Luminescent materials are used in a wide range of devices like phosphor lamps, display monitors and for medical imaging. Typically, an inorganic luminescent material consists of the luminescent ion or activator embedded in a host lattice. In particular, lanthanides (Ln) are very attractive as activators because of their high emission efficiency and the appropriate wavelength of their f-f transitions in the visible range. The most widely used host lattices are based on oxoanions of group 5 and namely yttrium and lanthanide vanadates. Up to now, research was mainly focused on the development of new chemical compositions of phosphors prepared by conventional solid state methods but few efforts have been made to develop alternative routes that could improve their physico-chemical properties.

This work aims at developing a soft chemistry approach to prepare vanadate hosts as well as luminescent Ln-doped vanadates, and focuses on the consequences of the preparation method on the properties. The method consists in using, for the different elements to be incorporated, molecular precursors which are coordination compounds. The multimetallic oxide materials are obtained by an appropriate thermal treatment in air of a solid homogeneous mixture of the different complexes.

For that purpose, EDTA-based complexes of general formula (NH₄)[Ln^III(EDTA)]·xH₂O and (NH₄)₃[V^V(O)₂(EDTA)]·H₂O are synthesized, characterized and used as precursors for the preparation of zircon-type MVO₄ hosts at a moderate temperature of 800°C, as evidenced by XRD and Raman analyses. Solid solutions such as Y_1-xPr_xVO₄ and Y_1-xGd_xVO₄ are also obtained. Linear correlations between chemical compositions and lattice parameters or Raman shifts are observed. SEM is used to characterize the particle size and morphology. A slightly disordered intergranular porosity is observed. Finally, Ln-doped YVO₄ are prepared and their emission spectra are recorded.

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