Smart meta-superconductor MgB2 constructed by the dopant phase of luminescent nanocomposite

On the basis of the idea that the injecting energy will improve the conditions for the formation of Cooper pairs, a smart meta-superconductor (SMSC) was prepared by doping luminescent nanocomposite Y₂O₃:Eu³⁺/Ag in MgB₂. To improve the superconducting transition temperature (T_C) of the MgB₂-based superconductor, two types of Y₂O₃:Eu³⁺/Ag, which has the strong luminescence characteristic, with different sizes were prepared and marked as m-Y₂O₃:Eu³⁺/Ag and n-Y₂O₃:Eu³⁺/Ag. MgB₂ SMSC was prepared through an ex situ process. Results show that when the dopant content was fixed at 2.0 wt.%, the T_C of MgB₂ SMSC increased initially then decreased with the increase in the Ag content in the dopant. When the Ag content is 5%, the T_C of MgB₂ SMSC was 37.2–38.0 K, which was similar to that of pure MgB₂. Meanwhile, the T_C of MgB₂ SMSC doped with n-Y₂O₃:Eu³⁺/Ag increased initially then decreased basically with the increase in the content of n-Y₂O₃:Eu³⁺/Ag, in which the Ag content is fixed at 5%. The T_C of MgB₂ SMSC doped with 0.5 wt.% n-Y₂O₃:Eu³⁺/Ag was 37.6–38.4 K, which was 0.4 K higher than that of pure MgB₂. It is thought that the doping luminescent nanocomposite into the superconductor is a new means to improve the T_C of SMSC.

Wet-Chemical Preparation of TiO₂-Based Composites with Different Morphologies and Photocatalytic Properties

TiO₂-based composites have been paid significant attention in the photocatalysis field. The size, crystallinity and nanomorphology of TiO₂ materials have an important effect on the photocatalytic efficiency. The synthesis and photocatalytic activity of TiO₂-based materials have been widely investigated in past decades. Based on our group’s research works on TiO₂ materials, this review introduces several methods for the fabrication of TiO₂, rare-earth-doped TiO₂ and noble-metal-decorated TiO₂ particles with different morphologies. We focused on the preparation and the formation mechanism of TiO₂-based materials with unique structures including spheres, hollow spheres, porous spheres, hollow porous spheres and urchin-like spheres. The photocatalytical activity of urchin-like TiO₂, noble metal nanoparticle-decorated 3D (three-dimensional) urchin-like TiO₂ and bimetallic core/shell nanoparticle-decorated urchin-like hierarchical TiO₂ are briefly discussed.