Mechanical Activation of α-AlF₃: Changes in Structure and Reactivity

α-AlF 3, the thermodynamically stable rhombohedral phase of aluminum fluoride, was used as starting material to produce nanostructured powders by high-energy ball milling. Both the polycrystalline and the nanostructured powders were studied by XRD, TEM, and 27 Al and 19 F MAS NMR. Thermally programmed desorption of NH 3 and IR spectroscopy of adsorbed CO probe molecules unambiguously demonstrate the formation of Lewis acid and Brønsted acid sites as a consequence of the mechanical impact. Catalytic test reactions using milled α-AlF 3 as solid catalyst proved experimentally the theoretically suggested catalytic activity of nanosized AlF 3 particles as a result of high structural distortion brought into the solid by milling.