Study of the centers responsible for the TL emission by EPR and PL analysis of Eu-doped CaSiO3 phosphors synthesized by the devitrification method

Abstract

CaSiO3 doped at different ppm of Eu were synthesized by the devitrification method. Polycrystals exhibit a prominent high-temperature TL peak that increases in intensity and shifts toward higher temperatures with increasing amounts of dopant. TL emission spectrum of CaSiO3: Eu displays two very broad bands centered at 400 and 440 nm corresponding to the temperatures of 229.5 and 373.5 degrees C, respectively. PL measurements indicate the presence of Eu2+ and Eu3+ ions. EPR spectrum arises from two defect centers. One of the centers with principal g-values 2.016, 2.0091, and 2.0051 is attributed to O- ion and the center correlates with the TL peak at 236 degrees C. Center II with an isotropic g-value of 2.0018 is attributed to an F+ center and the center relates to the TL peak at 120 degrees C. Center III is also tentatively identified as the F+ center which is associated with the TL peak at 365 degrees C.