New scheelite-type oxynitrides in systems RWO₃N-AWO₄ (R = rare-earth element ; A = Ca, Sr) from precursors obtained by the citrate route

François Cheviré (1) , Franck Tessier (1) , Roger Marchand (1)

1 Laboratoire Verres et Céramiques

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) Å, c = 11.5893(8) Å (NdWO₃N) and a = 5.299(3) Å, c = 11.631(9) Å (PrWO₃N). Neutron diffraction experiments performed on the Nd-phase did not evidence any oxygen/nitrogen order within the scheelite anionic subnetwork (S.G. I4₁/a). (Nd,A)W(O,N)₄ (A = Ca, Sr) solid solution domains were identified between NdWO₃N and the AWO₄ oxide composition.

Mots clés: Chemical synthesis; Neutron scattering; Crystal structure; Nitrides

Domaines: Chimie; Chimie inorganique

François Cheviré, Franck Tessier, Roger Marchand. New scheelite-type oxynitrides in systems RWO₃N-AWO₄ (R = rare-earth element ; A = Ca, Sr) from precursors obtained by the citrate route. Materials Research Bulletin, 2004, 39 (7-8), pp.1091-1101. ⟨10.1016/j.materresbull.2004.02.016⟩. ⟨hal-01201851⟩