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Studies of Pyroelectric Dynamics of Polymers by means of Temperature Jump Spectroscopy

温跃光谱研究聚合物热释电动力学

基本信息

批准号：
09651003
负责人：
FURUKAWA Takeo
金额：
$ 1.98万
依托单位：
Science University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09651003/
关键词：
Pyroelectricity Temperature Jump Dynamics Thermal Expansion Piezoelectricity Vinylidene Fluoride Ferroelectricity Polymer

项目摘要

A charge response is observed for a wide range of time in a poled ferroelectric polymer due to its pyroelectricity when its temperature is raised suddenly by applying a YAG laser pulse with a duration of several nanoseconds. This work is aimed to understand the dynamics of pyroelectricity by analyzing quantitatively the pyroelectric response curves. In addition to a YAG laser Surelite-I and a high speed digitizing oscilloscope TDS62O in our laboratory, we bought a second-harmonics-generating crystal. We also developed software to measure and anaylize the respons. As a result, the measurement in a range of 1 ns to 10 s became possible. We used a copolymer of vinylidene fluoride VDF with trifluoroethylene TrFE of content of 75/25 mol%. A film was obtained by casting from solution with dye. After poled by a high ac field, the film was subjected to a laser pulse, being connected to the oscilloscope. The pyroelectric response curves thus obtained show that there are several modes of response : the instantaneous mode, two oscillating modes and a gradual decreasing mode which is due to cooling of the sample. Oscillating modes result from the mechanical oscillation induced by the abrupt themal expansion. The thickness extensional and the length extensional mode oscillations are induced and are observed as oscillations of charge response as a result of coupling with piezoelectricity. The instantaneous mode corresponds to the pyroelectric primary effect which is only ca. 20% of total response. The response curves were also measured at elevated temperatures. The amount of the response increases as the temperature is raised up to just below the Curie temperature, and then decreases as the polarization vanishes. The oscillatory modes are found to vanish prior to the instantaneous mode at the Curie temperature.

在极化的铁电聚合物中，当其温度突然升高时，通过施加持续时间为几纳秒的YAG激光脉冲，由于其热电性，在很宽的时间范围内观察到电荷响应。本工作的目的是通过对热释电响应曲线的定量分析来了解热释电的动力学。除了实验室的YAG激光器Sureite-I和高速数字化示波器TDS 62 O外，我们还购买了一个二次谐波产生晶体。我们还开发了软件来测量和分析响应。结果，1 ns至10 s范围内的测量成为可能。我们使用含量为75/25摩尔%的偏二氟乙烯VDF与三氟乙烯TrFE的共聚物。通过从具有染料的溶液流延获得膜。在通过高交流场极化之后，膜经受连接到示波器的激光脉冲。由此获得的热释电响应曲线表明，有几种模式的响应：瞬时模式，两个振荡模式和一个逐渐下降的模式，这是由于冷却的样品。振荡模式是由突然的热膨胀引起的机械振荡引起的。厚度延伸和长度延伸模式振荡的诱导和观察作为与压电耦合的结果的电荷响应的振荡。瞬时模式对应于热释电初级效应，其仅为ca。占总响应的20%。还在升高的温度下测量响应曲线。响应量随着温度升高到刚好低于居里温度而增加，然后随着极化消失而减小。在居里温度下，振荡模先于瞬时模消失。