Effect of carbon doping on the structure and superconductivity in AlB$_{2}$-type (Mo$_{0.96}$Ti$_{0.04}$)$_{0.8}$B$_{2}$

Abstract

We report the effect of carbon doping in Ti-stabilized nonstoichiometric molybdenum diboride (Mo 0.96 Ti 0.04 ) 0.8 B 2 , which exhibits bulk superconductivity below T c = 7.0 K. It is found that (Mo 0.96 Ti 0.04 ) 0.8 (B 1−x C x ) 2 maintains the AlB 2 -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 towards higher binding energies. Contrary to (Mo 0.96 Ti 0.04 ) 0.8 B 2 , 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.

D-Wave Superconducting Gap Symmetry as a Model for Nb1−xMoxB2 (x = 0.25; 1.0) and WB2 Diborides

“…The field of experimental and theoretical studies of materials with strongly correlated charge carriers [46][47][48][49]57,[59][60][61]74,[98][99][100][101][102][103][104][105][106][107][108][109][110][111][112][113][114][115][116], including diborides [44,[46][47][48][49]107,108], is experiencing a boom. In this work, we deduced the primary superconducting parameters of highly compressed diborides: the P6/mmm phases of MoB 2 and WB 2 and ambient pressure superconductors Nd 0.75 Mo 0.25 B 2 .…”