Crystal growth and characterization of semiorganic nonlinear optical material: sodium p-nitrophenolate dihydrate

Sodium p-nitrophenolate dihydrate (NPNa) is a new semiorganic nonlinear optical crystal. It has a d(eff) of about 1.2 times that of potassium titanyl phosphate. Large single crystals of NPNa were grown from water and methanol solutions by isothermal solvent evaporation. The morphology of the grown crystals was indexed. The defect content of the methanol grown crystals was evaluated by chemical etching and synchrotron topography. The section topography carried out on a large uncut crystal revealed a considerable reduction in the defect density away from the seed. The improved optical transmission of NPNa crystals was achieved by purifying the starting materials. The mechanical hardness of the NPNa crystals in the 010 plane was evaluated by Vickers and Knoop indentations.