A study on the l-lysine-iodic acid: semi organic non linear optical single crystals for electro-optic applications

Non linear optical single crystals of l-lysine-iodic acid (LLI) of dimensions upto 24 × 14 × 5 mm³ have been grown successfully by slow evaporation technique from aqueous solution. The crystal structure of the grown material was solved by single crystal X-ray diffraction analysis and it was found that the LLI crystal belongs to monocinic system with space group P2₁. Functional groups of the grown crystal were identified by Fourier Transform Infrared (FTIR) spectral analysis. The UV–Vis spectral analysis was carried out to measure the transparent range of the LLI crystal which is nearly 85% and the band gap energy is found to be 5.51 eV. Thermal stability and decomposition temperature of LLI crystal was found by means of TGA and DTA analyses. The mechanical behavior of the grown crystal has been employed using Vicker’s micro hardness technique. The Second Harmonic Generation (SHG) efficiency of the crystal was investigated and it was found to be 3.2 times of KDP. The particle size dependent SHG studies of LLI crystals were performed using Nd:YAG laser. The laser damage threshold value of LLI crystal is found to be 8.54 GW/cm². Dielectric study indicates the reasonable dielectric constant and low dielectric loss of LLI crystal which are essential properties to develop optoelectronic devices. The ac and dc electrical conductivity measurements were carried out at various temperatures. Photoconductivity study exhibits the negative photoconductivity nature of the LLI crystal and the results are discussed for the first time.