Lattice Properties of Crystalline Solids with Glasslike Properties: Ultrasound Studies of Inclusion Compounds and Quasicrystals

该提案旨在研究各种各样的“玻璃状晶体”（同时反映晶体和玻璃状性质的材料）的弹性响应和超声衰减。 将解决的科学问题包括：（a）包结化合物，准晶和结构玻璃之间的关系，（B）是隧道状态（通常在低温下的玻璃中发现）固有的包结化合物和/或准晶，和（c）结构性能关系-在何种程度上可以使用各种结构特征来预测给定材料的弹性性能？ 本研究项目将使用共振超声光谱学（罗斯）来探测所研究材料的弹性特性。罗斯是一种新的技术，用于确定弹性模量的固体，基于测量的共振的自由振动的物体。 将使用标准脉冲回波技术测量材料的超声衰减。 这项建议将有助于在密西西比大学发展一个强大的固态计划。 高级本科生和研究生都将获得超声实验和低温物理技术的深入经验。“普通”材料是晶体（具有长程有序，即，原子排列成周期性阵列）或玻璃（没有长程有序）。 本计画将探讨包结化合物、准晶等特殊材料的性质。 这些是同时显示晶体和玻璃状性质的材料。 该项目将集中在这些显着的固体的弹性特性，使用一个相对较新的技术，共振超声光谱（罗斯）。 一项对显示玻璃状和晶体特征的不寻常组合的材料的研究预计将在两个方面产生影响。 首先，在这些材料中发现的类玻璃性质的调查，预计将导致一个更好的理解的玻璃态行为的起源。 由于这些材料是感兴趣的技术（热电）应用，更好地了解他们的属性是必不可少的设计材料的上级性能。其次，这项研究将有助于培养密西西比大学本科和研究生阶段的年轻科学家，他们将在凝聚态物理学领域获得深入的经验。

This proposal is designed to investigate the elastic response and ultrasonic attenuation of a wide variety of "glasslike crystals" (materials that simultaneously reflect both crystalline and glasslike properties). The scientific issues that will be addressed include: (a) the relationship between inclusion compounds, quasicrystals, and structural glasses, (b) are tunneling states (which are typically found in glasses at low temperatures) intrinsic to inclusion compounds and/or quasicrystals, and (c) structure-property relationships - to what extent can various structural features be used to predict the elastic properties of a given material? This research project will use Resonant Ultrasound Spectroscopy (RUS) to probe the elastic properties of the materials under investigation. RUS is a novel technique for determining the elastic moduli of solids, based on the measurement of the resonances of a freely vibrating body. The ultrasonic attenuation of the materials will be measured using a standard pulse-echo technique. This proposal will contribute toward the development of a strong solid-state program at The University of Mississippi. Both advanced undergraduate and graduate students will gain in-depth experience in ultrasound experiments and the techniques of low temperature physics."Ordinary" materials are either crystals (with long-range order, i.e., the atoms are arranged in a periodic array) or glasses (with no long-range order). This proposal will investigate the properties of some "extraordinary" materials such as inclusion compounds and quasicrystals. These are materials that simultaneously display both crystalline and glasslike properties. The project will focus on the elastic properties of these remarkable solids, using a relatively new technique, Resonant Ultrasound Spectroscopy (RUS). A study of materials that display the unusual combination of glasslike and crystalline features is expected to have an impact on two fronts. First, the investigation of the glasslike properties found in these materials is expected to lead to a better understaanding of the origin of glassy behavior. Since these materials are of interest for technological (thermoelectric) applications, a better understanding of their properties is essential for the design of materials with superior properties. Secondly, this research will contribute to the training of young scientists at the undergraduate and graduate level in Mississippi, who will gain in-depth experience in the field of condensed-matter physics.