Optical and EPR Spectroscopic Studies of Deep Red Light Emitting Fe-Doped LiAlO Phosphor Prepared Via Propellant Combustion Route.

LiAlO doped with Fe was synthesized by a propellant combustion route at furnace temperature of 773 K. The phosphor was characterized using powder x-ray diffraction, optical absorption, electron paramagnetic resonance (EPR) and photoluminescence spectroscopic techniques. The optical absorption spectrum exhibits a broad band at 242 nm characteristic of charge transfer between Fe-O. On excitation with 293 nm, emission band for the Fe ion was observed at 687 nm. The CIE (International Commission on Illumination or Commission Internationale de l'Elcairage) coordinates for the system were evaluated adopting standard procedure which suggested that the system can be effective as a deep red emitting phosphor. The EPR spectrum of this phosphor exhibits a number of resonance signals characteristic of Fe ions. The resonance signals at g = 3.16, 2.27 are attributed to Fe present at tetrahedral site with an axial symmetry. The resonance signals at g = 1.98 and 1.43 are attributed to Fe ions in octahedral site with an axial symmetry. Various EPR parameters such as the number of spins, Gibbs free energy, magnetic susceptibility, Curie constant and effective magnetic moment values are calculated and compared at room temperature and 110 K. [ABSTRACT FROM AUTHOR]