Study by Extended X-ray Absorption Fine-Structure Technique and Microscopy of the Chemical State of Yttrium in α-Polycrystalline Alumina

Yttrium-doped a-poly crystalline alumina was studied by microscopy observations and by extended X-ray absorption fine-structure experiments. The latter results were compared to those obtained for a standard Y₂O₃ powder and to theoretical spectra for Y₂O₃, and Y₃Al₅O₁₂ calculated on the basis of crystallographic data. Most of the yttrium in the doped alumina is precipitated as a Y₃Al₅O₁₂ phase. An observed threshold displacement involves a slight valence electron delocalization for the Y³⁺ ion.