1. Realization of Extreme Nonstoichiometry in Gadolinium Aluminate Garnets by Glass Crystallization Synthesis
- Author
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Fang, Xue, Castaing, Victor, Becerro, Ana Isabel, Cao, Weiwei, Veron, Emmanuel, Zanghi, Didier, Dyer, Matthew S., Genevois, Cécile, Allix, Mathieu, and Pitcher, Michael J.
- Abstract
The garnet aluminates RE3Al5O12(RE= Gd – Lu, Y) are an important class of optical materials with a range of applications. Typically, they do not tolerate large deviations from ideal stoichiometry, and their luminescence properties are controlled by dopant selection rather than modification of the host structure. Here, we use glass crystallization as a nonequilibrium synthesis route to a new family of highly nonstoichiometric gadolinium aluminate garnets, of formula Gd3+xAl5-xO12with x≤ 0.60. Remarkably, this range is much broader than the previously reported Y3+xAl5-xO12series (x≤ 0.4), despite the vast size contrast between Al3+and Gd3+, which are forced to share a crystallographic site in the nonstoichiometric materials: the endmember Gd3.6Al4.4O12lies halfway between ideal garnet and perovskite stoichiometries, with 30% of its octahedral Al3+sites substituted by Gd3+. In principle, this crystal chemistry should allow the synthesis of phosphor systems with rare-earth activators distributed over two different cation sublattices. To probe the response of luminescence properties to extreme nonstoichiometry in Gd3+xAl5-xO12, we synthesized three model phosphor systems by doping with Ce3+, Tb3+, or Tm3+/Yb3+and found that upconversion (Tm3+/Yb3+) phosphors have the most potential to be tuned by this approach. These results demonstrate that highly nonstoichiometric garnet aluminates are not limited to small rare-earth hosts such as YAG, opening new opportunities for development of different garnet-based optical and magnetic materials.
- Published
- 2024
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