FERROELECTRIC POLYMER SINGLE CRYSTAL, METHOD OF ITS MANUFACTURE, AND PIEZOELECTRIC ELEMENT, PYROELECTRIC ELEMENT AND NONLINEAR OPTICAL ELEMENT USING THE METHOD

摘要

PURPOSE: To allow lamella crystal to grow in a certain direction in a membrane plane by preparing ferroelectric polymer consisting of a copolymer of ethylene trifluoride or tetrafluoride and vinylidene fluoride in the form of a film or fiber. ;CONSTITUTION: Polyvinylidene fluoride and ethylene tri- or tetra-fluoride are mixed to prepare a membrane using dimethyl formamide as a solvent, and the obtained membrane is uniaxially elongated approximately five times as large at room temp. The Curie point of the membrane is 123°C while the melting point is 150°C. The two membrane ends perpendicular to the elongating direction are fixed and the temp. is raised from room temp. at a rate of approx 5°C/min, crystallized in the air at a temp. of 140°C, followed by slowly cooling to the room temp. The resultant ferroelectric polymer consisting of coplymer of these crystals and vinylidene fluoride is shaped in a film or fiber. The singlecrystal film has good orientation of molecular chain and a good degree of crystallization, and its poling film exibits a large polarization so that the piezoelectric coefficient and the electro-mechanical coupling factor are increased.;COPYRIGHT: (C)1996,JPO