Solubility, crystal growth, morphology, crystalline perfection and optical homogeneity of lithium p-nitrophenolate trihydrate, a semiorganic NLO crystal

Abstract

A good optical quality bulk single crystal of a semiorganic non-linear optical material, lithium p-nitrophenolate trihydrate has been grown by a slow cooling solution growth method. The solubility of the material was measured in water before attempting the growth by cooling. The grown crystal was subjected to X-ray diffraction for phase identification and high resolution X-ray diffraction study for assessing its crystalline quality. A rocking curve with full width half maximum of 18 arc s exhibits the good crystalline quality of the crystal. Transmission study shows that the crystal has ∼75–80% transmission in the visible and near infra red spectrum making it a potential material for non-linear optical applications in this spectral range. The refractive index homogeneity, which is an index of the optical quality of the crystal was investigated using birefringence and Mach–Zehnder interferometry. The uniformity of the fringe pattern in both the interferograms show that the crystal has good refractive index homogeneity and is free from any defects. The experimental morphology of the crystal has been found to match with the morphology simulated on the basis of the Bravias–Friedel–Donnay–Harker law.