LiF addition to (Cu,C) Ba2Ca3Cu4Oy superconductor

Samples of (Cu0.6C0.4)Ba2Ca3Cu4Oy ((Cu,C)-1234) with addition of 0.1 mol LiF have been synthesized by high pressure technique. It was found that LiF promotes the formation of superconducting phases with n higher than 4 of the (Cu,C)Ba2Can-1CunOy series. In order to obtain single-phase samples, for the same synthesis conditions, the oxygen content in the starting mixture (supplied by AgO) should be increased from 0.45 to 0.73 mol AgO, when using LiF. Samples with LiF have shown a certain morphology suggesting an enhanced 2D and suppressed 3D type of growth assisted by a liquid phase. Tc decreased from 116.5 to 113 K for the sample with LiF, but at the same time the transition width also decreased and Jc has shown a fish-tail effect