Reflections of superconductivity unrelated to valence electron density in metal doped Y123 cuprates

Through XRD, the superconductivity tests, the positron annihilation technology, oxygen content variation and theoretic calculations, the superconductivity of the high-Tc cuprates YBa2Cu3-x (Fe, Co, Al)xO7-δ (x=0.0~0.5) was investigated, and Zn doped cuprates were also mentioned for comparison. The results and theoretic calculations support congruously that the superconducting transition temperature Tc is unrelated to the density of valence electron, and the same conclusion is from Hall Effect experiments that the Tc is not related with the carrier concentration of oxygen hole. Thus it is concluded either hole pairing or electron pairing is only a precondition but is not a real decisive factor that superconducting state occurs. If still following electric-phonon coupling the microcosmic mechanism of high-Tc cuprates will go astray. Copyright © 2013, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved.