Effect of carbon doping on the structure and superconductivity in AlB2‐type (Mo0.96Ti0.04)0.8${(\text{Mo}_{0.96}\text{Ti}_{0.04})}_{0.8}$B2

Abstract

AbstractWe report the effect of carbon doping in Ti‐stabilized nonstoichiometric molybdenum diboride B2, which exhibits bulk superconductivity below Tc = 7.0 K. It is found that maintains the AlB2‐type phase with a uniform elemental distribution for x = 0.12 and 0.16. The substitution of carbon for boron leads to a slight increase in a‐axis, a remarkable reduction in c‐axis, the formation of planar defects along the (100) crystallographic planes, and a shift of the B 1s peaks toward higher binding energies. Contrary to B2, however, no superconductivity is observed down to 1.8 K for the C‐doped samples, which is ascribed to the electron filling of boron π bands resulting from the carbon doping.