Growth, structural, optical, thermal and mechanical properties of morpholinium 3,5-Dinitrosalicylate single crystals for nonlinear optical applications

A novel third-order nonlinear optical (NLO) active organic adduct, morpholinium 3,5-dinitrosalicylic acid M35DS was synthesized and single crystals of size 10 × 6 × 5 mm3 were grown from an aqueous solution by adopting the slow evaporation solution technique (SEST). The formation of a new crystalline adduct was confirmed by single crystal X-ray diffraction (SXRD) technique, and it revealed that the grown single crystals belong to the monoclinic crystal system with centrosymmetric space group C2/c. Powder X-ray diffraction (PXRD) and Fourier Transform Infrared (FTIR) spectroscopy techniques have been used to determine the phase purity and verify the presence of multifarious functional groups in the grown crystals, respectively. The determined optical properties by the UV–Vis-NIR transmittance analysis reveal that the grown M35DS crystal possesses an attractive optical transmittance in the visible and NIR regions with a lower cutoff wave length at 445 nm and these features are more appropriate for many emerging optical fields. The mechanical hardness of the grown single crystal was evaluated by the Vickers microhardness test at room temperature. Besides, the grown single crystal showed relatively good thermal stability of about 191 °C, which was determined by simultaneously recorded thermogravimetric (TG) and differential thermal analysis (DTA). The third-order nonlinear optical (NLO) properties were investigated using single beam Z-scan technique with an excitation source of a continuous wave laser at 532 nm. From this analysis, it is confirmed that the grown crystal exhibits a strong reverse saturable absorption, self-defocusing refraction and high third-order nonlinear susceptibility (χ3), which satisfies the requirements for designing standard third-order NLO devices.