A Study on the Structural Relaxation by the Simultabeous Measurements of enthalpy and Volume under High Pressure

研制了一台可以在高压下同时测量样品的热容和体积的绝热量热计，其测量热容的方法与通常的常压工作的绝热量热计的测量方法类似。圆柱形样品池非常大(650克)，由铜铍合金制成，以保持内部压力。样品体积可以通过测量安装在池内的波纹管的长度来获得。在低温恒温器外部的磁铁用不锈钢棒安装在波纹管的顶部。波纹管的长度可以通过用分辨率为0.1微米的磁铁传感器测量磁铁的位置来确定。量热仪的温度范围为100-375K，压力范围为0-200兆帕。温度测量的温度和压力范围为100NK，压力控制精度为1kPa(0.01bar)，空室热容测量精度为0.02%。被选为标准材料的水的测试测量表明，热容(0.2%)和体积(1x19；-5；%)的精度非常高。作为同时测量结构弛豫的初步实验，用不能测量样品体积的高压量热计研究了正丙醇和3-甲基戊烷的压力跃迁和温度跃迁玻璃的热弛豫。通过对有效驰豫时间的分析，首次发现了压力跃迁玻璃和温度跃迁玻璃的结构驰豫明显不同。

I have costructed an adiabatic calorimeter which can measure enthalpy and volume of sample simultaneously under high pressure, the method of the enthalpy measurement is similar to that of usual adiabatic calorimeters working at ambient pressure. The cylindrical sample cell is very massive (650 g) and made of copperberyllium alloy to keep the inside pressure. The sample volume can ve obtained by measuring the length of the bellows which is installed inside the cell. A magnet, which is outside the cryostat, is commected to the top of the bellows with a stainless-steel rod. The length of the bellows can be determined by measuring the positon of the magnet with magnet sensors with resolution of 0.1 mum. The temperature and pressure ranges of the calorimeter are 100-375 K and 0-200 MPa, respectively. The temperature and pressure ranges of the temperature measurement is 100 nK and the precision of the pressure control is 1 kPa(0.01 bar).the precision of the heat capacity measurement of the empty cell was 0.02 %. The test measurements for water, which is selected as a standard material, showed excellent accuracy of heat capacity (0.2 %) and volume (1x19^<-5>%). These are accurate enough for the measurements on the structural relaxation.As a preliminary experiment for the simultaneous measurements on the structural relaxation, the enthalpy relaxation of the pressure-jump and temperature-jump glasses of 1-propanol and 3-methylpentane was investigated by using an previous high-pressure calorimeter shich cannot measure volume of sample. from the analysisi on the effective relaxation times, clear difference between the structural relaxations of pressure-jump and temperature-jump glasses was found for the first time.