Study of relaxation process in the incommensurate phase by means of specific-heat spectroscopy.

利用比热谱研究非通约相的弛豫过程。

• 批准号: 02640253
• 负责人: EMA Kenji
• 金额: $ 1.02万
• 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 (C)
• 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
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02640253/
• 关键词: Specific-heat spectroscopy; Time-dependent heat capacity; Incommensurate phase; Relaxation process; sodium nitrite; Phosphatidylcholine

Recently we found that the heat capacity of ferroelectric sodium nitrite shows time-dependence when the temperature is changed suddenly within the incommensurate phase. Such a dynamic behavior of the heat capacity has been reported before for only limited cases including in the vicinity of the glass transition, and this is the first case that the "time-dependent heat capacity" is found in the incommensurate phase.Before starting the measurement, the precision of the calorimeter was improved. In the new apparatus, the temperature of the thermal bath is measured using an ac-driven wheatstone bridge, which is much more sensitive than the dc-driven bridge. An lock-in amplifier, a digital multimeter, etc, were purchased by the grant.Using the new apparatus, measurements were done on sodium nitrite by the relaxation method. It was found that the relaxation in the incommensurate phase proceeds over more than a few hundreds seconds, and that the relaxation shows a distinct deviation from the simple exponential behavior. We also done a simultaneous measurement of heat capacity and dielectric constant, and found that their relaxation processes agree quite well with each other.We also found that similar relaxation processes are seen during the main transition in aqueous suspensions of phosphatidylcholinesky such as DPPC, DMPC, and DSPC. From multi-Frequency ac-mode measurements, the relaxation time and the parameter beta which characterizes the distribution of relaxation time have been estimated. It is to be noted that the rexlaxation time strongly depends on the side-chain length.

最近，我们发现，当温度突然在不平质相内突然变化时，铁电钠的热容量显示出时间依赖性。仅在有限的情况下，包括玻璃过渡附近的有限案例，已经报告了热容量的这种动态行为，这是在不一致的阶段发现“与时间相关的热容量”的第一种情况。测量，量热计的精度得到提高。在新的设备中，使用AC驱动的惠斯通桥测量热浴的温度，该桥比DC驱动的桥更敏感。格兰特购买了一个锁定放大器，数字万用表等。使用新设备，通过放松方法对亚硝酸钠进行了测量。已经发现，在不一致的相位的放松在超过几百秒的时间内进行，并且放松与简单的指数行为明显偏离。我们还对热容量和介电常数进行了同时测量，并发现它们的放松过程彼此吻合。和DSPC。从多频AC模式测量值中，已经估计了弛豫时间和参数beta的特征，估计了弛豫时间分布的特征。应当注意，重新闭合时间很大程度上取决于侧链长度。

项目成果

K.Ema,H.Yao,and Y.Kawase: "Observation of slow dynamic process during the main transition in DSPC by timeーdependent heat capacity measurement." プロシ-ディングス.

K.Ema、H.Yao 和 Y.Kawase：“通过时间相关热容测量观察 DSPC 主转变期间的缓慢动态过程。”

K. Ema, H. Yao, and Y. Kawase: "Observation of slow dynamic process during the main transition in DSPC by time-dependent heat capacity measurement."

K. Ema、H. Yao 和 Y. Kawase：“通过时间相关热容测量观察 DSPC 主转变期间的缓慢动态过程。”