Studies of defects in combustion synthesized europium-doped LiAl5O8 red phosphor

Europium-doped LiAl5O8 red phosphor was prepared using a self-propagating (combustion) synthesis. The formation of crystalline LiAl5O8 was confirmed by X-ray diffraction. The morphological aspect of the resulting powders was examined by scanning electron microscopy. Electron spin resonance studies have been carried out in order to study the characteristics of the defect centres and the thermoluminescence (TL) peaks observed in this phosphor. Two types of centres (centre I and centre II) have been identified in LiAl5O8:Eu. Centre I is characteristic of a species exhibiting an isotropic g-value 2.0089 with a line width of 70 G and is assigned to a V-centre. Centre II is also characterized by an isotropic g-value 2.0059 with a line width of about 10 G. Centre II is ascribed to a F+-centre. A room temperature photoluminescence study shows a strong emission line at 613 nm corresponding to the 5D0→7F2 transition of Eu3+ ions.