New Synthesis Route of PbMo6S8 Superconducting Chevrel Phase from Ultrafine Precursor Mixtures: I. PbS, MoS2 AND Mo Powders

Fine powders of PbMo6S8 Chevrel phase (∼0.5 μm) obtained from new ultrafine precursor powders present excellent intrinsic superconducting properties, such as a critical temperature, Tc, of about 14 K. These results are due to ultrafine quasi-spherical PbS, MoS2, and Mo precursor powders (0.05–0.5 μm) of lead Chevrel phase synthesized by soft chemistry methods (precipitation, co-precipitation). Thus, a better reactivity between the grains of the mixture allows a decrease in the synthesis temperature of the resulting PbMo6S8 phase (800°C instead of 950-1000°C) required for the PbMo6S8 synthesis from the same precursor powders made by the classical ceramic route. These new Chevrel phase powders have very fine homogeneous grains with high potential surface reactivity, giving improved grain boundaries that are able to carry high current densities.