Mineral Elasticity by Brillouin Scattering at One Atm. and High Pressure

候选地幔相弹性性质的准确值对于确定地球内部的矿物学和化学性质具有根本的重要性。虽然斜辉石和石榴石是所有当代上地幔矿物学模型的重要组成部分，但这些矿物的弹性特性对许多相关成分都是不确定的。本研究计划的总体目标是确定化学成分和晶体结构对地球物理上重要材料弹性的影响。PI将通过布里渊散射测量来确定斜辉石和石榴石单晶在环境条件下的弹性特性，将启动一个实验项目，通过在金刚石砧池中压缩样品的布里渊散射测量来确定矿物在高压下的弹性特性。这些实验的目的是获得地幔矿物的体积模量和剪切模量的压力导数。目前这种特性的可靠值很少。这些结果将为测试地球上地幔和过渡带的矿物学模型提供改进的基础，并将大大提高我们对硅酸盐固体溶液中化学和晶体结构变化如何影响矿物弹性的理解。

Accurate values of the elastic properties of candidate mantle phases are of fundamental importance for placing constraints upon the mineralogy and chemistry of the Earth's interior. Although clinopyroxenes and garnets are essential major constituents of all contemporary models of upper mantle mineralogy, the elastic properties of these minerals are undetermined for many relevant compositions. The overall goal of this research program is to define the effects of chemical composition and crystal structure on the elasticity of geophysically important materials. The PI will determine the elastic properties of clinopyroxene and garnet single crystals under ambient conditions by Brillouin scattering measurements, will initiate an experimental program to determine the elastic properties of minerals at high pressure by Brillouin scattering measurements on samples compressed in a diamond anvil cell. The aim of these experiments is to obtain pressure derivatives of the bulk and shear moduli for the mantle minerals. Extremely few reliable values of such properties are presently available. These results will provide an improved basis for testing mineralogical models of the Earth's upper mantle and transition zone, and will greatly enhance our understanding of how chemical and crystal structural changes affect mineral elasticity within silicate solid solutions.