Materials Science Forum Vol. 848

Abstract: A reel-to-reel Hall sensor array system was build and an inverse operation algorithm was applied to obtain the lateral distribution of critical current density by the remanent field around the superconducting tape. Simulation analysis was conducted to verify the validity of the algorithm. Commercial YBCO and Bi2223 tape and YBCO tape with artificial defects were measured. The standard deviation of lateral critical current density on the cross section of conductor was used as a parameter describing the lateral inhomogeneity of critical current density. The result shows that this measurement method is a stable and efficient way to evaluate the lateral inhomogeneity of critical current of high temperature tapes.

Abstract: Monolithic SiO₂-TiO₂ aerogels were prepared via supercritical drying using tetraethoxysilane and tetrabutyltitanate as precursors and ethanol as solvent. Influence of the heat-treatment on the microstructure and properties of SiO₂-TiO₂ aerogels were investigated in detail. The results showed that the as-prepared SiO₂-TiO₂ aerogels had low densities, high specific surface areas, small average pore diameters, and three-dimensional nanoporous structures. The anatase TiO₂ phase of SiO₂-TiO₂ aerogels could form during supercritical drying process, and the transition to rutile TiO₂ phase occurred after experiencing 1200°C for 2 h. SiO₂-TiO₂ aerogels containing 30 wt% TiO₂ (ST3) still presented relatively high specific surface area of 451 m²/g even they undergo the treatment of 1000°C for 2 h. And the SEM images indicated that the agglomerated particles derived from ST3 appeared gradually to some extent. The glassy luster of ST3 heat-treated at 1200°C for 2 h illuminates SiO₂ started to vitrify. Besides, the thermal conductivity of ST3 at room temperature is up to 0.03257 W·m^-1·K^-1.

Abstract: The ZnO semiconductor multicrystalline film is utilized as the sensing material, and a sensors array is demonstrated in this paper. Based on the coupling effect of piezoelectric and semiconducting, an ultra-high sensitivity to the deformation is obtained that the gauge factor of the single units is derived up to 199, which is 100 times of that of the commercial foil gage (gauge factor = 2). After calibration on every sensing unit, the distribution of the uniform and non-uniform strain applied on the device is measured and mapped by the sensors array successfully. The results show a good application of the device on the deformation field sensing by contact test method.