Nanostructured Nd:YAG powders via gel combustion: The influence of citrate-to-nitrate ratio

Nanostructured neodymium doped yttrium aluminum garnet (Nd:YAG) powders were synthesized at low temperature by a gel combustion method with citric acid as fuel and nitrate as oxidizer. The method involves exothermic decomposition of an aqueous citrate–nitrate gel. The decomposition is based on a thermally induced anionic redox reaction. A variety of 1.0 at% Nd:YAG powders with different agglomerate structures were obtained by altering the citrate-to-nitrate ratio γ. The gel with γ = 0.277 yielded nanocrystalline Nd:YAG at 800 °C without the formation of any intermediate phase. For other gels nanostructured Nd:YAG powders were obtained at 850 °C. The gel with γ = 0.1 yielded nanostructured Nd:YAG powder with an average particle size of ∼40 nm. The stoichiometric citrate-to-nitrate ratio (γ = 0.277) gave the lowest amount of agglomeration. The decomposition of the gel was investigated by TG–DSC and FTIR. The produced ashes and calcined powders were characterized by XRD, BET and FETEM analysis.