Potassium Chloride Crystals Research Articles

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.

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.

Impact of subthreshold laser defect accumulation on the optical stability of crystals

Optoacoustic means are used to study the kinetics of laser damage accumulation in potassium chloride crystals. This approach allows us to observe the accumulation of changes in KCl crystals when it is irradiated by a series of laser pulses of subthreshold intensity in a variety of actions (alloying, applying an external electric field, UV illumination). Number of laser pulses N cr required to destroy a specimen at the same density of radiation power depends on density power I as N ~ I −4. Results are explained by the formation and accumulation of structural defects during photochemical reactions under the action of laser radiation.

Design, Synthesis and Vibrational Spectroscopic Studies of the Nonlinear Optical Crystal l-histidine Potassium Chloride

L-Histidine Potassium Chloride (LHPC) crystals were grown by slow evaporation technique. The grown crystals were characterized by powder X-ray diffraction and analyzed by FT-IR and FT-Raman techniques. The geometry optimization, harmonic vibrational wavenumbers, natural bond orbital and thermodynamical analysis have been carried out using density functional theory (DFT) method at B3LYP/6-311++G(d,p) basis set. Optimized geometry values show a small deviation between the experimental and theoretical values, which reveals the inter- and intra-molecular hydrogen bonding in the crystal. Normal coordinate analysis has been performed on the basis of potential energy distribution analysis using MOLVIB program. The potential energy distribution analysis is useful to predict the vibrational modes, unambiguously. The natural bond orbital analysis has been performed in order to study the intramolecular bonding interactions among bonds and delocalization of unpaired electrons. HOMO and LUMO energies, molecular electrostatic potential and the first-order hyperpolarizability have been also studied. The scaled wavenumbers are in good agreement with the experimental wavenumbers. The first-order hyperpolarizability (β) of the title compound is found to be 9.50x10-30 e.s.u. The large hyperpolarizability and lowering of HOMO-LUMO energy gap supported the nonlinearility of the LHPC crystal. On the basis of vibrational analysis the thermodynamic properties of LHPC at different temperatures have been calculated, revealing the correlations between heat capacity, enthalpy and entropy.

Thermostimulated surface segregation processes in ionic crystals: Potassium chloride

The chemical and phase composition, and cleavage surface morphology and the vapor composition of potassium chloride (KCl) crystals formed as a result of the thermostimulated surface autosegregation (TSAS) are studied by methods of microprobe analysis, high-resolution scanning electron microscopy, optical digital microscopy, and quadrupole mass spectrometry. It is experimentally found that the stoichiometry (K/Cl <1) in the surface layers changes due to a decrease in the potassium surface concentration from 5% in the initial samples to 12% after annealing at a temperature of 1023 K. After annealing at a temperature of 573 K for 5 h at P = 10−3 Pa, the potassium deficiency increases to 17%. The competing processes resulting in TSAS in potassium chloride are the self-diffusion of potassium to the surface and its subsequent sublimation. During the annealing processes the sublimation of potassium dominates, but at a temperature near fusion, the self-diffusion of potassium to the surface increases. It is concluded that potassium chloride analogous to sodium chloride is a rather stable compound to TSAS. This is an additional argument of the important role of ionic bonds in a decrease in the tendency of chemical compounds to surface autosegregation.

Reinvestigation of crystal growth of thiosemicarbazide potassium chloride and thiosemicarbazide lithium chloride

Reinvestigation of the growth of thiosemicarbazide potassium chloride crystal (1) (Chandrasekaran et al. [1]) and thiosemicarbazide lithium chloride crystal (2) (Maadeswaran et al. [2]), unambiguously confirms that compounds 1 and 2 are pure thiosemicarbazide and do not contain any alkali metal or chloride ions. In this paper we demonstrate the use of classical halide test, flame test, as well as infrared (IR) spectra for correct product characterization.

Correction to “Luminescent Studies of “Exciplex Tuning” for Nanoclusters of Dicyanocuprate(I) Ions Doped in Potassium Chloride Crystals”

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionORIGINAL ARTICLEThis notice is a correctionCorrection to “Luminescent Studies of “Exciplex Tuning” for Nanoclusters of Dicyanocuprate(I) Ions Doped in Potassium Chloride Crystals”Haiyan Lu, Renante Yson, Xiaobo Li, Christie Larochelle, and Howard H. Patterson*Cite this: J. Phys. Chem. C 2013, 117, 13, 6918Publication Date (Web):March 21, 2013Publication History Published online21 March 2013Published inissue 4 April 2013https://doi.org/10.1021/jp400576jCopyright © 2013 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views193Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (101 KB) Get e-Alerts Get e-Alerts

Pb-doped KCl: from adsorption to habit and crystal structure modification

Many papers dealing with alkali-halides crystal morphology have been published since the Sixties. The relationship between crystal growth or dissolution morphology and the presence of surface specific impurities is commonly recognized. Authors usually attributed morphological changes to the random adsorption of the impurity on specific crystal surfaces. The results of our research clearly show that several morphological changes can be correctly interpreted in terms of 2D-epitaxially absorbed phases [1], [2] leading both to morphological and structural changes. In the case of potassium chloride crystals, both in-situ and ex-situ observations on growing and etched crystals were performed [3] in order to demonstrate that the appearance of the octahedron in the crystal morphology is due to the step bunching effect ascribable to the precipitation of PbCl2 crystallites along the n steps on the {100} forms. Inspired by the Lian et al. [3] detailed “morphodrome” showing the crystal habit and surface modifications of KCl crystals grown in the presence of Pb as specific impurity, we performed a new series of growth and dissolution experiments in order to improve the old data. The impurity concentration ranges from 5 to 10000 ppm at constant crystallization temperature. Moreover we tried to enlarge the impurity concentration range, joining the molar ratio of the two known perovskite structures (KCl:PbCl2 and KCl:2PbCl2) in order to evaluate the continuity between morphological and structural changes from the cell distortion (anomalous mixed crystal formation due to impurity adsorption and 2D epitaxy between KCl and PbCl2) to the symmetry breakdown (from the anomalous mixed crystal at higher symmetry to the perovskite structure at lower symmetry).

Femtosecond electron diffraction: Preparation and characterization of (110)-oriented bismuth films

Here, we present a new approach to synthesize (110)-oriented ultrathin membranes of bismuth (Bi). This rather exotic orientation was achieved by directing the growth through rationale control of lattice matching. Bi films were hetero-epitaxially grown on the (100)-surface of freshly cleaved potassium chloride crystals. The sample orientation was characterized by x-ray and electron diffraction. In addition, high quality free-standing films were obtained after dissolution of the substrate in water and controlled evaporation. Femtosecond electron diffraction (FED) was, therefore, used to monitor the coherent shear acoustic phonons in (110)-oriented free-standing Bi films produced by impulsive femtosecond optical excitation. The small de Broglie wavelength (flat Ewald sphere) of keV-electrons combined with an off-Bragg detection scheme provided a magnified view of shear atomic motions, i.e., lattice distortions in the transverse direction. All-optical pump-probe experiments are usually insensitive to shear displacements, a fact that makes FED a unique non-contact method to achieve the complete characterization of elastic properties of nanoscale materials.

Investigations on growth, thermal, electrical, and etching studies of KCl-doped triglycine sulfate single crystals

Single crystals of pure triglycine sulfate (TGS) and potassium chloride (KCl)-doped TGS with different concentrations (0.2, 0.4, 0.6, and 1 mol%) were grown from aqueous solutions by natural evaporation process at room temperature. Thermal stability of the grown crystals was investigated by differential thermal analysis (DTA) and thermogravimetric (TG) studies. DTA curve shows a lower decomposition temperature for KCl-doped TGS crystal than that of pure TGS crystal. The dielectric properties of pure TGS and KCl-doped TGS crystals were performed in the frequency range of 1-500 kHz at 30 C and this study showed that the dielectric constant was increased due to KCl concentration. DC electrical conductivity measurements were made in the temperature range from 35 to 100 Ca nd showed that the DC conductivity was increased with the increase of temperature as well as doping concentrations of KCl. The etching feature of the surface of the grown crystals was studied in water etchant.

The effect of surface charge and KNO 3 additive on the crystallization of potassium chloride

In this study, crystal growth and dissolution rates of potassium chloride crystals in pure solution and in the presence of potassium nitrate were investigated in a stagnant type single crystal cell using an image analyzer system. Closely sized seed crystals were separated with respect to their surface potentials using an electrostatic separator and then growth and dissolution behavior of potassium chloride crystals having different surface charges were systematically measured in pure solution and at 10, 100 and 1000 ppm additive concentrations at around 20 °C. In high supersaturation levels, very thin but very long rod-like growth, growing perpendicular to the surface, were observed. This is considered to result from surface nucleation. A dead zone was detected and its width was a function of surface potential of seed crystals. It was determined that, potassium nitrate additive, which has a common ion with KCl leads to increase the surface potential but not to affect the growth behavior, significantly.

10.1007/s11455-008-2010-x

Optical damage thresholds for the surface of sodium and potassium chloride crystals irradiated by 80-fs laser pulses have been determined. P-polarized terawatt radiation of a chromium-forsterite laser operating at a wavelength of 1240 nm was incident on a sample surface at an angle of 35°. The optical damage of the crystal surface was observed when the electric field strength reached a critical level of 76 MV/cm for NaCl and 64 MV/cm for KCl.

Impact of Water-Based Drilling-In Fluids on Solids Invasion and Damage Characteristics

Summary Drilling the U-formation (shale and sandstone) in Saudi Arabia requires high drilling fluid density (±95 lbm/ft3) to mechanically stabilize the shale and balance the reservoir pressure. Two fluids have been used to drill this formation: KCl/BaSO4/CaCO3 and potassium formate/CaCO3 drilling fluids. Barite is added in the first fluid with CaCO3 to reduce the amount of solids needed to formulate the drillin fluid. However, BaSO4 is insoluble in acids and requires chelating agents (DTPA) to remove it from the formation. Formate drill-in fluids with low solids content can be used, but they are expensive and corrosive at pH values less than 7-8. A third drilling fluid was developed recently by Al-Yami et al. (2007) to overcome some of the problems associated with these two systems. The objectives of this study are to determine solids invasion and damage characteristics for the three fluids. Coreflood tests were conducted using reservoir cores at bottomhole conditions. The cores were then examined by environmental-scanning-electron-microscope (ESEM) analysis to investigate solids invasion, solids type, and location of damage. The three drilling fluids examined did damage the core plugs either through external filter cake, internal filter cake, or both. The ESEM images showed that the least damage occurred when Mn3O4 water-based drill-in fluid was used. The highest damage was observed when barite/CaCO3 mud was examined. This was followed by the potassium formate drill-in fluids. Kaolinite booklets were not attacked by the filtrate of the three drill-in fluids examined. The damage that was noted with potassium formate mud resulted from incompatibility of mud filtrate with the formation brine where potassium chloride crystals were noted in the cores.

Multiple Unit Asymmetric Membrane Capsule: A Means for Delivery of Highly Water Soluble Drug

A multiple unit, non-disintegrating asymmetric polymeric capsular system was used to deliver highly water-soluble drug in a controlled manner. A highly water-soluble drug, metformin hydrochloride (MHCl), was selected as a model drug to demonstrate how the controlled release could be generated in vitro by changes in the core as well as the coating formulation. Formation of asymmetric capsule wall membrane involved wet phase inversion process, in which the asymmetric membrane (AM) was precipitated on glass mold pins by dipping the mold pins into a coating solution containing the good and bad solvents for the polymer followed by quenching in an aqueous quench bath. The study optimized by 23 factorial design evaluates the influence of coating formulation namely concentration of ethylcellulose and pore former (glycerol) and core component namely controlled release potassium chloride crystals. Scanning Electron Microscopy (SEM) showed the presence of outer dense non porous region and inner, thick, porous region for the prepared AM. Statistical test were applied at P &gt; 0.05 on all the formulations undergoing in vitro release studies. Results showed the solubility of MHCl to have been modulated (reduced) over an extended period of time with pH independent, and osmotic pressure dependant drug release. The release kinetics was found to be zero order.

Formation of fine crystals of potassium chloride dissolved in aqueous ethanol solution by spray evaporation

Spray evaporation of aqueous ethanol solution with dilute potassium chloride (KCl) was examined for the generation of extremely small electrolyte crystals in dry state. Ethanol content in the aqueous solution played an important role in decreasing the solubility of KCl. Evaporation of small liquid droplets of the aqueous ethanol solution produced a small amount of KCl crystals. The concentration of ethanol in the solution was the operative variable, and the ultrasonic spray nozzle and flow rate of the solution were fixed in this study. The crystals collected were observed by SEM, and crystal size distributions were obtained for different operative conditions. The average crystal size ranged from 100 to 800 nm. When the ethanol content increased in the solution, the crystal size decreased. We consider the crystal size according to the slight solubility of KCl in liquid droplets of aqueous ethanol solution.

Luminescent Studies of “Exciplex Tuning” for Nanoclusters of Dicyanocuprate(I) Ions Doped in Potassium Chloride Crystals

Nanoclusters of dicyanocuprate (I) ions doped in potassium chloride crystals have been studied. Several emission bands are observed in this system and each emission band can be tuned by site-selective spectroscopy. These bands are assigned to different [Cu(CN)2]− luminescent nanoclusters in the host lattice. The Cu+ ions substitute for K+ ions in the lattice and the CN− ions substitute for Cl− ions in the host with dimer and trimer nanoclusters bonded together by CN− bridges. This is unlike KAg(CN)2 or KAu(CN)2 substituted in a KCl lattice, in which Ag−Ag or Au−Au bonding directly occurs. Ab initio calculations show that the LUMO is a bonding MO while the HOMO is antibonding. Extended Hückel calculations indicate the formation of the LUMO excited-state well is deeper than the ground-state HOMO potential well and with a shorter internuclear separation characteristic of exciplex behavior. Time-resolved luminescence measuremence at room temperature and 78 K demonstrate that, upon pulsed excitation, energy transfer occurs between the dimer and trimer nanoclusters. We conclude that the presence of different luminescent Cu(CN)2− nanoclusters in different environments results in tunability over a wide wavelength range.

Morphology of potassium chloride in aqueous and in formamide solution — An experimental and computational investigation

The morphology of potassium chloride grown in pure water as well as in water–formamide solution was investigated. Surface morphology of the crystals was examined by using scanning electron microscopy. It has been observed that the potassium chloride crystals are largely grown with {100} face at different concentrations in pure water, which contradicts earlier reports. Experimental results show that the potassium chloride crystals grown in formamide are also cubic in nature. However, it has been found that the sodium chloride crystals are octahedrons under similar conditions. The difference in the morphological behavior of these two alkali halides with formamide was investigated with computational methods. The calculated results revealed that formamide is largely preferred to adsorb on the {111} surface of NaCl, which can lead to octahedrons. However, the energetics is not substantially different for the adsorption of additives to the important surfaces of potassium chloride and results in the formation of a competing stable {100} surface.

Crystal growth and characterization of a semiorganic nonlinear optical single crystal of gamma glycine

Gamma glycine has been successfully synthesized by taking glycine and potassium chloride and single crystals have been grown by solvent evaporation method for the first time. The grown single crystals have been analyzed with XRD, Fourier transform infrared (FTIR), and thermo gravimetric and differential thermal analyses (TG/DTA) measurements. Its mechanical behavior has been assessed by Vickers microhardness measurements. Its nonlinear optical property has been tested by Kurtz powder technique. Its optical behavior was examined by UV–vis., and found that the crystal is transparent in the region between 240 and 1200 nm. Hence, it may be very much useful for the second harmonic generation (SHG) applications.

Optical damage of the surface of sodium and potassium chlorides by femtosecond laser pulses

Optical damage thresholds for the surface of sodium and potassium chloride crystals irradiated by 80-fs laser pulses have been determined. P-polarized terawatt radiation of a chromium-forsterite laser operating at a wavelength of 1240 nm was incident on a sample surface at an angle of 35°. The optical damage of the crystal surface was observed when the electric field strength reached a critical level of 76 MV/cm for NaCl and 64 MV/cm for KCl.