V. Sivasubramani

Growth and characterization of semi-organic third order nonlinear optical (NLO) potassium 3,5-dinitrobenzoate (KDNB) single crystals

The semi-organic single crystal of potassium 3,5-dinitrobenzoate (KDNB) was successfully grown by slow evaporation solution technique (SEST) at room temperature. The lattice parameters of the grown KDNB crystal were confirmed by single crystal X-ray diffraction. The functional groups of the KDNB crystal were confirmed by Fourier transform infrared (FTIR) spectroscopy analysis. The optical quality of the grown crystal was identified by UV-Vis NIR spectral analysis. The grown crystal has good optical transparency in the range of 410–1100 nm. In the photoluminescence spectrum, sharp broad emission peaks were observed, which indicate violet and blue emission. The photoconductivity study reveals that the grown crystal has a negative photoconductive nature. The thermal behaviour of the crystal has been investigated by thermogravimetric and differential thermal analysis (TG-DTA). Vickers microhardness analysis was carried out to identify the mechanical stability of the grown crystal and the indentation size effect (ISE) was explained satisfactorily by Hays–Kendalls approach and proportional specimen resistance model [PSRM]. A chemical etching study was carried out and the etch pit density (EPD) was calculated. Laser damage threshold (LDT) energy has been measured by using a Nd:YAG laser (1064 nm). The dielectric permittivity and dielectric loss as a function of frequency were measured for the grown crystal. The solid state properties such as plasma energy, Penn gap and Fermi energy were evaluated for the KDNB crystal using the empirical relation. These estimated values were utilized to report the electronic polarizability. This matches well to the value calculated from Clausius–Mossotti relation, Lorentz–Lorentz equation, optical band gap energy and coupled dipole method (CDM). The third-order nonlinear optical properties such as refractive index (n2), absorption co-efficient (β) and susceptibility (χ(3)) were studied using Z-scan technique at 632.8 nm of He–Ne laser.

Bulk growth of organic non-linear optical (NLO) L-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) single crystals by Sankaranarayanan–Ramasamy (SR) method

Abstract Organic non-linear optical single crystals of L-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) are grown by Sankaranarayanan–Ramasamy (SR) method and slow evaporation solution technique (SEST) with the sizes of about 45 mm length, 15 mm diameter and 6 × 5 × 5 mm3, respectively. The grown crystals were characterised by single crystal X-ray diffraction to determine the crystallographic unit cell parameter values. The etch pit density of SEST and SR method grown LAPP crystals have been calculated using chemical etching analysis. The mechanical and optical properties of the SEST and SR method grown LAPP crystals are studied using Vickers microhardness and UV–vis NIR measurement, respectively. Laser damage threshold analysis has been made on cut and polished SEST and SR method grown LAPP crystal of 5 mm thickness. Photoconductivity study of LAPP crystal grown by SEST and SR method reveals positive photoconductivity nature. The thermal properties of the grown crystal were carried out by thermogravimetric and differential thermal analysis. The second-harmonic generation efficiency of LAPP crystal was determined using powder Kurtz–Perry technique and it was found to be 2.3 times that of standard potassium dihydrogen phosphate material.

Synthesis, crystal growth, physicochemical properties and quantum chemical investigations of a D–π–A type organic single crystal: 2-amino-5-nitropyridinium p-phenolsulfonate (2A5NPP) for nonlinear optical (NLO) applications

Efficient organic nonlinear optical (NLO) 2-amino-5-nitropyridinium p-phenolsulfonate (2A5NPP) single crystals have been grown by slow cooling method using methanol as a solvent. Single crystal X-ray diffraction (SXRD) analysis revealed the unit cell parameters of the grown crystal. The morphology of the grown crystal was identified by single crystal XRD analysis as well. The crystallinity of the title crystal was studied by powder X-ray diffraction (PXRD) analysis. The presence of functional groups was determined by FTIR spectral analysis. The optical transmittance revealed that the grown crystal is transparent in the visible and NIR region with a lower cutoff wavelength of 408 nm. The chemical etching analysis showed that the grown crystal has a lower etch pit density (EPD). The title compound is thermally stable up to 200 °C, as assessed by thermogravimetric (TG) and differential thermal analysis (DTA). The photocurrent (Ip) and dark current (Id) values were found to be 5.3 × 10−11 A and 3.3 × 10−11 A at 50 V, respectively, by photoconductivity analysis. A dielectric study was carried out to find the distribution of charges within the crystal. Theoretical calculations were performed using the B3LYP/6-311++G(d,p) level basis set. The structural parameters of 2A5NPP were studied using the DFT method and the calculated results were compared with the experimental values. The charge transfer characteristic of the title compound was studied by frontier molecular orbital (FMO) analysis. The first-order hyperpolarizability of the 2A5NPP molecule was found to be 2.9 × 10−29 e.s.u, which is 37 times higher compared to the reference urea molecule. The Mulliken charge of the obtained molecule was theoretically analyzed. Hydrogen bonding of the obtained molecule was confirmed by NBO analysis. The Kurtz–Perry powder technique was used to evaluate the second harmonic generation (SHG) efficiency of the title crystal and it was found to be 22 times that of the reference KDP material.

Crystal growth, structural, optical, thermal and dielectric studies of non-linear optical 2-amino-5-nitropyridinium nitrate (2A5NPN) single crystals

Abstract Single crystals of 2-amino-5-nitropyridinium nitrate (2A5NPN), semiorganic non-linear optical crystals have been grown by conventional slow evaporation solution technique using water as solvent. Optically good quality crystal having dimension up to 10 × 10 × 10 mm3 was grown. The single-crystal X-ray diffraction (XRD) studies confirm that 2A5NPN crystallises in monoclinic crystal system with the space group P21/n and the morphology of the grown crystal was identified. The powder XRD pattern of the grown crystal was recorded. Fourier transform infrared (FTIR) measurement was carried out to identify the various functional groups present in the compound. The optical property of the grown crystal was analysed using UV–Visible Near Infrared analysis. The thermal stability of the compound was ascertained using thermogravimetric and differential scanning calorimetric analysis. The etch pit density of the grown crystal was calculated by chemical etching analysis using dimethyl sulphoxide as an etchant. The frequency and temperature dependent dielectric constant and dielectric loss of the grown crystal was analysed. The photoluminescence analysis was carried out.

Growth of organic non-linear optical 4-Hydroxy L-Proline (HLP) single crystal by conventional solution method and its structural, vibrational, optical and mechanical characterisations

Good quality and transparent organic non-linear optical crystal 4-Hydroxy L-Proline (HLP) was grown by slow evaporation solution technique (SEST), which has the size of 10 × 5 × 5 mm3. The crystal system was identified and lattice parameters were measured by single-crystal X-ray diffraction. Functional groups of HLP are identified by FTIR spectrum measurement. The optical quality of the grown crystal was measured by UV–vis–NIR analysis. The mechanical stability of the grown HLP crystal was tested by Vickers microhardness analysis and the work hardening co-efficient value was also calculated. The dielectric constant and loss studies were carried out at various temperature to establish the dielectric nature of the HLP crystal. The frequency and temperature response of the dielectric property of the crystal was measured. The second order non-linear optical (NLO) property of the crystal was confirmed by powder Kurtz-Perry technique.

Studies on 2-amino-5-nitropyridinium nitrate (2A5NPN): A semi-organic third order nonlinear optical single crystal

2-amino-5-nitropyridinium nitrate (2A5NPN) is a semi-organic nonlinear optical crystal and optically good quality 2A5NPN single crystals were successfully grown by slow evaporation solution growth technique (SEST) at ambient temperature. The crystallographic structure of the grown crystal was determined by single crystal X-Ray diffraction analysis and it belongs to Monoclinic crystal system with centro symmetric crystalline nature. The crystallinity of the grown crystal was confirmed by powder X-ray diffraction analysis. The other physical properties of grown crystals are also characterized using TG-DTA, UV-Visible NIR, chemical etching, photoconductivity and Z-scan measurements. The Z-scan method reveals that the 2A5NPN crystal possesses multi photon absorption behaviour and the significantly higher third order susceptibility and it is a promising potential NLO material.

Growth of organic nonlinear optical (NLO) ammonium D,L-tartrate (AMT) single crystal by conventional and unidirectional method and its characterization

Abstract High-quality, transparent uniaxial ammonium D,L-tartrate (AMT) single crystal having dimension of 15 mm diameter and 60 mm length was grown by Sankaranarayanan–Ramasamy (SR) method with a growth rate of 1 mm per day. Single-crystal X-ray diffraction was carried out to confirm the AMT crystals. The presence of functional groups of crystallized AMT molecules were identified by FTIR spectral analysis. The dislocation density of the AMT crystals grown by slow evaporation solution technique (SEST) and SR method were characterized using chemical etching analysis. A comparative laser damage threshold analysis was made on the AMT crystals grown by conventional and SR method which shows that the crystal grown by SR method has higher damage threshold. The SR method grown AMT crystal has higher microhardness and also higher optical transmittance compared to conventional method grown crystal. The thermal properties of the SEST and SR method grown AMT crystals were measured by photoacoustic spectrum analysis. The second harmonic generation efficiency of AMT was determined using the powder Kurtz–Perry technique.

Directional growth, physicochemical and quantum chemical investigations on pyridinium 2-carboxylate: 4-nitrophenol (P2C4N) single crystal for nonlinear optical (NLO) applications

An organic nonlinear optical (NLO) single crystal of pyridinium 2-carboxylate: 4-nitrophenol (P2C4N) was grown by the Sankaranarayanan-Ramasamy (SR) method using the (1 1 −1) plane. A transparent crystal of size 180 mm in length and 10 mm in diameter was grown over a period of 60 days. The lattice parameters and the molecular structure of the grown crystal were confirmed by single crystal XRD and nuclear magnetic resonance (NMR) spectrum analysis, respectively. The crystalline perfection of the SR method-grown crystal was evaluated by HRXRD analysis; from the observed results, it is evident that the crystal quality is quite good. UV-Vis-NIR analysis shows that the SR method-grown crystal has good transparency (90%) in the visible and NIR regions. The band gap of the title crystal was estimated by the Taucs plot method and was found to be 3 eV. The title material is thermally stable up to 141 °C, and it demonstrates positive photoconductive behaviour. Vickers microhardness studies revealed that the grown crystal can be categorized as a soft material. The laser damage threshold of P2C4N was found to be 2.9 GW cm−2, which shows that the grown crystal possesses excellent resistance to high power radiation. Z-Scan studies proved that the grown crystal possesses self-defocusing effects and negative nonlinearity. The theoretical spectra were calculated using the B3LYP/cc-pVTZ basis set and were compared with the experimental FT-IR and FT-Raman spectra of the title molecule. The full vibrational assignments of the observed spectra have been proposed by normal coordinate analysis (NCA) followed by force-field calculations. Quantum chemical studies, such as optimized geometry, HOMO–LUMO, natural bonding orbital (NBO) analysis, AIM analysis, hyperpolarizability and molecular electrostatic potential (MEP) were performed for the title molecule. The results are discussed in detail.

Investigations on structural, optical, dielectric, laser damage threshold and NLO properties of 2-amino-5-nitropyridinium p-tolunesulfonate (2A5NPT) single crystal

The highly efficient organic nonlinear optical (NLO) 2-amino-5-nitropyridinium p-tolunesulfonate single crystals have been grown by conventional slow evaporation technique using Millipore water as a solvent in the period of 60 days. The single crystal XRD confirms the unit cell parameters of the grown crystal. The morphology of the grown crystal was analyzed using Bruker-Kappa APEXII single crystal instrument and their planes are identified. The optical transmittance range and the cut-off wavelength are recorded using UV-Visible NIR characterization. The laser damage threshold (LDT) studies were carried out using Nd:YAG laser and LDT value was found to be 3.7 GW/cm2. The dielectric constant and dielectric loss of 2A5NPT single crystals were measured. The SHG efficiency was tested by powder Kurtz-Perry technique and the SHG efficiency is 15 times greater than that of standard KDP material.

Comparative investigations of nonlinear optical (NLO) ammonium D,L-tartrate (AMT) single crystals grown by conventional and unidirectional method

Unidirectional AMT single crystal of diameter 15 mm and length 55 mm was grown with the growth period of 60 days by Sankaranarayanan-Ramasamy (SR) method. The growth conditions have been optimized. A maximum growth rate of 1 mm per day was realized. Employing SEST method AMT crystal of size 12×10×5 mm3 has been grown. The conventional and SR method grown AMT crystals were subjected to TG-DTA, Vickers microhardness, UV-Vis NIR, dark current and photocurrent measurements. TG-DTA evaluated the thermal properties of the grown crystal. AMT was found to be thermally stable up to 206°C. The mechanical behavior of the conventional method grown AMT crystal is affected by the presence of solvent inclusions and it reveals the SR method grown crystal is harder than the AMT crystal grown by conventional method. The SR method grown AMT crystal has 15% higher transmittance as against conventional slow evaporation method grown crystal. The obtained photocurrent value for SR and conventional method grown AMT crystal...