Phase Transitions and Volume and Energy Band Gap Variation in the Multimegabar Regime

兆巴体系中的相变以及体积和能量带隙变化

• 批准号: 9218249
• 负责人: Arthur Ruoff
• 金额: --
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-03-01 至 1996-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9218249&HistoricalAwards=false
• 关键词: Phase; Transitions; Volume; Energy; Band

Techniques for x-ray diffraction studies (using Cornell High Energy Synchroton Service) and optical studies which will extend the static pressure range higher than the 560 GPa attained will be developed. To do this requires further miniaturization of diamond tips, of sample size and of x-ray apertures and optical beam diameters. The crystal structure of oxygen and sulfur will be found ?materials which have previously been metallized (they have 60% reflectivity at the diamond sample interface at high pressure)! since this should induce theorists to work on these materials. Superconductive bahavior will be looked for in them. Hydrogen, nitrogen (including high temperature) and LiH will be pressurized to pressures in excess of 4 Mbars and higher with the intent of reaching meatllization. The metallization of alkali hydrides as an analogous series with hydrogen hydride as the highest member of the series will be studied. %%% Ultrapressures cause enormous changes in solids. Solid xenon has its volume decreased by 72% at 1.5 Mbars while silicon has its volume decreased by 34% at 2.5 Mbars (the pressure at the earth's core is 3.6 Mbars and at the deepest spot in the ocean only 1kbar). These enormous changes cause changes in crystal structure, and changes in electronic structure resulting in important changes in physical properties. Theorists, using quantum mechanics with approximatims (necessary to make the problem soluble) attempt to calculate these structural changes. Results provide an exacting test of their theories and set the stage for doing computer based solid state physics. Interest is also in developing new materials with possible exotic properties. It has been predicted that hydrogen will become metallic at high pressure and that it will be a high temperature superconductor. Metallic xenon and metallic oxygen have been made and work is being done to make metallic hydrogen to see if it indeed is a high temperature superconductor. High pressure is viewed as a tool for making and processing new materials with unusual properties.

X射线衍射研究技术（使用Cornell High Energy Synchroton服务）和光学研究，这将扩大 静压范围高于560 GPa， 开发 要做到这一点，需要进一步缩小金刚石 样品尺寸和X射线孔和光束的尖端 直径。 氧和硫的晶体结构 找到了吗？先前已经金属化的材料（它们具有 高压下金刚石样品界面处的反射率为60%）！ 因为这会促使理论家们研究这些材料。 超导电池将在其中寻找。 氢气， 氮气（包括高温）和LiH将被加压 压力超过4 Mbar和更高，目的是 达到肉化。 碱金属的金属化作为一种 以氢化氢为最高成员的类似系列 系列将进行研究。 %%% 超高压引起固体的巨大变化。 固体氙具有 其体积在1.5 Mbar时减少了72%，而硅具有其 体积在2.5 Mbar（地球的压力）时下降了34%， 核心是3.6毫巴，在海洋最深处只有1千巴）。 这些巨大的变化导致晶体结构的变化， 电子结构的变化导致了 物理性质 理论家们利用量子力学 近似（解决问题所必需的）尝试 计算这些结构变化。 结果提供了一个精确的 测试他们的理论，并为做基于计算机的 固体物理学。 开发新材料也很有兴趣 可能有奇异的特性 据预测， 氢在高压下会变成金属， 高温超导体。 金属氙和金属 氧气已经被制造出来， 氢，看看它是否确实是高温超导体。 高压被视为制造和加工新产品的工具。 具有不寻常属性的材料。