Understanding the formation thermodynamics of fresnoitic trivanadates: DFT calculations and soft base hydrolysis synthesis

A wet chemistry method is proposed for the facile and scalable synthesis of several members of trivanadates M2V3O8 (M = K, Rb, Cs, NH4) with the fresnoite-type of lattice, known formerly using the solid-state chemistry methods. Phase composition, morphology and porosity of microstructured samples are characterized using X-ray powder diffraction, FT-IR spectroscopy, and scanning electron microscopy. The same fabrication technique fails for synthesis of hypothetical compounds M2V3O8 (M = Li, Na), since yielding an amorphous product. DFT computational screening of all possible fresnoitic trivanadates determines the main peculiarities of their electronic structures and establishes the M cation size as basic factor of their thermodynamic stability, elucidating the enhanced stability of compounds with the larger cations.