Influence of aliovalent impurity doping and effect of sensitized luminescence in KCl single crystals for dosimetry appli
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Influence of aliovalent impurity doping and effect of sensitized luminescence in KCl single crystals for dosimetry applications D. N. Krishnakumar1 · Rajesh Narayana Perumal2 Received: 1 December 2019 / Accepted: 23 January 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Sensitized luminescence properties of various alkali halide single crystals of dosimetric importance doped with aliovalent impurities are studied. Single crystals of KCl co-doped with (Ce,Mn), (Ce,Mg) (Ce,Tb) and (Eu,Tb) are grown using the Czochralski technique. The XRD of grown crystals showed good crystalline nature with face-centred cubic KCl structure. Thermally stimulated luminescence (TSL) and optically stimulated luminescence (OSL) characteristics of grown crystals are investigated after subjecting to gamma dose. TSL response of KCl:Eu,Tb and KCl:Ce,Tb showed an enhancement of 6.5 times and 3.5 times, respectively, compared to singly doped KCl:Tb. Co-doping of the divalent activators such as Mn and Mg did not result in enhanced TSL response with rare earth sensitizers. Notwithstanding the low TSL response, KCl:Ce,Mn showed very high OSL response, six times than that of single-doped KCl:Tb and 3.5 times than that of KCl:Ce,Tb and KCl:Eu,Tb. However, KCl:Ce,Mg did not exhibit noticeable OSL intensity enhancement compared to single doping. The high TSL and OSL response is apparently the conclusive evidence of the energy transfer mechanism between dopants, which is confirmed by photoluminescence studies. The dose–response curve of KCl:Ce,Mn that exhibited very high OSL response showed linearity up to 100 Gy, which indicated the material is a good candidate for dosimetric applications. The growth and characterisation of aliovalent impurity-doped KCl single crystals and mechanism of resonance energy transfer between the dopants are discussed in this paper.
1 Introduction Developing highly efficient luminescence materials for application in various niche areas has been the interest of the researchers for the last few decades. One way of enhancing luminescence efficiency is using suitable impurities that absorb luminescence from the host and then emit light of desired wavelength depending on the characteristics of the impurity incorporated. Another method of enhancing luminescence efficiency is through energy transfer between a donor and an acceptor, called sensitized luminescence technique. In this technique, an impurity atom, called activator or acceptor, having no appreciable absorption band in the given region of a spectrum (generally UV and visible) is * D. N. Krishnakumar [email protected] 1
Research and Development Centre, Bharathiar University, Coimbatore 641046, India
Centre for Radiation, Environmental Science and Technology, SSN College of Engineering, Chennai 603110, India
2
made to emit luminescence upon excitation in this region. It results in absorption and transfer from another impurity atom, called sensitizer or donor, or from the host lattice. Sensitized luminescence and resonan
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