X-ray irradiated thermo- and radioluminescence, structural and thermal characterization of septarian (powder&bulk) from Madagascar

The luminescence properties of septarian have been investigated for the first time in this study, which has been the subject of many studies in both geological and geophysical fields. This sediment with a calcium carbonate structure exhibited high luminescence properties with X-ray excitation. The radioluminescence (RL) and thermoluminescence (TL) properties were investigated as well as their structural (FT-IR, XRD), morphological (SEM), thermal (TG-DTA) and absorption (UV-Vis-NIR) properties of this sediment. The broad RL peak of septarian was observed at 640 nm. There was a significant increase in the RL intensities of the sifted samples compared with the bulk sample. The TL glow curves of septarian irradiated with X-rays exhibited intense main TL glow peak having the maximum temperatures at 116 °C and about 390 °C with a heating rate of 2 °C/s. Also; the TL kinetic parameters were reported; activation energy (E), frequency factor (s) and the order of kinetics (b) of the first peak have been determined in detail by using peak shape (PS) and Computerized Glow Curve Deconvolution (CGCD) methods. SEM and EDS analysis were performed for the two different layers of septarian. The light colored side with the amorphous structure of the sample has more impurities (such as Fe, Al, Zr, K) than the crystallized and darker side.