S. Vallidevi and G. Selvarajan
Abstract
A sustainable and eco-friendly method was employed to synthesize light green-colored single crystals of Nickel Chloride Thiourea Urea (NCTU) using a slow evaporation technique at room temperature, with ethanol as a benign solvent. This low-energy, solvent-efficient route aligns with green chemistry principles and minimizes environmental impact. The synthesized crystals, approximately 35 mm in width and 36 mm in height, were subjected to a comprehensive set of characterization techniques including UV-Visible spectroscopy, FTIR, X-ray diffraction (XRD), micro hardness testing, and thermo gravimetric-differential thermal analysis (TG-DTA). Spectral analysis confirmed strong metal ligand coordination and enhanced optical transparency, while nonlinear optical (NLO) testing revealed second harmonic generation (SHG) efficiency surpassing that of standard KDP. Thermal analysis indicated good stability up to 175 °C, supporting the materialâs potential for durable, energy-efficient photonic applications. The use of environmentally benign reagents, ambient synthesis conditions, and the resulting multifunctional performance position NCTU crystals as a promising material for sustainable optoelectronic and nonlinear optical technologies.