In the current investigation, L-Proline Potassium pentaborate octahydrate single crystals are successfully grown from aqueous solution by slow evaporation technique at ambient conditions. Single-crystal X-ray Diffraction technique proves that the LPPPB crystal belongs to monoclinic crystal system. The optical transparency is analyzed by UV–Vis–NIR spectroscopic technique. It exhibits 92.7% transparency of the title compound with a wide band gap of 6.4 eV. The different types of vibrations such as symmetric stretching, asymmetric stretching, wagging, rocking, intramolecular hydrogen bond interaction, and scissoring vibrations are well established by FTIR technique. The Z-scan technique is employed to assess the nonlinear absorption and refraction behavior of the LPPPB crystal. It declares the saturable absorption and self-defocussing behavior. The hardness number of the LPPPB crystal is calculated by Microhardness Study. The creditability of the LPPPB crystal for nonlinear optical device applications is proved by simultaneous TG–DSC analysis.

We report pure potassium penta borate octa hydrate (PPB) and methyl orange dye-doped potassium penta borate octa hydrate (MOPPB) for optical limiting applications. The crystals were grown by slow evaporation solution growth technique at ambient conditions. The single crystal X-ray diffraction (SXRD) evinces the orthorhombic class of the pristine and MOPPB crystals. Formation of PPB and incorporation of MO dye in PPB was confirmed through Fourier transform infrared (FTIR) study. Calculated hardness number and stiffness constant with Vicker’s Micro hardness study portrays the soft nature of the title crystals. The decrease in bandgap of MOPPB is due to the additional energy levels introduced between the valence band and conduction band which in turn increases the net polarizability of the crystal. Relative second harmonic generation (SHG) efficiency of pure PPB and MOPPB is 0.45 times and 0.40 times that of SHG output of KDP. Z-scan studies shows that both crystals show reverse saturable absorption (RSA) ascribed due to two-photon absorption (TPA) process. MOPPB [ β = 1.68 × 10 –5 m/W, n 2 = 10.2 × 10 –12 m 2 /W, χ (3) = 3.5 × 10 –9 m 2 /V 2 ] possess higher NLO coefficients than pure PPB [ β = 0.98 × 10 –5 m/W, n 2 = 4.62 × 10 –12 m 2 /W, χ (3) = 6.1 × 10 –9 m 2 /V 2 ] which assured the superiority of azo dye incorporation in PPB crystals. Pristine and MOPPB crystals depict the optical limiting (OL) behavior under continuous wave (CW) diode laser irradiation at 785 nm. Thus, the linear and nonlinear properties bestow the MOPPB single crystal as a versed material for OL devices used for the safeguard of optical components from laser damage.

An organic-inorganic non linear optical (NLO) crystal L-Valine Potassium Penta Borate octa hydrate (LVPPB) single crystals were synthesized and grown by slow evaporation technique at ambient temperature. The single crystal X-Ray diffraction (XRD) analysis portrayed the monoclinic nature of the synthesized crystal. The UV-vis cut off wavelength was observed as 225 nm. The various functional groups CH3, CH, NH3 COO-, BO3, BO4 and K-O in LVPPB were identified using the Fourier transform infrared (FTIR) technique. The thermogravimetric and differential thermal analysis (TG-DTA) thermogram was utilized to determine the thermal stability of the grown crystal. The work hardening co-efficient was calculated as 2, using microhardness study. The second harmonic generation (SHG) efficiency of the LVPPB was found to be 0.9 times that of KDP.

L-Asparagine potassium penta borate octa hydrate(LASPPB) single crystals were synthesized from its aqueous solution at ambient temperature. Single crystal XRD confirmed the orthorhombic nature of the crystals. The UV-Vis spectroscopy highlighted the transparent nature of the LASPPB crystal. The lower cut-off wavelength was equivalent to 204 nm. The optical band gap was 6.06eV. The various functionalities incorporated in the synthesized compound were analysed by FTIR technique. The Second harmonic efficient of the LASPPB was 0.77 times that of KDP. The TG/DTA analyses showed the thermal stability and the melting point of LASPPB. The micro hardness test revealed the soft category of the material.