Structural transition in the normal state of the superconductor Mo3Sb7

Low-temperature X-ray diffraction measurements on a correlated-electron superconductor Mo3Sb7 revealed that the high-temperature cubic state with the Ir3Ge7 type structure (space group Im3¯m) transforms to tetragonal below TS=53TS=53 K, at which spin-gap formation was recently suggested. The effect of electron correlations to the structural instability is briefly discussed in connection with the condensation of the high-temperature local moments to the spin-singlet-like state.