Development of resonant ultrasound spectroscopy and its application to superionic conductors

在本课题研究期间，取得了以下研究成果.制作了高低温测量用传感器组件，为了测量晶体的谐振超声谱（罗斯）的温度依赖性，采用玻璃陶瓷缓冲板制作了传感器组件。高温（300 K-800 K）下的组装工作良好，在几种晶体中获得了精细的光谱。低温组件（80 K-300 K）正在测试中.制作了球形整形工具和位置控制单元，制备了球形整形工具。利用该工具获得了良好的球形碱金属卤化物晶体。可选地，位置控制单元被制成将样品设置在传感器组件的缓冲板之间。测量了球形、长方体和圆柱形的碱金属和银卤化物晶体的罗斯谱和弹性常数。每个晶体的弹性常数可以很好的精度确定。通过使用这些数据，偏离柯西关系（C12=C44）的估计和比较的多极极化由于局部密度近似（LDA）的模型计算讨论的离子扩散的容易性。此外，由弹性常数导出了Gruneisen参数，并通过比较AgBr和NaCl的值讨论了离子导电性.为了从测量的罗斯谱确定球形样品的弹性常数，与冈山大学地球内部研究所合作，编制了计算程序。

In the term of the project, the research results were obtained as follows.1. Making the assemblies of sensor for high and low temperature measurements.To measure the temperature dependence of the resonant ultrasound spectra (RUS) of crystals, the sensor assemblies were made by using buffer plates of glass ceramics for the ultrasound propagation. The assembly for high temperature (300K-800K) worked well, and the fine spectra were obtained in several crystals. The low temperature assembly (80K-300K) was now being tested.2. Making the sphere shaping tool and the position controle unit.The tool for sphere shaping of samples was prepared. The good sphere crystals of alkali halides were obtained by using this tool. Optionally, the position control unit was made to set the sample between the buffer plates of sensor assembly.3. Measurements of RUS spectra and determination of the elastic constants.Measurements were done for several crystals of alkali and silver halides with sphere, rectangular parallelpiped, and cylindrical shapes. The elastic constants of each crystal could be determined in good accuracy. By using the data, the deviation from the Cauchy relation (C12=C44) was estimated and compared with a model calculation of the multipole polarization due to the local density approximation (LDA) to discuss about the ease of the ionic diffusion. In addition, Gruneisen parameters were derived from the elastic constants and the ionic conduction was discussed by comparing the values of AgBr and NaCl.4. Computatinal program far sphere samples.To determine the elastic constants for sphere samples from the measured RUS spectra, a computational program was completed by getting the co-operation of Institute for Study of the Earth's Interior, Okayama University.