The growth and characterization of 2,4-dinitro phenyl hydrazone of benzophenone and mixed crystals

Good quality benzophenone (BP) crystals were grown by solution technique using CHCl₃ as solvent by adopting slow evaporation method at room temperature. The grown crystals were subjected to various characterization studies to analyze its purity and applications. The condensation product 2,4-dinitro phenyl hydrazone of benzophenone (DNPBP) was prepared by adopting standard procedure. Then mixed crystal of BP and DNPBP was also grown by solution growth. Both the condensation product and mixed crystals were characterized by UV, FTIR, ¹H NMR spectra. Thermal (TG and DTA) studies have proved to be very useful techniques not only to study the thermal properties of BP, DNPBP and mixed crystal but also to study their purity. Second harmonic generation (SHG) efficiency of the grown crystals was determined.     

The Respective Benefits of X-ray Crystallography and NMR for the Structural Determination of the Inclusion Complex Between Butyl-isothiocyanate and Alpha-cyclodextrin

Isothiocyanates are natural products extracted from plants. These molecules which exhibit very interesting antifungal properties, are insoluble in water. To increase their solubility, we have prepared inclusion complexes with different cyclodextrins. Among all the isothiocyanates studied, we have investigated in more detail the structure of one complex: butyl-isothiocyanate and alpha-cyclodextrin, using two different techniques. Firstly, ¹H NMR experiments were performed and revealed the inclusion phenomenon. In parallel, crystals of butyl-isothiocyanate–alpha-cyclodextrin were grown and their crystallographic structure determined. This confirmed the inclusion of the ITC molecules and allowed us to determine the exact position of the guest. Finally, we showed that even though the complex structure was determined separately in solution and in the solid state, the structural characterisations obtained with these two techniques are complementary, enhancing the respective benefits of X-ray crystallography and NMR.     

Spectral, optical, and thermal studies of pure and Zn(II)-doped l-histidine hydrochloride monohydrate (LHHC) crystals

The influence of doping the transition metal Zn(II) on the growth, spectral, optical, and thermal properties of l-histidine hydrochloride monohydrate (LHHC) crystals grown by slow solvent evaporation method has been investigated. Structural characterizations of the grown crystals were carried out by single crystal X-ray diffraction analysis and it shows slight structural changes as a result of doping. The FT-IR spectral study reveals the presence of various functional groups and confirms the slight distortion of the structure of the crystals due to doping. The energy dispersive X-ray analysis reveals the incorporation of Zn(II) in the crystalline matrix of LHHC crystal. The UV?CVis spectral study was carried out to analyze the optical transmittance of the grown crystals and found that the transmittance is very high in the visible and UV regions for both pure and doped crystals. The second harmonic generation (SHG) for the grown crystals was confirmed by Nd:YAG laser. The scanning electron microscopy reveals the presence of defect centers and crystal voids. The thermal stability and purity of the grown crystals were analyzed by thermogravimetry, differential thermal analysis, and differential scanning calorimetry techniques.     

Crystal growth, thermal and optical studies on a semiorganic nonlinear optical material for blue-green laser generation

The semiorganic nonlinear optical material l-histidine bromide (l-HB) has been synthesized in aqueous solution and characterized by FT-IR, FT-Raman and FT-NMR spectroscopic techniques. The single crystals with dimensions 9mm x 4mm x 3mm were grown by slow evaporation techniques. The grown crystals were subjected to single crystal X-ray diffraction to determine the unit cell dimensions. The thermal stability of the grown crystal was analyzed by thermogravimetric (TG), differential thermal (DT) and differential scanning calorimetric (DSC) analyses. The UV-vis transmittance spectrum shows that it has a good optical transmittance in the entire visible region with the lower cutoff wavelength at 220 nm. The SHG conversion efficiency and laser damage threshold were measured using a Nd:YAG laser (1064 nm). The optical birefringence was measured in the visible region as a function of temperature in the range 30-150 degrees C by interference technique.     

Synthesis, structural, thermal and optical studies of 1-ethyl-2,6-dimethyl-4-hydroxy pyridinium halides

1-Ethyl-2,6-dimethyl-4-hydroxy pyridinium chloride dihydrate and bromide dihydrate salts have been synthesized and their single crystals were grown by the slow evaporation of aqueous solution at 30 degrees C. The grown crystals were characterized by elemental analysis, FT-NMR and FT-IR techniques to confirm the formation of the expected compound. Optical transmittance window in aqueous solution was found to be 275-1100 nm by UV-vis-NIR technique. Thermogravimetric and differential thermal analyses reveal thermal stability and the presence of two water molecules in the crystal lattices. The crystal structure of chloride salt was also determined by X-ray diffraction method.     

Preparation and characterization of a bis thiourea sodium iodide (BTSI)

A semi-organic nonlinear optical single crystal of bis thiourea sodium iodide (BTSI) has been successfully grown from aqueous solution using the slow evaporation solvent technique (SEST) at room temperature. Obtained crystals using the SEST method were characterized by using different characterization techniques. Structural studies of the grown crystals have been carried out by single-crystal XRD to confirm the crystal system and functional groups by FT-IR spectroscopy. Single-crystal XRD reveals orthorhombic structure of semi-organic BTSI single crystals and its unit cell parameters. Metal complex coordination of the single crystal is studied by FT-IR spectroscopy. The optical absorption study revealed excellent optical transparency of BTSI crystal in the entire visible region with a sharp lower cutoff wavelength 298 nm. The energy band gap of BTSI is found to be 4.16 eV. Thermal stability and thermal decomposition of BTSI single crystals were investigated by TGA–DTA and DSC analysis. The surface appearance of BTSI crystals by scanning electron microscopy reveals the formation of layer growth pattern. The structural perfection and growth features of the grown crystal were analyzed by wet chemical etching studies. The above studies reveal the effect of incorporation of sodium iodide into the lattice of thiourea crystals. The as-grown BTSI single crystals can be used as a potential candidate for NLO material as well as in electronic and optoelectronic devices.     

Growth, structural, vibrational, optical, laser and dielectric aspects of L-alanine alaninium nitrate single crystal

Bulk single crystals of l-alanine alaninium nitrate [abbreviated as LAAN], an intriguing material for frequency conversion has been grown from its aqueous solution by both slow solvent evaporation and by slow cooling techniques. The optimized pH value to grow good quality LAAN single crystal was found to be 2.5. The grown crystals were subjected to single crystal X-ray diffraction studies to determine the unit cell dimensions and morphology. Vibrational frequencies of the grown crystals by Fourier transform infrared spectroscopic technique were investigated. Also, the presence of hydrogen and carbon atoms in the grown sample was confirmed using proton and carbon NMR analyses. The dielectric constant and dielectric loss measurements of the as grown crystal at different temperatures and frequencies of the applied field are measured and reported. LAAN has good optical transmission in the entire visible region with cutoff wavelength within the UV region confirms its suitability for device fabrications. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm. Its Laser Damage Threshold (LDT) was measured and also tested by using a Q-switched Nd:YAG laser and the value of LDT of LAAN is 17.76GW/cm2 respectively, is found to be better than certain organic and semiorganic materials.     

Thermal, FTIR and Raman spectral analysis of Cu(II)-doped lead iodate crystals

The 0.04 M copper-doped lead iodate crystals grown in silica gel were characterized by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and thermo analytical techniques (TG, DTA, DTG and DSC). Raman and FTIR spectrum clearly indicate that the functional groups of undoped lead iodate were not altered by the addition of the dopant. Thermal analysis suggests that the thermal stability of lead iodate crystals decreases due to copper doping.     

Thermal and optical properties of ZTS single crystals in the presence of 1,10-phenanthroline (Phen)

The influence of heteroaromatic N-base (1,10-phenanthroline) (Phen), a new additive as complexing agent on tris(thiourea)zinc(II)sulphate (ZTS) crystals from aqueous solutions at 30 °C is investigated. Crystals were grown using low concentration of the dopant (0.005 M L^?1) in the aqueous growth medium and the growth promoting effect (GPE) is much greater because of an increase in the metastable zone width. High dopant concentration decreases GPE. The crystalline perfection of the grown crystals is quite good both in doped and undoped crystals as evaluated by high-resolution X-ray diffractometry (HRXRD). The diffraction curve of a typical Phen doped as-grown ZTS crystal was observed to contain a single peak indicating that the crystal does not contain any epitaxial layer on the surface or internal structural grain boundaries. Not much variation is observed in FT-IR and XRD of pure and doped ZTS. Phen depresses the NLO efficiency of ZTS. It could be ascribed due to the disturbance of charge transfer in the presence of the dopant. The grown crystals were also characterized by UV–Vis, SEM and TG–DTA techniques.     

Synthesis, spectral, optical and thermal studies of 1-methyl-2,6-dimethyl-4-hydroxypyridinium chloride monohydrate and bromide monohydrate

Semiorganic 1-methyl-2,6-dimethyl-4-hydroxypyridinium chloride monohydrate (MDMPCl.H(2)O) and bromide monohydrate (MDMPBr.H(2)O) salts have been synthesized. Single crystals of MDMPCl.H(2)O and MDMPBr.H(2)O were grown by the slow evaporation method from aqueous solution at constant temperatures 30 and 32 degrees C respectively. The grown crystals were characterized by elemental analysis, FT-IR and FT-NMR techniques and their molecular structures were elucidated. Thermogravimetric, differential thermal analyses and differential scanning calorimetry reveal the presence of water molecules in the crystal lattices and thermal stabilities. Optical transmittance windows in aqueous solution were found as 300-1100 nm using UV-vis-NIR spectrophotometer.     

Growth and thermal behavior of mixed crystals of calcium cadmium tartrate in silica gels

In this study, calcium cadmium tartrate single crystals were grown in silica gel at ambient temperature. Effects of various parameters like gel pH, gel aging, gel density, and concentration of reactants on the growth of these crystals were studied. Crystals having different morphologies and habits were obtained. Transparent, diamond-like pyramidal-shaped crystals of calcium cadmium tartrate were obtained. Some of the crystals obtained were faint yellowish, with some milky white crystals being attched to them due to fast growth rate; faces are well developed and polished. The grown crystals were characterized by thermoanalytic techniques (TG, DTA, and DTG), and powder X-ray diffraction (XRD). The crystal system is confirmed to be orthorhombic having lattice parameters a = 7.9411 Å, b = 7.0396 Å, and c = 6.7271 Å as determined by powder XRD analysis. TG, DTA, and DTG analyses show a remarkable thermal stability. The results of these observations are described and discussed.     

Growth and characterization of unidirectional (100) KDP single crystal by Sankaranarayanan-Ramasamy (SR) method

Unidirectional (100) potassium dihydrogen orthophosphate (KDP) single crystals were grown by Sankaranarayanan-Ramasamy (SR) method. The (100) oriented seed crystals were mounted at the bottom of the glass ampoules and the crystals of 20mm diameter, 30 mm height and 15 mm diameter, 65 mm height were grown by SR method. The grown crystals were characterized by high-resolution X-ray diffractometry anlaysis, UV-vis spectroscopy, dielectric and microhardness studies. The high-resolution X-ray diffractometry anlaysis indicates that the crystalline perfection is excellent without having any very low angle internal structural grain boundaries. The SR method-grown unidirectional KDP has 15% higher transmittance compared to conventional method-grown crystals. The dielectric constant was higher and the dielectric loss was less in SR method-grown crystal. The crystals grown by SR method have much higher hardness value than conventional method-grown crystals. The quality of the crystal grown by SR method is better than conventional method-grown crystal.     

Growth and characterization of NLO based l-arginine maleate dihydrate single crystal

Single crystals of l-arginine maleate dihydrate (LAMD) were successfully grown from aqueous solution by solvent evaporation technique. As-grown crystals were analyzed by different instrumentation techniques such as X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectra and UV–vis near infrared (NIR) transmittance spectra. Thermal behavior has been studied with TGA/DTA analyses. The optical second harmonic generation (SHG) conversion efficiency of LAMD was determined using Kurtz powder technique and found to be 1.5 times that of KDP.     

Growth of compound Bi(III)- VI(A)-VII(A) crystals with special morphologies under mild conditions

A series of crystals Bi(III)-VI(A)-VII(A), including the platelike crystals BiOCl, polygonal tubular crystals BiSCl, bundle-rodlike crystals Bi(19)S(27)Br(3), and BiSI, have been grown with use of mild solution routes in an ethanol system. The products are characterized by means of X-ray powder diffraction (XRD), electron diffraction (ED), scanning electronic microscopy (SEM), and Raman spectrum techniques. A possible mechanism of the reaction and of the growth of the crystals is proposed.     

Effect of NaCl and KCl doping on the growth of sulphamic acid crystals

The nonlinear optical single crystals of doped sulphamic acid (SA) were grown from aqueous solution by doping with NaCl and KCl using slow evaporation method. Powder X-ray diffraction studies confirm that the grown crystals belong to orthorhombic system. The density and melting point measurements of the grown crystals were determined by floatation technique and capillary tube method, respectively. The range of optical transmittance was ascertained by recording the UV–Vis–NIR spectrum. Atomic absorption study reveals the presence of dopants in the doped crystals. The thermal analyses indicated that the doped SA crystals are more stable than pure crystals. The Vicker's microhardness studies revealed that the dopants increased the hardness of the crystals. SHG efficiency studies of the crystals are found to be increased in the presence of NaCl and KCl dopants.     

Polydipropylsiloxane Single Crystals

Polydipropylsiloxane single crystals, grown from a dilute n-butylacetate solution, were characterized by electron microscopy and by selected-area electron-beam diffraction techniques. The electron diffraction study shows that the growth face was parallel to the (100) plane. Fracture of single crystals parallel to the fold plane takes place during the electron diffraction examination to give ribbon like lamellae about 300 A wide and 80 A thick. Fracture normal to the fold plane was also observed.     

Shish-kebab structures of nylon-6 obtained from quiescent solutions by application of self-seeding

A study has been made of the morphology and structure of nylon-6 crystals grown from diluted 1,4-butanediol solution. Isothermal crystallization from homogeneous solution resulted in smooth ribbons or lath-shaped crystals aggregated into sheaves. Shish-kebab structures of nylon-6 could be grown from the quiescent solution by self-seeding techniques. Electron microscopic investigations and small-angle x-ray measurements showed that the molecules in the lath-shaped backbones of the shish kebab are folded and oriented perpendicular to the long axis of the crystals. The polyamide laths have the α-monoclinic crystal structure with the hydrogen bonds parallel to the long axis. It is suggested that due to the anisotropic type of bonding in the crystal lattice the crystals fragment laterally during the heating stage in the self-seeding technique. Structural defects, e.g., twinning sites introduced during the dissolution and subsequent crystallization may cause the growth of shish-kebab structures from quiescent solution.     

Growth, structural, spectral, mechanical, thermal and dielectric characterization of phosphoric acid admixtured L-alanine (PLA) single crystals

Phosphoric acid admixtured L-alanine (PLA) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 18 mm×12 mm×8 mm have been obtained in 28 days. The grown crystals were colorless and transparent. The solubility of the grown samples has been found out at various temperatures. The lattice parameters of the grown crystals were determined by X-ray diffraction technique. The reflection planes of the sample were confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. Fourier transform infrared (FTIR) studies were used to confirm the presence of various functional groups in the crystals. UV-visible transmittance spectrum was recorded to study the optical transparency of grown crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique and a study of its second harmonic generation efficiency in comparison with potassium dihydrogen phosphate (KDP) has been made. The mechanical strength of the crystal was estimated by Vickers hardness test. The grown crystals were subjected to thermo gravimetric and differential thermal analysis (TG/DTA). The dielectric behavior of the sample was also studied.     

The existence of mosaic block structures in polymer single crystals

X-ray line broadening measurements were used to determine the apparent “mosaic block” sizes of randomly oriented polyethylene and polyoxymethylene single crystals. Both dried-down and uncollapsed crystals were examined. PE lamellae were grown at 80, 85, and 90°C by isothermal crystallization from a 0.1% solution in xylene. POM crystals were grown at 125°C by self seeding from an 0.05% solution of the polymer in o-dichlorobenzene. A given preparation was split into two parts. One part was dried down in the usual manner, the other was exchanged to paraffin oil and the crystals never permitted to dry down. Previously reported studies used dried-down crystals and gave crystallite sizes of approximately 300 Å. More recently, using electron microscopy, it has been postulated that PE single crystals are free of “mosaic block” over regions of several thousand angstroms. It is evident from this present study that crystallite sizes in uncollapsed lamellae are significantly larger than those observed for the same crystals dried down. In the case of uncollapsed lamellae, one can explain the observed crystallite sizes solely on the basis of chain obliquity rather than by invoking the “mosaic block” model. It has also been determined that there is an upper limit to the crystallite sizes that can be observed in PE and POM crystals using wide-angle x-ray techniques. This limit may account for discrepancies between x-ray and electron diffraction.     

Growth and characterization of n-WS2 and niobium-doped p-WS2 single crystals

Single crystals of n- and p-WS₂ were obtained by chemical vapor transport using chlorine and bromine as transporting agents. The best niobium-doped WS₂ crystals were obtained when the concentration of the charge (formulated (1 ? x)WS₂ · (x)NbS₂) was ? 37 mg charge/ml of tube, and x = 0.01 to 0.03. A thermodynamic analysis of the crystal growth process is consistent with the observed doping concentration and other properties of the crystals obtained by this process. The crystals grown are characterized by electrical transport and surface photovoltage measured capacitance techniques.