Role of defect centres in thermoluminescence mechanism of Tb(3+) doped MgAl(2)O(4)

Abstract

Magnesium aluminated (MgAl(2)O(4)) doped with terbium was prepared by combustion synthesis. Defect centres of various techniques such as Electron Spin Resonance (ESR), Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL). TL studies on MgAl(2)O(4):Tb(3+) show two TL peaks at 120 and 340 degrees C. (TL) and Optically Stimulated Luminescence (OSL). TL studies on MgAl(2)O(4):Tb(3+) MgAl(2)O(4): Tb(3+) exhibits OSL when stimulated with 470 nm blue light. ESR study shows two defect centres with g = 2.011 and g = 2.0052 which are assigned to V-centre and F(+) centre, respectively. Step annealing ESR technique study suggests that V-centre is correlated to 120 degrees C TL peak whereas F(+) centre is correlated with both the 120 and 340 degrees C TL peaks. A TL mechanism is proposed. ESR-OSL correlation studies are carried out. The results of ESR-OSL correlation study along with TL bleaching study support the proposed TL mechanism of 120 degrees C TL peak.