Daben Yang

0–3 Piezoelectric composite film with high d33 coefficient

Abstract This paper reports the influence of solvent treatment on the behaviour of 0–3 piezoelectric composite films. In our experiments, 0–3 composite piezoelectric films are prepared and treated in a solvent for a period of time, and their piezoelectric properties are measured. It is found that the characteristics of composite piezoelectric films are significantly influenced by the solvent treatment. In the case of treated specimens, the piezoelectric properties are increased more than those of virgin specimens, d33 values being 1–5 times larger than those of virgin specimens. This influence of solvent treatment on the behaviour of 0–3 composite piezoelectric films is analysed in the light of chemical coupling-induced percolation. This strongly suggests that it is possible to obtain 0–3 composite piezoelectric films with excellent piezoelectric parameters in this way.

Dielectric and piezoelectric properties of 0-3 composite film in PCM/PVDF and PZT/PVDF

Abstract 0-3 composite film of ferroelectric ceramics PCM and PZT in the matrix of a PVDF polymer has been studied in detail. The experimental results show that ϵ in PCM/PVDF and PZT/PVDF exhibits a broad relaxation peak at about 1KHz. It is possible that this is due to the αc relaxation of the polymer. Piezoelectric coefficient (d33, g33) of PCM/PVDF and PZT/PVDF were increased with weight fraction of ceramics from 40% to 80%. It was found that piezoelectric properties of PCM/PVDF were larger than that of PZT/PVDF, and the figure of merit in PCM/PVDF composite was highest about 15600.

PVDF/SiO/sub 2/ hybrid composite electret films and effects

A new hybrid composite electret film based on PVDF polymer and inorganic electret SiO/sub 2/ by Sol-Gel process is described. The preparation and composite techniques, hybrid microstructure, dielectric, piezo- & pyroelectric, charge storage properties, electret effects, and origin mechanism analysis are discussed.

Composite smart electronic materials based on electromechanical ceramics

Electromechanical ceramics have been introduced into the study of smart electronic materials. Effects of electromechanical phase on electrical resistivity of composites have been studied. The results indicate that it is possible to realize varistors with a positive voltage coefficient of resistance using electromechanical ceramics like PZT and PMN.

Layer-by-layer self-assembly of polyaniline/molybdenum trioxide nanocomposite ultrathin films by doping-induced deposition

Electroactive polyaniline (PANI)/MoO3 nanocomposite ultrathin films were fabricated by a novel molecular self-assembly process based on the alternate deposition of PANI and inorganic polyanion isopolymolybdic acid (IPMA). Unlike the already-used layer-by- layer process based on electrostatic attraction, the process was based on acid-base reaction (or doping) of emeraldine base and IPMA. The process was monitored by UV/Vis spectroscopy and ellipsometry measurement.

Electrical resistivity of smart composites with electromechanical coupling

This paper describes the effect of electromechanical phase on electrical resistivity of a composite consisting of magnetostrictive phase, conductive phase and insulating phase. It is found that the resistance of three-phase composite increases with increase of applied magnetic field beyond a certain va1e ot magnetic field. This resistivity vs. magnetic field characteric seems to be a novel magnetoresistance effect, which is different from the conventional magnetoresistors. The mechanism of resistance variation of three-phase composite with applied magnetic field is analysed, and the influence of material parameter of the polymer matrix like elastic modulus on the resistance vs. magnetic field characterics is discussed.

Organic electronic crystals and electronic and optic properties

Abstract The significance of two new types organic electronic crystals based on substituted phenylthiourea and N-phenylphthalic imidine have been illustrated in this paper. Five crystal materials: p-methylphenylthiourea (I, C8H10 N2S), p-chlorophenylthiourea (I, C7H7ClN2S), 2, 4, 6-tribromophenylthiourea (I, C7H5Br3N2S), N-(phenyl) phthalic imidine (IV, C14 H9NO2) and N-(p-methylphenyl) phthalic imidine (V, C15H11NO2) were prepared and confirmed by IR,NMR,MS and elementary analysis. The crystal and molecular structures were determined by X-ray diffraction. The relative dielectric constants er, piezoelectric parameters d33 and refractive index n were measured respectively. The synthesis preparation, molecular structure, dielectric and piezoelectric and optic properties were discussed.

Preparation and properties of organic polymer sub-micrometer function films

Two methods for preparing organic polymer sub-micrometer thin films, electropolymerization and low pressure chemical vapor deposition, are discussed. The influences of the mononer concentration, the electrolytic concentration, the current density and the electrolytic time on polypyrrole sub-micrometer thin films are studied. In addition, the influences of the driving voltage, oxide concentration and solvent are discussed for LPCVD polypyrrole films. The NH/sub 3/-sensing properties of films of different thickness are tested and studied. The molecular structure of polypyrrole and microstructure of films are analysed by elemental analysis and FT-IR. The NH/sub 3/-sensing mechanism is discussed.

Influence of metallized interface on ferroelectric domain layer wave

This paper is concerned with the properties of SH (Shear Horizontal) wave in two-layer piezoelectric plate with 180/spl deg/ domain wall. Besides the dispersion equation of the symmetry vibration mode, that of the asymmetry vibration mode has been obtained. It is concluded that the asymmetric vibration mode has obviously dispersion properties under the condition of metalized surface. The distribution of the displacement u and electric potentials /spl Phi/ for asymmetric mode have been analyzed. The properties of the asymmetric mode are affected by the change of the surface electric condition that lead to the change of the surface charge distribution.

Nonlinear humidity effect of polymer based composite film

The nonlinear humidity properties of electronic polymer humidity-sensing composite film in high humidity range (80/spl sim/100%RH) is studied in this paper. Its nonlinear resistance changes in high humidity range are 1 k/spl Omega//spl sim/10/sup 3/ k/spl Omega/. The influence of composite humidity-sensing film microstructure on nonlinear properties is discussed. The characteristics of composite new phase-polymethylpenylacetylene is discussed. The composite film conduction mechanism is analyzed and studied. The humidity nonlinear response mechanism can be explained by the theory model of the combining electronic conductance with size effect.