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Modeling and characterization of dielectrophoretically structured piezoelectric composites using piezoceramic particle inclusions with high aspect ratios

Author: Ende, D.A. van den · Maier, R.A. · Neer, P.L.M.J. van · Zwaag, S. van der · Randall, C.A. · Groen, W.A.
Type:article
Date:2013
Source:Journal of Applied Physics, 3, 113
Identifier: 470026
doi: doi:10.1063/1.4914113
Article number: 034103
Keywords: Applied field · Bulk PZT · Coupling factor · Degree of alignments · Equiaxed particles · Equivalent circuit model · High aspect ratio particles · High electric fields · High-field · Measured impedance · Piezoceramic · Piezoelectric charge constant · Piezoelectric composite · Piezoelectric property · Piezoelectric strain constant · Poling directions · Polymer composite · PZT · Short fiber composites · Thickness modes · Voltage constants · Ceramic materials · Composite materials · Dielectric properties of solids · Electrophoresis · Permittivity · Piezoelectric ceramics · Piezoelectric transducers · Piezoelectricity · High Tech Systems & Materials · Industrial Innovation · Mechatronics, Mechanics & Materials · HOL - Holst · TS - Technical Sciences

Abstract

In this work, the piezoelectric properties at high electric fields of dielectrophoretically aligned PZT - polymer composites containing high aspect ratio particles (such as short fibers) are presented. Polarization and strain as a function of electric field are evaluated. The properties of the composites are compared to those of PZT-polymer composites with equiaxed particles, continuous PZT fiber-polymer composites, and bulk PZT ceramics. From high-field polarization and strain measurements, the effective field dependent permittivity and piezoelectric charge constant in the poling direction are determined for dielectrophoresis structured PZT-polymer composites, continuous PZT fiber-polymer composites, and bulk PZT ceramics. The changes in dielectric properties of the inclusions and the matrix at high fields influence the dielectric and piezoelectric properties of the composites. It is found that the permittivity and piezoelectric charge constants increase towards a maximum at an applied field of around 2.5-5 kV/mm. The electric field at which the maximum occurs depends on the aspect ratio and degree of alignment of the inclusions. Experimental values of d33 at low and high applied fields are compared to a model describing the composites as a continuous polymer matrix containing PZT particles of various aspect ratios arranged into chains. Thickness mode coupling factors were determined from measured impedance data using fitted equivalent circuit model simulations. The relatively high piezoelectric strain constants, voltage constants, and thickness coupling factors indicate that such aligned short fiber composites could be useful as flexible large area transducers. cop. 2013 American Institute of Physics.