SCANDIUM FLUORIDES

A new modification of scandium fluoride has been synthesised. The comp ound is deficient in fluorine, with the composition ScF276. It belongs to the tetragonal system, lattice parameters being a = 3.792 and c = 6.740 Angstrom and may be obtained at low temperatures by the decompos ition of the precursor NH4ScF4. The reaction is topotactic, tetragonal parameters of the precursor are a = 4.021 and c = 6.744 Angstrom. Str uctural relationships with various fluorides and ammonium aminofluorid es are discussed. This synthesis route with IR-assisted decomposition should be considered as a soft-chemistry approach. (C) 1997 Elsevier S cience S.A.