Columbia International Publishing Journal of Luminescence and Applications (2014) Vol. 1 No. 2 pp. 40-60 doi:10.7726/jla.2014.1005 Research Article ______________________________________________________________________________________________________________________________ *Corresponding e-mail: bnlnarasappa@rediffmail.com 1 Department of Physics, Jnana Bharathi Campus, Bangalore University, Bangalore – 560 056 40 Synthesis, Characterization and Thermoluminescence Studies of LiNaSO 4 : Eu 3+ nanophosphor Y.S. Vidya 1 and B.N. Lakshminarasappa 1* Received 13 December 2013; Published online 2 August 2014 © The author(s) 2014. Published with open access at www.uscip.us Abstract Na2SO4, LiNaSO4 and LiNaSO4: Eu 3+ nanophosphors were successfully synthesized by slow evaporation technique followed by calcination at 400° C. The resultant products were characterized by using powder X- ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), UV – Vis, scanning electron microscope (SEM) and transmission electron microscope (TEM). Doping with Li + ion stabilized the thenardite phase (Phase V) while, codoping with Eu 3+ promoted the phase transformation from stable thenardite to metastable mirabilite (Phase III) crystal structure. The average crystallite size was calculated by using Debye – Scherrer’s formula and Williamson – Hall (W – H) plots. The optical energy band gap (Eg) of Na2SO4, LiNaSO4 and LiNaSO4: Eu 3+ were estimated from Wood and Tauc’s relation which varies from 4.2 – 4.33 eV. Thermoluminescence (TL) studies were investigated by using γ – irradiation in the dose range 0.5 – 5 kGy at a heating rate of 5 °C s -1 . A well resolved glow peaks at ~ 180 °C, ~ 150 °C and ~115 °C were recorded for Na2SO4, LiNaSO4 and LiNaSO4: Eu 3+ nanophosphors respectively. It was observed that isovalent doping of Li + served as quencher, while codoping of hypervalent Eu 3+ acted as activator to enhance the TL intensity of glow peak. In the present study, the extent of TL fading of LiNaSO4: Eu 3+ was 31 % compared to LiNaSO4 (52 %) and Na2SO4 (59 %). So, LiNaSO4: Eu 3+ phosphor might also have potential use in dosimetry. The kinetic parameters namely activation energy (E), frequency factor (s) and order of kinetics (b) was estimated and the results were discussed. Keywords: Sodium sulphate; Codoping; Thermoluminescence; Fading; Kinetic Parameters 1. Introduction Alkali sulphates were known for a long time as versatile and excellent phosphor materials. These sulphates attracted the attention of many workers in view of their potential applications in radiation dosimetry, TV screens, cathode ray tubes etc. A variety of defect centres were likely to be formed in sulphate based phosphors (Kher et al., 2008; Panigrahi et al., 2003; Zhang et al., 2001;