Ultrarapid Microwave Synthesis of Superconducting Refractory Carbides

Nb1−xTaxC Carbides can be synthesized by high power MW methods in less than 30 s. In situ and ex situ techniques probing changes in temperature and dielectric properties with time demonstrate that the reactions self-terminate as the loss tangent of the materials decreases. The resulting carbides are carbon deficient and superconducting; Tc correlates linearly to unit cell volume, reaching a maximum at NbC.