Synthesis, Crystal Growth, Optical, Thermal, Piezoelectric and Laser Damage Threshold Characterization of Aniline-4-Sulphonic Acid for Nonlinear Optical (NLO) Applications

The organic single crystal of aniline-4-sulphonic acid (A4SA) was synthesized and grown by slow evaporation solution technique (SEST) using distilled water as a solvent. The lattice parameters of the grown crystal were confirmed by single-crystal X-ray diffraction analysis. The X-ray diffraction exposes that the A4SA crystal belongs to an orthorhombic system with space group Pca2₁. Functional groups of A4SA crystal were confirmed by Fourier transform infrared (FTIR) and FT-Raman spectrum analyses. The optical quality of the grown crystal was identified by the UV-Visible NIR spectrum analysis. The grown crystal has good optical transmittance in the range of 300–900 nm. The photoconductivity analysis was carried out to calculate the photo and dark current values. Photoconductivity study indicates that A4SA crystal shows a negative photoconductivity nature. Intermolecular interactions of A4SA are executed by the Hirshfeld surface analysis. The chemical etching was investigated to calculate the etch pit density. Photoluminescence analysis for grown crystals is obtained. Thermogravimetric, differential thermogravimetric analysis and differential scanning calorimetry (TG, DTA, DSC) measurements investigate the thermal stability of a grown crystal. Vickers microhardness analysis was performed to study the mechanical properties of the material. The Nd:YAG laser, with a wavelength of 1064 nm, was used to examine the LDT analysis. It shows a good LDT value of 5.02 GW/cm². The third-order non-linear susceptibility was measured and analysed by Z-scan technique using (He–Ne) laser of wavelength 632.8 nm.