Absence of host cation segregation in the (Gd,Y)₃Al ₅O₁₂ mixed garnet optical ceramics

Recently non-uniform distribution of dopants in transparent optical ceramics was observed. It was demonstrated that dopants with low segregation coefficients (K <0:2) with respect to the melt crystal growth are segregated to the grain boundaries when the grains of the ceramics are developed. This communication discusses segregation of host cations that form crystal matrix. Experimental examination of spatial distribution of Gd³⁺ and Y ³⁺ host cations in Ce³⁺-doped (Gd,Y)₃Al ₅O₁₂ ceramic sample demonstrated that no detectable redistribution of Gd³⁺ and Y³⁺ cations in the vicinity of the grain boundaries was detected. These results are in good agreement with comparable segregation behavior of Gd³⁺ and Y³⁺ [K(Y ³⁺) ≈ K(Gd³⁺)] when the garnet solidification is performed from liquid phase. This observation also confirms qualitative match of segregation in liquid and solid states.