Séminaire

Mardi 30 Janvier 2018 à 11h00.

Synthèses et propriétés spectroscopiques de molybdates et tungstates cubiques dopés terres rares en vue de la fabrication de céramiques transparentes pour l’optique

''Surprisingly, today available rare earth (RE3+) luminescent ions-doped cubic optical transparent ceramics used as laser sources or phosphors for lighting are limited to a very small number. The main objective of this project is to select carefully new RE3+ luminescent ions-doped tungstate/molybdate chemical compositions, fulfilling two conditions, cubic crystallographic system and size of the crystallites up to 100 nm, different of usual garnets, sesquioxides or fluorites, owing to their long longevity, low cost, and excellent chemical stability. The choice of RE3+ ions has been Nd3+ and Yb3+ for IR and visible lasers and Eu3+ for red phosphors. The host lattices, in which the substitution of optically un-active trivalent La3+ or Y3+ by RE3+ ions will take place have been preferred. For each composition, nano-powder materials are researched by various methods: Pechini, combustion, hydrothermal, methods and high-temperature solid state reaction.
The first results on both synthesis and spectroscopic characterizations have been obtained on Yb3+, Nd3+ and Eu3+-doped La2MoWO9 , La2Mo2O9 and Y6MoO12 compounds [1-4]. Our attention will be now focused on both the crystal growth by using the micro-pulling down method (µ-PD) and the fast SPS (Spark Plasma Sintering) and the slower but efficient HIP (Hot Isostatic Pressing) techniques to show the feasibility of transparent ceramics. Important information on the spectroscopic properties will be obtained by using site selective and time resolved spectroscopy techniques on both nano-powders, single crystals and transparent ceramics.

References RC] [1] M. Bieza, M. Guzik, E. Tomaszewicz, Y. Guyot, G. Boulon, Opt. Mat. 63 (2017) 3-12.
[2] M. Bieza, M. Guzik, E. Tomaszewicz, Y. Guyot, K. Lebbou, E. Zych, G. Boulon, J. Phys. Chem. C, 2017, 121 (24), 13290–13302.
[3] M.Bieza, M. Guzik, E. Tomaszewicz, Y. Guyot, K. Lebbou, G. Boulon, J. Phys. Chem. C, 2017, 121 (24), 13303–13313.
[4] M. Bieza, M. Guzik, E. Tomaszewicz, Y. Guyot, G. Boulon, J. Eur. Cer. Soc., 2017 under review.''