Structure and compositional trends in alkali-metal containing titanium and vanadium oxide chalcogenides and the new van der Waals phase Ti2Te2O

Abstract

We report the solid-state synthesis of all eighteen layered oxide chalcogenides in the structural family A M 2 Q 2 O (A = K/Rb/Cs; M = Ti/V; Q = S/Se/Te), allowing the determination of trends in composition and reactivity within the series. All materials are isostructural, crystallising in the primitive tetragonal space group P 4 / m m m as reported previously for five compounds in the series. The titanium or vanadium ions have intermediate valency on a single crystallographic site, leading to temperature-independent paramagnetism and correlated electronic behaviour which is influenced by the compositional variation. Furthermore, the alkali metal ions in Image 1 and Image 2 can be removed by oxidative deintercalation using Image 3 at room temperature to produce a new metastable van der Waals layered phase, Image 4 . During the deintercalation reaction the oxide chalcogenide layers undergo a relative shift by ( 0.5 , 0.5 ) in the ab plane such that Image 4 is body-centered with space group I 4 / m m m .