Search

Multilayer ZnO varistors were prepared by aqueous gel tape casting with water-soluble acrylamide as binder. 0.8wt% PAA dispersant was found to be the optimum concentration needed to prepare stable slurry. Plasticizer glycerol has a positive effect on the fluidity of the suspension and oxygen anti-polymerizing inhibitor PEG 2000 deteriorated the fluidity. The addition of 15wt. % PEG2000 eliminates the surface exfoliation absolutely due to the oxygenation of ether units. The solid loading of the slurry was about 71wt% compared to the custom acrylic formulation binder 60wt%. The multilayer ZnO varistors prepared by aqueous gel tape casting display comparable good electrical properties to those prepared by water-based tape casting using custom acrylic formulation binder which is attributed to the high solid loading of slurry.

The ZnO varistor ceramics were fabricated through microwave sintering at 800~1150°C using ZnO powder doped and undoped TiO2 prepared by planetary ball mill. And the effects of milling time, sintering temperature and doping on microwave sintering technique have been studied. The result shows that the powder is more homogeneously and with smaller particle size with the increasing of milling time, therefore the electric properties is improved. However the particle size and the electric properties tend towards stability after 20h milling time. The density and electric properties increase with the increasing of sintering temperature, but decrease sharply at 1100°C, so the best sintering temperature is 1100°C. Doping TiO2 improves the electric properties of ZnO, however the electric properties decrease with more than 2.5% doping.

The glass powder as a binder phase in the silver paste mainly plays the role of binding. The composition, content and particle size of the glass powder have significant effects on the properties of the silver paste. In this paper, the effects of the sintering temperature, holding time, glass powder content and glass powder size on the adhesion and square resistance of the silver film were studied. The research results showed that when the glass powder content was 6%(in mass) of the total silver paste, the sintering temperature was 680°C, the holding time was 7 minutes and the glass powder size was 2.47μm, the silver paste can get good properties. The adhesion strength and square resistance of the silver film were respectively 2.5 N/mm2 and 14 mΩ /.

The Micro-bridge structure pays an important role in the mechanical support, thermal isolation and electrical connection for the UFPA detector, the quality of which has a direct effect on the imaging performance of the UFPA detector. A kind of Micro-bridge pixel is provided in this paper with thick-film pixel size of 360μm×360μm and desk-type adiabatic frame support, and the analysis results by FEM show that the minor thermal conductivity G and high responsivity can be obtained.

As a typical composite with perovskite structure, (Ba1-xSrx)TiO3(briefly named BST) shows many merits, This paper provides a new sol-gel method to prepare BST gel, and carry out a research and analysis on the thermal evolution of gel. The BST nanopowder is prepared by the heat treatment through the traditional sintering method and microwave sintering technique, respectively. The synthesis temperature of perovskite phase by sol-gel method decreases from 1380°C to 900°C, comparing with that by traditional solid-state reaction method. The XRD and SEM results show that microwave sintering technique can control effectively the grain growth size of BST ceramic, and the powder has the uniform chemical components and grain size of around 60nm. Furthermore, the grain size is reduced, the dielectric constant increased dramatically and the dispersivity reduced.

A thick film array of high sensitive UFPA detector, with 16×16 units, is described in this paper. A micromachining capacitive pixel structure of infrared detector is provided, with the doped (Ba, Sr) TiO3 (BST) thick film as sensitive material. The key factors that affect the detector performance are described, and the basic physical and electrical parameters of ferroelectric materials that the detector needs are given. In addition, the heat insulation technique and the corresponding parameters are provided. The capacitance increment of pixel for this structure is approximately equal to that of infrared detector with equivalent sensitive area, and then the parasitic capacitance between the pixel and substrate electrode lead is reduced. It is easy to design the integrated circuit because the infrared detector with this structure needs only low precision for the circuit. This design idea for array structure of infrared matches the development trend of structure design of infrared focal plane pixel with large array, which paves the way to develop new UFPA detector.

MnO2 doped Bi0.5(Na0.82K0.18)0.5TiO3/P(VDF-TrFE) 0-3 composites with high pyroelectric coefficient were prepared for different volume fractions of MnO2 doped Bi0.5(Na0.82K0.18)0.5TiO3 ceramic powder in P(VDF-TrFE) copolymer matrix. The dielectric constant, dielectric loss and the piezoelectric coefficient increased as MnO2 doped Bi0.5(Na0.82K0.18)0.5TiO3 ceramic volume fraction increased. The pyroelectric coefficient and figure of merit of Bi0.5(Na0.82K0.18)0.5TiO3/P(VDF-TrFE) with different MnO2 amount and 0.8mol% MnO2 doped Bi0.5(Na0.82K0.18)0.5TiO3/P(VDF-TrFE) as a function of ceramic volume fraction were studied respectively. The results indicated that 0.8mol% MnO2 doped Bi0.5(Na0.82K0.18)0.5TiO3/P(VDF-TrFE) in 20vol% ceramic volume fraction show the best pyroelectric properties with pyroelectric coefficient p= 7.8×10-5C/m2K and figure of merit FD=11.4×10-6Pa-0.5.