Materials Research Bulletin, Vol.39, No.7-8, 1091-1101, 2004
New scheelite-type oxynitrides in systems RWO3N-AWO(4) (R = rare-earth element; A = Ca, Sr) from precursors obtained by the citrate route
RWO3N oxynitrides were isolated as single phases for R = Nd and Pr, after thermal ammonolysis of reactive precursors prepared using the citrate complexation/calcination route. Both stoichiometric compounds crystallize with a scheelite-type tetragonal unit cell, with a = 5.2821(3) Angstrom, c = 11.5893 (8) Angstrom (NdWO3N) and a = 5.299(3) Angstrom, c = 11.631(9) Angstrom (PrWO3N). Neutron diffraction experiments performed on the Nd-phase did not evidence any oxygen/nitrogen order within the scheelite anionic subnetwork (space group: I4(1)/a). (Nd,A)W(O,N)(4) (A = Ca, Sr) solid solution domains were identified between NdWO3N and the AWO(4) oxide composition. (C) 2004 Elsevier Ltd. All rights reserved.