Crystal growth of semiorganic sodium p-nitrophenolate dihydrate from aqueous solution and their characterization

Sodium p-nitrophenolate dihydrate $(NPNa.2H_2O)$, is a semiorganic nonlinear optical crystal which is reported to have an effective nonlinear optical coefficient of 5 pm/V. The crystal is usually grown from methanol. By suitably varying the growth parameters, we obtained stable, transparent, sodium p-nitrophenolate dihydrate using water as a solvent. Large single crystals of the dimension $20 \times 17 \times 8 mm^3$were grown by a temperature-lowering method. Preliminary characterizations were carried out on the grown sample and compared with methanol-grown $NPNa.2H_2O$. The optical transmission study on these crystals revealed that the crystals grown from aqueous solution have a higher percentage of transmission, thereby favourably affecting optical performance