Phase evolution mechanism study and fabrication of PbMo6S8 superconducting materials with two-step sintering process

PbMo6S8 superconducting materials are considered to have great potential for practical applications at low temperatures and high fields due to their high upper critical field, low anisotropy, and low preparation cost. In this work, PbMo6S8 bulks were prepared through a solid-state sintering process using PbS, Mo, and MoS2 as raw materials. The phase evolution mechanism during the sintering of PbMo6S8 was studied in detail. It was found that during sintering at 750 degrees C for 24 h, both the S and Pb atoms diffuse into the Mo and MoS2 par-ticles, leading to the formation of the PbMo6S8 phase. After sintering at 950 degrees C for 72 h, a high superconducting phase content was obtained in the bulk; however, numerous pores remained. Therefore, in order to obtain a higher density for the bulk, a two-step sintering process was developed. Based on this technique, PbMo6S8 bulks with a higher bulk density and a higher superconducting phase content were obtained. This study pro-vides an effective method for the fabrication of high-quality precursor powders, which can be the foundation for the future fabrication of PbMo6S8 superconducting long wires or tapes for practical applications.