Superconducting TaC nanoparticle-containing ceramic nanocomposites thermally transformed from mixed Ta and aromatic molecule precursors

We report the structure and synthesis approach for obtaining a ceramic nanocomposite pellet comprising ∼50 nm-sized TaC nanoparticles. A mixture of Ta metal powder and the carbon precursor 1,2,4,5-tetraphenylethynyl benzene, pelletized by vacuum pressing at 131 MPa, on further thermal treatment with Ar at 1400 °C yields such a ceramic composite. On air oxidation, the TaC nanoparticles are converted to Ta2O5nanoparticles at 760 °C. Hardness measurements revealed that the composite exhibited a global hardness in the range of 1.23–1.57 GPa. However, nanoindentation studies showed that, locally, hardness of the TaC nanoparticles (∼15 GPa) approached that of the densified TaC ceramic. Superconducting studies of the pellet consistently exhibited two transitions withTcvalues of 10 K and 8.5 K, respectively, that corresponded to bulk TaC and to a component of unknown origin. The results discuss the morphological and constitutional characterizations of the TaC nanoparticle-containing composite.