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

将开发用于X射线衍射研究(使用康奈尔高能同步服务)和光学研究的技术，这些技术将扩大静态压力范围，使其高于560 Gpa。要做到这一点，需要进一步小型化钻石尖端、样品大小以及X射线孔径和光束直径。氧和硫的晶体结构将被发现？？以前已经金属化的材料(它们在高压下在金刚石样品界面具有60%的反射率)！因为这应该会促使理论家对这些材料进行研究。我们将在它们身上寻找超导行为。氢气、氮气(包括高温)和氢化锂将被加压到超过4兆巴或更高的压力，以达到肉质化的目的。将碱氢化物的金属化作为一个类似的系列来研究，氢化氢是该系列中最高的成员。超压会引起固体的巨大变化。固体氙气的体积在1.5兆巴时减少了72%，而硅的体积在2.5兆巴时减少了34%(地核的压力为3.6兆巴，海洋最深处的压力只有1千巴)。这些巨大的变化导致晶体结构的变化，以及电子结构的变化，导致物理性质的重要变化。理论家们利用量子力学的近似性(使问题变得可解所必需的)试图计算这些结构变化。这些结果为他们的理论提供了严格的测试，并为开展基于计算机的固体物理奠定了基础。人们对开发可能具有奇异性质的新材料也很感兴趣。有人预测，氢将在高压下变成金属，它将是一种高温超导体。金属氙气和金属氧已经被制造出来，并正在进行制造金属氢的工作，以确定它是否真的是高温超导体。高压被视为一种制造和处理具有特殊性能的新材料的工具。

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.