The Yb<sup>3+</sup>-Er<sup>3+</sup> co-doped YAG nanocrystal powders have been successfully prepared by the simple sol-gel method at a low temperature. The gel was prepared from nitrates of yttrium, aluminum, ytterbium, erbium and citric acid, and was heat-treated at temperatures from 800 to 1000°C. The phase purity and microstructural features of the materials were analyzed by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM result shows that the YAG nanocrystal particle size is about 20-50nm. The luminescence spectra for different Yb<sup>3+</sup> and Er<sup>3+</sup> dopant concentration was obtained at about 1.52um which is in the eyesafe regime where significantly higher pulse energies can be used without damaging human eyes.
In recent years there has been increasing interest in the synthesis of nanocrystalline metal oxides. Nanostructured garnets are of special interest due to their improved properties such as lower temperature sinterability, greater thermal stability, increased hardness, good optical properties etc. In our idea, the sol-gel method is a useful and attractive technique for the preparation of nanocrystalline powders because of its advantages: good stoichiometric control, the production of ultrafine particles and low temperature. In this paper, we reported the preparation and characterization of Yb<sup>3+</sup> and Ho<sup>3+</sup> codoped yttrium scandium gallium garnet (YSGG) nanocrystal powders by the sol-gel technique. The phase purity, mass loss, composition and microstructure features of the materials were analyzed by means of X-ray diffraction (XRD), TG analysis, infrared spectroscopy (IR) and transmission electron microscopy (TEM).