Synthesis of a new nanocrystalline titanium aluminum fluoride phase by reaction of Ti2AlC with hydrofluoric acid

A new nanocrystalline phase of titanium aluminum fluoride, with a stoichiometry of Ti2AlF9-exact stoichiometry measured herein is Ti2.1Al0.9F9,-was synthesized by the fluorination of Ti2AlC in anhydrous hydrofluoric acid at 55 degrees C for 2 h. The results from X-ray diffraction, scanning and high-resolution transmission electron microscopy and selected area diffraction, together with crystal structure solution via simulated annealing, confirmed the formation of a nanocrystalline material with a trigonal structure belonging to the R3 space group. The structure can also be viewed as being comprised of corner-sharing octahedra that are arranged in a distorted simple cubic arrangement. Thermogravimetric analysis, in argon, indicates that this phase is stable up to approximate to 850 degrees C. Density functional theory calculations estimate the band gap to be approximate to 5 eV and the bulk modulus to be approximate to 109 GPa.