Bulk growth of organic 4-hydroxy l-proline (HLP) single crystals grown by conventional slow evaporation and Sankaranarayanan–Ramasamy (SR) method

Abstract

Organic single crystals of 4-hydroxy l-proline (HLP) were grown by conventional slow evaporation and Sankaranarayanan–Ramasamy (SR) method in an aqueous medium. With a vision to improve the crystal quality, SR method was adopted and optically transparent HLP single crystal, (110) directed, with the size of 80 mm length and 15 mm diameter was grown. The crystalline structure of the grown crystal was analyzed by single crystal X-ray diffraction (SXRD) analysis. The conventional and SR method grown HLP crystals were characterized and the results were compared by UV–Vis–NIR, photoluminescence, chemical etching, Vickers microhardness, dielectric permittivity, dielectric loss, photoconductivity, photoacoustic, laser damage threshold (LDT) and second harmonic generation (SHG) measurements. The thermal property of the grown crystal was carried out by thermogravimetric (TG) and differential thermal analysis (DTA). The SHG efficiency of HLP crystal was determined using Kurtz–Perry powder technique. The comparative optical transmittance study clearly indicates that the transmission of SR method grown HLP crystal is 10% higher and quite good in the entire visible and near infrared region which suggest its suitability for optical device applications. The distribution of structural defects and the etch pit density (EPD) of the grown crystals were determined by chemical etching analysis. The Vickers microhardness measurement reveals that the hardness of SR method grown HLP crystal is higher compared to conventional method grown crystal. The dielectrics, photoconductivity, photoacoustic and laser damage threshold studies clearly indicate that the crystal grown by SR method possesses good quality compared to conventional method grown crystal.