Observation of Vacancies, Faults, and Superstructures in LnMoO (Ln = La, Y, and Lu) Compounds with Direct Mo-Mo Bonding.

Among oxide compounds with direct metal-metal bonding, the YMoO (ABO) structural family of compounds has a particularly intriguing low-dimensional structure due to the presence of bioctahedral BO dimers arranged in one-dimensional edge-sharing chains along the direction of the metal-metal bonds. Furthermore, these compounds can have a local magnetic moment due to the noninteger oxidation state (+4.5) of the transition metal, in contrast to the conspicuous lack of a local moment that is commonly observed when oxide compounds with direct metal-metal bonding have integer oxidation states resulting from the lifting of orbital degeneracy typically induced by the metal-metal bonding.