Luminescence Studies on Lamp Phosphors

Photoluminescence and thermoluminescence of cerium magnesium aluminate CeMgAl11O17(Eu,Tb) and calcium halophosphates Ca5(PO4)3(F,Cl):Mn,Sb, two fluorescent materials currently in use for the commercial production of lamps in India, have been studied for possible applications in radiation and ultraviolet dosimetry. Cerium magnesium aluminate is highly sensitive to the visible spectral region. It has a linear response to 254 nm UV radiation over a wide range. Its UV sensitivity is significantly higher as compared to that of other known phosphors; however, its UV response is rate-dependent and may not play a significant role in UV dosimetry. Photoluminescence of CeMg aluminate is characteristic of Eu2+ and Tb3+ dopants, whereas the thermoluminescence emission of the UV irradiated powder at room temperature is dominated by Eu2+ dopant. Calcium halophosphate is insensitive to room lights, has a linear gamma response over 0.2-102 Gy and may be useful in the case of radiation accidents.