Influence of Y-doped induced defects on the optical and magnetic properties of ZnO nanorod arrays prepared by low-temperature hydrothermal process

One-dimensional pure zinc oxide (ZnO) and Y-doped ZnO nanorod arrays have been successfully fabricated on the silicon substrate for comparison by a simple hydrothermal process at the low temperature of 90°C. The Y-doped nanorods exhibit the same c-axis-oriented wurtzite hexagonal structure as pure ZnO nanorods. Based on the results of photoluminescence, an enhancement of defect-induced green-yellow visible emission is observed for the Y-doped ZnO nanorods. The decrease of E(2)(H) mode intensity and increase of E(1)(LO) mode intensity examined by the Raman spectrum also indicate the increase of defects for the Y-doped ZnO nanorods. As compared to pure ZnO nanorods, Y-doped ZnO nanorods show a remarked increase of saturation magnetization. The combination of visible photoluminescence and ferromagnetism measurement results indicates the increase of oxygen defects due to the Y doping which plays a crucial role in the optical and magnetic performances of the ZnO nanorods

Properties of Vortex Propagation in a Niobium Film with Spacing-graded Density of Pinning Sites

[[abstract]]The vortex propagation has been investigated in Nb superconductors with one dimension spacing-graded density of submicrometer-scaled holes in this research. A rectification effect can be discerned because the applied ac is transformed into a net dc voltage. These results demonstrate that the rectification is mainly characterized by the asymmetric pinning landscape and the rectified voltage depends considerably on temperature and the amplitude of applied ac. The dc voltage increases steeply up to the maximum value and then decreases to zero dc voltage with the increase of ac. The shape of peaks in the dc voltage signal become steeper and move to higher applied ac regime with the decrease of temperature

Mechanical Properties of Ag-sheathed Bi-based Superconducting Tapes

[[abstract]]Flexible Ag-sheathed Bi-based superconducting tapes have fabricated by powderin- tube technique. The critical current density (Jf) does not varied when the bending radius is larger than the critical bending radius Ro, bending radius without deteriorating transport properties. The bending tests were studied under magnetic field up to 5,000 G. The critical bending radius Ro (or Critical bending strain ~0) was found to be independent of magnetic field from 0 to 5,000 G. The J,(B)/J,(O) curves are superimposed in the same curve, i.e., the transport behavior of a tape at magnetic field is not affected by bending. It implies that the intrinsic pinning properties of a bent tape are unchanged in magnetic field. The results are useful for making a react-and-wind magnets and cables