Hao Xue

Preparation and properties of BaTiO3 ceramic fibers for ferroelectric applications

Solution for BaTiO3 was prepared via sol-gel route in this paper. Ceramic fibers of BaTiO3 were then obtained by gel-spinning technique with the solution. FTIR spectra of the samples of fibers were characterized. TG-DTA spectra of the gel fibers were also conducted by a thermal analyzer. Different sintering conditions were performed, in order to obtain ceramic fibers with better ferroelectric and piezoelectric properties. The crystal structures of the samples were identified with XRD. The microstructures of the ceramic fibers were observed with SEM, Meanwhile, ferroelectric and piezoelectric properties of the BaTiO3 ceramic fibers were characterized by using of a workstation measurement system, with the remnant polarization of 9.41 μC/cm2, coercive field of 3.13 kV/cm, piezoelectric constant of 172 pC/N and mechanical-electrical parameter of 0.56.

Development of Ammonia Gas Sensors with PPy Films on Base of Mg2SiO4 Porous Ceramics for Better Behavior of Chemo-Electrical Relationship

A new kind of gas sensors were prepared via chemical polymerization of polypyrrole (PPy) as sensitive layer on base of Mg2SiO4 porous ceramics. Thermal stability of the PPy sensitive layer was characterized with thermogravimetric analysis, including TG and DTA. Chemical structure of the samples was identified with X-ray diffraction (XRD) analysis. Microstructure of the PPy film was observed by a scanning electron microscope (SEM). Chemo-electrical relationship of the gas sensors was investigated with the resistance variation of PPy films at different gas concentrations. Based on series of experimental results, linear behavior of the chemo-electrical relationship was obtained for the gas sensor, y=0.00344x+1.33754, with R2=0.9734.

Synthesis of plate-like SrTiO3 particles

Micro-scale plake-like SrTO3 particles were synthesized by two routes of topochemical conversion. One is by growing on Sr3Ti2O7 (S3T2) core particles in molten salt condition, and the other is from the layer-structured SrBi4Ti4O15 (SBT) precursor in a KCl medium. The effects of the morphology and size of the precursor to platelet SrTiO3 crystals were studied. X-ray diffraction analysis revealed that the crystallographic {010} plane of SBT was converted into the pseudo-cubic {001} plane of SrTiO3. The polycrystalline SrTiO3 particles from BST precursor exhibited a plate-like shape with 10-15μm in length and a high aspect ratio, and were more suitable for preparing textured ceramics by templated grain growth process than the platelets from the S3T2 precursors.

Characterization of Microwave Ceramics with Low Permittivity and High Quality Factors

A new type of porous ceramics, Mg2SiO4, for microwave application with low permittivity and high quality factors were prepared via gel-casting processing in this paper. Microstructure of the ceramics was observed and crystal structure of the samples was also identified. Moreover, emphasis was paid on the characterization of the microwave ceramics. Dielectric properties of the ceramics were measured by an automatic system of microwave measurement, resulting in dielectric constant of 3.51 and quality factor of 11,774 for the ceramic sample at frequency about 10GHz. Mechanical performance of the samples were also evaluated with maximal bending strength of 140MPa.

Crystal Structure and Dielectric Properties of PZT Ferroelectric Ceramic Fibers

The crystal structures of PZT ceramic fibers with continuum spinning process were identified, showing a pure tetragonal phase of perovskite for the samples treated at around 900°C. The microstructures of the PZT fibers were observed, displaying relatively complex evolution with the increasing of temperature during heat treatment. With the increasing of frequency, the dielectric constants and loss tangents became smaller for all of the samples. Meanwhile, the dielectric constant was larger and the loss tangent smaller for the samples treated at higher temperature. Optimal properties were obtained for the fibers treated at 1000°C for 1 h.

Structure and Multiferroic Properties of Bi0.9Y0.1FeO3-PbTiO3 Ceramics

Bismuth ferrite, BiFeO3, was an important multiferroic material, which simultaneously exhibited ferroelectric ordering and antiferromagnetic ordering in the bulk form. The solid solutions of Bi0.9Y0.1FeO3 with PbTiO3 were prepared by the conventional solid state reaction. It was clear that in Bi0.9Y0.1FeO3-PbTiO3 solid solution, the structure remined rhobohedral for 85 mole% of Bi0.9Y0.1FeO3, from 80 to 70mole% it were rhobohedral and tetragonal, and below 65 mole%, the structure transformed to tetragonal. The dielectric and ferroelectric properties of the ceramics had been significantly improved by means of ionic substitution of Ti4+ for Fe3+, which reduced the electric conductivity. The dielectric constants of the ceramic samples were enhanced from 84 to 241 and the remnant polarizations were improved from 0.494 to 2.17 μC/cm2.

Heat treatment of piezoelectric Pb(ZrTi)O-3 ceramic fibers prepared with continuous spinning

Ceramic of Pb(ZrTi)O3 is one kind of typical smart materials, with excellent ferroelectric and piezoelectric properties. In this paper, a novel heat treatment was applied for the ceramic fibers prepared via sol-gel route with continuous spinning. Aided with microwave energy, dense ceramic fibers are obtained after treated at around 900°C for 1h, in which the diameters of the fibers are between 5μm and 30μm. The samples were also characterized with thermal analysis, FTIR spectroscopy and X-ray diffraction. By using of a scanning electron microscope, SEM, it was observed that a dense microstructure of the fiber was reached.

Preparation and Performance of Polypyrrole Film with Micro-Antennal Morphology for Medical Biology

PPy film with micro-antennal morphology was prepared by potentio-static method without any templates directly onto the surfaces of iron, platinum and gold-plated plastic sheets, respectively. Morphology of PPy film was observed with scanning electron microscopy, and its electrochemical properties were determined by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Attention was paid to the influence of reaction time, potential value, types of substrates, types and conconcentrations of electrolyte on the morphology and electrochemical properties of PPy film. Stable PPy film with thriftily long antennae was obtained on different substrates with good electrochemical properties. The film was applied for a prototype of biosensor, in which bioactive substance of glucose oxidase was immobilized.