Text

theses

Thick film dome-shaped two-phase (lead zirconate titanate ("Pb" [〖"Zr" 〗_"x" 〖"Ti" 〗_"1-x" ] "O" _"3" "(0≤x≤1)" )-Epoxy) structures have been fabricated using a modified sol-gel and spin-coat deposition process. Processing parameters and poling technique (Corona versus contact poling) were studied to elucidate their influences on piezoelectric and dielectric properties. 3 primary studies were carried out in the investigation. To study how time/speed profiles in spin-coating process influence the dielectric and piezoelectric properties of the samples, 4 different time/speed profiles built up form original profile were tested. Poling conditions, such as corona poling and contact poling were studied at the same material structure and compositions. Different poling voltages (45kv/mm and 70kv/mm) with corona poling techniques at low volume fractions of PZT (i.e. 0.1~0.3) were studied on samples fabricated with same techniques to investigate the influences of poling voltage. The combinations of depositing technique and viscosity were studied at low volume fractions such as 0.35 volume fraction of PZT to address the uniformity issue in thickness at lower volume fractions. The piezoelectric strain coefficient d33 for this dome structure was 9 times higher than that previously reported values for a composite PZT-epoxy dome structure of similar structure and composition. The sample morphology was examined with the aid of scanning electron microscopy (SEM) images and the material distribution was studied by energy dispersive x-ray spectroscopy (EDS). The piezoelectric strain coefficients, capacitance and effective dielectric constant increased with increasing PZT content. Samples of all volume fractions of PZT (i.e. 0.1~0.7) that were Corona poled allowed for higher poling voltages (45 kV/mm compared to 2.5kv/mm in contact poling), and exhibited higher values of piezoelectric strain coefficients with same material composition , longitudinal piezoelectric coefficient (@110Hz), effective dielectric constant (@2kHz), and dielectric loss (@2kHz), were 11.1 pC/N, 28.7 and 0.004 respectively for the PZT volume fraction equal to 0.7.. The piezoelectric properties were examined both in terms of piezoelectric effect and converse piezoelectric effect. Piezoelectric strain coefficients and capacitance were measured @110Hz by Piezometer, and displacement of certain volume fractions of PZT were studied by Keyence interferometer. To better examine the polarization-electric field relation, P-E hysteresis loop were measured. Other dielectric properties such as conductance, resistance, and impedance spectrum verse increasing frequency were obtained by Hp impedance analyzer within the frequency range from 2kHz to 20Mhz. Investigation of composite structures such as these may lead to development of actuators with enhanced displacement and sensors with better sensitivity.

ETD_7193

M.S.

Includes bibliographical references

by Wanlin Du

doi:10.7282/T31G0PCF

ETD graduate

The author owns the copyright to this work.