Studies on the synthesis, structure, growth and physical properties of an organic NLO crystal: 2-Amino-5-nitropyridinium Phenolsulfonate

A noncentrosymmetric crystal was prepared from 2-amino-5-nitropyridine (2A5NP) and p-Phenolsulfonic acid, which was designed for second harmonic generation. Good quality single crystals of 2-amino-5-nitropyridinium Phenolsulfonate (2A5NPP) were successfully grown by the slow evaporation method with dimensions 10 × 4 × 3 mm³. The unit cell dimensions were determined from single crystal X-ray diffraction studies. The structural perfection of the grown crystals has been analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements. Fourier transform infrared (FTIR) spectral studies have been performed to identify the functional groups. The optical transmittance window and the lower cutoff wavelength of the 2A5NPP have been identified by UV-vis-NIR studies. Thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study its thermal properties. Powder test with Nd:YAG laser radiation shows a high second harmonic generation. The laser induced surface damage threshold for the grown crystal was measured using Nd:YAG laser.     

The growth of l-Glutamic acid hydrochloride crystals by Sankaranarayanan-Ramasamy (SR) method

An efficient semiorganic nonlinear optical crystal l-Glutamic acid hydrochloride has been grown by using the novel uniaxial crystal growth method of Sankaranarayanan and Ramasamy with a slight modification in the experimental setup. This method allows the crystals to grow in one specified axis with well developed facet. The grown crystal has a cylindrical morphology with good optical quality. The grown crystal has been characterized by powder X-ray diffraction and UV-Vis-NIR analyses. The NLO efficiency of the crystal has been confirmed by using the Kurtz powder technique.     

Synthesis, structure, growth and physical properties of a novel organic NLO crystal: 1,3-Dimethylurea dimethylammonium picrate

A novel noncentrosymmetric crystal was prepared from 1,3-dimethylurea dimethylammonium picrate, C₁₁H₁₈N₆O₈ (DMUP), which was designed for second harmonic generation. DMUP crystals exist in noncentro symmetric space group Cmc2₁ with unit cell dimensions a = 14.288(4) Å, b = 17.023(5) Å, c = 6.8268(13) Å, α = β = γ = 90° and volume = 1660.5(8) Å³. The crystal structure of DMUP has been determined using single crystal X-ray diffraction studies. The single crystals of DMUP were successfully grown by the slow evaporation method with dimensions 10 mm × 4 mm × 3 mm using dimethylformamide as solvent. The structural perfection of the grown crystals has been analysed by High-resolution X-ray diffraction (HRXRD) rocking curve measurements. Powder test with Neodymium-doped Yttrium aluminum garnet (Nd:YAG) laser radiation shows a high second harmonic generation (SHG). The laser induced surface damage threshold for the grown crystal was measured using Nd:YAG laser.     

Studies on the growth and physical properties of nonlinear optical crystal: 2-Amino-5-nitropyridinium-toluenesulfonate

Single crystals of 2-amino-5-nitropyridinium-toluenesulfonate (2A5NPT) were grown by the slow cooling method. The unit cell dimensions were determined from single crystal X-ray diffraction studies. The thermal parameters - thermal diffusivity (α), thermal effusivity (e), thermal conductivity (K) and heat capacity (C_p) of 2A5NPT were measured by an improved photopyroelectric technique at room temperature. Single and multiple shot experiments performed on the grown crystals for the second harmonic of pulsed Nd:YAG laser (532 nm) show that it exhibits a high laser damage threshold which is a favorable property for nonlinear optical applications. Dielectric constant and dielectric loss of the grown crystal were evaluated for the frequency range 1 kHz-1 MHz in the temperature region 40-130 °C. Hardness values were measured using Vickers hardness measurement.     

Investigation on growth and characterization of a new inorganic NLO material: Zinc sulphate (ZnSO4:7H2O) doped with Magnesium Sulphate (MgSO4:7H2O)

Single crystal of Zinc sulphate doped with Magnesium sulphate, a nonlinear material, was grown from aqua solution by slow evaporation method at room temperature. Good quality single crystals were grown by slow evaporation technique (four weeks) and the crystals subjected to single crystal X-ray diffraction and FT-IR analyses to confirm the formulation of new crystals. The TGA and DTA reveal that the material has good thermal stability. The UV-Vis spectrum confirms that the material has wide optical transparency and the existence of the second harmonic generation has also been ascertained by Kurtz powder method.     

Synthesis, crystal growth and characterization of organic material: N-Bromosuccinimide (NBS) for NLO applications

The organic nonlinear optical crystal of N-Bromosuccinimide (NBS) was grown by slow cooling solution growth technique using methanol as solvent. Single crystal and powder X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectral analyses were carried out to confirm the NBS crystals. The ultra violet (UV)-Visible and photoluminescence spectral studies were carried out, the green band at 2.02 eV can be attributed to radiative recombination between deep donors and shallow acceptors. The second harmonic generation (SHG) behaviour of NBS was tested by Kurtz-Perry powder technique. The hardness behaviour, laser damage threshold and dielectric characteristics of NBS crystals were studied.     

Dielectric and structural studies on sulphamic acid (SA) single crystal

Sulphamic acid single crystal of the size 14 × 8 × 6 mm³ has been grown by slow cooling solution growth method at 35.5 °C. Fermi resonance vibrations of N-S stretching and SO₃ rocking have been observed from micro-Raman analysis. Different shapes of etch patterns have been observed for etchants like water, ethanol and HCl for different etching periods. The dielectric constant and dielectric loss have been measured for different frequencies at different temperatures.     

Crystal structure and characterization of a novel organic crystal: 4-Dimethylaminobenzophenone

Single crystals of a novel organic material, dimethylaminobenzophenone were grown from aqueous solution employing the technique of controlled evaporation. Dimethylaminobenzophenone belongs to the monoclinic system, with a = 12.5755(7) Å, b = 7.9749(4) Å, c = 13.0946(7) Å, α = 90°, β = 111.6380(10)° and γ = 90°. Fourier transform infrared study has been performed to identify the functional groups. The transmittance of dimethylaminobenzophenone has been used to calculate the refractive index n; the extinction coefficient K and both the real ?_r and imaginary ?_i components of the dielectric constant as functions of photon energy. The optical band gap of dimethylaminobenzophenone is 2.9 eV. The structural prefection of the grown crystals has been analyzed by high-resolution X-ray diffraction rocking curve measurements. Thermo gravimetric analysis and differential thermal analysis have also been carried out, and the thermal behavior of dimethylaminobenzophenone crystal has been studied. The dielectric properties and mechanical properties have been investigated.     

Growth and characterization of pure and potassium chloride-doped Zinc Tris-thiourea Sulphate (ZTS) single crystals

Single crystals of pure and potassium chloride-doped Zinc Tris-thiourea Sulphate (ZTS) were grown from aqueous solution by slow evaporation technique. The grown crystals were subjected to various studies such as XRD, FTIR, atomic absorption, SHG and TGA-DTA studies. The melting point and density of the grown crystals were also measured. The various studies revealed the incorporation of the impurity (potassium chloride) into ZTS crystals and the investigations indicated that the impurity played an important role in the changes of the spectral and structured properties of ZTS crystals.     

Growth and characterization of nonlinear optical diglycinehydrobromide single crystals

Diglycinehydrobromide (DGHB) a semi-organic nonlinear optical material with the molecular formula C₄H₁₁N₂O₄⁺Br⁻ has been synthesized at ambient temperature. Chemical composition of the synthesized material was confirmed by CHN analysis. Functional groups present in the sample were identified by FT-IR and Raman spectral analysis. Bulk single crystals of DGHB were grown by slow evaporation method at constant temperature. Powder X-ray diffraction pattern of the grown DGHB has been indexed. Unit cell parameters of the grown DGHB crystals were determined. Thermal stability of DGHB was determined from TGA/DTA and DSC response curves. Mechanical hardness of the grown crystal DGHB was determined and Vickers hardness number was calculated. The optical transparency and the lower cutoff of UV transmission were identified from the recorded UV-vis-IR spectrum of DGHB. The Kurtz powder second harmonic generation test shows that the crystal is a potential candidate for optical second harmonic generation.     

Crystal structure and characterization of a novel organic optical crystal: 2-Aminopyridinium trichloroacetate

2-Aminopyridinium trichloroacetate, a novel organic optical material has been synthesized and crystals were grown from aqueous solution employing the technique of controlled evaporation. 2-Aminopyridinium trichloroacetate crystallizes in monoclinic system with space group P2₁/c and the lattice parameters are a = 8.598(5) Å, b = 11.336(2) Å, c = 11.023(2) Å, β = 102.83(1)° and volume = 1047.5(3) Å³. High-resolution X-ray diffraction measurements were performed to analyze the structural perfection of the grown crystals. Thermal analysis shows a sharp endothermic peak at 124 °C due to melting reaction of 2-aminopyridinium trichloroacetate. UV-vis-NIR studies reveal that 2-aminopyridinium trichloroacetate has UV cutoff wavelength at 354 nm. Dielectric studies show that dielectric constant and dielectric loss decreases with increasing frequency and finally it becomes almost a constant at higher frequencies for all temperatures. The negative nonlinear optical parameters of 2-aminopyridinium trichloroacetate were derived by the Z-scan technique.     

Crystal structure,crystal growth and characterization of novel organic NLO material: 2,4,4′-Trimethoxybenzophenone

Single crystals of 2,4,4′-Trimethoxybenzophenone (TMB) were grown by slow evaporation solution growth technique using acetone as a solvent. TMB crystallizes in monoclinic system with noncentrosymmetric space group, P2₁, and the cell parameters are a = 8.485(5) Å, b = 8.173(5) Å, c = 10.254(5) Å, β = 102.085(5)° and V = 695.3(7) Å³. Gaussian 98W has been used to calculate the first-order hyperpolarizability of TMB. Fourier transform infrared (FTIR) spectroscopic studies were performed for the identification of different modes present in the compound. TMB crystals are transparent in the entire visible region and have a lower optical cutoff at 400 nm. The powder second harmonic generation efficiency of TMB was determined to be 6 times that of urea. The observed SHG response for TMB is due to effective charge transfer arising from the donor–π–acceptor–π–donor (D–π–A–π–D) structure of the molecule. From the thermogravimetric/differential thermal analysis, the TMB was found to be thermally stable up to 79 °C. The dielectric and mechanical properties of the TMB were also studied.     

Growth and characterization of glycinium oxalate (GOX) single crystals

Glycinium oxalate (GOX) single crystals were grown by slow cooling solution growth method. The X-ray diffraction and Fourier transform infra red studies confirm the grown crystal. The hardness values of GOX are found to be higher than glycine. The increase in hardness may be due to the C-H---O bonding. The UV-Visible studies show that GOX crystals can be used for nonlinear applications. The dielectric measurement indicates that the GOX crystals have domains of varying sizes and varying relaxation time. The SHG output of GOX was 210 mV at given pulse energy of 5 mJ/s and KDP was 240 mV.     

Growth and characterization of a new non-linear optical l-histidinium dihydrogen phosphate single crystal

New non-linear optical single crystal of l-histidinium dihydrogen phosphate was grown by slow evaporation and temperature lowering technique from aqueous solution. Solubility studies have been carried out for three different solvents (water, acetone and ethanol). The grown crystals have been subjected to single crystal X-ray diffraction analysis to identify the cell parameters and morphology. Optical transmission spectra reveal the optical properties of the grown crystals. The NLO property of the crystal has been confirmed by Kurtz SHG test. Comparing the output power it has been confirmed that l-HDP crystals possess higher SHG efficiency than KDP. Thermal studies were carried out to check the thermal stability of the crystals.     

Growth and characterization of the nonlinear optical single crystal: l-Lysinium trifluoroacetate

A novel organic nonlinear optical (NLO) crystal, l-lysinium trifluoroacetate (with the molecular formula as (H₃N)⁺CH₂CH₂CH₂CH₂CH(H₃N)⁺COO⁻CF₃COO⁻), was grown by the controlled evaporation of its aqueous solution. The X-ray powder diffraction was used to determine its cell parameters. The calculated results based on the diffraction data reveal that l-lysinium trifluoroacetate belongs to the monoclinic crystallographic system, space group P2₁, with cell parameters: a = 5.698(5), b = 23.542(8), c = 8.500(6) Å, β = 91.62(9)°, V = 1139.96 Å³. The grown crystals were characterized by the elemental analyses, Fourier transform infrared and Raman spectra. Experiments of thermogravimetric (TG) and differential thermal analysis (DTA) were carried out to study its thermal properties. The optical behaviours, including transmission spectrum and second harmonic generation (SHG), were investigated to study its linear and nonlinear optical properties. Optical nonlinearities were analyzed and discussed involved with its crystal structure.     

Growth and characterization of l-asparagine thiourea monohydrate (LATM): A nonlinear optical single crystal

l-Asparagine thiourea monohydrate (LATM) single crystal has been successfully grown (size 15 × 10 × 3 mm³) by slow evaporation solution growth technique. To the best of our knowledge this is the first report to the literature. The grown crystal was characterized by powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopic analysis. The UV-Vis transmittance spectrum shows that the material has wide optical transparency in the entire visible region. The relative second harmonic generation was confirmed by Kurtz powder technique. The mechanical properties have been studied using Vickers microhardness tester. The birefringence of the crystal was measured in the visible region and it was found to vary with the wavelength.     

Feasibility study on Czochralski (Cz) growth of 3-methoxy 4-hydroxy benzaldehyde (MHBA) single crystals for nonlinear optical applications

Reported large nonlinear optical coefficients such as d₂₂ = 23.8d₃₆^KDP, d₂₁ = 13.5d₃₆^KDP, d₂₃ = 29.1d₃₆^KDP, d₂₅ = 12.8d₃₆^KDP of 3-methoxy 4-hydroxy benzaldehyde (MHBA) attract research on its bulk crystal growth for device application. The X-ray rocking and X-ray topographic studies of Cz-grown organic monoclinic crystals invariably reveal closely aligned sub-crystals which made melt growth difficult. In this context, the single crystal growth of MHBA by Czochralski pulling technique has been successfully demonstrated for the first time in the literature. Comparison study of obtained X-ray powder diffraction data with the literature confirmed the monoclinic structure. High-resolution X-ray diffraction (HRXRD) study confirms the better crystalline perfection of the grown crystal in comparison to that of solution-grown crystals and revealed the optimization of the growth process along [211¯] direction. TG, DTA and optical transmission studies carried out on the grown crystal exhibit its thermal and optical properties for SHG application.     

Effect of annealing of poly(3-hexylthiophene)/fullerene bulk heterojunction composites on structural and optical properties

Composite films of P3HT/PCBM-(poly[3-2,5-diyl]/[6,6]-phenyl C₆₁ butyric acid methyl ester) are widely used as an active layer in plastic solar cells. We have studied the influence of thermal annealing on nano-structural and optical properties of thin spin-coated P3HT/PCBM-films. Their structural properties were studied by X-ray diffraction in grazing incidence geometry. It was found that the crystallinity of the investigated films is drastically increased upon annealing. Furthermore, the anisotropic dielectric function of such films was determined by spectroscopic ellipsometry. Significant changes were observed both in parallel and perpendicular components of the dielectric function after annealing. These changes were attributed to the formation of crystalline domains upon annealing.     

Layer-by-layer growth of thin epitaxial Fe3Si films on GaAs (001)

Molecular beam epitaxy of Fe₃Si films on GaAs (001) is studied in situ by grazing incidence X-ray diffraction. Fe₃Si grows layer-by-layer. During deposition the growth front roughens as indicated by the damping of the X-ray oscillations and corresponding atomic force micrographs. The X-ray oscillations are modified during growth at substrate temperatures of 180 °C and below.     

Epitaxial growth of transparent tin oxide films on (0 0 0 1) sapphire by pulsed laser deposition

The growth of epitaxial SnO₂ on (0 0 0 1) sapphire using pulsed laser deposition is examined. X-ray diffraction analysis shows that the films are highly a-axis oriented SnO₂ with the rutile structure. Three distinct symmetry-equivalent in-plane epitaxial orientations were observed between the film and substrate. With increasing growth temperature, both the growth rate and surface roughness increase with columnar grain formation. Carrier concentration ranged from 10¹⁷ to 10¹⁹ cm⁻³, with mobility of 0.5-3 cm²/V s. The resistivity of the films increases with increasing growth temperature, suggesting a lower density of oxygen vacancy-related defects formed during high temperature deposition.