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

新颖研究加急奖：通过涉及微乳液的化学处理制备高温超导体

• 批准号: 8807321
• 负责人: Dinesh Shah
• 金额: --
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-07-01 至 1990-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8807321&HistoricalAwards=false
• 关键词: Expedited; Award; Novel; Research; Preparation

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.

一项生产均匀、超细（~100）、致密、单分散超导陶瓷的新技术获得了该奖项。该方法利用单室油包水微乳液在其外部和内部之间形成高度选择性屏障的能力，从而在乳液微滴空间中创建微体积反应器。通过适当的处理，混合金属氢氧化物（超导陶瓷的前体）只能在这些微乳的内部区域诱导共沉淀。在略高于脂质凝胶-液相转变温度的温度下，用预先计算好的Cu++、Cu+、Ba++和y++ +离子的比例以及~ 1% w/w的双棕榈酰磷脂酰胆碱组成的混合金属氯离子溶液进行超声处理，将一些金属离子和氯离子包裹在油包水微乳液中。这个与罗德岛大学的合作项目代表了首次尝试使用单室囊泡共沉淀金属氢氧化物，这是最近发现的高温超导陶瓷的前体。临界转变温度和临界磁场强度与陶瓷相的化学计量和组成密切相关。在提出的技术中，通过改变原始溶液中阳离子的比例，这些可以很容易地改变。然而，相反，临界电流密度取决于用于获得最终产品的加工步骤。通过生产超细、致密和均匀的颗粒，有望获得比目前烧结超导陶瓷更高的临界电流密度。