Effect of Calcination of the Raw Materials on the Microstructure and Electrical Properties of ZnO-Based Linear Resistance Ceramics

ZnO-based linear resistance ceramics were fabricated by the conventional ceramic method. The effect of calcination of the raw materials on the microstructure and electrical properties was investigated in detail. The results show that the electrical properties, such as resistivity, nonlinear coefficient and resistance temperature coefficient, have been obviously influenced by the calcining process. The optimal samples fabricated with the materials calcinated for twice possess the highest stabilization of resistivity. Meanwhile, the resistance temperature coefficient is improved by 30%, and the nonlinear coefficient of voltage decreases to 1.16, decreased by 20.7%.

Preparation of Ta-Ti Co-Doped VO2 Polycrystal Thin Film with High Resistance Temperature Coefficient and without Hysteresis

Using vanadyl acetylacetonate (C10H14O5V) as precursor, use Tantalum Ethoxide (Ta(OC2H5)5) and Tetrabutyl titanate （C16H36O4Ti）as doper, by sol-gel method fabricate Ta, Ti mono doping and Ta-Ti co-doped V1-x-yTaxTiyO2 thin film. XRD spectrum indicated that the film was oriented in (011) direction. XPS results indicated the valence state of V, Ta, Ti in the film is +4, at all. While Ta mono doping, single 1at.%Ta can deduce the phase transiton temperature (Tt) by 7.8°C, phase transition hysteresis (ΔT) by 1°C. When the doping rate is 6at.%, Tt=22°C, ΔT=1°C. Ti dopings has little affection to Ttbut deduce ΔT obviously. Ta-Ti co-doped V0.93Ta0.06Ti0.01O2film thin films without phase transition hysteresis were also fabricated, and its TCR is as high as -7.58%/K at 25°C.

Influence of Al2O3 Doping on the Microstructure and Current–Voltage Characteristics of ZnO-Based Linear Resistance Ceramics

ZnO-based linear resistance ceramics were synthesized using Al2O3 doped ZnO-based system as raw materials by sintered at 1340 °C for 3 h. The effects of Al2O3 content ranged from 1 to 15 wt% on the microstructure and electrical properties of the ceramics were investigated in detail. The results show that the electrical properties such as nonlinear coefficient, resistivity and resistance temperature coefficient have been obviously influenced by Al2O3 doping. The optimal samples obtained by doping Al2O3 with 9 wt% have a nonlinear coefficient of 1.3, resistivity of 130 (Ω•cm) and resistance temperature coefficient of -5.4×10-3/ °C.

The Study on the Infrared Thermal Radiation Response of Y1Ba2Cu3O7-X Semiconducting Film

Y1Ba2Cu3O7-x semiconducting thin films with different buffer have been manufactured by direct current magnetic sputtering and annealing method, and their infrared thermal radialization respond have been studied. The microstructure of Y1Ba2Cu3O7-x film is analyzed by XRD and Raman spectrum. The electronic resistance temperature coefficient value and hall effect of Y1Ba2Cu3O7-x film are measured. The results show that the uniformity of the semiconducting Y1Ba2Cu3O7-x thin film which have buffer layer is better and their Signal-to-Noise is higher. It is believed that the Y1Ba2Cu3O7-x not only have good speciality for its thermal radiation respond in infrared band but also have good performance in sub-millimeter band. It will act as new sensor elements of infrared bolometer working at room temperature.

Low Output Capacitance 1500V 4H-SiC MOSFETs with 8 mΩ·cm2 Specific On-Resistance

SiC MOSFETs are characterized with a specific on-resistance of 8 m⋅cm2 at room temperature and a blocking voltage of 1500 V. Due to the negative shift in the threshold voltage, devices typically show a reduction in on-resistance with temperature. However, this work shows that a positive resistance temperature coefficient can be achieved by proper device design. SiC MOSFETs were characterized for use in high-frequency resonant converters, where an important switching device figure of merit is the product of the device on-resistance and output capacitance (Ron×Coss). For devices with an active area of 3.6×10-3 cm2, the output capacitance is 12.5 pF at a drain bias of 270V. Thus, these device achieve a resonant converter figure of merit Ron×Coss = 28 ⋅pF at room temperature and 34 ⋅pF at 150°C, better than commercial silicon superjunction devices operating at the same temperatures.