In this study, the thermoluminescence characteristics of naturally occurring salt (NaCl) were assessed for the development of a radiation dosimeter. For this purpose, mined crystalline samples of salt were procured directly from Khewra salt mines in Pakistan. The samples were hand crushed, sieved, and compressed to pellets comparable in size to standard TLD chips, and irradiated to gamma radiation doses in the range of 5 mGy and 5000 mGy. Thermoluminescence (TL) response showed three main peaks in the glow curve around 115–130 °C, 150–170 °C, and 220–240 °C. A linear TL response was observed for the dose range of 5–100 mGy. The TL response became supra-linear for the dose ranges of 100–1000 mGy and 1000–5000 mGy. The Tm-Tstop method was applied to identify the overlapping peaks of the glow curve. Computerized glow curve deconvolution (CGCD) was then employed for the characterization of electron trap parameters such as frequency factor (s), activation energy (E), and the kinetic order (b), using General Order (GO) kinetics. The figure-of-merit (FOM) was found to be 1.08%, 0.94%, 0.77%, and 0.75%, at 500 mGy, 1 Gy, 2 Gy, and 5 Gy, respectively. The TL intensity faded by 20% within the first 24 h after irradiation and finally stabilized after two weeks. In addition, structural, morphological, and elemental analyses, were also performed using various analytical techniques. X-ray diffraction (XRD) showed that the salt crystallizes in a face-centered cubic structure. Scanning electron microscope (SEM) micrographs indicated that the crystallites are closely packed and cubic-shaped with non-uniform size, and mostly found in the agglomerated form. Similarly, the elemental analysis confirmed the presence of impurities such as Mg, Sr, S, K, O, and Ca, in the samples. The present study concludes that the pellets made from salt samples from Khewra mines have a potential for use as radiation dosimeters.

Thermoluminescence study of pellets prepared using NaCl from Khewra Salt Mines in Pakistan

Luminescent and Mechanical Properties of Cerium Doped Potassium Chloride Single Crystal

Effect of Ce concentration on the structural, mechanical, electrical and optical properties of Ce-doped large-sized KCl0.5Br0.5 crystals

Effect of Pr ion concentration on the luminescence properties of NaCl:0.01Ce3+,Pr3+ crystals grown in large size

Structural, mechanical, electrical and optical properties of NaxK1-xCl:Ce3+ crystals grown in large size by the Czochralski method

Structural, mechanical, thermal and optical properties of NaCl:Ce3+ single crystals grown in large size by the Czochralski method

The pure and Ce3+-doped NaCl crystals were grown using the resistance heating Czochralski method The structural, mechanical, and optical properties of the grown crystal were investigated by X-ray diffraction (XRD), micro-hardness, optical absorption, photoluminescence (PL), PL excitation (PLE) spectroscopy, and decay time measurement The XRD data indicated that the NaCl host lattice was compressed when Ce atoms were incorporated and the peaks shifted to the large angle side The ICP-AES and XPS analyses verified that Ce3+ is the dominant state of cerium in NaCl crystal The hardness of the NaCl:Ce3+ crystal was larger than that of pure NaCl crystal and it was anisotropic Optical absorption confirmed that the three states of 5d level splitting of Ce correspond to the absorption peaks of 202, 215, and 227 nm The intense emissions located at 342 and 356 nm were attributed to the radiation transitions 5d → 2F5/2 and 5d → 2F7/2 in Ce3+, respectively The energy-level scheme for the Ce3+ ion in the NaCl crystal was proposed from the PL and PLE analysis The luminescence decay time of NaCl:Ce3+ crystal is 3857 ± 016 ns These observations indicate that the NaCl:Ce3+ crystal should be a promising material for use in radiation dosimetry and scintillation applications

Optical and mechanical properties of NaCl: Ce 3+ crystal grown by the Czochralski method

Large-sized Ce3+ doped KBr crystal was grown using the resistance heating Czochralski method. The material has more well-defined optical and mechanical properties than the pure KBr single crystal. The structural, optical properties and quality of the grown KBr:Ce3+ crystal were investigated by x-ray diffraction (XRD), optical absorption, photoluminescence (PL), PL excitation spectroscopy, micro-hardness and stress measurements. The XRD data indicated that the KBr host lattice changed when Ce ions were incorporated. Optical absorption and PL measurements confirmed the presence of cerium ions in the doped KBr crystal. A broad and intense blue emission around 394 nm, attributable to the transition from the 5d excited state to the 4f ground state of the Ce3+ ions, was observed in the PL emission. The hardness of the KBr:Ce3+ crystal was greater than that of the pure KBr crystal. The stress values of different parts in the crystal were different, and the stress was mainly dependent on the process parameters. High stresses were always found to exist near the growth interfaces, at the shoulder-expanding locations, the tailing locations and the sites where the diameters undergo sharp changes. The optimized process parameters were the main measures to avoid the crack of the large-sized KBr:Ce3+ crystal. These observations indicate that the KBr:Ce3+ crystal is a promising material for use in optical, dosimetry and scintillation applications.

Yongju Li

Papers

Structural, mechanical, thermal and optical properties of NaCl:Ce3+ single crystals grown in large size by the Czochralski method

Optical and mechanical properties of NaCl: Ce 3+ crystal grown by the Czochralski method

Structural, Optical and Mechanical Properties and Cracking Factors of Large-Sized KBr:Ce 3+ Single Crystal

Luminescent and Mechanical Properties of Cerium Doped Potassium Chloride Single Crystal

The Structure and Liquid Flow Effect of Melt during NaCl Crystal Growth