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Studies on Properties of Ferroelectric Polymers at Low Temperatures and Their Applications

铁电聚合物低温性能及其应用研究

基本信息

批准号：
01460228
负责人：
OHIGASHI Hiroji
金额：
$ 5.25万
依托单位：
Yamagata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-01460228/
关键词：
Low Temperature Physics Ferroelectric Polymer Piezoelectric Polymer Physical Acoustics Ultrasonic Transducer Pyroelectric Property Ceramic Super Conductor P (VDF-TrFE) (Copolymer of VDF and TrFE)高分子強誘電体液晶高分子高分子圧電体強誘電性超音波 P(V

项目摘要

The main purpose of this study is to clarify the electromechanical, pyroelectric and related properties of ferroelectric polymers at low temperatures, to apply ferroelectric polymers to ultrasonic transducers operating at low temperatures for studying low temperature acoustic properties of functionlty substances. For this purpose we introduced an cryostat (RD-204), which can works down to 8K and is optionally equipped with facilities for high frequency measurements, and we constructed a system for precise measurement of sound velocity and absorption at low temperatures. The ferroelectric polymers mainely studied are copolymers of vinlyidene fluoride and trifluoroethylene [P(VDF-TrFE)]. The main research results we obtained are as follows:(1) Despite of strong temperature dependence of the dielectric constant and stiffness constant.,the electromechanical coupling constant k_t is almost independent of temperature (8K-300K) for many ferroelectric polymers studied[PVDF, P(VDF-TrFE), P(VDF- … More TeFE)]. This stems from the fact that the electrostriction coefficients of these polymers are temperature-independent.(2) The value of k_t of P(VDF-Trfe) is large (0.3) even at very low temperatures, and therefore it is a good transducer for ultrasonic transducers working at low temperatures (LTs).(3) Dynamical pyroelectric voltage in P(VDF-TrFE) generated on irradiation of chopped light increases with decreasing temperature owing to more rapid decreasing of heat capacity, showing that P(VDF-TrFE) has a potential for sensitive LT pyroelectric detectores. The measured temperature dependence of heat capacity and pyroelectric coefficient are found to be well described by the lattice vibration theory for 3- and 1- dimensional and optical vibrational modes.(4) We find for the first time that the clathrate compound of hydroquinone and methanol is a ferroelectric crystal of the first oeder whose Curie temperature is at 68K. We observed a discontinuity in sound velocity and a peak in dielectric permittivity at that temperature. We consider that the alignment of dipoles of OH-groups is responsible for the ferroelectricity.(5) In addition to these results, we get a lot of important information on LT acoustic properties of P(VDF-TrFE), liquid crystalline polymers, carbon-fiber composite plastics, and a copper oxide superconductor, using P(VDF-TrFE) films as ultrasonic at low temperature. We found the formation of ferroelectric domains in P(VDF-TrFE) and clarified ots mechanism. Less

本研究的主要目的是阐明铁电聚合物在低温下的机电、热释电及相关性质，将铁电聚合物应用于低温超声换能器，研究功能物质的低温声学性质。为此，我们引入了一个低温恒温器（RD-204），它可以工作到8 K，并可选择配备高频测量设施，我们构建了一个系统，用于精确测量声速和吸收在低温下。研究的铁电聚合物主要是偏氟乙烯和三氟乙烯的共聚物[P（VDF-TrFE）]。主要研究结果如下：（1）尽管介电常数和刚度常数具有很强的温度依赖性，对所研究的许多铁电聚合物[PVDF，P（VDF-TrFE）]的机电耦合常数k_t几乎与温度无关（8 K-300 K）。 ...更多信息特费）]。这是因为这些聚合物的电致伸缩系数与温度无关。(2)P（VDF-Trfe）的k_t值即使在非常低的温度下也很大（0.3），因此它是用于低温工作的超声换能器（LT）的良好换能器。(3)P（VDF-TrFE）在斩波光照射下产生的动态热释电电压随着温度的降低而增加，这是由于其热容下降得更快，表明P（VDF-TrFE）具有作为灵敏LT热释电探测器的潜力。测得的热容和热释电系数的温度依赖性被发现是很好地描述的晶格振动理论的3-和1-维和光学振动模式。(4)首次发现对苯二酚-甲醇笼形化合物是第一类铁电晶体，其居里温度为68 K。我们观察到在该温度下声速的不连续性和介电常数的峰值。我们认为，OH-基团的偶极子的排列是负责的铁电性。(5)除了这些结果，我们得到了很多重要的信息LT声学性能的P（VDF-TrFE），液晶聚合物，碳纤维复合塑料，和氧化铜超导体，使用P（VDF-TrFE）薄膜作为超声波在低温下。发现了P（VDF-TrFE）铁电畴的形成，并阐明了其形成机理。少