Investigation of defect centres responsible for TL/OSL in MgAl(2)O(4):Tb(3+)

Abstract

Magnesium aluminate doped with Tb(3+) (MgAl(2)O(4):Tb(3+)) was prepared by combustion synthesis. Three thermoluminsence (TL) peaks at 120, 220 and 340 degrees C were observed. PL and TL emission spectrum shows that Tb(3+) acts as the luminescent centre. Optically stimulated luminescence (OSL) was observed when stimulated by 470 nm blue light. Electron spin resonance (ESR) studies were carried out to identify the defect centres responsible for the TL and OSL processes in MgAl(2)O(4):Tb(3+). Two defect centres were identified in irradiated MgAl(2)O(4):Tb(3+) phosphor by ESR measurements which was carried out at room temperature and these were assigned to V and F(+) centres. V centre (hole centre) is correlated to 120 and 220 degrees C TL peaks and F(+) centre (electron centre), which acts as a recombination centre is correlated to 120, 220 and 340 degrees C. (C) 2009