Molten salt syntheses of alkali metal titanates

Abstract

Submicrometer dispersions of rod-like alkali metal titanates were prepared by the flux method, from the reaction of TiOSO₄ or TiO₂ precursors in molten alkali metal nitrates, doped with carbonates or hydroxides. Mono-, di-, tetra-, and hexatitanates are formed as a function of the precursor nature and the melt composition. As a rule, in these syntheses poorly crystalline or amorphous solids are obtained, showing the structure of polytitanates on the nanoscopic level. Lamellar potassium hexatitanate can be exchanged by action of a diluted acid, leading to protonic form, free from the alkali metal but retaining initial morphology. Reactivity of TiOSO₄ and TiO₂ in molten alkali metal nitrates and their mixtures with the corresponding carbonates was studied by mass spectrometry of the gases evolved during heating of the reaction mixtures. For both pure and doped nitrates it changes in the expected row Li>Na>K, following the melts oxobasicity sequence.