X-ray emission spectra of vanadium atoms in a new series of (Cu,V)-based high- Tc superconductors

Abstract

Non-resonant V L 2,3 and O Kα X-ray emission spectra of a new series of (Cu,V)Sr 2Ca n−1 Cu n O y ( n=3–7) superconductors are presented. We have found that oxygen atoms surround V-atoms in the given compounds, form a (VO 4) 3− tetrahedrons and have a pentavalent state. This induces holes due to the substitution of divalent copper by pentavalent vanadium ions providing a hole-doping mechanism of superconductivity in this series of compounds. A spectral estimation of the oxygen concentration shows that the oxygen content under high-pressure/high-temperature synthesis conditions is not changed considerably from the start to the final product.