Bulk Crystal Growth and Optical and Thermal Properties of the Nonlinear Optical Crystal l -Histidinium-4-nitrophenolate 4-Nitrophenol (LHPP)

Good-quality single crystals of the nonlinear optical (NLO) crystal l -histidinium-4-nitrophenolate 4-nitrophenol (LHPP) with a large size of 40 × 25 × 10 mm 3 have been grown by the slow cooling method. Its morphology has been indexed to reveal that the crystal is a rhombohedra with major forms of (−100) and (−101). The optical transmittance range has been identified by UV–vis NIR studies. Second-harmonic generation (SHG) on powder samples has been measured using the Kurtz and Perry technique, and the results display that LHPP is a phase-matchable NLO material with its SHG efficiency being 3.55 times as large as that of KDP. Its specific heat and the principal thermal expansion along the principal crystal axes have been measured at different temperatures. The average principal thermal expansion coefficients have been calculated on the basis of experimental measurements between 298 and 410.5 K, and the relationship between the structure and the thermal properties has been discussed. Surface morphologies of the laser-induced damaged crystal were observed with an optical microscope, and the nature origin of the damage was analyzed.