Characterization, photoluminescence and correlation between thermoluminescence and ESR of combustion synthesized CaAl2O4:Sm3+CaAl2O4:Sm3+ material

Samarium-doped monoclinic CaAl2O4CaAl2O4 phosphor was prepared at furnace temperatures as low as 500 °C in a short time of 5 min by using the combustion route. Powder X-ray diffraction and scanning electron microscopy studies were used to characterize the prepared combustion powder. Photoluminescence spectra revealed that samarium ions are present in trivalent oxidation states. The CaAl2O4CaAl2O4:Sm exhibits two thermoluminescence glow curves at around 135 and 325 °C. The defect centres formed in the phosphor are studied using the technique of electron spin resonance (ESR). Irradiated CaAl2O4CaAl2O4:Sm shows ESR lines due to a radiation induced Fe3+Fe3+ ion and a defect centre. The defect centre is characterized by an isotropic gg-value 2.0036 and is assigned to an F+F+ centre. The radiation induced Fe3+Fe3+ ion appears to correlate with the main TSL peak at 325 °C.