Development of superconductors with porous structures

点击翻译按钮获取中文摘要

i. Construction of the high-pressure synthesis apparatusThe high-pressure synthesis apparatus of the cubic multianvil type has been changed to the 6-8 Kawai type anvil to enable a higher pressure condition up to 20 GPa at 2000 °C.ii. Development of new superconductors with silicon nano-networksThe silicon clathrate superconductor Ba_8Si_<46> previously found in our group,.was transformed into the silicon rich compound BaSi_6 under extremely high pressure conditions. A new silicon rich phase LaSi_5 in the La-Si binary system has been prepared under a high pressure of 15 GPa, which became a superconductor with Tc = 11 K.iii. High pressure synthesis of carbon clathrate compoundIn the course of the study to prepare carbon clathrate compounds, two different types of crystalline three-dimensional C_<60> polymers have been prepared, body centered orthorhombic and face centered cubic 3D polymers. Their structural analyses, electrical conductivity measurements, and micro-Vickers measurements were carried out.iv. Development of new layer structured nitride superconductorsZr_5N_5F_6 and Hf_5N_5F_6 were prepared, and their single crystals were grown using a high-pressure flux method. The structural analysis revealed that the compounds had a long periodic structure based on the LaOF type layer structure. The true chemical composition was found to be close to Zr_5(N_40)F_6. The interlayer fluorine atoms could be partially removed, and the layer compound was changed to a new superconductor with Tc=4.5 K.v. Synthesis of thin films of nitride superconductorsMolybdenum nitride thin films were obtained using PLD and MBE deposition with nitrogen RF radical source. B-Mo2N were successfully deposited as thin films, which showed superconductivity of Tc = 5.2 K.