Laser ablation synthesis and characteristics of Tm-doped Gd2O3 nanoparticles

Synthesis of nano-sized particles of thulium-doped gadolinium sesquioxide is reported. The nanopowder was obtained by laser ablation of solid target composed of a mixture of Tm₂O₃ and Gd₂O₃ powders using radiation of pulse-periodical CO₂ laser. Morphological features, structural characteristics of nanoparticles and their densification behavior were investigated. It was shown that the as-synthesized nanopowder consists of loosely agglomerated particles with spherical shape and a diameter from 10 to 40 nm. It was revealed that the obtained sample is in the form of solid solution of Tm₂O₃ in Gd₂O₃ with monoclinic crystalline phase exhibiting the following lattice parameters: a = 14.095 Å; b = 3.571 Å c = 8.758 Å β = 100.182 °. Using X-ray diffraction analysis it was determined that, as opposed to other rare-earth sesquioxides (for instance, Y₂O₃ and Lu₂O₃), the phase transformation of monoclinic modification into cubic modification was not observed under thermal treatment at a temperature up to 1200 °C. This was also confirmed by an absence of stepwise variation in density of Tm:Gd₂O₃ compact which was evident for Gd₂O₃ sample prepared from powder with cubic phase and micro-sized particles. (paper)