Formation of superconducting pellets and oriented films from Y2BaCuO5(green phase)

摘要

One of the derivatives of the 1hyphen;2hyphen;3 highhyphen;Tcsuperconductors is known as the green phase (Y2BaCuO5). In a novel approach, the latter is proposed as the starting material to make oriented films deposited on MgO (001) by a simple painting method. Best results are obtained with a heat treatment up to 1040thinsp;deg;C and a slow cooling rate from 980 to 920thinsp;deg;C, giving films withTc,50percnt;=83 K and Dgr;Tc=6 K. Scanning electron microscopy assisted by localized xhyphen;ray fluorescence permitted us to correlate theTcrsquo;s andJcrsquo;s with the general morphology of these films. Test pellets made with the 2:1:1 phase are also shown to be superconducting with a transition midhyphen;point atTc,50percnt;=93 K and width of around 2 K.