Band-gap tuning by solid-state intercalations of Mg, Ni, and Cu into Mo3Sb7

Mo3Sb7 was synthesized by heating the elements in the stoichiometric ratio in a sealed silica tube at 700 °C. The title compounds AδMo3Sb7 (A = Mg, Ni, Cu) were prepared by annealing prereacted Mo3Sb7 with different amounts of A in powder form between 500 and 750 °C. According to our single-crystal structure studies, the A atoms can be intercalated in small amounts into the cubic voids of the Mo3Sb7 structure without noticeable symmetry changes (space group Im[Formula: see text]m). The different cations cause different band-gap decreases that depend on the element as well as its concentration.