Lead-Free Piezoelectric Transducers for Microelectronic Wirebonding Applications

Author name used in this publication: K. W. KwokAuthor name used in this publication: S. H. ChoyAuthor name used in this publication: H. L. W. Chan2010-2011 > Academic research: refereed > Chapter in an edited book (author)published_fina

Study of piezoelectric fibre/cement 1-3 composites

To improve the compatibility between the sensor material and civil engineering structural material, a new functional cement-based composite for smart structure applications has been studied. Piezoelectric lead zirconate titanate (PZT) fibres, fabricated using a slurry method, are embedded in a cement matrix to form PZT/cement 1–3 composites. By incorporating PZT fibres into the cement matrix, composites with low PZT volume fractions ranging from 0.05 to 0.22 have been fabricated. The 1–3 composites have good piezoelectric properties that agree quite well with theoretical modeling. The thickness electromechanical coupling coefficient of the composites could reach ∼0.5 even for low volume fraction of PZT. These composites have potential to be used as sensors in civil structure health monitoring systems

Lead magnesium niobate-lead titanate ceramic fibres fabricated by a modified sol-gel technique

Lead magnesium niobate-lead titanate (PMN-PT) ceramic fibres with a nominal composition of 0.65Pb(Mg 1/3 Nb 2/3 )O 3 -0.35PbTiO 3 have been fabricated by a modified sol-gel technique. The ceramic fibres with 100 μm diameter were well-crystallized after being calcined at 850°C and sintered at 1200°C. After being poled, the electromechanical coefficient of the single PMN-PT ceramic fibre is 0.5. The relative permittivity of the single ceramic fibre was higher than that of a ceramic disc while their hysteresis loops are comparable. The characterization of the ceramic fibres reveals that the modified sol-gel method can be used to fabricate PMN-PT ceramic fibres with good piezoelectric and ferroelectric properties

Piezoelectric and pyroelectric properties of 65PMN-35PT/P(VDF-TrFE) 0-3 composites

Lead magnesium niobate–lead titanate (PMN-PT with 35 mol% PT) ceramic powder fabricated using the Columbite method have been incorporated into a polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE) 70/30 mol%) copolymer matrix to form 0–3 composites. With the composition near the morphotrophic phase boundary (MPB) region, PMN-PT has high piezoelectric properties as a result of the enhanced polarizability arising from the coupling between two equivalent energy states. P(VDF-TrFE) ferroelectric copolymer films can be poled to give piezoelectric and pyroelectric performance without prior mechanical stretching. The composites with both phases being ferroelectric were prepared using solvent casting to disperse the ceramic powder homogeneously in the copolymer matrix. Composites with PMN-PT volume fraction ϕ ranging from 0.05 to 0.4 were fabricated. The piezoelectric and pyroelectric coefficients of the composites were studied as a function of ceramic volume fraction ϕ under different poling conditions. Both the piezoelectric and pyroelectric coefficients of the PMN-PT/P(VDF-TrFE) 0–3 composites were found to be higher than that of the PZT/P(VDF-TrFE) 0–3 composites

Polarization response of proton irradiated 0.9Pb(Mg1/3Nb2/3)O-3-0.1PbTiO(3)/polyvinylidene fluoride-trifluoroethylene 0-3 composites

Polyvinylidene fluoride-trifluoroethylene [P(VDF-TrFE) 70∕30mol%] copolymer can be transformed from a normal ferroelectric to a relaxor ferroelectric material after proton irradiation. The phase transition peak broadens and shifts towards lower temperature as the measurement frequency decreases. The occurrence of a slim polarization-electric field loop is another evidence of the effect of proton irradiation. In the present study, 0-3 composites are fabricated by incorporating 0.9Pb(Mg1∕3Nb2∕3)O3‐0.1PbTiO3 ceramic powder into a P(VDF-TrFE) 70∕30mol% copolymer matrix. 0.9PMN-0.1PT ceramic is a relaxor ferroelectric with high dielectric permittivity. It was found that the relative permittivity of an unirradiated PMN-PT∕P(VDF-TrFE) 0-3 composite increases with increasing ceramic volume fraction. With a dosage of 1000kGy (where 1Gy=100rad ⁠), the composite exhibits a broad peak in the relative permittivity. In the unirradiated composites, the remnant polarization increases gradually with PMN-PT volume fraction. After irradiation, the remnant polarization of the composites with different PMN-PT volume fractions is similar to that of the irradiated copolymer. Energy storage capabilities of the samples were evaluated which showed that proton irradiated composites have a potential for energy storage applications

Piezoelectric cement-based 1-3 composites

This paper presents a new functional material for smart structure applications. Piezoelectric PZT/cement 1-3 composites that have good compatibility with civil engineering structural materials have been studied. The composites with different volume fractions of PZT ranging from 0.25 to 0.77 were fabricated by the dice-and-fill method. It was found that the 1-3 composites have good piezoelectric properties that agreed quite well with theoretical modeling. The thickness electromechanical coupling coefficient could reach 0.55 in the composite with a ceramic volume fraction of 0.25. Those composites have potential to be used as sensors in civil structure health monitoring systems