Identification of α‐Al ₂ O ₃ Precipitates in Rutile Single Crystals

Abstract

After high‐temperature reaction between Al 2 O 3 and TiO 2 crystals, precipitates found in rutile were characterized by electron microprobe and X‐ray diffraction methods and by optical and electron microscopy. The precipitates were identified as α‐Al 2 O 4 . Geometric and crystallographic orientation relations with the TiO 2 matrix constitute a reverse case of rutile precipitation in star sapphire .