Photoluminescence and thermoluminescence in Dy<sup>3+</sup>‐, Ce<sup>3+</sup>‐, and Tb<sup>3+</sup>‐activated MgB<sub>4</sub>O<sub>7</sub> phosphor for dosimetry application
Abha H. Oza, Vibha Ojha, Shrikrishna Dhale, S.J. Dhoble
Abstract
Abstract Samples of microcrystalline rare earth‐doped magnesium borate materials were synthesized via modified solid‐state diffusion and were characterized using X‐ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Photoluminescence (PL) results for the MgB 4 O 7 :Dy sample depicts blue emission that resulted from a 4 F 9/2 – 6 H 15/2 transition that peaked at 484 nm, which was much stronger than the yellow emission arising due to the 4 F 9/2 – 6 H 13/2 transition at 576 nm. From the emission spectra for MgB 4 O 7 :Tb, it seems that at higher concentrations of Tb 3+ ion, the green emission becomes strong and directly relates to the energy transfer from the 5 D 3 excited state to the 5 D 4 excited state through a cross‐relaxation, whereas the blue emission is suppressed in MgB 4 O 7 phosphors. The thermoluminescence (TL) of the samples was measured immediately after irradiation and compared by TL curve with CaSO 4 :Dy. MgB 4 O 7 :Dy showed very good TL sensitivity for the desirable dosimetric curve at ~218°C and the best glow curve structure. In comparison with the dosimetric peaks for MgB 4 O 7 :Ce and MgB 4 O 7 :Tb, the MgB 4 O 7 :Dy phosphor is equally sensitive to CaSO 4 :Dy. MgB 4 O 7 :Dy and MgB 4 O 7 :Tb showed linearity for a 1–5 kGy dose. The activation energies and frequency factors were also calculated for samples MgB 4 O 7 :RE (where RE = Dy, Tb, Ce) using the peak shape method.