A facile semi-open method for synthesis of non-centrosymmetric superconducting Li2(Pd,Pt)3B bulks and thin films

Non-centrosymmetric superconductor Li2(Pd1-xPtx)3B, x = 0-1 was synthesized from mixtures of the elements. A simple semi-open method is proposed using endings-pressed stainless steel tubes placed in a high-vacuum furnace. Heating regime employed a short-time overheating at 900 oC and a slow cooling step between Ts and 550 oC within 3 h. To adequately compensate Li-losses and attain maximum critical temperature, the optimum Ts and starting Li-content were found to change from 720 to 740 oC and from Li2.4 to Li2.6, respectively, when x was changing from 0 to 1. It was shown that placing Li separately in the tube also produces superconducting samples, Li being supplied to the (Pd,Pt)-B mixture through the vapour transport. This result enables the possibility of thin films growth using a (Pd,Pt)-B precursor film heat treated in a Li-vapour atmosphere. Preliminary results on thin films growth are introduced.