Chloride Crystals Research Articles

Di-thiourea cadmium chloride crystals synthesis under UV radiation influence

In this work, the effect of ultraviolet radiation (λ=367nm) on the synthesis of di-thiourea cadmium chloride crystals by the chemical bath technique was studied. The results were analyzed and characterized by different techniques: X-ray diffraction (XRD), Raman scattering, scanning electron microscopy (SEM) and thermo-gravimetric analysis (TGA). It was found that the effect of ultraviolet radiation (UV) on the crystals causes a preferential growth in the (001) and (020) planes due to an increase in the formation of the CdCl and CS bonds caused by UV radiation. A morphological change was observed in the crystals assisted by UV radiation, and finally, it was found that the decomposition of the crystals starts from 497K thus transforming the di-thiourea cadmium chloride into cadmium sulfide. Also, the growth rate is increased by incorporating ultraviolet radiation into the reaction.

Spectrally resolved thermoluminescence of pure potassium chloride crystals

Alkali halides are wide band gap dielectric materials, which are very important for luminescence dosimetry. Nevertheless, only some of them were studied comprehensively. Potassium chloride (KCl) is alkali halide material, which shows pronounced thermoluminescence (TL) and optically stimulated luminescence (OSL). The material occurs also in natural mineral form as sylvite (or sylvine). This paper presents results of spectrally resolved thermoluminescence (SR-TL) measurements of pure KCl crystals in temperature range 300–550K for various doses of beta irradiation. Four emission bands were found relating to different recombination centers in this material. TL curves relating to these centers have different shape. It indicates that recombination centers are not filled concurrently.

Organic Nanowire Lasers with Epitaxially Grown Crystals of Semiconducting Oligomers

AbstractEpitaxially grown nanowires of semiconducting thiophene/phenylene co‐oligomers (TPCOs) were prepared by mask‐shadowing deposition on a cleaved (001) surface of a potassium chloride (KCl) crystal. Under optical pumping, single nanowires of both unsubstituted (p‐type) and cyano‐substituted (n‐type) TPCOs exhibited axial Fabry–Pérot (F‐P) lasing above a threshold fluence which decreased to 11–15 μJ cm−2 with increasing nanowire lengths. Their lying molecular orientation and stacking along the nanowire axis in both TPCOs are suitable for effective light propagation with transverse‐electric mode resulting in better lasing performances compared to two‐dimensional platelet crystals of TPCOs.

Sodium Chloride Crystallization by Electric Discharge in Brine

Electrical discharges in liquids are currently used to synthesize nanoparticles. The plasma-liquid interaction is complex, where parameters such as electric field, ion charges and other species present are important. In order to understand the mechanism of crystallization, mother liquor (saturated solution of NaCl, MgCl2 and KCl) was used to study the effectiveness and selectivity of the crystallization caused by the application of plasma. Discharge was applied with the solution at room temperature or during cooling. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and chemical analysis was used to evaluate the structure and composition effects on crystal structure and composition. It was observed that the discharge induces selectively crystallization, and when compared to crystals obtained conventionally by cooling, were smaller and more uniform. We therefore confirm that plasma in liquid can also be used to selectively crystallize materials in atmospheric pressure, where the sizes of the crystals must be dependent on the parameters used.

Cultivating Salt: Socio-Natural Assemblages on the Saltpans of the Venezuelan Islands, Seventeenth to Nineteenth Century

ABSTRACTThis paper discusses the socio-natural assemblages of salt cultivation involving humans, other organisms and natural phenomena on the Venezuelan islands of La Tortuga and Cayo Sal from the seventeenth to the nineteenth century. The research is based on archaeological, documentary and oral evidence marshalled to understand the dynamics of past solar sea salt production. In the past, a keen knowledge of the climatic conditions, the tides, and the effects of the microorganisms involved in the concentration of brine and the subsequent crystallisation of sodium chloride (NaCl) was indispensable to augmenting the quantity and quality of a salt harvest. These natural phenomena could be managed through anthropic intervention to the benefit of a saltpan enterprise by investing in infrastructure and tools such as dikes and pumps, thereby modifying the natural environment of a salt lagoon. This research indicates that the Dutch in the seventeenth, the Anglo-Americans in the seventeenth and eighteenth, as well as the Dutch Antilleans and a US American in the eighteenth and nineteenth centuries, approached the process of obtaining salt on the Venezuelan saltpans differently. This resulted in different configurations of the socio-natural assemblages on the saltpans and a variable final product conditioned by distinct market necessities.

Thermal characterization and non-isothermal kinetics of 4-fluorobenzyltriphenylphosphonium chloride crystal

4-Fluorobenzyltriphenylphosphonium chloride (4-FBTC), a quaternary phosphonium salt, was synthesized, a single crystal was grown by slow evaporation method, and the structure was confirmed by single crystal XRD and spectral analyses. The single crystal XRD analysis showed the triclinic crystal structure with molecular formula, C50H48P2F2Cl2O3. Thermal studies were carried out at three different heating rates (5, 10 and 15 °C min−1) under N2 atmosphere, which shows the single-stage decomposition at all heating rates. The conventional, non-isothermal decomposition kinetic studies using model-free method were carried out to calculate the kinetic parameters like activation energy, pre-exponential factor, half-life and rate constant at various conversion percentages (1, 2.5, 5, 10 and 20%). Lifetime of 4-FBTC at room temperature for different conversion percentages was calculated to estimate the stability of the compound. Specific heat capacity and change in enthalpy were calculated using DSC analysis at 10 °C min−1 heating rate under N2 atmosphere.

Growth Mechanism of Hollow Sodium Chloride Single Crystals Grown from a Mixed Solvent of Cyclohexane and Acetone

AbstractRecently, hollow sodium chloride crystals have been proposed as potential high‐value‐added crystals. The crystal growth mechanism of such crystals is elucidated using X‐ray diffraction (XRD), optical microscopic imaging, and analysis of both the chloride ions and water content in the mixed solvent of cyclohexane and acetone. A series of experimental conditions, including the stirring time after injecting the aqueous sodium chloride solutions into the mixed solvent and the ratio of cyclohexane and acetone, are evaluated in detail. Based on experimental data, possible growth mechanisms are proposed to explain the formation of hollow sodium chloride crystals.

Synchronized effect of Ca2+ ion doping concentration on structural, UV–vis and second harmonic generation efficiency of zinc thiourea chloride (ZTC) crystal: An interesting comparative study

In present investigation attention has been focused to explore the synchronic effect of increasing concentration of metallic impurity Ca2+ ion on structural, linear and nonlinear optical properties of zinc thiourea chloride (ZTC) crystal. The pure and Ca2+ (1wt%, 3wt%, 5wt%) ion doped ZTC crystals have been grown by slow solvent evaporation technique. The Fourier transform infrared spectral analysis has been employed to confirm the functional groups of grown crystals. The crystalline phase and structural parameters of pure and Ca2+ ion doped ZTC crystal has been comparatively examined by means of powder X-ray diffraction analysis. The influence of Ca2+ ion doping on optical transparency of ZTC crystal has been ascertained in the range of 190–1000nm by means of UV–vis spectral analysis. The Kurtz-Perry test has been employed to confirm the second order nonlinear optical behavior of grown crystals. The change in value of second harmonic generation (SHG) efficiency of ZTC crystal attributed by each selected concentrations of metal dopant Ca2+ ion has been evaluated. The distinct application of grown crystals for device fabrication has been discussed in light of obtained results.

Crystallization Test for Early Detection of Malignancy

Background: Cancer can involve any tissue of the body. In most of the cases, patients present themselves to a medical facility when the disease has reached an advanced stage and is not amenable to treatment. So, the line of action in order to cure cancer should be its early detection and prompt treatment of precancerous lesions. This is one of the cornerstones of cancer prevention. Aim: Aim of the study was to determine the efficiency of crystallisation test for early detection of malignancy. Methods: 110 subjects were included in the present study. 50 subjects were normal comprising the control group and 60 subjects were diagnosed with dysplastic changes. All samples are collected by finger prick with aseptic precautions. Crystallization tests were carried out strictly maintaining all necessary conditions. The results obtained were than analysed and studied. Results: Crystallization pattern with only cupric chloride solution alone is very haphazard and completely lacking of co-ordination. The pattern of admixture of normal blood solution and cupric chloride is typical and shows co-coordinated arrangement of crystals. Blood crystallization pattern in control group shows very specific arrangement of needle like crystals of cupric chloride. Hollow Glans formation characterizes the benign condition while hollow glans along with gap star formation characterizes the precancerous conditions. Present study of malignant pattern proves that transverse bar or transverse formation is confirmatory finding in advanced cases. Conclusions: Inference of the test shows that control group had shown 100% positivity while all cases of malignant as well as premalignant conditions was shown 99% positivity.

Additive Enhanced Creeping of Sodium Chloride Crystals.

This article investigates the mechanism behind the creeping of sodium chloride induced by additives. Here, an experimental approach is complemented with theoretical considerations to describe how creeping patterns of brine evolve and how the introduction of additives into the solution affects the morphology of the resultant crystals. We have found that these additives cause kinetic roughening and morphological instability mainly due to the reduction of surface free energy. There was also a marked increase in three-dimensional nucleation of the NaCl crystals and thus branching.

Optical spectra and emission characteristics of terbium-doped potassium–lead double chloride crystals (KPb2Cl5:Tb3+)

Optical transitions in KPb2Cl5:Tb3+ crystals are studied experimentally and theoretically. The absorption cross-section spectra are plotted and the oscillator strengths of transitions from the ground terbium state to excited multiplets are determined. Intensity parameters Ωt for KPC:Tb3+ are determined by the Judd–Ofelt method to be Ω2 = 2.70 × 10–20 cm2, Ω4 = 7.0 × 10–20 cm2, and Ω6 = 0.72 × 10–20 cm2. These values were used to calculate such characteristics of spontaneous radiative transitions as oscillator strengths, probabilities of radiative transitions, and radiative lifetimes. The emission spectra of KPb2Cl5:Tb3+ crystals upon UV excitation and the decay kinetics of luminescence from the excited 5 D 3 and 5 D 4 levels are studied experimentally, the lifetimes of these levels are determined, and the dependences of the rates of nonradiative relaxation from the excited 7 F j (j = 0–5), 5 D 4, and 5 D 3 levels to lower-lying terbium levels are calculated. It is shown that the population of the 5 D 4 level in KPC:Tb3+ crystals occurs according to a cascade scheme, which leads to quenching of the 5 D 3 level. The calculated data agree well with the known experimental rates of multiphonon nonradiative transitions for Dy:KPC, Nd:KPC, Er:KPC, Tb:KPB, and Nd:KPB crystals. It is shown that transitions in the near-IR (3–6 μm) region in double halide crystals (MPb2Hal5) are almost unquenched and the rates of nonradiative relaxation of excited levels spaced by energy gaps ΔE ji > 1000 cm–1 are W ji NR < 103s–1. This circumstance suggests that it is possible to obtain stimulated emission in KPb2Cl5:RE3+ crystals in the IR spectral region up to 6 μm.

Influence of Surfactants on Sodium Chloride Crystallization in Confinement.

We study the influence of different surfactants on NaCl crystallization during evaporation of aqueous salt solutions. We found that at concentrations of sodium chloride close to saturation, only the cationic surfactant CTAB and the nonionic surfactant Tween 80 remain stable. For the nonionic surfactant, the high concentration of salt does not significantly change either the critical micellar concentration (CMC) or the surface tension at the CMC; for the cationic surfactant, the CMC is reduced by roughly 2 orders of magnitude upon adding the salt. The presence of both types of surfactants in the salt solution delays the crystallization of sodium chloride with evaporation. This, in turn, leads to high supersaturation which induces the rapid precipitation of a hopper crystal in the bulk. The crystallization inhibitor role of these surfactants is shown to be mainly due to the passivation of nucleation sites at both liquid/air and solid/liquid interfaces rather than a change in the evaporation rate which is found not to be affected by the presence of the surfactants. The adsorption of surfactants at the liquid/air interface prevents the crystallization at this location which is generally the place where the precipitation of sodium chloride is observed. Moreover, sum frequency generation spectroscopy measurements show that the surfactants are also present at the solid/liquid interface. The incorporation of the surfactants into the salt crystals is investigated using a novel, but simple, method based on surface tension measurements. Our results show that the nonionic surfactant Tween 80 is incorporated in the NaCl crystals but the cationic surfactant CTAB is not. Taken together, these results therefore allow us to establish the effect of the presence of surfactants on sodium chloride crystallization.

Luminescence and scintillation properties of TlCdCl3 crystal

We report the photoluminescence and the scintillation properties of a newly developed thallium cadmium chloride (TlCdCl3) crystal. This crystal will provide excellent detection efficiency for X- and γ-rays due to its high effective atomic number (Zeff = 68.7) and density (ρ = 5.31 g/cm3). The crystal sample can be easily prepared from the melt using the Bridgman method. The photoluminescence band appeared near the wavelength of 450 nm under excitation at 270 nm. By tri-exponential equation fitting with a deconvolution of instrumental response, the photoluminescence decay time value was found to be approximately 24 ns (∼77.6%), 60 ns (∼19.8%) and 870 ns (∼2.6%). An X-ray-induced scintillation spectrum showed a broad emission band near the wavelength of 450 nm. The scintillation decay time constant was estimated to be approximately 2.6 ns (∼8%), 45 ns (∼47%) and 170 ns (∼45%) using a tri-exponential fitting. The scintillation light yield reached 2200 photons/MeV calibrated with a GSO commercial scintillator.

Energetically benign synthesis of lanthanum silicate through “silica garden” route and its characterization

Lanthanum silicate synthesis through “silica garden” route has been reported as an alternative to energy intensive milling procedure. Under optimum conditions lanthanum chloride crystals react with water glass (sodium silicate) to produce self generating hollow lanthanum silicate precipitation tube(s) (LaSPT). The micro tubes are irregular, thick, white coloured and amorphous but are hierarchically built from smaller tubules of 10–20 nm diameters. They retain their amorphous nature on being heated up to 600 °C beyond which crystallization starts. The major phase in the LaSPT heated at 900 °C is La2Si2O7. “As synthesized” LaSPT is heterogeneous and comprises non stoichiometric phases. The exterior and interior surfaces of these tubes are remarkably different in their morphology and chemical composition. LaSPT sintered at 1200 and 1300 °C show fair amount of ionic conductivity.

First-principles estimate of Peierls energy in sodium chloride

The Peierls barrier height for edge dislocations in sodium chloride crystal has been estimated from first principles based on the density functional theory. The calculation was performed using a plane-wave expansion of the Bloch functions of a periodic structure with sp. gr. Pmmm and a supercell containing an edge dislocation dipole of dominating slip system \({1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}\langle 110\rangle \{ \overline 1 10\} \). It is shown within the generalized gradient approximation for the exchange-correlation energy that, among the two symmetric positions of dislocation line in the Peierls relief, configuration I, which has a compact core of size d ≈ b (b is the Burgers vector length), is characterized by minimum energy. The second symmetric position corresponds to configuration II with an extended core (d ≈ 2b). Its energy exceeds the Peierls relief minimum by 1.2 × 10–2 eV (per lattice period). An application of compressive stress changes the form of crystalline relief: its minimum moves to position II.

Optical and electrical analysis of Cu2+ ion doped zinc thiourea chloride (ZTC) crystal: An outstanding 30 × 24 × 04 mm3 bulk monocrystal grown from pH controlled aqueous solution

The present investigation is aimed to grow the bulk crystal and investigate the UV-visible, photoconductivity, and dielectric properties of Cu2+ ion doped zinc thiourea chloride (ZTC) crystal. For bulk growth, the most commercial slow solvent evaporation technique has been adopted and a 30×24×04mm3 bulk single crystal of Cu2+ ion doped ZTC material has been grown by controlling the pH of aqueous solution. The doping of Cu2+ ion in ZTC crystal has been confirmed by energy dispersive spectroscopic technique. The assertive influence of Cu2+ ion on optical transparency of ZTC crystal has been ascertained in the wavelength range of 200–900nm. The vital optical constants such as extinction coefficient, reflectance and refractive index have been evaluated using the transmittance data. The negative photoconductivity nature of Cu2+ ion doped ZTC crystal has been evaluated in the voltage range limited up to 100V. The frequency and temperature effect on response of dielectric constant and dielectric loss of Cu2+ ion doped ZTC crystal has been exclusively investigated. The obtained results were integrated to discuss the benefits and utility of grown crystal for advanced technological device applications.

Growth and characterization of tristhiourea potassium chloride single crystal

Single crystals of tris thiourea potassium chloride have been grown by slow evaporation technique at room temperature. The grown crystals were characterized by XRD, TG-DTA, UV and FTIR. The presence of functional group is identified from the UV and FTIR spectra. The TG curve undergoes a two step weight loss on heating the compound from 0° to 1200 °C. The thermal stability are due to the bonding between the thiourea molecule and the potassium ions. The SHG efficiency increases due to the inclusion of potassium ions.

Heterogeneous nucleation and growth analysis of GBBC optical materials

In accordance with experimentally determined solubility data for glycine barium bromo chloride crystal, the metastable zone results revealed that it increases with the rise of cooling rates, whereas it decreases as the saturation temperature increases. Nucleation theory parameters were estimated by making a fit of the analytical probability distribution from the stochastic model with the experimental probability distribution. Growth patterns depending upon supersaturation were also studied. Additionally, transparent as-grown bulk crystals have crystallized from the optimized growth parameters.

Growth and charatcterisation of mercuric chloride doped urea single crystals

Semiorganic non-linear optical single crystals of urea mercuric chloride were grown from aqueous solution using slow evaporation method. The grown crystals were subjected to different characterisations Viz., XRD, FTIR, UV, TGA and powder SHG. XRD study reveals that the crystal belongs to triclinic system with the space group P1. The vibrational frequencies of various functional groups have been derived from FTIR spectrum. Thermal stability of the grown crystal was investigated by TG-DTA studies and it is observed that the title compound is thermally stable up to 170 °C. Optical absorption study has been carried out and a good transparency in the entire visible region is observed with the lower cut-off wavelength of 245 nm. Kurtz powder method was employed to explore the non-linear optical characteristics of the grown crystal.

Growth and Characterization of NaCl doped Organometallic L-Asparagine Cadmium Chloride Monohydrate (LACCM) Crystals

Single crystals of sodium chloride (NaCl) doped organometallic nonlinear optical material L-asparagine cadmium chloride monohydrate (LACCM) were successfully grown by slow evaporation method at room temperature. Grown crystals were characterized by single crystal and powder X-ray diffraction analysis, scanning electron microscopy, energy-dispersive analysis by X-ray and thermal studies. The second harmonic generation was confirmed by the Kurtz and Perry powder technique. The presence of various functional groups was identified from FTIR spectral analysis. The mechanical strength of the grown crystal has been determined with the aid of Vickers hardness test. The second harmonic efficiency and dielectric constant increases significantly due to the introduction of sodium ions into the lattice of l-aspargine cadmium chloride crystal, so that this crystal is a potential material for nonlinear frequency conversion.