Synthesis of chromium-doped YAG nanocrystals via Pechini synthesis and coprecipitation

Chromium IV-doped Yttrium Aluminum Garnet (YAG) materials are widely used as saturable absorbers (SA) in YAG:Nd lasers. However, the low doping rate
(about 1%at) reported in literature leads to poor SA properties whereas the complex doping mechanism of the matrix leads to a cohabitation between various
ions: Cr3+, octahedral Cr4+ and tetrahedral Cr4+. As only the latter is responsible for the SA properties, its concentration must be manageable to achieve better
properties. We successfully synthesized YAG:Cr powders with a Cr doping rate of up to 30%at via Pechini synthesis and coprecipitation. UV-Vis spectroscopy
suggests that the synthesis route has an influence on the Cr oxidation state and on its crystallographic environment. The goal of this proposal is 1/to identify these
features depending on the synthesis route and thermal treatment to unravel the synthesis and doping mechanisms and 2/to define the best conditions leading to
the most efficient SA.