Synthesis of nanosize powders and thin films of Yb-doped YAG by sol-gel methods

Yb-doped YAG is becoming a very promising optical material. We present a synthesis of single-phase Yb-doped YAG powders and thin films at a significantly lower temperature by sol-gel methods than by other conventional techniques. Yb-doped YAG powders and thin films on Si(100) substrates with a series of different doping concentrations were prepared. The lattice deformation, IR, and Raman vibrations were studied via the change of the doped concentration. This could be one of the reasons why, in general, about 20 atomic % Yb:YAG presents the better laser and scintillation properties. Scanning electron microscopy and transmission electron microscopy were used to investigate the morphology of the structures. A strong preferred orientation of crystal growth in thin films was found during the conversion of the structure from amorphous to crystalline. The Avrami model was used to analyze the isothermal transformation kinetics. On the basis of the experimental results, the effective activation energy of crystallization in the thin films was calculated as 653 ± 10 kJ/mol.