Polyvinylidene fluoride (PVDF), a piezoelectric material, has many useful applications, for example, as sensors, transducers, and surface acoustic wave (SAW) devices. Models of performance of these devices would be useful engineering tools. However, the benefit of the model is only as accurate as the material properties used in the model. The purpose of this investigation is to measure the elastic, dielectric and piezoelectric properties over a frequency range, including the imaginary part (loss) of these properties. Measurements are difficult because poled material is available as thin films, and not all quantities can be measured in that form. All components of the elastic stiffness, dielectric tensor, and electromechanical coupling tensor are needed in the models. The material studied here is uniaxially oriented poled PVDF that has orthorhombic mm2 symmetry. Presented are the frequency dependence of all nine complex elastic constants, three complex dielectric constants, and five complex piezoelectric constants. The PVDF was produced at Raytheon Research Division, Lexington, MA. Measurements were made on thin films and on stacked, cubical samples. The elastic constants c/sub 44//sup D/ and c/sub 55//sup D/, the dielectric constants e/sub 11//sup T/ and e/sub 22//sup T/, as well as the piezoelectric constants g/sub 15/ and g/sub 24/ reported here have not been published before. The values were determined by ultrasonic measurements using an impedance analyzer and a least square data-fitting technique.

This paper describes the design of an ultrasonic spray pyrolysis system and the determination of the optimal conditions for deposition of ZnO thin films. The film is desired to have strong piezoactivity, high resistivity, and good thickness uniformity. Zinc acetate is the source solution for the ZnO film on top of a SiO₂/Si wafer. Controlled experiments show that the zinc acetate solution of 0.05 mol% doped with 30 at.% of LiCl can provide good ZnO films at the substrate temperature of 420°C. The optimal substrate rotation rate and nozzle tilting angle are also determined to improve the uniformity of the film. ZnO thin films deposited with these conditions show good c-axis orientation, and a resistivity higher than 10⁷ Ω·cm after annealing in oxygen, and good thickness uniformity across a 4^′′ substrate wafer. Properties of the ZnO film developed in this study are comparable to those obtained with conventional techniques.