Synthesis,crystal growth,structural, spectral,thermal, mechanical,linear and nonlinear optical studies of organic single crystal 4-Iodo 4-nitrostilbene (IONS): A potential NLO material

An organic nonlinear optical material 4-Iodo 4-nitrostilbene (IONS) has been synthesized and good optical quality single crystal was grown from ethyl methyl ketone solvent by the solution growth technique. Single and powder X-ray diffraction analyses reveals that the grown crystal belongs to monoclinic crystal system with noncentrosymmetric space group ‘P2₁’ and it has good crystalline nature. Functional groups and molecular structure of the title compound were confirmed by FTIR and ¹H NMR respectively. The UV–Vis–NIR absorption study reveals no absorption in the visible region and the cut-off wavelength was found to be at 412.84 nm, TG/DTA, mass spectral analysis, photoluminescence and microhardness studies have been carried out for the grown crystals and results are discussed in detail. The second harmonic efficiency of the IONS was determined by Kurtz–Perry powder technique which reveals that the IONS crystal (3.1 V) has greater efficiency i.e., 143 times to that of KDP (21.7 mV).     

Optical,thermal and microhardness studies on dichloridobis(1-ethyl-2,6-dimethylpyridinium-4-olate-κO) zinc(II)

A newly engineered host–guest hydrogen bonded metal–organic coordination compound, dichloridobis(1-ethyl-2,6-dimethylpyridinium-4-olate-κO)zinc(II) (EDMPZC), [C₁₈H₂₆Cl₂N₂O₂Zn] has been designed and synthesized. Single crystals of dimensions (5 × 5 × 2 mm³) have been grown by slow evaporation technique. The unit cell dimensions and morphology are identified from single crystal XRD analysis. Further, it has been characterized by FT-IR absorption, FT-NMR spectroscopy, elemental analyses (CHN and XRF) and their thermal stability investigated following TG/DTA and DSC techniques. The thermal transport properties, thermal effusivity (e), thermal diffusivity (α), thermal conductivity (K) and heat capacity (C_p) have been measured by the photopyroelectric technique at room temperature. The laser damage threshold of the grown crystal was measured using Q-switched Nd:YAG laser (1064 nm, 10 ns, 10 Hz). The mechanical stability of the crystal has been studied from the Vicker's microhardness measurement. The UV absorption edge is 262 nm with a wide optical transmittance window covering the UV–Vis–NIR region and the optical band gap of the compound is found to be 3.5 eV.     

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.     

Effect of magnesium chloride on growth,crystalline perfection,structural, optical,thermal and NLO behavior of γ-glycine crystals

In the present study, single crystals of γ-glycine possessing excellent non-linear optical properties were successfully grown at room temperature in the presence of magnesium chloride (MgCl₂) for the first time by using the slow solvent evaporation method. The second harmonic conversion efficiency of γ-glycine crystal was determined using Kurtz powder technique with Nd:YAG laser and was found to be 6 times greater than that of the standard inorganic sample potassium dihydrogen phosphate (KDP). The crystalline perfection of the grown crystal was analyzed using high-resolution X-ray diffraction (HRXRD) rocking curve measurements. The grown crystal was subjected to single crystal XRD and powder XRD, which confirmed that the crystal has hexagonal structure and belongs to space group P3₁. Inductively coupled plasma optical emission spectrometry (ICP-OES) was carried out to quantify the concentration of Mg element in the grown γ-glycine single crystal. Fourier transform infrared (FTIR) spectral studies were made to identify the functional groups. The optical band gap was likewise estimated for γ-glycine crystal using UV–vis–NIR study. The optical measurements of γ-glycine crystal helped to calculate the optical constants such as refractive index (n), the extinction coefficient (K), electric susceptibility (χ_c) and both the real (∈_r) and imaginary (∈_i) components of the dielectric permittivity functions of photon energy, which is essentially required to develop optoelectronic devices. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study thermal stability and decomposition point of the grown crystal.     

Study of optimum growth condition and characterization of zinc mercury thiocyanate (ZMTC) single crystals in silica gel

Some bimetallic thiocyanate complexes exhibit excellent nonlinear optical properties. Single crystals of one such material, zinc mercury thiocyanate ZnHg(SCN)₄ have been grown in silica gel with gel technique by the process of diffusions and the optimum growth condition has been studied. Crystals of 4 mm length have been obtained. Their structural, optical and thermal properties have been studied. Structural analysis was carried out using an X-ray diffractometer and the crystal structure was confirmed to be tetragonal. Fourier transform infrared spectrum was obtained to confirm the functional groups. Transmission spectrum has been recorded in the solution state and the cut-off wavelength has been determined. Thermal stability of the grown crystal has been investigated by thermogravimetric and differential thermal analyses. Nonlinear optical property of the crystal has been confirmed using the Kurtz powder technique and a study of its second harmonic generation efficiency in comparison with urea has been made.     

Effect of l-alanine,Mn(II) and glycine dopants on the structural,crystalline perfection,second harmonic generation (SHG), dielectric and mechanical properties of BTCA single crystals

Bis thiourea cadmium acetate (BTCA) single crystals were grown at room temperature with different dopants by aqueous solution technique. The crystal system of the grown crystals with all the dopants was confirmed by powder X-ray diffraction study which confirms that there is no extra phase due to doping of l-alanine (LA), Mn(II) and glycine (Gly). It was further confirmed by FT-IR as well as FT–Raman spectroscopy analysis. The effect of LA, Mn(II) and Gly doping on the crystalline perfection was assessed by high-resolution X-ray diffractometry (HRXRD) analysis which revealed that the grown crystals with Gly doping are more perfect in comparison of other dopants. The SHG efficiency was measured using the Kurtz powder technique and shows that the grown crystals with Gly doping are more efficient in comparison of other dopants which is in tune with crystalline perfection. The low values of dielectric constant and loss also revealed that the grown crystals are defect free. The hardness values were found to be increased by increasing the doping concentration.     

Doping effect of urea on growth,spectral, thermal,mechanical, electrical,nonlinear and optical studies of Sr(HCOO)<Subscript>2</Subscript>·2H<Subscript>2</Subscript>O crystal: enhanced third-order NLO properties with a high laser-induced damage threshold

Pure and urea doped (with 3 different concentrations, viz. 0.005, 0.05, and 0.1 M) strontium formate dihydrate (SFD, Sr(HCOO)₂·2H₂O) single crystals were grown from aqueous solutions by using slow solvent evaporation technique. In order to understand the effect of urea doping on the structural, chemical, thermal, morphological, optical properties of SFD crystals, the grown crystals were characterized by carrying out CHN analysis, powder X-ray diffraction, high resolution X-ray diffraction, Fourier transform infrared spectral, thermogravimetric, UV–Vis–NIR spectral, photoluminescence spectral, second harmonic generation efficiency, and Z-scan measurements. The results obtained indicate that the urea molecule have entered into the SFD crystal matrix and has improved the crystallinity. Also, the results indicate that urea doping significantly tunes the optical and thermal properties without significantly distorting the crystal structure of SFD crystal. The laser damage threshold (LDT) energy for the grown crystal has been measured by using a Q-switched Nd:YAG laser as a source in single-shot mode (1064 nm, 10 Hz, 420 mJ). The result of laser damage threshold (LDT) energy indicates that grown title crystal has excellent resistance to laser radiation than those of some known inorganic NLO materials. Its third-order nonlinear optical properties were investigated by Z-scan technique and proved that the grown crystal possesses two-photon absorptions (TPA) and the self-defocusing effect.     

Phase separation during the melting of oxide borates LnCa4O(BO3)3 (Ln=Y, Gd)

GdCa₄O(BO₃)₃ (GdCOB) and YCa₄O(BO₃)₃ (YCOB) single crystals have been grown from the melt by the Czochralski method. Subsequent DTA analysis of the single crystals showed different behavior for both substances. During the first heating both crystals showed a single sharp melting peak at 1490°C (GdCOB) or at 1504°C (YCOB), respectively. In subsequent heating/cooling runs only GdCOB shows one single peak, whereas YCOB shows five peaks. Moreover, phase separation of the melt can be observed by optical observation and by EDX measurements. This behavior can be explained by a miscibility gap in the YCOB melt. The YCOB crystal is formed from the stoichiometric melt by a monotectic reaction.     

Optical, structural and microhardness properties of KDP crystals grown from urea-doped solutions

Potassium dihydrophosphate single crystals were grown from aqueous solutions onto a point seed using temperature reduction method by doping with different molar values of urea. The characterization of the grown crystals was made by visible and Fourier transform infrared spectroscopy, Vicker's hardness studies, X-ray powder diffraction, non-linear optical and laser damage threshold measurements. By comparing these crystals with the ones grown from the pure solution, it is shown that 0.2-2.0 M of the urea additive enhances the laser damage threshold and the second harmonic efficiency more than by 25 and 20%, respectively. By means of the Bond method using a multipurpose three-crystal X-ray diffractometer it is shown that the presence of urea additive increases the crystal lattice parameter c of the grown crystals, whereas the lattice parameter a is by an order less sensitive to the changing urea concentration in the solution. The Vicker's hardness studies at room temperature carried out on (1 0 0) and (0 0 1) crystallographic planes show an increased hardness of the doped crystals (grown in the presence of urea additive) on the plane (0 0 1) in comparison with that of pure potassium dihydrophosphate crystal.     

Microhardness studies in gel-grown ADP and KDP single crystals

Microhardness studies were carried out on (100) faces of gel-grown ADP and KDP single crystals. Slip lines were observed on (100) face of ADP crystal at the corners of the impressions. Microcracks around the indentation were found on (100) face of KDP crystal from 10g load which spread out as the load increased. Vickers hardness numberH _v decreased with increase in load. ΔH _v at 50g load for solution-grown crystals and gel-grown crystals (present case) was determined. Work hardening indexn for both ADP and KDP crystals was less than 2 showing soft-material characteristics. Using Wooster’s empirical relation, values of C₁₁ from hardness were calculated and found to be close to the reported ones. The work was done under a research project sanctioned by the Council of Scientific and Industrial Research (CSIR), New Delhi.     

Growth and electro-optic studies in mixed (NH4) x K1−x H2PO4 single crystals

Single crystals and mixed crystals of KH₂PO₄ (KDP) and NH₄H₂PO₄ (ADP) were grown with different dopant concentrations of NH₄H₂PO₄ in KH₂PO₄ in solution by Holden’s rotary crystallizer technique. The effect of additives like Borax (Na₂B₄O₇·10H₂O), seed crystal rotation rate and qualities of the crystals were studied. The half-wave voltages (in longitudinal mode) for KDP mixed with 1% ADP (by weight) were found and hence the unclamped (low frequency) electro-optic coefficients (r ₆₃) were calculated for various wavelengths in the visible region of the spectrum. It was noted that the half-wave voltage increases with increase in wavelength and temperature.     

Sunset yellow dyed triglycine sulfate single crystals: enhanced thermal,mechanical, optical and di-/piezo-/ferro-/pyro-electric properties

Single crystals of pure and sunset yellow (SSY) dye doped (0.05 mol%) triglycine sulphate (TGS) were grown by slow evaporation solution technique with the vision to improve the properties of pure TGS crystal. The external morphology of TGS crystal was deduced from its internal crystal structure by using two of the well established models, namely Bravais–Friedel–Donnay–Harker model (B–F–D–H) and Hartman–Perdok (H–P) periodic-bound chain (PBC) vectors model. The selective nature of sunset yellow dye to selectively stain the particular growth sectors of TGS crystal was studied. The structural analysis of both the crystals was carried out using powder XRD and FTIR studies. UV–Vis–NIR spectroscopy was carried out on both pure and SSY dyed TGS crystals to study their linear optical properties and various optical parameters namely optical band gap, refractive index, extinction coefficient and optical conductivity were determined. The thermal stability, melting point, ferro- to para-electric transition temperature, piezoelectric charge coefficient, ferroelectricity and mechanical hardness got enhanced as an effect of SSY dye doping in TGS matrix. The piezoelectric conversion efficiency (d₂₂) got enhanced from ~?56 pm/V for pure TGS single crystal to ~?85 pm/V for SSY doped TGS single crystal. The true-remanent polarization was determined for dyed TGS crystal using ‘Remanent Hysteresis Task’ which showed the presence of very small contributions of non-switchable components. ‘Time-Dependent Compensated (TDC)’ hysteresis task revealed the absence of resistive leakage in SSY-Doped TGS crystal. The pyroelectric coefficient got enhanced from ~?761 µCm^?2/°C for pure TGS single crystal to ~?850 µCm^?2/°C for SSY doped TGS single crystal. Comparative optical, mechanical, dielectric, piezoelectric, ferroelectric and pyroelectric studies provide useful scientific information of an important class of TGS crystals and suggest SSY-Doped TGS crystal as a better alternative than pure TGS crystal for various opto-electronics and ferroelectric devices applications.     

Synthesis,growth and characterization of π conjugated organic nonlinear optical chalcone derivative

A new potentially useful nonlinear optical organic material, 1-(5-chlorothiophen-2-yl)-3-(2,3-dimethoxyphenyl)prop-2-en-1-one, has been synthesized and grown as a high-quality single crystal by the slow evaporation technique. The grown crystals were characterized by FT-IR, NMR, thermal analysis, and UV–visible spectroscopy. The material is thermally stabile up to 111 °C. The mechanical property of the grown crystals was studied using Vickers microhardness tester and the load dependence hardness was observed. The third order nonlinear optical properties of the material such as real and imaginary part of χ⁽³⁾, nonlinear absorption coefficient and nonlinear refractive index were determined using nanosecond laser pulses at 532 nm wavelength by employing Z-scan technique. The nonlinear refractive index is found to be of the order of 10⁻¹¹ cm² W⁻¹. The magnitude of third order susceptibility is of the order of 10⁻¹³ esu. The observed increase in the third order nonlinearity in these molecules clearly indicates the electronic origin. The compounds exhibit good optical limiting at 532 nm. The best optical limiting behavior of this molecule is due to the substituted strong electron donor.     

Studies on growth and characterization of an NLO crystal: L-alanine hydrogen chloride (LAHC)

A nonlinear optical (NLO) salt viz. L-alanine hydrogen chloride (LAHC) has been synthesized and solubility of the synthesized salt in de-ionized water was determined at different temperatures. Single crystals of L-alanine hydrogen chloride (LAHC) salt were grown by solution method with slow evaporation technique. The grown crystals were characterized by single crystal X-ray diffraction (XRD) and powder XRD analyses to study the crystal structure. The crystallinity of LAHC crystal was confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. FTIR study was used to confirm the presence of various functional groups in the grown crystals. UV–visible transmittance spectrum was recorded to study the optical transparency of LAHC crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz–Perry powder test. The density of LAHC crystal was determined by floatation method. The mechanical strength of the crystal was estimated by Vickers hardness test. The grown crystals were subjected to TG/DTA analyses. The dielectric behavior of the sample was also studied.     

Formation of semiconductor Cu2−xSe rod-like crystals through a solvothermal reaction

Micron-sized rod-like crystals of Cu_2−xSe were successfully grown for the first time by a hydrothermal reaction from CuCl₂·2H₂O and Se powder at 60°C for 2 h. X-ray powder diffraction patterns (XRD), X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM) images, and transmission electron microscope (TEM) images show that the product is cubic Cu_2−xSe rod-like crystal and well crystallized. Hydrazine hydrate was used as solvent in the process and played an important role in the formation of rod-like Cu_2−xSe crystals. The optical properties of Cu_2−xSe, such as absorption spectra, photoluminescence (PL) spectra, and Raman spectrum are also reported for the first time.     

γ-MnS nano and micro architectures: Synthesis, characterization and optical properties

γ-MnS nanocrystalline materials have been prepared by reaction of Na₂[Mn(HL)₂(H₂O)₂]; 1:2 (M:L) chelate complex with alkaline solution of thiocarbamide in aqueous solution phase. Effect of metal chelate complex, reaction time and surfactant sodium dodecyl sulfate; SDS on phase, morphology and size of the products have been investigated. The metal chelate complex was synthesized by reacting Mn(II) ions with eriochrome black T (NaH₂L) in alkaline medium. γ-MnS crystals were formed when metal complex was used as metal source whereas Mn₃O₄ was the dominant product when MnSO₄·H₂O was used as metal source. Materials thus formed having various morphologies were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) to determine the crystallinity, phase, structure and morphology. The optical properties of the thus prepared samples were determined by UV–vis absorption spectra and photoluminescence spectra. A possible formation mechanism of crystals has been discussed in this article.     

Influence of NH4Cl on the < 1 0 0> directed growth and properties of ADP crystal

Good quality, pure and ammonium chloride added < 1 0 0> directed ADP single crystals with different sizes were grown by Sankaranarayanan-Ramasamy method with the vision to improve the properties of the crystal. The grown crystals have cylindrical morphology and the crystals were subjected to UV-Vis., DTA, microhardness, laser damage threshold, dielectric, piezoelectric and SHG studies. The addition of ammonium chloride improves the quality and yields crystals with transparency more than 80% in minimum duration of growth. Higher laser damage threshold and mechanical stability were observed in ammonium chloride added ADP crystals. Low dielectric loss shows that the grown crystal contains minimum defects. Good piezoelectric behaviour was observed for the grown crystals. The SHG efficiency of the crystals was obtained using Nd-YAG laser, which is approximately 3 times that of pure ADP and shows the suitability of the ingot for nonlinear optical applications.     

Nucleation studies and surface SHG analysis of l-arginine phosphate monohydrate (LAP) family crystals

The metastable zone width and the nucleation parameters, such as interfacial tension, radius of the critical nucleus and critical free energy change have been estimated for pure l-arginine phosphate (LAP), potassium thiocynate (KSCN) mixed LAP (LAP:KSCN) and sodium sulfite (Na₂SO₃) mixed LAP LAP:Na₂SO₃ single crystals. Pure and additive mixed LAP single crystals are grown by slow cooling technique. The surface second harmonic generation (SHG) analysis is done on (100) face of the grown crystals. The SHG intensity on (100) face of the crystals are measured.     

Synthesis and characterization of pure,urea and thiourea doped organic NLO l-arginine trifluoroacetate single crystals

Optically transparent l-arginine trifluoroacetate (LATF) single crystals by doping with organic materials urea and thiourea were grown by slow solvent evaporation technique. Powder X-ray diffraction confirms improvement in the crystalline quality for urea doped crystals. Urea doping in LATF also improves the percentage of transmittance. The vibrational frequencies of the grown crystals were assigned by Fourier Transform infrared spectroscopy. The thermal analysis (TG/DTA) indicated the better thermal stability for urea doped LATF crystals. EDAX analysis was carried out to calculate the percentage of elements present in doped and pure LATF. The hardness has been remarkably improved on urea and thiourea doped LATF crystals. The second harmonic generation (SHG) analysis showed 2.5 times than standard KDP for pure LATF and 2.2, 2.07 times than KDP for urea and thiourea doped LATF.     

Growth and characterization of strontium metaborate scintillators

The undoped and 0.5% Ce³⁺-doped strontium metaborate SrB₂O₄ single crystals has been grown successfully by micro-pulling down method with radio frequency (RF) heating system, and scintillation characteristics including optical properties and radiation response were studied for these crystals. The Ce³⁺-doped SrB₂O₄ crystal showed absorption band around 240–320 nm, which is corresponding to the 4f-5d transition of Ce³⁺. Intense emission band at 375 nm due to the Ce³⁺ 5d–4f transition was observed under ²⁴¹Am 5.5 MeV α-ray excitation. The scintillation decay time showed fast (50 ns) and slow (1430 ns) components ascribed to the Ce³⁺ 5d–4f transition and lattice defect in the crystal, respectively. The scintillation light yield of Ce³⁺-doped SrB₂O₄ was calculated to be about 1000 ph/n under ²⁵²Cf irradiation.