Yadong Jiang

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.

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.

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.

Preparation of the piezoelectric composite film PI/PZT

The PI/PZT Composite piezoelectric film has been prepared, the PZT powders are obtained by method of Sol-Gel. The influence of coupling agent on the composite film has been discussed. The surface micrograph of the composite film has been analysed by SEM. As PI has high insulation, the PI/PZT compound will increase the polarizing electric intensity and the polarization along a direction in polarizing process. That makes the piezoelectricity of the composite film increased.

PVDF/SiO/sub 2/ electronic flexible hybrid composite films

A new electronic flexible hybrid composite film in organic-inorganic two-phase system PVDF/SiO/sub 2/ by Sol-Gel process is described. The PVDF/SiO/sub 2/ film preparation and composite techniques, hybrid microstructure, dielectric, piezo- and pyroelectric, charge storage properties, effects, and origin mechanism analysis are discussed.