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.     

Microhardness studies on nonlinear optical L-alanine single crystals

Vickers and Knoop microhardness tests were carried out on grown L-alanine single crystals by slow evaporation technique over a load range of 10–50 g on selected broad (2 0 3) plane. Vickers (H _v ) and Knoop (H _k ) microhardness for the above loads were found to be in the range of 60–71 kg/mm² and 35–47 kg/mm², respectively. Vickers microhardness number (H _v ) and Knoop microhardness number (H _k ) were found to increase with increasing load. Meyer’s index number (n) calculated from H _v shows that the material belongs to the soft material category. Using Wooster’s empirical relation, the elastic stiffness constant (c ₁₁) was calculated from Vickers hardness values. Young’s modulus was calculated using Knoop hardness values. Hardness anisotropy has been observed in accordance with the orientation of the crystal.     

Growth, optical transmission and X-ray photoemission studies of BaB2O4 single crystals

Beta barium borate (-BBO) crystals have been grown by the top seeded solution growth technique (TSSG) using Na₂O as a flux. The crystals exhibited high transparency and the absence of inclusions and found to have sodium contamination in the range 150 to 230 p.p.m. The effect of this contamination on some crystal properties of interest has been investigated. The presence of impurities causes optical absorption below 550 nm in BBO crystals of both and -phases. X-ray photo emission spectroscopy (XPS) measurements performed on these crystals show that sodium gives rise to a measurable shift in the binding energies of the constituent ions. Further, the results show that Na⁺ ions enter into the lattice substitutionally and provide charge trapping sites close to the band edge.     

Growth and characterization of some novel crystals for nonlinear optical applications

The advent of high intensity lasers coupled with the recent advances in crystal technology has led to rapid progress in the field of nonlinear optics. This article traces the history of materials development that has taken place over the past forty odd years and dwells on the current status in this important area. The materials aspect is discussed under three classes viz. inorganic, organic and semiorganic crystals. In the end, some of the crystal growth work that has been carried out in author’s laboratory is presented.     

Growth of Cu2+ and Mg2+ doped nonlinear optical LATF crystals and their characterization

Single crystals of pure, Cu²⁺ and Mg²⁺ doped l-arginine trifluoroacetate (LATF) have been grown by the temperature lowering method. The presence of Cu²⁺ and Mg²⁺ was determined by atomic absorption spectroscopy (AAS). Single crystal X-ray diffraction studies were performed to calculate the lattice parameters of the pure and doped crystals. Absorption of these crystals was analyzed and the result confirms that they possess low absorption in the range 230–1100 nm. Thermal analysis (TGA, DTA) and Fourier transform infrared (FTIR) spectroscopy were carried out to investigate the thermal behavior and molecular vibrations of these crystals, respectively. The second harmonic generation (SHG) measurement reveals the NLO properties of pure and doped crystal. Surface morphologies of these crystals were also observed and studied in detail by atomic force microscopy.     

Growth and characterization of 4-methyl benzene sulfonamide single crystals

Single crystals of 4-methyl benzene sulfonamide (4MBS) were successfully grown from aqueous solution by low temperature solution growth technique. The grown crystal was characterized by single crystal XRD and powder XRD methods to obtain the lattice parameters and the diffraction planes of the crystal. UV–vis–NIR absorption spectrum was used to measure the range of optical transmittance and optical band gap energy. The optical transmission range was measured as 250–1200 nm. FTIR spectral studies were carried out to identify the presence of functional groups in the grown crystal. The thermal behavior of the crystal was investigated from thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC) study. The absence of SHG was noticed by Kurtz and Perry powder technique. The third order NLO behavior of the material was confirmed by measuring the nonlinear optical properties using Z-scan technique and it was found that the crystal is capable of exhibiting saturation absorption and self-defocusing performance.     

Linear and nonlinear optical properties of 4-nitrobenzoic acid (4-NBA) single crystals

4-Nitrobenzoic acid (4-NBA) single crystals were studied for their linear and nonlinear optical properties. The crystals were grown by slow solvent evaporation method at room temperature. The structure and functional groups were confirmed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopic studies. The 4-NBA crystal has an optical absorption at 263 nm and a wide transparency window for the visible light. Theoretical predictions for the measured optical absorption and charge transfer mechanism in 4-NBA were explained with HOMO and LUMO illustrations. The crystal is found to be birefringent and has produced an optical quality interference pattern. The optic plane of the crystal is observed along \(\langle 1 0 0\rangle \) direction. The crystal exhibits nonlinear optical effects viz. reverse saturable absorption and self-defocussing of laser beam. Considerable nonlinear refraction \((n_{2})\) and nonlinear absorption (\(\beta \)) coefficients and third-order nonlinear optical susceptibility \((\chi ^{(3)})\) were determined using Z-scan technique.     

Growth and characterization of L-Glycine thiourea nonlinear optical single crystal for optoelectronic applications

l-Glycine thiourea single crystals have been grown by slow evaporation solution growth technique (SEST). The cell parameters were estimated from single crystal X-ray diffraction analysis and it was found that the material crystallized in the orthorhombic symmetry with space group P2₁2₁2₁ and the theoretical data were estimated. The powder X-ray analysis proved its crystalline nature without the formation of secondary phases. The presence of functional groups and the nature of bonds appearing in the material were identified by FTIR spectroscopy. Optical constants were estimated by UV–Visible spectrum and the lower cut off wavelength was observed at 200 nm. The scanning electron microscope analysis has been carried out to determine the surface morphology of the grown crystal. Energy dispersive spectrum was done to confirm the composition of elements present in the title material. The second harmonic generation (SHG) efficiency was done by Kurtz powder technique and the conversion efficiency was compared with KDP crystal of the title compound. Third order nonlinear optical susceptibility was measured using z-scan technique and it was found that the crystal has a positive refractive index which is self focusing in nature. The obtained results showed that l-glycine thiourea crystals are potential materials for NLO device fabrication.     

Growth and characterization of RuO2 single crystals

Using the vapor transport technique in a flowing oxygen system, we have grown the largest single crystals of RuO₂ ever reported (10 mm × 5 mm × 5 mm). Polycrystalline RuO₂, a mixture of polycrystalline RuO₂ and purified Ru metal powder, or purified Ru metal powder were used as the starting material. Optimum conditions are given for growing large high quality crystals. The morphology, stoichiometry and resistivity of selected single crystals of RuO₂ are discussed.     

Microhardness studies of SnI2 and SnI4 single crystals

The variation in the microhardness of tin-di-iodide (SnI₂) and tin-tetra-iodide (SnI₄) crystals has been determined using Vicker’s microhardness indentor. It is observed that the microhardness of the crystals depends on the applied load and is independent of the duration of loading. Vickers Hardness Numerals (vhn) for SnI₂ is found to be greater than that of SnI₄ crystals. Mayer’s equation and implications have been discussed.     

Microhardness,FTIR and transmission spectral studies of Mg2+ and Zn2+ doped nonlinear optical BTCC single crystals

Pure, Mg²⁺ and Zn²⁺ doped BTCC single crystals are grown from their aqueous solutions at 301 K. The grown crystals are characterized by single crystal XRD, FTIR and UV–Vis-NIR spectral studies. The preliminary investigations of the UV–Vis-NIR spectra on the doped samples suggest an increased percentage of transmission in comparison to pure BTCC crystals. The SHG efficiency of the metal doped BTCC crystals is found better than the pure ones. It is estimated from the microhardness studies that the mechanical strength of the BTCC crystals are improved due to the metallic (Mg²⁺ and Zn²⁺) substitutions.     

Growth and thermal studies of SnSe single crystals

Single crystals of SnSe have been grown by a direct vapour transport (DVT) technique. The confirmation of single crystallinity and lattice parameter determination of the grown crystals have been made by using electron and X-ray diffraction techniques respectively. The thermal analysis of the crystals has been studied by the well known TGA and DTA techniques. The results obtained during the analysis showed the stability of SnSe phase at higher temperatures. The implications of the results have been discussed.     

Growth of CuInTe2 single crystals by iodine transport and their characterization

The single crystals with stoichiometry close to 1:1:2 of CuInTe₂ (CIT) have been grown by chemical vapor transport (CVT) technique using iodine as the transporting agent at different growth temperatures. Single crystal X-ray diffraction studies have confirmed the chalcopyrite structure for the grown crystals and the volume of unit cell is found to be the same for the crystals grown at different conditions. Energy dispersive X-ray (EDAX) analysis of CIT single crystals grown shows almost the same stoichiometric compositions. Scanning electron microscope (SEM) analysis reveals kink, step and layer patterns on the surface of CIT single crystals depending on the growth temperatures. The optical absorption spectra of as-grown CIT single crystals grown at different conditions show that they have same band gap energies (1.0405 eV). Raman spectra exhibit a high intensity peak of A₁ mode at 123 cm^?1. Annealed at 473 K in nitrogen atmosphere for 40 h CIT single crystals have higher hole mobility (105.6 cm²V^?1s^?1₎ and hole concentration (23.28 × 10¹⁷ cm^?3) compared with values of hole mobility (63.69 cm² V^?1 s^?1) and hole concentration (6.99 × 10¹⁵ cm^?3) of the as-grown CIT single crystals.     

Growth,characterization and dielectric property studies of gel grown barium succinate single crystals

. Single crystals of barium succinate (BaC4H4O4) were grown in silica gel medium using controlled chemical reaction method. Plate-like single crystals of size up to 3 × 2 × 0·2 mm³ was obtained. Single crystal X-ray diffraction (XRD) studies confirmed that structure of the title compound is tetragonal. Powder X-ray diffraction (PXRD) pattern of the grown crystal and the Fourier transform infrared (FT–IR) spectrum in the range 400–4000 cm^–1 are recorded. The vibrational bands corresponding to different functional groups are assigned. Thermal stability of the grown crystals is confirmed by differential scanning calorimetry (DSC). Dielectric constant and dielectric loss have been calculated and discussed as a function of frequency at different temperatures.     

Growth and characterization of Ni substituted Bi2Se3 single crystals

Journal of Superconductivity and Novel Magnetism - In this article, we report synthesis and magneto-transport analysis of Ni substituted Bi2Se3 crystals. Phase purity and crystalline growth are...