Heat Capacity at Constant Volume and Molecular Motion of Crystal, Orientationally Disordered Crystal and Liquid

晶体、无序晶体和液体的定体积热容和分子运动

基本信息

批准号：
02453008
负责人：
OGUNI Masaharu
金额：
$ 4.61万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

The present research aimed at making progress in the thermodynamic understanding on the coupling effects between orientational degrees of freedom and between them and the other degrees of freedom in orientationally disordered crystals.1) Effort was made to construct an automatic high-pressure calorimeter which measures simultaneously both heat capacity and volume at constant pressure to allow one to derive heat capacity at constant volume later from. The calorimeter is workable in the temperature range of 13 K to 500 K and enables high-precision thermometry of 10^<-5> K and heat capacity measurement with inaccuracy around 1 % at high pressures. We have so far succeeded in maintaining high pressure up to 200 MPa with its imprecision of 1 kPa within the high-pressure system. The remaining problem to be solved is in preparation of a thin sample-ampoule of indium which separates the sample and high pressure medium within the calorimeter cell.2) Orientationally disordered crystals, 2-haloge … More nothiophenes and pyridinium salts, were studied through heat capacity measurements under atmosphere. In the former crystals, glass transitions of one step and of two steps were observed in 2-bromothiophene and 2-chlorothiophene, respectively, and their properties changed continuously with a variation of composition between the two substances. These indicate that two reorientational processes couple with each other in both the dynamic and thermodynamic properties. In the latter cystals, pyridium iodide exhibited one phase transition while the chloride two phase transitions leading to the same high-temperature states in their orientational degrees of freedom. In pyridinium hexafluorophosphate, orientational disorderings of the cation and anion proceeded under strong coupling with each other showing only one phase transition as in the iodide. These suggest that the coupling effects stated above play quite important role in the evolution of orientational disordering both in the static and dynamic aspects. Less

本研究旨在在对定向自由度之间以及它们与其他自由度之间的耦合效果方面的热力学理解方面取得进展。在定向无序的晶体中。1）1）努力为构建自动高压热量量表的努力，该量子构建一种自动的高压热量计量，该量子仅在恒定体积下以恒定压力来促进热量和允许在恒定体积的高温下造成热量。量热仪在13 K至500 K的温度范围内可行，并实现10^<-5> K的高精度温度计，并且在高压下的不准确度约为1％。到目前为止，我们已经成功地保持了高达200 MPa的高压，其在高压系统中的促进了1 kPa。剩余的问题是准备稀薄的乳化样品，该样品会在量热计细胞内分离样品和高压培养基。2）在大气下进行热容量测量。在以前的晶体中，分别在2-溴硫醇和2-氯噻吩中观察到一个步骤和两个步骤的玻璃转变，它们的性质随着两种物质之间的组成变化而连续变化。这些表明，两个重新定位过程在动态和热力学特性中彼此之间彼此之间。在后一个循环中，碘化吡啶叶暴露了一种相变，而氯化吡啶叶则在其定向自由度下导致相同的高温度状态。在六氟磷酸吡啶量中，阳离子和阴离子的定向无序彼此之间进行了强耦合，仅显示出一种相变。这些表明，上面所述的耦合效应在静态和动态方面的定向无序的演变中起着非常重要的作用。较少的