Growth of Benzimidazole Single Crystal by Sankaranarayanan−Ramasamy Method and Its Characterization by High-Resolution X-ray Diffraction, Thermogravimetric/Differential Thermal Analysis, and Birefringence Studies

In the present study, single crystals of benzimidazole (BMZ) possessing excellent nonlinear optical properties were grown for the first time by the recently invented Sankaranarayanan−Ramasamy (SR) method at 25 °C using a constant temperature bath. High-resolution X-ray diffraction (HRXRD) analysis indicates that the crystalline perfection is excellent without having any low/very low angle internal structural grain boundaries. Single-crystal XRD analysis confirms that the grown ingot belongs to the orthorhombic crystal system with a space group of Pna21. Thermogravimetric/differential thermal analysis (TG/DTA) analysis indicates a single-stage weight loss observed at 165 °C. Also, it has been found that the birefringence measured over a wide wavelength range between 5200 and 6860 Å is nearly constant showing that the BMZ crystals grown are suitable for efficient second harmonic generation and polarization devices. The present study indicates that the SR method is superior to slow evaporation solution and vertical Bridgman techniques for the growth of BMZ single crystals.