Measurement of Temperature and Pressure Changes of Elastic Moduli of Minerals

提出了在气体压力下测量两种样品组合体弹性常数压力导数的共振法，确定了边界条件：（1）球形样品-薄气体层-中心有球形空腔的球形容器，空腔容器表面无应力;（2）球形样品-无限大范围的气体，应力分量在样品表面连续。在这两个组合的测量产生了良好的信号/噪声比的共振峰。这是在高达300 MPa的气压下测量共振峰的第一个重要结果。在组合（1）中，存在着集中在薄气层中的“气体模”，气体模与样品模耦合，对确定弹性常数的压力导数产生干扰。集合体（2）不受气体模的干扰，但对单个模需要用不同的方法进行一系列复杂的分析，本课题将共振法推广到单斜晶体，采用长方体试样。对单斜辉石（透辉石MgCaSi_2O_6i）单晶进行了测量，根据63个识别出的模式确定了全部13个独立的弹性常数。另一种铬透辉石单晶也进行了测量，并与加州大学洛杉矶分校的D.G.Isaak合作确定了弹性常数

The resonance method for measuring pressure derivatives of elastic constants was developed under gas pressure in two kinds of sample assemblage to specify the boundary condition : (1) spherical sample-thin gas layer-spherical container with a spherical cavity at the center ; stress free on the surface of cavity container ; (2) spherical sample-gas in infinite range ; stress components continuous at the sample surface. Measurements in both assemblages yielded resonance peaks of good signal/noise ratio. This is the first and important result of measuring resonance peaks under gas pressure up to 300 MPa. In the assemblage (1), it turned out there exist 'gas modes' concentrated in the thin gas layer, and the gas modes couples with the sample mode and make interference in determining pressure derivatives of elastic constants. The assemblage (2) is free from the interference caused by the gas modes, but a series of complicated analysis is needed in different way for individual mode.In this term of project, the resonance method was extended to monoclinic crystals using rectangular parallelepiped specimen. A single crystal of monoclinic pyroxene (diopside MgCaSi_2O_6i) was measured, and all of thirteen independent elastic constants were determined based on 63 identified modes. Another single crystal of chrome-diopside was also measured and the elastic constants were determined in co-operative work with D.G.Isaak at UCLA