Experimental Studies in Metastable Crystallization

卡西迪博士将利用这笔通过“探索研究小额拨款”项目获得的奖金，对陨石中发现的某些矿物质可能是亚稳态生长的假设进行实验验证。这些研究的实验室设备和设施位于匹兹堡的西屋科技中心。金刚石和碳化硅颗粒最近在大多数种类的原始石质陨石中被发现。这些物质可能是由蒸汽凝结成结晶的。然而，它们可能没有在平衡条件下结晶。亚稳态晶体生长的可能性已经提高，因为发现晶体金刚石可以在极低的压力和中等温度的等离子体中人工产生。其他高温矿物出现在原始陨石中，通过类比，这些矿物也可能是亚稳态生长的。卡西迪博士的研究将探索这些矿物质的亚稳态生长。如果这项研究取得成功，关于宇宙尘埃颗粒凝聚理论的某些假设将不得不重新检验。

Dr. Cassidy will use this award, made through the Small Grants for Exploratory Research program, to experimentally test the hypothesis that certain minerals found in meteorites could have grown metastably. Laboratory equipment and facilities for these studies are available at the Westinghouse Science and Technology Center in Pittsburgh. Diamonds and SiC grains have recently been identified in most classes of primitive stony meteorites. These materials probably condensed in the crystalline state from vapor. They may not have crystallized under equilibrium conditions, however. The possibility of metastable crystal growth has been raised by the discovery that crystalline diamond can be produced artificially in a plasma at very low pressures and moderate temperatures. Other high temperature minerals occur in primitive meteorites and, by analogy, these may also have grown metastably. Dr. Cassidy's research will explore the metastable growth of these minerals. If the research is successful, certain assumptions about the condensation theory of cosmic dust grains will have to be reexamined.