Synthesis,growth and third order nonlinear optical studies of a rhombohedral crystal: Sodium tetraborate pentahydrate

An apt and a futuristic nonlinear optical material sodium tetraborate pentahydrate (STBPH) was synthesized and grown by the technique of slow evaporation. The structural parameters of the crystal was confirmed by single crystal XRD revealed rhombohedral crystal system. Crystal's broad optical transparency was revealed by UV–Vis absorption spectrum. From the absorption spectrum, theoretical calculations were made to determine absorption coefficient, band gap, Urbach energy and reflectance. The functional groups were identified by FT-IR and FT-Raman spectra. Vicker's microhardness measurement disclosed that the grown crystal belongs to soft material category. Photoluminescence (PL) spectral study of STBPH indicated violet and blue emission peaks respectively at 343.06 nm and at 453.11 nm, 490.19 nm. Dielectric studies reveal the dielectric nature of the grown crystal. TGA-DTA studies showed that the crystal holds good thermal stability. The third order nonlinearities of STBPH was investigated by Z-scan technique manifest its suitability in nonlinear optical applications.