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ABSTRACT (Maximum 200 words) iThe longitudinal (d 3 3 ) and transverse (d 3 1 ) piezoelectric coefficients of a piezoelectric composite material (NTK PR-306) are determined as functions of frequency and temperature by using laser Doppler vibrometry to measure the strain induced in the sample by an electric field. Measurements are performed over the temperature range from -50 0 C to 50 0 C and over a frequency range from 0.1-10 kHz. Some measurements were made at frequnecies up to 100 kHz in order to demonstrate the ability of the technique at frequencies in the vicinity of an electromechanical resonance. The results show that the viscoelastic relaxation affects the piezoelectric response of the composite material primarily through the dielectric stiffness rather than the elastic stiffness. The d 3 3 coefficient is observed to relax in a normal fashion near the glass transition of the polymer phase wheras the relaxation in the d 3 1 coefficien varies over the entire measured range of temperature.
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GENERAL INSTRUCTIONS FOR COMPLETING SF 298The Report Documentation Page (RDP) is used in announcing and cataloging reports. It is important that tis information be consistent with the rest of the report, particularly the cover and title page. The longitudinal (d 3 ,) and transverse (d 31 ) piezoelectric coefficients of a piezoelectric composite material (NTK PR-306) are determined as functions of frequency and temperature by using laser Doppler vibrometry to measure the strain induced in the sample by an electric field. Measurements are performed over the temperature range from -50 C to 50 C and over a frequency range from 0. 1-10 kHz. Some measurements were made at frequencies up to 100 kHz in order to demonstrate the ability of thetechnique at frequencies in the vicinity of an electromechanical resonance. The results show that the viscoelastic relaxation affects the piezoelectric response of the composite material primarily through the dielectric stiffness rather than the elastic stiffness. The d 33 coefficient is observed to relax in a normal fashion near the glass transition of the polymer phase whereas the relaxation in the d 31 coefficient varies over the entire measured range of temperature.
The electromechanical properties of two electrostrictive materials designed for use in underwater acoustic applications are determined as functions of temperature and electric field. The materials are 0.859 Pb(Mg1/3Nb2/3)O3–0.141 PbTiO3 doped with 2.5% SrTiO3 or BaTiO3. Dielectric properties are determined as functions of temperature and electric field. The equivalent piezoelectric coefficients were found as functions of temperature to be equal to or superior to the lead zirconate–titanate ceramics at very modest dc bias fields (2 kV/cm) at temperatures in the range from 10 to 35 °C. Outside of this temperature range, the piezoelectric and dielectric coefficents decrease rapidly. Electromechanical losses were found to be sufficiently small for the SrTiO3 composition but not the BaTiO3 composition.
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