Preparation and optical characteristics of novel oxynitride phases in the R₃(Ta/Nb)-O-N system (R = La, Eu, Gd, Ho, Y, Yb)

Erwan Ray (1) , Franck Tessier (1) , François Cheviré (1)

1 ISCR - Institut des Sciences Chimiques de Rennes

The synthesis of reactive nitridation precursors prepared by the citrate route has been evidenced with the R₃TaO₇ and R₃NbO₇ stoichiometries (R = La, Eu, Gd, Ho, Y, Yb). Novel oxynitride phases have been isolated in the fluorite-type series R₃Ta(O,N,□)₈ and R₃Nb(O,N,□)₈ where  represents anionic vacancies. The niobium/tantalum substitution leads to a modification of the absorption properties toward higher wavelengths. The comparison between GdTa, Gd₂Ta and Gd₃Ta-based oxynitride phases highlights a blue shift of the position of the absorption edge with increasing Gd/Ta ratio. Unlike with RTa and R₂Ta stoichiometries, R₃Ta-oxynitride phases generally show a very narrow formation range in temperatures as well as low absorption in the visible.

Mots clés: Oxynitrides; Rare earth tantalates/niobates; Optical properties; Solid solution

Domaines: Matériaux

Erwan Ray, Franck Tessier, François Cheviré. Preparation and optical characteristics of novel oxynitride phases in the R₃(Ta/Nb)-O-N system (R = La, Eu, Gd, Ho, Y, Yb). Solid State Sciences, 2011, 13 (5), pp.1031-1035. ⟨10.1016/j.solidstatesciences.2011.01.025⟩. ⟨hal-00719428⟩