ChemInform Abstract: High-Pressure Synthesis and Characterization of a New Series of V-Based Superconductors (Cu0.5V0.5) Sr2Can-1CunOy

A new series of high transition temperature (T{sub c}) superconductors (Cu,V)Sr{sub 2}Ca{sub n{minus}1}Cu{sub n}O{sub y} [(Cu,V)-(n{minus}1)n-Sr, n = 3--7] was synthesized under a high-pressure/high-temperature condition of 6 GPa and 1,300 C. X-ray diffraction and transmission electron microscopy measurements revealed that they have M-12(n{minus}1)n-type structures with M = (Cu,V) and a stacking sequence of planes, SrO-(Cu,V)O-SrO-CuO{sub 2}-(Ca-CuO{sub 2}){sub n{minus}1}. Simple tetragonal lattices without any superstructures were observed for every member of the series implying a random arrangement of copper and vanadium in the (Cu,V) plane. Electron-probe microanalysis indicated partial substitution of strontium for calcium in the (Cu,V)-12(n{minus}1)n-Sr phases. All the (Cu,V) phases gave large diamagnetic susceptibilities at a low temperature indicating a bulk nature of superconductivity. The highest T{sub c} was found to be 107 K for the (Cu,V)-1234-Sr phase.