Structural and superconducting properties of MgB2-xBex -: art. no. 172503

We prepared MgB2-xBex (x=0, 0.2, 0.3, 0.4, and 0.6) samples where B is substituted with Be. MgB2 structure is maintained up to x=0.6. In-plane and interplane lattice constants were found to decrease and increase, respectively. The superconducting transition temperature T-c decreases with x. We found that the T-c decrease is correlated with in-plane contraction but is insensitive to carrier doping, which is consistent with other substitution studies such as Mg1-xAlxB2 and MgB2-xCx. Implication of this work is discussed in terms of the two-dimensional nature of the sigma band.