Novel Synthesis of radioluminescent CsI:Tl microcrystals under ambient conditions by antisolvent recrystallization method

Thallium doped Cesium Iodide (CsI:Tl) radioluminescent microcrystals are promising candidate for scintillation applications that include medical imaging, nuclear safety and high energy particle detection applications. This paper introduces, for the very first time, an antisolvent recrystallization method to synthesize microcrystals of CsI:Tl. The antisolvent recrystallization method is useful for synthesizing microcrystals at room temperature under atmospheric pressure and humidity conditions with high product yield approaching similar to 90 %. The polycrystalline nature of the CsI:Tl microcrystals is confirmed from the X-ray diffraction analysis, wherein the crystallite size is found to be in the range of 20-25 nm. The scanning electron microscopy revealed the size of microcrystals in the range of 1-13 mu m. The doping concentration of thallium (with 0.06, 0.10, 0.20, 0.50 and 1.00 mol%) strongly affects the luminescence yield. At higher concentration of doping, a shift towards long wavelength is observed. The strongest luminescence yield is observed in the sample of 0.2 mol% Thallium doping, which is around 76 % of luminescence compared to single crystal of CsI:Tl. This work provides a low-cost alternative to the growth of radioluminescent microcrystals in comparison with the existing single crystal growth approaches.