical current density will be obtained than that presently available with sintered superconducting ceramics.