Xiao Hua Sun

Fabrication of PST Nanotubes with Sol-Template Method and its Usage in Aluminum Foil Capacitor

Lead strontium titanate (PST) nanotubes were fabricated with sol-gel method on AAO template. Thermal evolution and phase transformation process of PST were characterized by Thermogravimetry and Differential thermal analysis (TG/DTA) and X-ray diffraction (XRD). It was found that PST began to crystallize at 560°C and became perovskite structure without other phases. The morphology and structure of PST nanostructures was characterized by SEM and TEM. The capacitor of AAO and PST-AAO compound aluminum foil annealed at different temperature were tested with precision impedance analyzer. It revealed that the microstructures of PST were polycrystalline nanotube array and the capacitor of compound aluminum foil was increased for PST existing in the AAO, which indicated that this compound method could improve the capacitor of aluminum foil effectively.

Effect of Characteristic Size on the Effective Thermal Conductivity of Anodic Aluminum Oxide (AAO) Porous Thin Films

Based on the surface morphology, a model is presented to investigate the heat transfer in anodic aluminum oxide (AAO) porous thin films. The extra thermal resistance from the micropores will inevitably cause a change in thermal properties, which can be analyzed by the Fourier law. The effect of the characteristic size on the thermal conductivity is discussed in details by means of the theory of phenomenological model of phonon scattering. Considering the effects of porosity and the distribution of micropores reflected by parameter D, the function of the effective thermal conductivity of AAO porous thin films expressed by two independent variables, εp and D. The temperature field is simulated with the effective thermal conductivity and the result demonstrates a bigger temperature rise in AAO porous thin films.

Enhanced Dielectric Properties of Pb0.3Sr0.7TiO3 Thin Films by Ultrasonic Processing

Pb0.3Sr0.7TiO3 (PST) thin films have been prepared from precursor solution sonicated for different time on Pt/Ti/SiO2/Si substrates by sol-gel method. The effect of ultrasonic processing on the chemical bonding of PST precursor solution and the thermal evolution of PST dry gel are characterized with FT-IR and TG-DT technology. The structure, dielectric properties and leakage current density of PST thin films are investigated as functions of sol ultrasonic processing time. It’s found that ultrasonic processing brings about the partial sol structure rearrangement, the delay of PST formative temperature, the reduction of crystallization and dielectric constant, and the significant improvement of leakage current, dielectric loss and the figure of merit (FOM). The results suggest that the enhancement in the quality of thin films prepared with sol-gel method can be obtained by the suitable ultrasonic processing on precursor solutions. The PST thin film prepared from precursor solution sonicated for 8 h shows the highest FOM for its appropriate tunability of 57.36% and low dielectric loss of 0.0144.

Research on Thermal Effect Caused by Absorbing Inclusion in Dielectric Irradiated by Pulse Laser

The thermal effect caused by absorbing inclusion irradiated by pulse laser is affected by size of inclusions, pulse duration, repetition interval and number of pulse laser. The temperature both in the center of inclusion and the interface between inclusion and dielectric increases firstly with the increase of the size of inclusion, then trends to a constant value when the size is over the critical radius. Pulse duration and repetition interval of pulse change the energy acumulation in inclusion then have influence on the peak temperature in the center and interface. The temperature fluctuates periodically but the overall assumes the trend of increase.

Colloidal Dispersion of High Solid Loading ZnO Powders with 2 wt% Al2O3 Stabilized with Polyelectrolyte

The high solid loading slurries with ZnO-Al2O3 powders stabilized with polyelectrolytes have been studied. The influence of Sodium poly(acrylate) (PA 30) on the fluidity and stablility of the slurries was investigated. Morphological features of ZnO-Al2O3 powders in suspension and fracture surface of green compact were observed using TEM and SEM. The slurries with pH 9 were prepared after milled using ZnO mixed powders and the PA 30 solution of pH 8. As 0.2 wt% PA 30 added, the lowest viscosity and the highest sediment were obtained. ZnO and Al2O3 particles had been homogeneous dispersed. The maximum density (66.7 %TD) of green compact was obtained.

The Temperature Field Caused by Sphere Inclusion in Dielectric Irradiated by Single Pulse Laser

The thermal effect arisen from absorbing inclusions is the main factor which causes the damage of optical materials or component irradiated by the longer pulse duration laser. The unsteady heat conduction depends markedly on both the thermal properties of inclusions and the parameters of laser. Based on the differential equation of heat conduction, the temperature distribution caused by single absorbing inclusion is solved by use of finite difference method. The effect of the laser intensity and the pulse duration on temperature field is analyzed in detail. The result demonstrates that the smaller size inclusion and the smaller pulse duration cause relative safe thermal effect, consequently, the less probability to be damaged by thermal effect.

Influence of Thickness on the Structural, Electrical and Optical Properties of Al-Doped ZnO Films Deposited by RF Magnetron Sputtering

Transparent conducting aluminum-doped zinc oxide (AZO) films with different film thickness had been prepared on soda-lime glass substrates by radio frequency magnetron sputtering using a high density ceramic target. The structural, morphology, electrical, and optical properties of the AZO thin films were investigated by X-ray diffraction, scanning electron microscope, Hall-effect measurement and optical transmission spectroscopy, which were strongly influenced by film thickness. With the film thickness increasing from 140 nm to 710 nm, the resistivity decreases from 9.78 × 103 to 3.23 × 103 Ω.cm and an average optical transmission decreases from 88% to 80% in the visible range and the optical bandgap decreases from 3.47 to 3.24 eV.

Orientation Control and Dielectric Properties of Ba0.6Sr0.4TiO3 Thin Films on Pt/Ti/SiO2/Si Substrates with PbO Seeding Layer

Ba0.6Sr0.4TiO3 (BST) thin films were fabricated by solgel technique on Pt/Ti/SiO2/Si substrate without and with PbO seeding layer from precursor solutions with different concentrations. The crystal structure, surface morphology, dielectric properties and leakage current density of BST thin films are investigated as functions of the concentration of PbO precursor solution. Its found that the growth orientation of BST thin films with PbO seeding layer can be modulated through adjusting the concentration of PbO precursor solution. BST thin film with PbO seeding layer from 0.05 M precursor solution shows the highest dielectric constant and tunability, which may be attributed to the high crystallization and amplitude of the polarization in high (100) preferred orientated films. The leakage current density of BST films increases with the increasing concentration of PbO precursor solution and agrees well with the space-charge-limited current mechanism at room temperature.

Enhanced the Dielectric and Tunable Properties of BZNT Thin Films through Adjusting Annealing Process

Bismuth zinc niobate titanium (Bi1.5Zn0.5 Nb0.5Ti1.5O7) (BZNT) thin films were deposited on Ptuf02fTiuf02fSiO2uf02fSi substrates by radio frequency (rf) magnetron sputtering. The microstructure, surface morphology, stress, dielectric and tunable properties of thin films were investigated as a function of initial annealing temperature. It’s found that high initial annealing temperature increases the grain size, dielectric constant and tunability of BZNT films simultaneously and decreases the tensile stress in films. The BZNT thin film annealed from 500 °C to 700 °C shows the highest FOM value of 45.67 with the smallest dielectric loss and upper tunability.

The Influence of O2/Ar on the Dielectric Properties of Bismuth Zinc Niobate Titanium Thin Films Prepared by RF Magnetron Sputtering

BZNT (Bi1.5Zn0.5Nb0.5Ti1.5O7) thin films were prepared on Pt/Ti/SiO2/Si substrates by radio frequency (RF) magnetron sputtering in different O2/Ar ranging from 4:16 to 7:13. The structure and surface morphology of BZNT thin films were investigated by x-ray diffraction (XRD) and atom force microscopy (AFM). The analysis of component in BZNT films were carried out by x-ray photoelectron spectroscopy (XPS). The dielectric measurements were conducted on metal-insulator-metal capacitors at the frequency from 100 Hz to 1M Hz. It’s found that the O2/Ar ratios significantly influence the elements content in BZNT thin films and the morphology and dielectric properties of BZNT thin films. At 1M Hz, the dielectric constant of BZNT thin films deposited at O2/Ar ranging from 4:16 to 7:13 is 212, 187, 171, 196, respectively. The BZNT thin film prepared at O2/Ar = 6:14 shows the highest figure of merit for its very low dielectric loss of 0.0024.