Formation of a Cr³⁺-rich luminescent thin phase along a grain boundary of α-Al₂O₃

Abstract

An α-Al₂O₃ bicrystal doped with Cr³⁺ was fabricated by diffusion bonding at high temperatures. It was found that a ruby phase with approximately 200 nm thickness was formed along the grain boundary. This thin phase shows Cr³⁺:Al₂O₃-induced luminescence, confirmed by confocal micro-luminescence spectroscopy.