Rare-Earth Fluorite-like Li 0.42 La 4.58 Mo 3 O 15.76±δ F 0.42±ε Molybdates: Crystal Growth and Atomic Structure.

Rare-earth fluorine-containing molybdates of the Ln₅Mo₃O_16+δ oxygen–electron conductor family with the LiLa₄Mo₃O₁₅F composition were synthesized for the first time as single crystals by the flux method. An accurate X-ray diffraction analysis of the obtained crystals was carried out at 20 and −183 °C. The LiLa₄Mo₃O₁₅F compound is isostructural to the fluorine-free analogue with a cubic structure (space group Pn 3 ¯ n). It is shown that lithium atoms replace one of the two positions of lanthanum in the more distorted LaO₈ polyhedron. According to X-ray diffraction analysis, fluorine atoms replace the positions of over-stoichiometric oxygen located in the vast cavities of the structure. So, fluorine anions can promote the interstitial conductivity of F-containing LiLa₄Mo₃O₁₅F molybdates. [ABSTRACT FROM AUTHOR]