Growth and anisotropic studies on potential nonlinear optical crystal imidazole–imidazolium picrate monohydrate (IIP) in different orientations for NLO device fabrications

A new organic NLO material Imidazole–imidazolium picrate monohydrate (IIP) was grown by the slow evaporation technique using acetonitrile as a solvent. The solubility and meta stable zone width was determined. The IIP crystal belongs to orthorhombic system with noncentrosymmetric space group P212121. The morphology of the IIP crystal was studied. Optical transmittance spectrum confirms a wide optical window exhibited by IIP crystal. The transmittance of IIP crystal was used to calculate the extinction coefficient (k) and absorption coefficient (α). The thermal stability of the crystal was determined using TG-DTA studies. The laser induced surface damage threshold and mechanical behavior of the IIP crystal were analyzed in different planes at different temperatures. The second harmonic generation (SHG) effective nonlinearity of IIP is 3.6 times that of standard reference material potassium dihydrogen phosphate (KDP) crystal.

► Organic IIP was grown by slow evaporation and slow cooling methods.
► The refractive index for IIP crystal is 1.79 in the range 400–1100 nm.
► The grown IIP crystal was found to be thermally high stable upto 215 °C.
► No cracks have been observed up to 90 g of load.
► The powder SHG efficiency of this material is 3.6 times that of KDP.