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Development of Heat Capacity Spectroscopy and Application to Relaxation Process in Amorphous Materials

热容光谱学的发展及其在非晶材料弛豫过程中的应用

基本信息

批准号：
62850120
负责人：
SAITO Yasutoshi
金额：
$ 5.76万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1988
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-62850120/
关键词：
Heat capacity spectroscopy Ac method Amorphous materials Liquid crystals Glass transition 緩和機構

项目摘要

The frequency dependence of the heat capacity is expected to be observed near the glass transition temperature of a supercooled material. However, the maximum measurable frequency in conventional ac calorimetry is ultimately limited by the thermal divvusivity and the size of sample. The purpose of this research is to develop a new technique that makes it possible to obtain the frequency-dependent heat capacities over a wide range of frequency between 1 Hz and 100 kHz.A cryostat working in a temperature region from liquid helium temperature up to ablut 100゜c and a high-precision system for temperature control have been constructed. The electrical circuits using a lock-in amplifier have been also constructed for heat capacity measurements on the basis of ac method. The calorimetry system has been automated by using a microcomputer. A thin metal resistor element for the use as heater/thermometer has been devised by vapor deposition(Ni, Au) and rf sputtering(Au, Pt). It has been found that the measurement system can be simplified by combining the two elements with the same temperature coefficient of resistance. A thin wire method has been also developed. The performance of the system has been tested by doing experiments on the blass transition of glycerol. The materials of liquid crystals have been also studied. Thermodynamic properties of pentylcyanobiphenyl and the related compounds (replacing the benzene ring by cyclohexane ring) have been studied by DTA, heat capacity measurements and Raman spectroscopy. The relaxation mechanisms have been discussed about the blass transition phenomena of the mixtures.

在过冷材料的玻璃化转变温度附近可以观察到热容的频率依赖性。然而，在传统的交流量热法中，最大可测频率最终受到热扩散率和样品尺寸的限制。本研究的目的是发展一种新的技术，使其能够在1 Hz到100 kHz的宽频率范围内获得与频率相关的热容，并建立了一个工作在液氦温度到大约100 ℃温度范围内的低温恒温器和一个高精度的温度控制系统。本文还建立了用锁相放大器测量交流法热容的电路。量热系统已采用微机实现自动化。采用气相沉积（Ni，Au）和射频溅射（Au，Pt）技术，设计了一种用作加热器/温度计的薄金属电阻元件。已经发现，通过将具有相同电阻温度系数的两个元件组合，可以简化测量系统。还开发了细线法。通过对甘油的热态转变实验，对系统的性能进行了测试。对液晶材料也进行了研究。用差热分析、热容测量和拉曼光谱研究了戊基氰基联苯及其相关化合物（苯环被环己烷环取代）的热力学性质。讨论了该混合物相变现象的弛豫机制。