The fluorite-like LiSm4Mo3O15F ceramics: Synthesis and conductivity

Abstract

Fluorite-like compounds of the Sm5Mo3O16 composition and, for the first time, their fluorine- and lithium-containing analogues of the LiSm4Mo3O15F composition have been obtained by solid-phase synthesis in vacuum sealed quartz ampoules. The resulting materials were characterized by XRD, differential scanning calorimetry, thermogravimetry, scanning electron microscopy, and impedance spectroscopy. It was found that LiSm4Mo3O15F samples are isostructural to cubic Sm5Mo3O16 compounds with a fluorite-like structure. It is shown that the double replacement of samarium with lithium and oxygen with fluorine leads to the appearance of a reversible phase transition accompanied by a jump in conductivity by 2 orders of magnitude. The conductivity of the LiSm4Mo3O15F compound reaches the value of 10−3 S/cm at 600 °C which is about half an order of magnitude higher than the conductivity of non-fluorinated compounds at this temperature.