Effective growth and characterization of piperazinium orthophthalate single crystal yielding high second harmonic generation efficiency

Good quality organic non-linear optical single crystal of piperazinium orthophthalate (PPA) was grown successfully by solution growth at room temperature by achieving the supersaturation state in slow evaporation method. The powder XRD analysis confirms the crystalline nature and structural parameters of the grown PPA crystal. The FTIR and Raman spectra confirm the existence of acid-base functional groups along with their vibrational mode exhibited, present in the grown PPA crystal. UV–Vis spectrum exhibits better transparency in the visible region with cut-off wavelength of 330 nm and the energy band gap (E_g) is analyzed to be 3.8 eV. Photoluminescence spectra shows good optical property with the excitation of 342 nm and two emission peaks in near edge UV band with blue emission at 364 and the energy transition in deep level defect states in crystals by exhibiting the green emission at 533 nm respectively. The thermal stability and the thermal absorption of the PPA crystal were identified by the TG - DTA analysis and obtained thermal stability was up to 88 °C. Vickers micro hardness test illustrates the mechanical stability of the grown PPA crystal and it belong to soft category (n = 4.6). Etching studies illustrates the growth pattern of the grown crystal using water as etchant. FE-SEM analysis shows the perfect smooth morphology of the grown PPA crystal. Second harmonic generation study illustrates the grown PPA crystal (λ = 532 nm) exhibit good nonlinear optical response.