Growth, Structure, Electrical Transport and Thermal Stability of New Allotropic MoC4 Crystals

Carbide materials are interesting and useful functional materials, such as for thermal barrier coatings and wide-band-gap semiconductors. In this paper, a novel molybdenum carbide material, MoC4 crystals, was obtained using the chemical vapor transport (CVT) method. MoC4 crystals have a monoclinic structure, and their space group is P2(1)/n (No. 14) (a = 5.5347(14) angstrom, b = 4.8498(7) angstrom, c = 5.6013(14) angstrom, and V = 130.91(6) angstrom(3)). The electrical properties of MoC4 crystal demonstrate the metallic behavior that the Bloch-Gruneisen model can well describe. A Hall measurement shows that MoC4 has a high hole carrier concentration of up to 0.6 x 10(23) cm(-3) on average and carrier mobility of mu = 76-125 cm(2) V-1 s(-1). In addition, MoC4 was found to be thermodynamically stable above 1500 degrees C, and so it may be used as high-temperature conductors or electrodes.