Insight into the structural, mechanical and optical properties of NaCl:Tb crystals for the WLED and TLD applications

Abstract

Green emitting NaCl:XTb [ X = 0.0, 0.002, 0.004, 0.006, 0.008, 0.01 and 0.02] single crystals were grown by adopting the Czochralski method and their structural, mechanical and optical properties were studied by carrying out X-ray diffraction (XRD), micro-hardness, optical absorption, photoluminescence (PL), thermo-luminescence (TL), etc. measurements. XRD results revealed the absence of lattice distortion due to doping with Tb ions. Hardness analysis displayed more hardness for the Tb-doped crystals than for the pure NaCl crystal. Optical absorption spectra confirmed five main peaks corresponding to 4f8→4f75 d1(8S) and 7F6→5LJ=9,10 transitions of the Tb3+ ions. PL emission spectra (excitated at 372 nm) indicated the maximum intensity peak at 545 nm corresponding to 5D4→7F5 transition of the Tb3+ ions. The emission peak intensity was found to increase with the increase in Tb concentration; and the CIE coordinates of NaCl:0.02 Tb were found as x = 0.3008 and y = 0.5000, located in the green region. TL glow curves exhibited higher intense peaks for the NaCl:0.02 Tb crystal irradiated with γ-ray; the peak parameters (E, s, μg and b) were also estimated. Dose response and energy storage stability of the NaCl:0.02 Tb crystal irradiated with γ-ray were studied for dosimetry application. The research results show that the NaCl:Tb crystal would be potential candidates for the WLEDs and TLD applications.