Improvement of optical properties of KDP crystals by borax additive

KDP (Potassium dihydrogen phosphate, KH2PO4) single crystals were grown in Borax (Sodium tetraborate decahydrate, Na2B4O7·10H2O or Na2[B4O5(OH)4]·8H2O) added aqueous solutions by the slow cooling method and Sankaranarayanan-Ramasamy (SR) technique. The concentrations of Borax were 0.05, 0.1, 0.5, and 1 mol%. Impurities containing hydroxyl (-OH) groups such as Borax can increase the number of hydrogen bonds in KDP crystals, which plays a key role in governing the optical properties of KDP crystals. This comment was proved by the results of the measurements: Ultraviolet–visible (UV–Vis) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD) analysis, and Second Harmonic Generation (SHG). Borax is an important candidate in the current research of impurity-doped KDP crystal for nonlinear optical applications.