Photoluminescence and EPR investigation of combustion synthesized BaAl 2 O 4 :Cr 3+

Recently, many aluminate materials have been extensively studied as phosphors for the next generation of display and lighting devices. Synthesis of aluminate oxide phosphors has been achieved by a variety of routes: solid-state reactions, sol―gel techniques, microwave processing, hydrothermal synthesis and combustion synthesis. In the present investigation, we have successfully employed low temperature combustion method for the preparation of BaAl 2 O 4 :Cr 3+ . Powder X-ray diffraction analysis was used to characterize the as-prepared combustion products, while the optical properties were studied using photoluminescence. The morphological aspect of the resulting powders was examined by scanning electronic microscopy, which showed crystallites with irregular morphology in the form of plates. PL excitation spectrum revealed two broad intense bands located at 421 nm and 552 nm due to Cr 3+ ions, while emission spectrum showed peaks due to Cr 3+ ions at 705 nm. EPR spectrum of undoped BaAl 2 O 4 showed signals attributable to unintentional Fe 3+ impurity ions, while EPR spectrum of BaAl 2 O 4 :Cr 3+ contained an additional signal around 3450 G. corresponding to g ≅ 1.98, typical of Cr 3+ ions.