Synthesis, structural, optical, thermal and dielectric studies on new organic nonlinear optical crystal by solution growth technique

Single crystals of l-phenylalanine-benzoic acid (LPBA) were successfully grown from aqueous solution by solvent evaporation technique. Purity of the crystals was increased by the method of recrystallization. The XRD analysis confirms that the crystal belongs to the monoclinic system with noncentrosymmetric space group P21. The chemical structure of compound was established by FT-NMR technique. The presence of functional groups was estimated qualitatively by Fourier transform infrared analysis (FT-IR). Ultraviolet–visible spectral analyses showed that the crystal has low UV cut-off at 254 nm combined with very good transparency of 90% in a wide range. The optical band gap was estimated to be 6.91 eV. Thermal behavior has been studied with TGA/DTA analyses. The existence of second harmonic generation (SHG) efficiency was found to be 0.56 times the value of KDP. The dielectric behavior of the sample was also studied for the first time.

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► The chemical structure of compound was established by FT-NMR technique.
► SHG efficiency of LPBA is 0.56 times than that of KDP crystal.
► The optical cut-off wave length for this crystal was observed at 254 nm.
► LPBA crystal is a potential candidate for device fabrication.