Synthesis, growth and characterization of semi-organic nonlinear optical L-threnoninum sodium fluoride (LTSF) crystal for photonics application

Abstract

L-threoninum sodium fluoride (LTSF), a nonlinear optical single crystal has been successfully grown using aqueous solution by slow evaporation method in atmospheric temperature. A well-developed crystal was harvested over a period of 65 days. Crystallographic information of the titular crystal was collected using single crystal X-ray diffraction analysis which confirmed that the LTSF crystal belongs to non-centrosymmetric space group P212121 (D24). Powder X-ray diffraction pattern of LTSF crystal confirms the crystallinity perfection. Transparency and linear optical parameters such as band gap (Eg), extinction coefficient (K), reflectance (R), refractive index (n0) were identified using UV–visible–NIR spectrum analysis. The functional groups and vibrational modes were identified from FT-IR analysis and the presence of sodium fluoride was confirmed. The presence of ions (Na+) and (Fˉ) was confirmed by elemental analysis. The thermal stability of the material is found to be 296 °C from TG/DTA studies. Laser damage threshold of the grown crystal measured using Q-switched Nd: YAG laser and is found to be 4.10 GW/cm2. The surface micromorphology of the as-grown crystal was analyzed by etching studies. The second harmonic generation (SHG) efficiency of the LTSF crystal was measured and is found to be 3.61 times than the KDP and two times greater than the pure L-threonine crystal.