Correlation between segregation of rare earth dopants in melt crystal growth and ceramic processing for optical applications

The paper deals with segregation of rare earth doping cations in solid-state hosts. Increased concentration of Ce³⁺ and Nd ³⁺ on the grain boundaries of transparent garnet optical ceramics was recently reported. These experimental results correlate well with low segregation coefficients of Ce³⁺ and Nd³⁺ large rare earth cations and the higher segregation coefficients for small rare earth cations like Yb³⁺ in the garnet structure observed in the melt crystal growth and thin film liquid phase epitaxy from flux. Thus, the segregation in solid-state grain growth is qualitatively similar to that observed in the melt/flux growth of the garnet single crystals. The data on segregation in the melt/flux crystal growth are widely available and can be used for preliminary estimation of the dopant distribution in the ceramics produced from the solid state. This information could help to predict distribution of doping cations in the solid state hosts that is important in development of uniform and highly efficient optical materials.