Nucleation and growth of YAG: Yb crystallites: a step towards the dispersity control

Abstract

In this work, the dynamics of changing the ceramic powder phase composition and the size of garnet crystallites during calcination of the precursor at various temperature and time conditions were studied on the example of YAG: Yb oxide composition. The precursor powder was synthesized by the chemical precipitation of a salts solution by ammonia. Based on the obtained data, a model of the garnet crystallite nucleation and growth has been proposed. The crystallite growth process, in this case, includes 3 stages: the crystallite nucleation, the stage of growth due to the conversion of the amorphous phase to crystalline, and the stage of agglomeration and crystallite growth due to their mutual absorption. The dependence of the YAG: Yb crystallite size on the calcination time in the temperature range of 830 °C–1200 °C has been approximated using the regression equation. The approximation error of the obtained equation was 4%. The approach proposed in the framework of this work can be used to describe the change of crystallite size during calcination both for systems with a garnet structure and for other oxide compositions. A description of the dependence of crystallite size on temperature and time of heat treatment opens up the possibility of controlling the particle size, their agglomeration degree, and the specific surface area of the ceramic powder, which is an important step towards obtaining materials with desired properties