Optical properties, micro-crystallization and etching studies of an organic/inorganic hybrid nonlinear optical crystal: 1-Ethyl-3-methyl imidazolium tribromoplumbate (EMITB)

Single crystals of 1-ethyl-3-methyl imidazolium tribromoplumbate (EMITB), an organic–inorganic nonlinear optical (NLO) material, were grown by the controlled evaporation solution growth method. The grown crystals were characterized by the single-crystal diffraction and X-ray powder diffraction. Second-harmonic generation (SHG) on powder samples has been measured using Kurtz and Perry technique, which indicated that EMITB is a phase-matchable material, and its SHG coefficient is measured to be four times larger than that of KDP. The optical transmittance window and the lower cutoff wavelength of the EMITB have been identified by UV–vis–NIR studies. Its growth morphology was predicted by the Bravais–Friedel–Donnay–Harker (BFDH) model and the influence of pH values on crystal growth using slow solvent evaporation method was also investigated. The results show that both high and low pH values are disadvantageous to the growth of EMITB crystal, and EMITB crystal exhibits a regular crystalline morphology when pH value of the growth solution ranges from 3.8 to 4.0. Etching studies illustrated that the crystal grows in the two dimensional nucleation mechanism.

► The optimized pH value of aqueous solutions for the growth of single-crystals of the NLO material imidazole lead(II) halide hybrids (EMITB) is found to be 3.8.
► The studied EMITB crystal has a wide transparent range in 335–1100 nm.
► The nonlinear optical coefficient is more than four times of d36 of KDP.