Luminescence Characterization of Chromium‐Containing theta‐Alumina

Abstract

Characteristic photostimulated luminescence (fluorescence) in the visible range is reported from theta transition alumina prepared by using a variety of methods. The luminescence is associated with trace concentrations of chromium and can be intensified by intentional chromium doping. The luminescence from theta‐alumina is similar to, albeit considerably weaker than, the R‐line luminescence from alpha‐alumina. The theta‐alumina spectrum is characterized by a doublet at ∼14575 and 14645 cm −1 at 77 K and is blue‐shifted from the R‐lines of alpha‐alumina by ∼150 cm −1 . The doublet is attributed to Cr 3+ ions in octahedral coordination and can be used for phase identification in microstructural characterization.