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Physical and chemical properties of a Ga-doped ZnO crystal

International Nuclear Information System (INIS)

Stashans, Arvids; Olivos, Katia; Rivera, Richard

2011-01-01

First-principles calculations based on density functional theory and strengthened by Hartree-Fock computations have been performed to study a Ga-doped wurtzite-type ZnO crystal. The large 108-atom supercell used throughout this work allows one to model a single point defect within the periodic supercell model. Thus, the Ga impurity produced purely local effects on the properties of the material. The electronic band structure was obtained for both pure and impurity-doped materials. The occurrence of free electrons in the conduction band was observed after the incorporation of Ga, implying the Ga dopant's contribution to n-type electrical conductivity in the ZnO crystal, in agreement with known experimental data. An analysis of the charges on atoms and obtained atomic displacements in the region surrounding the defect showed that there is some alteration in the chemical bonding because of the presence of Ga atoms. In particular, the ionic bonding is strengthened in the defect's neighbourhood.
Physical and chemical properties of a Ga-doped ZnO crystal

Energy Technology Data Exchange (ETDEWEB)

Stashans, Arvids; Olivos, Katia; Rivera, Richard, E-mail: arvids@utpl.edu.e [Grupo de FisicoquImica de Materiales, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador)

2011-06-01

First-principles calculations based on density functional theory and strengthened by Hartree-Fock computations have been performed to study a Ga-doped wurtzite-type ZnO crystal. The large 108-atom supercell used throughout this work allows one to model a single point defect within the periodic supercell model. Thus, the Ga impurity produced purely local effects on the properties of the material. The electronic band structure was obtained for both pure and impurity-doped materials. The occurrence of free electrons in the conduction band was observed after the incorporation of Ga, implying the Ga dopant's contribution to n-type electrical conductivity in the ZnO crystal, in agreement with known experimental data. An analysis of the charges on atoms and obtained atomic displacements in the region surrounding the defect showed that there is some alteration in the chemical bonding because of the presence of Ga atoms. In particular, the ionic bonding is strengthened in the defect's neighbourhood.
Effects of crystallization on thermal properties and chemical durability of the glasses containing simulated high level radioactive wastes

International Nuclear Information System (INIS)

Kawamoto, Takamichi; Terai, Ryohei; Hara, Shigeo

1978-01-01

In order to improve the thermodynamic stability of the glasses containing high level radioactive wastes, the conversion to glass-ceramics by the heat-treatment was carried out with two kinds of glasses, and the change of thermal properties and chemical durability by crystallization was investigated. One of the glasses has a composition of SiO 2 -Al 2 O 3 -ZnO-TiO 2 system, and another one has a composition which could grow the nephelite crystals from Na 2 O in wastes and Al 2 O 3 and SiO 2 added as glass-forming materials. Transition and yield points shifted to higher temperatures by the conversion and the glass-ceramics were found to be more stable than the original glasses. The glass-ceramics of the composition of SiO 2 -Al 2 O 3 -ZnO-TiO 2 showed poor durability, whereas the chemical durability of the glass-ceramics containing nephelite crystals was considerably improved. In the latter case, improvement of the durability is attributable to that some parts of glass are converted to nephelite crystals and the crystals are more durable than glass under most conditions. (auth.)
Production and several properties of single crystal austenitic stainless steels

International Nuclear Information System (INIS)

Okamoto, Kazutaka; Yoshinari, Akira; Kaneda, Junya; Aono, Yasuhisa; Kato, Takahiko

1998-01-01

The single crystal austenitic stainless steels Type 316L and 304L were grown in order to improve the resistance to stress corrosion cracking (SCC) using a unidirectional solidification method which can provide the large size single crystals. The mechanical properties and the chemical properties were examined. The orientation and temperature dependence of tensile properties of the single crystals were measured. The yield stress of the single crystal steels are lower than those of the conventional polycrystal steels because of the grain boundary strength cannot be expected in the single crystal steels. The tensile properties of the single crystal austenitic stainless steel Type 316L depend strongly on the orientation. The tensile strength in orientation are about 200 MPa higher than those in the and orientations. The microstructure of the single crystal consists of a mixture of the continuous γ-austenitic single crystal matrix and the δ-ferrite phase so that the effects of the γ/δ boundaries on the chemical properties were studied. The effects of the δ-ferrite phases and the γ/δ boundaries on the resistance to SCC were examined by the creviced bent beam test (CBB test). No crack is observed in all the CBB test specimens of the single crystals, even at the γ/δ boundaries. The behavior of the radiation induced segregation (RIS) at the γ/δ boundaries in the single crystal austenitic stainless steel Type 316L was evaluated by the electron irradiation test in the high voltage electron microscope (HVEM). The depletion of oversized solute chromium at the γ/δ boundary in the single crystal austenitic stainless steel Type 316L is remarkably lower than that at the grain boundary in the polycrystalline-type 316L. (author)
An effect of re-extraction crystallization parameters on physical and chemical properties of AUC

International Nuclear Information System (INIS)

Yahi, Boussad

1990-07-01

This study is concerned with direct cristallization of ammonium uranyl carbonate (AUC) from a uranium loaded organic phase (30% TBP in kerosene), with ammonium carbonate (NH4)2 CO3. The effects of operating conditions (NH4)2 CO3 concentration, flowration residence time, temperature on the physical properties of AUC crystals (particle size distribution, specific area, density..) are reported. All products were identified (both by chemical analysis, X-Ray diffraction) as being ammonium uranyl ratio and (NH4)2 CO3 concentration favor the formation of fine AUC grains and aggregates. This is due mainly to the high concentration of (NH4)+ in the system which leads to a high solution supersaturation and consequently to a rapid formation rate of crystal (germination). The reverse phenomenon is observed at low phase ratio and (NH4)2 CO3 concentration, where germination and crystal growth ara slow and the product is mainly monocrystal. In the intermediate range, a mixture of polycrystal and aggregates is obtained. Residence time and temperature are also shown to have an effect on the processes (the effect of time being more important than temperature)
Crystal Graph Convolutional Neural Networks for an Accurate and Interpretable Prediction of Material Properties

Science.gov (United States)

Xie, Tian; Grossman, Jeffrey C.

2018-04-01

The use of machine learning methods for accelerating the design of crystalline materials usually requires manually constructed feature vectors or complex transformation of atom coordinates to input the crystal structure, which either constrains the model to certain crystal types or makes it difficult to provide chemical insights. Here, we develop a crystal graph convolutional neural networks framework to directly learn material properties from the connection of atoms in the crystal, providing a universal and interpretable representation of crystalline materials. Our method provides a highly accurate prediction of density functional theory calculated properties for eight different properties of crystals with various structure types and compositions after being trained with 1 04 data points. Further, our framework is interpretable because one can extract the contributions from local chemical environments to global properties. Using an example of perovskites, we show how this information can be utilized to discover empirical rules for materials design.
Model of coordination melting of crystals and anisotropy of physical and chemical properties of the surface

Science.gov (United States)

Bokarev, Valery P.; Krasnikov, Gennady Ya

2018-02-01

Based on the evaluation of the properties of crystals, such as surface energy and its anisotropy, the surface melting temperature, the anisotropy of the work function of the electron, and the anisotropy of adsorption, were shown the advantages of the model of coordination melting (MCM) in calculating the surface properties of crystals. The model of coordination melting makes it possible to calculate with an acceptable accuracy the specific surface energy of the crystals, the anisotropy of the surface energy, the habit of the natural crystals, the temperature of surface melting of the crystal, the anisotropy of the electron work function and the anisotropy of the adhesive properties of single-crystal surfaces. The advantage of our model is the simplicity of evaluating the surface properties of the crystal based on the data given in the reference literature. In this case, there is no need for a complex mathematical tool, which is used in calculations using quantum chemistry or modeling by molecular dynamics.
Effect of calcium deficiency on the mechanical properties of hydroxyapatite crystals

International Nuclear Information System (INIS)

Viswanath, B.; Shastry, V.V.; Ramamurty, U.; Ravishankar, N.

2010-01-01

The deterioration of the mechanical properties of bone with age is related to several factors including the structure, organization and chemistry of the constituent phases; however, the relative contribution of each of these factors is not well understood. In this study, we have investigated the effect of chemistry (calcium deficiency) on the mechanical properties of single crystals of hydroxyapatite. Single crystals of stoichiometric crystals grown by the flux method and calcium-deficient platelet crystals grown using wet chemical methods were used as model systems. Using nanoindentation, we show that calcium deficiency leads to an 80% reduction in the hardness and elastic modulus and at least a 75% reduction in toughness in plate-shaped hydroxyapatite crystals. Measurement of local mechanical properties using nanoindentation and nanoscale chemistry through elemental mapping in a transmission electron microscope points to a direct correlation between the observed spatial variation in composition and the large scatter in the measured hardness and modulus values.
Electrical properties of molecular crystals

International Nuclear Information System (INIS)

Barraud, A.

1968-01-01

This literature survey summarizes the electrical properties of molecular crystals: molecular crystal structure, transport and excitation mechanisms of charge-carriers, and differences compared to inorganic semi-conductors. The main results concerning the electrical conductivity of the most-studied molecular crystals are presented, together with the optical and photo-electrical properties of these crystals. Finally the different types of electrical measurements used are reviewed, as well as the limits of each method. (author) [fr
Crystal growth, defects, and mechanical and spectral properties of a novel mixed laser crystal Nd:GdYNbO{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Ding, Shoujun; Dou, Renqin [Chinese Academy of Sciences, Anhui Institute of Optics and Fine Mechanics, Hefei, Anhui Province (China); University of Science and Technology of China, Hefei (China); Liu, Wenpeng; Zhang, Qingli; Peng, Fang; Luo, Jianqiao; Sun, Guihua; Sun, Dunlu [Chinese Academy of Sciences, Anhui Institute of Optics and Fine Mechanics, Hefei, Anhui Province (China)

2017-01-15

A mixed laser crystal of Nd-doped GYNO crystal was grown successfully by Czochralski method. The crystal belongs to monoclinic system with space group I2/a, the structural parameters are obtained by the X-ray Rietveld refinement method. The defects and dislocations along three crystallographic orientations were studied by using the chemical etching method with the phosphoric acid etchant. The mechanical properties (including hardness, yield strength, fracture toughness, and brittle index) of the crystal were estimated by Vickers hardness test. The transmission spectrum was measured at room temperature, and the absorption peaks were assigned. Spectral properties of the as-grown crystal were investigated by Judd-Ofelt theory, and the Judd-Ofelt intense parameters Ω{sub 2,4,6} were obtained to be 9.674 x 10{sup -20}, 2.092 x 10{sup -20}, and 4.061 x 10{sup -20} cm{sup 2}, respectively. (orig.)
Thermodynamics of Binary Mixed Crystals in the Sub-quasi-chemical/Debye Approximation

Science.gov (United States)

van der Kemp, W. J. M.; Verdonk, M. L.

1995-03-01

A new statistical model for the description of the thermodynamic properties of binary mixed crystals is discussed. The model is based on an asymmetrical analogue of the quasi-chemical approximation and the Debye model of a solid. With two interchange -energy parameters and two interchange-Debye-temperature parameters, all important thermodynamic functions, at constant volume, of the binary mixed crystal can be calculated as a function of temperature and composition. The binary system {( 1 - x)Nai + xKI}(s) is used for illustration of the model.
Relating mechanical properties and chemical bonding in an inorganic-organic framework material: a single-crystal nanoindentation study.

Science.gov (United States)

Tan, Jin Chong; Furman, Joshua D; Cheetham, Anthony K

2009-10-14

We report the application of nanoindentation and atomic force microscopy to establish the fundamental relationships between mechanical properties and chemical bonding in a dense inorganic-organic framework material: Ce(C(2)O(4))(HCO(2)), 1. Compound 1 is a mixed-ligand 3-D hybrid which crystallizes in an orthorhombic space group, in which its three basic building blocks, i.e. the inorganic metal-oxygen-metal (M-O-M) chains and the two organic bridging ligands, (oxalate and formate) are all oriented perpendicular to one another. This unique architecture enabled us to decouple the elastic and plastic mechanical responses along the three primary axes of a single crystal to understand the contribution associated with stiff vs compliant basic building blocks. The (001)-oriented facet that features rigid oxalate ligands down the c-axis exhibits the highest stiffness and hardness (E approximately 78 GPa and H approximately 4.6 GPa). In contrast, the (010)-oriented facet was found to be the most compliant and soft (E approximately 43 GPa and H approximately 3.9 GPa), since the formate ligand, which is the more compliant building block within this framework, constitutes the primary linkages down the b-axis. Notably, intermediate stiffness and hardness (E approximately 52 GPa and H approximately 4.1 GPa) were measured on the (100)-oriented planes. This can be attributed to the Ce-O-Ce chains that zigzag down the a-axis (Ce...Ce metal centers form an angle of approximately 132 degrees) and also the fact that the 9-coordinated CeO(9) polyhedra are expected to be geometrically more compliant. Our results present the first conclusive evidence that the crystal orientation dominated by inorganic chains is not necessarily more robust from the mechanical properties standpoint. Rigid organic bridging ligands (such as oxalate), on the other hand, can be used to produce greater stiffness and hardness properties in a chosen crystallographic orientation. This study demonstrates that
Crystallization characteristics and physico-chemical properties of glass–ceramics based on Li2O–ZnO–SiO2 system

Directory of Open Access Journals (Sweden)

Saad M. Salman

2017-09-01

Full Text Available Glass materials based on lithium zinc silicate system of the composition 24Li2O–20ZnO–56SiO2 LZS (mol% were prepared and converted to glass–ceramics using controlled heat-treatment schedules. The LZS base glass system was modified by addition of Al2O3 and MO/ZnO replacements where MO = CaO, CdO and SrO oxides. Several crystalline phases were developed, including lithium zinc orthosilicate, α-quartz, β-spodumene solid solution, lithium meta and disilicate, Ca-wollastonite, Cd or Sr metasilicate, and Sr-zinc silicate of hardystonite type. The effects of crystallization process on some properties, like thermal expansion coefficient (TEC, chemical stability, and density of glass–ceramics were evaluated. The TEC of crystalline samples varied from 72 × 10−7 to 149 × 10−7 K−1, 25–600 and density values in the range, 2.67–3.29 g/cm3. The addition of Al2O3 and MO/ZnO replacements in the base glass led to improve the chemical durability of the glass–ceramics samples. As a result of the thermal and physico-chemical properties of the studied glass–ceramic, the materials acquire excellent properties and can be used to seal a variety of different metals and alloys.
Crystallization characteristics and physico-chemical properties of glass–ceramics based on Li2O–ZnO–SiO2 system

International Nuclear Information System (INIS)

Salman, Saad M.; Salama, Samia N.; Abo-Mosallam, Hany A.

2017-01-01

Glass materials based on lithium zinc silicate system of the composition 24Li2O–20ZnO–56SiO2 LZS (mol%) were prepared and converted to glass–ceramics using controlled heat-treatment schedules. The LZS base glass system was modified by addition of Al2O3 and MO/ZnO replacements where MO=CaO, CdO and SrO oxides. Several crystalline phases were developed, including lithium zinc orthosilicate, α-quartz, β-spodumene solid solution, lithium meta and disilicate, Ca-wollastonite, Cd or Sr metasilicate, and Sr-zinc silicate of hardystonite type. The effects of crystallization process on some properties, like thermal expansion coefficient (TEC), chemical stability, and density of glass–ceramics were evaluated. The TEC of crystalline samples varied from 72×10−7 to 149×10−7K−1, 25–600 and density values in the range, 2.67–3.29g/cm3. The addition of Al2O3 and MO/ZnO replacements in the base glass led to improve the chemical durability of the glass–ceramics samples. As a result of the thermal and physico-chemical properties of the studied glass–ceramic, the materials acquire excellent properties and can be used to seal a variety of different metals and alloys. [es
Chemical and nuclear properties of lawrencium (element 103) and hahnium (element 105)

International Nuclear Information System (INIS)

Henderson, R.A.

1990-01-01

The chemical and nuclear properties of Lr and Ha have been studied, using 3-minute 260 Lr and 35-second 262 Ha. The crystal ionic radius of Lr 3+ was determined by comparing its elution position from a cation-exchange resin column with those of lanthanide elements having known ionic radii. Comparisons are made to the ionic radii of the heavy actinides, Am 3+ through Es 3+ , obtained by x-ray diffraction methods, and to Md 3+ and Fm 3+ which were determined in the same manner as Lr 3+ . The hydration enthalpy of -3622 kJ/mol was calculated from the crystal ionic radius using an empirical form of the Born equation. Comparisons to the spacings between the ionic radii of the heaviest members of the lanthanide series show that the 2Z spacing between Lr 3+ and Md 3+ is anomalously small, as the ionic radius of Lr 3+ of 0.0886 nm is significantly smaller than had been expected. The chemical properties of Ha were determined relative to the lighter homologs in group 5, Nb and Ta. Group 4 and group 5 tracer activities, as well as Ha, were absorbed onto glass surfaces as a first step toward the determination of the chemical properties of Ha. Ha was found to adsorb on surfaces, a chemical property unique to the group 5 elements, and as such demonstrates that Ha has the chemical properties of a group 5 element. A solvent extraction procedure was adapted for use as a micro-scale chemical procedure to examine whether or not Ha displays eka-Ta-like chemical under conditions where Ta will be extracted into the organic phase and Nb will not. Under the conditions of this experiment Ha did not extract, and does not show eka-Ta-like chemical properties
Chemical composition of cadmium selenochromite crystals doped with indium, silver and gallium

International Nuclear Information System (INIS)

Bel'skij, N.K.; Ochertyanova, L.I.; Shabunina, G.G.; Aminov, T.G.

1985-01-01

The high accuracy chemical analysis Which allows one to observe doping effect on the cadmium selenochromite crystal composition is performed. The problem on the possibility of impurity atom substitution for basic element is considered on the basis of data of atomic-absorption analysis of doped crystals. The crystals of cadmium selenochromite doped with indium by chromium to cadmium ratio are distributed into two groups and probably two types of substitution take place. At 0.08-1.5 at.% indium concentrations the Cr/Cd ratio >2. One can assume that indium preferably takes cadmium tetrahedral positions whereas at 1.5-2.5 at. % concentrations the Cr/Cd ratio =2 and cadmium is substituted for silver which does not contradict crystallochemical and physical properties of this compound. In crystals with gallium the Cr/Cd ratio <2. Gallium preferably substitutes chromium
Optical and electrical properties of ZrSe3 single crystals grown by chemical vapour transport technique

International Nuclear Information System (INIS)

Patel, Kaushik; Prajapati, Jagdish; Vaidya, Rajiv; Patel, S.G.

2005-01-01

Single crystals of the lamellar compound, ZrSe 3 , were grown by chemical vapour transport technique using iodine as a transporting agent. The grown crystals were characterized with the help of energy dispersive analysis by X-ray (EDAX), which gave confirmation about the stoichiometry. The optical band gap measurement of as grown crystals was carried out with the help of optical absorption spectra in the range 700-1450 nm. The indirect as well as direct band gap of ZrSe 3 were found to be 1.1 eV and 1.47 eV, respectively. The resistivity of the as grown crystals was measured using van der Pauw method. The Hall parameters of the grown crystals were determined at room temperature from Hall effect measurements. Electrical resistivity measurements were performed on this crystal in the temperature range 303-423 K. The crystals were found to exhibit semiconducting nature in this range. The activation energy and anisotropy measurements were carried out for this crystal. Pressure dependence of electrical resistance was studied using Bridgman opposed anvils set up up to 8 GPa. The semiconducting nature of ZrSe 3 single crystal was inferred from the graph of resistance vs pressure. The results obtained are discussed in detail. (author)
Growth and characterization of Bi2Se3 crystals by chemical vapor transport

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W. H. Jiao

2012-06-01

Full Text Available Regularly-shaped high-quality Bi2Se3 crystals were grown by a chemical vapor transport using iodine as the transport agent. In addition to exhibiting a characteristic Dirac cone for a topological insulator, the Bi2Se3 crystals show some outstanding properties including additional crystallographic surfaces, large residual resistance ratio (∼10, and high mobility (∼8000 cm2·V−1·s−1. The low-temperature resistivity abnormally increases with applying pressures up to 1.7 GPa, and no superconductivity was observed down to 0.4 K.
Impact of crystallization on the structure and chemical durability of borosilicate glass

International Nuclear Information System (INIS)

Nicoleau, Elodie

2016-01-01

This work describes a new approach to help understand the chemical durability of partially crystallized nuclear waste conditioning matrices. Among the studies carried out on nuclear waste deep geological disposal, long term behavior studies have so far been conducted on homogeneous glassy matrices. However, as the crystalline phases may generate modifications in the chemical composition and properties of such matrices, the description and a better understanding of their effects on the chemical durability of waste packages are of primary importance. A protocol to study the durability of heterogeneous model matrices of nuclear interest containing different types of crystalline phases was developed. It is based on a detailed description of the morphology, microstructure and structure of the glassy matrix and crystalline phases, and on the study of various alteration regimes. Three crystal phases that may form when higher concentrations of waste are immobilized in Uranium Oxide type conditioning glasses were studied: alkali and alkaline earth molybdates, rare earth silicates and ruthenium oxide. The results highlight the roles of the composition and the structure of the surrounding glassy matrix as the parameters piloting the alteration kinetics of the partially crystallized glassy matrices. This behavior is identical whatever the nature of the crystalline phases, as long as these phases do not lead to a composition gradient and do not percolate within the glassy matrix. Given these results, a methodology to study partially crystallized matrices with no composition gradient is then suggested. Its key development lies firstly in the evaluation of the behavior of partially crystallized matrices through the experimental study of the residual glassy matrix in various alteration regimes. This methodology may be adapted to the case of new glass formulations with more complex compositions (e.g. highly waste-loaded glass), which may contain crystals formed during cooling
Origin of electronic properties of PbGa2Se4 crystal: Experimental and theoretical investigations

International Nuclear Information System (INIS)

Babuka, T.; Kityk, I.V.; Parasyuk, O.V.; Myronchuk, G.; Khyzhun, O.Y.; Fedorchuk, A.O.; Makowska-Janusik, M.

2015-01-01

Graphical abstract: In the presented work the structural and electronic properties of the PbGa 2 Se 4 single crystal were investigated experimentally as well as theoretically. The XPS spectra, Urbach’s rule and steepness parameters of PbGa 2 Se 4 single crystal have been investigated for the first time. The quantum chemical calculations were also never performed before for the studied structure. The theoretically obtained data help to explain the properties of material. - Highlights: • Urbach’s rule and steepness parameters for PbGa 2 Se 4 crystals explored for the first time. • Non-reactivity of the PbGa 2 Se 4 surface was established by XPS. • DFT approach shows its efficiency to describe electronic properties of PbGa 2 Se 4 . • Electronic parameters are affected by existence of electron–phonon interaction. - Abstract: The PbGa 2 Se 4 crystal is a promising material for optoelectronic applications. It is caused by coexistence of the large polarized Pb cations and a huge contribution of anharmonic phonon subsystem caused by chalcogenide anions. In the present work the electronic and optical properties of the mentioned material were studied theoretically as well as experimentally by optical and X-ray photoelectron spectroscopy methods. The DFT approach has been used for the quantum chemical electronic properties calculations. Urbach rule and steepness parameters of the PbGa 2 Se 4 crystal have been evaluated for the first time. These parameters and Urbach energies increase with increasing temperature of the samples that is typical for the semiconducting materials. The XPS measurements of the investigated crystal reveal that all the spectral features are originated from core-level states of the constituent elements. Simultaneously these results also confirm non-reactivity of the PbGa 2 Se 4 surface. However, the titled single crystal possesses a number of intrinsic structural defects and vacancies thereby affecting its electronic properties. The

Chemical Potential Tuning and Enhancement of Thermoelectric Properties in Indium Selenides.

Science.gov (United States)

Rhyee, Jong-Soo; Kim, Jin Hee

2015-03-20

Researchers have long been searching for the materials to enhance thermoelectric performance in terms of nano scale approach in order to realize phonon-glass-electron-crystal and quantum confinement effects. Peierls distortion can be a pathway to enhance thermoelectric figure-of-merit ZT by employing natural nano-wire-like electronic and thermal transport. The phonon-softening known as Kohn anomaly, and Peierls lattice distortion decrease phonon energy and increase phonon scattering, respectively, and, as a result, they lower thermal conductivity. The quasi-one-dimensional electrical transport from anisotropic band structure ensures high Seebeck coefficient in Indium Selenide. The routes for high ZT materials development of In₄Se₃ - δ are discussed from quasi-one-dimensional property and electronic band structure calculation to materials synthesis, crystal growth, and their thermoelectric properties investigations. The thermoelectric properties of In₄Se₃ - δ can be enhanced by electron doping, as suggested from the Boltzmann transport calculation. Regarding the enhancement of chemical potential, the chlorine doped In₄Se₃ - δ Cl 0.03 compound exhibits high ZT over a wide temperature range and shows state-of-the-art thermoelectric performance of ZT = 1.53 at 450 °C as an n -type material. It was proven that multiple elements doping can enhance chemical potential further. Here, we discuss the recent progress on the enhancement of thermoelectric properties in Indium Selenides by increasing chemical potential.
Symmetry and physical properties of crystals

CERN Document Server

Malgrange, Cécile; Schlenker, Michel

2014-01-01

Crystals are everywhere, from natural crystals (minerals) through the semiconductors and magnetic materials in electronic devices and computers or piezoelectric resonators at the heart of our quartz watches to electro-optical devices. Understanding them in depth is essential both for pure research and for their applications. This book provides a clear, thorough presentation of their symmetry, both at the microscopic space-group level and the macroscopic point-group level. The implications of the symmetry of crystals for their physical properties are then presented, together with their mathematical description in terms of tensors. The conditions on the symmetry of a crystal for a given property to exist then become clear, as does the symmetry of the property. The geometrical representation of tensor quantities or properties is presented, and its use in determining important relationships emphasized. An original feature of this book is that most chapters include exercises with complete solutions. This all...
Crystal growth and physical properties of Ferro-pnictides

Energy Technology Data Exchange (ETDEWEB)

Aswartham, Saicharan

2012-11-08

The thesis work presented here emphasizes important aspects of crystal growth and the influence of chemical substitution in Fe-As superconductors. High temperature solution growth technique is one of most powerful and widely used technique to grow single crystals of various materials. The biggest advantage of high temperature solution growth technique is the, possibility of growing single crystals from both congruently and incongruently melting materials. Solution growth technique has the potential to control high vapour pressures, given the fact that, in Fe-based superconductors elements with high vapour pressure like As, K, Li and Na have to be handled during the crystal growth procedure. In this scenario high temperature solution growth is the best suitable growth technique to synthesize sizable homogeneous single crystals. Using self-flux high temperature solution growth technique, large centimeter-sized high quality single crystals of BaFe{sub 2}As{sub 2} were grown. This pristine compound BaFe{sub 2}As{sub 2} undergoes structural and magnetic transition at T{sub S/N} = 137 K. By suppressing this magnetic transition and stabilizing tetragonal phase with chemical substitution, like Co-doping and Na-doping, bulk superconductivity is achieved. Superconducting transitions of as high as T{sub c} = 34 K with Na substitution and T{sub c} = 25 K with Co-doping were obtained. A combined electronic phase diagram has been achieved for both electron doping with Co and hole doping with Na in BaFe{sub 2}As{sub 2}. Single crystals of LiFe{sub 1-x}Co{sub x}As with x = 0, 0.025, 0.05 and 0.075 were grown by a self-flux high temperature solution growth technique. The charge doping in LiFeAs is achieved with the Co-doping in Fe atoms. The superconducting properties investigated by means of temperature dependent magnetization and resistivity revealed that superconductivity is shifted to lower temperatures and with higher amount of charge carriers superconductivity is killed
Chemical Potential Tuning and Enhancement of Thermoelectric Properties in Indium Selenides

Directory of Open Access Journals (Sweden)

Jong-Soo Rhyee

2015-03-01

Full Text Available Researchers have long been searching for the materials to enhance thermoelectric performance in terms of nano scale approach in order to realize phonon-glass-electron-crystal and quantum confinement effects. Peierls distortion can be a pathway to enhance thermoelectric figure-of-merit ZT by employing natural nano-wire-like electronic and thermal transport. The phonon-softening known as Kohn anomaly, and Peierls lattice distortion decrease phonon energy and increase phonon scattering, respectively, and, as a result, they lower thermal conductivity. The quasi-one-dimensional electrical transport from anisotropic band structure ensures high Seebeck coefficient in Indium Selenide. The routes for high ZT materials development of In4Se3−δ are discussed from quasi-one-dimensional property and electronic band structure calculation to materials synthesis, crystal growth, and their thermoelectric properties investigations. The thermoelectric properties of In4Se3−δ can be enhanced by electron doping, as suggested from the Boltzmann transport calculation. Regarding the enhancement of chemical potential, the chlorine doped In4Se3−δCl0.03 compound exhibits high ZT over a wide temperature range and shows state-of-the-art thermoelectric performance of ZT = 1.53 at 450 °C as an n-type material. It was proven that multiple elements doping can enhance chemical potential further. Here, we discuss the recent progress on the enhancement of thermoelectric properties in Indium Selenides by increasing chemical potential.
Physical Properties of Liquid Crystals

CERN Document Server

Gray, George W; Spiess, Hans W

1999-01-01

This handbook is a unique compendium of knowledge on all aspects of the physics of liquid crystals. In over 500 pages it provides detailed information on the physical properties of liquid crystals as well as the recent theories and results on phase transitions, defects and textures of different types of liquid crystals. An in-depth understanding of the physical fundamentals is a prerequisite for everyone working in the field of liquid crystal research. With this book the experts as well as graduate students entering the field get all the information they need.
Dispersion properties of photonic crystal fibres

DEFF Research Database (Denmark)

Bjarklev, Anders Overgaard; Broeng, Jes; Dridi, Kim

1998-01-01

Approximate dispersion and bending properties of all-silica two-dimensional photonic crystal fibres are characterised by the combination of an effective-index model and classical analysis tools for optical fibres. We believe for the first time to have predicted the dispersion properties of photonic...... crystal fibres. The results strongly indicate that these fibres have potential applications as dispersion managing components...
Chem I Supplement: Liquid Crystals--The Chameleon Chemicals.

Science.gov (United States)

Brown, Glenn H.

1983-01-01

Presents information relevant to everyday life so as to stimulate student interest in the properties of the two basic types of liquid crystals: thermotropic and lyotropic. Describes the applications of liquid crystals to electronics, biomedicine, and polymer science and appraises the future of liquid crystal research. (JM)
Structural studies of crystals of organic and organoelement compounds using modern quantum chemical calculations within the framework of the density functional theory

International Nuclear Information System (INIS)

Korlyukov, Alexander A; Antipin, Mikhail Yu

2012-01-01

The review generalizes the results of structural studies of crystals of organic and organometallic compounds by modern quantum chemical calculations within the framework of the density functional theory reported in the last decade. Features of the software for such calculations are discussed. Examples of the use of quantum chemical calculations for the studies of the electronic structure, spectroscopic and other physicochemical properties of molecular crystals are presented. The bibliography includes 223 references.
Atom interaction propensities of oxygenated chemical functions in crystal packings

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Christian Jelsch

2017-03-01

Full Text Available The crystal contacts of several families of hydrocarbon compounds substituted with one or several types of oxygenated chemical groups were analyzed statistically using the Hirshfeld surface methodology. The propensity of contacts to occur between two chemical types is described with the contact enrichment descriptor. The systematic large enrichment ratios of some interactions like the O—H...O hydrogen bonds suggests that these contacts are a driving force in the crystal packing formation. The same statement holds for the weaker C—H...O hydrogen bonds in ethers, esters and ketones, in the absence of polar H atoms. The over-represented contacts in crystals of oxygenated hydrocarbons are generally of two types: electrostatic attractions (hydrogen bonds and hydrophobic interactions. While Cl...O interactions are generally avoided, in a minority of chloro-oxygenated hydrocarbons, significant halogen bonding does occur. General tendencies can often be derived for many contact types, but outlier compounds are instructive as they display peculiar or rare features. The methodology also allows the detection of outliers which can be structures with errors. For instance, a significant number of hydroxylated molecules displaying over-represented non-favorable oxygen–oxygen contacts turned out to have wrongly oriented hydroxyl groups. Beyond crystal packings with a single molecule in the asymmetric unit, the behavior of water in monohydrate compounds and of crystals with Z′ = 2 (dimers are also investigated. It was found in several cases that, in the presence of several oxygenated chemical groups, cross-interactions between different chemical groups (e.g. water/alcohols; alcohols/phenols are often favored in the crystal packings. While some trends in accordance with common chemical principles are retrieved, some unexpected results can however appear. For example, in crystals of alcohol–phenol compounds, the strong O—H...O hydrogen bonds between
A quantum-chemical study of oxygen-vacancy defects in PbTiO3 crystals

International Nuclear Information System (INIS)

Stashans, Arvids; Serrano, Sheyla; Medina, Paul

2006-01-01

Investigation of an oxygen vacancy and F center in the cubic and tetragonal lattices of PbTiO 3 crystals is done by means of quantum-chemical simulations. Displacements of defect-surrounding atoms, electronic and optical properties, lattice relaxation energies and some new effects due to the defects presence are reported and analyzed. A comparison with similar studies is made and conclusions are drawn on the basis of the obtained results
Advances in chemical physics advances in liquid crystals

CERN Document Server

Prigogine, Ilya; Vij, Jagdish K

2009-01-01

Prigogine and Rice's highly acclaimed series, Advances in Chemical Physics, provides a forum for critical, authoritative reviews of current topics in every area of chemical physics. Edited by J.K. Vij, this volume focuses on recent advances in liquid crystals with significant, up-to-date chapters authored by internationally recognized researchers in the field.
Fluorination of Metal Phthalocyanines: Single-Crystal Growth, Efficient N-Channel Organic Field-Effect Transistors, and Structure-Property Relationships

Science.gov (United States)

Jiang, Hui; Ye, Jun; Hu, Peng; Wei, Fengxia; Du, Kezhao; Wang, Ning; Ba, Te; Feng, Shuanglong; Kloc, Christian

2014-01-01

The fluorination of p-type metal phthalocyanines produces n-type semiconductors, allowing the design of organic electronic circuits that contain inexpensive heterojunctions made from chemically and thermally stable p- and n-type organic semiconductors. For the evaluation of close to intrinsic transport properties, high-quality centimeter-sized single crystals of F16CuPc, F16CoPc and F16ZnPc have been grown. New crystal structures of F16CuPc, F16CoPc and F16ZnPc have been determined. Organic single-crystal field-effect transistors have been fabricated to study the effects of the central metal atom on their charge transport properties. The F16ZnPc has the highest electron mobility (~1.1 cm2 V−1 s−1). Theoretical calculations indicate that the crystal structure and electronic structure of the central metal atom determine the transport properties of fluorinated metal phthalocyanines. PMID:25524460
Crystal growth, structure, defects, mechanical and spectral properties of Nd{sub 0.01}:Gd{sub 0.89}La{sub 0.1}NbO{sub 4} mixed crystal

Energy Technology Data Exchange (ETDEWEB)

Ding, Shoujun; Lu, Wancheng; Xu, Jinrui [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, Anhui Province (China); University of Science and Technology of China, Hefei (China); Zhang, Qingli; Luo, Jianqiao; Liu, Wenpeng; Sun, Guihua; Sun, Dunlu [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, Anhui Province (China)

2017-10-15

A novel mixed laser crystal of Nd:GdLaNbO{sub 4} (Nd:GLNO) was grown successfully by conventional Czochralski method. The unit cell parameters were obtained by Rietveld refinement method. The density of the as-grown crystal was measured by Archimedean buoyancy method and calculated in theory. Absorption spectrum of Nd:GLNO crystal was recorded at room temperature, and 11 absorption peaks were assigned. The defects of Nd:GLNO crystal were revealed by using chemical etching method with phosphoric acid as etchant. The mechanical properties (including hardness, yield strength, elastic stiffness constant, fracture toughness and brittleness index) were systemically estimated based on Vickers hardness test. All these obtained results play a quite important role in further investigation of Nd:GLNO crystal. (orig.)
Surface crystallization and magnetic properties of amorphous Fe80B20 alloy

International Nuclear Information System (INIS)

Vavassori, P.; Ronconi, F.; Puppin, E.

1997-01-01

We have studied the effects of surface crystallization on the magnetic properties of Fe 80 B 20 amorphous alloys. The surface magnetic properties have been studied with magneto-optic Kerr measurements, while those of bulk with a vibrating sample magnetometer. This study reveals that surface crystallization is similar to the bulk process but occurs at a lower temperature. At variance with previous results on other iron-based amorphous alloys the surface crystalline layer does not induce bulk magnetic hardening. Furthermore, both the remanence to saturation ratio and the bulk magnetic anisotropy do not show appreciable variations after the formation of the surface crystalline layer. The Curie temperature of the surface layer is lower with respect to the bulk of the sample. These effects can be explained by a lower boron concentration in the surface region of the as-cast amorphous alloy. Measurements of the chemical composition confirm a reduction of boron concentration in the surface region. copyright 1997 American Institute of Physics
Crystal-chemical characteristics of nontronites from bottom sediments of Pacific ocean

International Nuclear Information System (INIS)

Palchik, N. A.; Moroz, T. N.; Grigorieva, T. N.; Nikandrova, N. K.; Miroshnichenko, L. V.

2017-01-01

A crystal-chemical analysis of the nontronite samples formed in deep-water sediments of the underwater Juan-de-Fuca ridge in the Pacific ocean has been performed using powder X-ray diffraction, IR spectroscopy, and Mössbauer spectroscopy. A comparison with the previously investigated nontronites from different regions of the Sea of Okhotsk showed that the structural features of these formations are due to the difference in the physicochemical parameters of their crystallization. The values of the basal interplanar spacing d_0_0_1 (within 11–13 Å) in the samples analyzed are determined by the degree of hydration and cation filling of the interlayer space, while the differences in the IR spectra are due to isomorphic substitutions in the structure. The character of cation distribution and the nature and concentration of stacking faults in nontronite structures are determined. The differences in the composition, structure, and properties of nontronites of different origin are confirmed by theoretical calculations of their structural parameters.
Crystal-chemical characteristics of nontronites from bottom sediments of Pacific ocean

Energy Technology Data Exchange (ETDEWEB)

Palchik, N. A., E-mail: nadezhda@igm.nsc.ru; Moroz, T. N.; Grigorieva, T. N. [Russian Academy of Sciences, Sobolev Institute of Geology and Mineralogy, Siberian Branch (Russian Federation); Nikandrova, N. K. [Russian Academy of Sciences, Institute of Mineralogy, Ural Branch (Russian Federation); Miroshnichenko, L. V. [Russian Academy of Sciences, Sobolev Institute of Geology and Mineralogy, Siberian Branch (Russian Federation)

2017-01-15

A crystal-chemical analysis of the nontronite samples formed in deep-water sediments of the underwater Juan-de-Fuca ridge in the Pacific ocean has been performed using powder X-ray diffraction, IR spectroscopy, and Mössbauer spectroscopy. A comparison with the previously investigated nontronites from different regions of the Sea of Okhotsk showed that the structural features of these formations are due to the difference in the physicochemical parameters of their crystallization. The values of the basal interplanar spacing d{sub 001} (within 11–13 Å) in the samples analyzed are determined by the degree of hydration and cation filling of the interlayer space, while the differences in the IR spectra are due to isomorphic substitutions in the structure. The character of cation distribution and the nature and concentration of stacking faults in nontronite structures are determined. The differences in the composition, structure, and properties of nontronites of different origin are confirmed by theoretical calculations of their structural parameters.
Crystal chemistry and magnetic properties of ternary rare earth sulfides

International Nuclear Information System (INIS)

Plug, C.M.; Rijksuniversiteit Leiden

1977-01-01

The results of magnetic measurements on two groups of ternary rare earth sulphides are described, the MLnS 2 (M=Li, Na, K) type of compounds and the series Ln 2 ZrS 5 , where Ln denotes one of the rare earths. None of these compounds is metallic, excluding the possibility of RKKY-interaction. In chapter II a survey of the relevant theory on magnetic properties and crystal field splitting is given. In spite of the similarity in chemical properties of the rare earths, the crystal chemistry of their compounds is rather complex. This is due to the lanthanide contraction. The third chapter deals with the description and classification of the numerous crystal structures of both ternary and binary rare earth sulphides that have been observed. Rather simple relations between various structures are presented using a new method of structure classification. The magnetic interactions expected to be based on superexchange via the anions, which is usually very structure dependent. Experiments to study the crystallographic ordering, applying both X-ray and electron diffraction methods and the results of the magnetic measurements on the compounds MLnS 2 are reported in chapter IV. The compounds Ln 2 ZrS 5 are candidates for a systematic study of the variation of the magnetic properties along the rare earth series. The results of magnetic measurements on these compounds are presented in chapter V, combined with the results of specific heat measurements. Also the magnetic structure of two representatives, Tb 2 ZrS 5 and Dy 2 ZrS 5 , determined by neutron diffraction experiments below the ordering temperature, is reported
Role of crystal orientation on chemical mechanical polishing of single crystal copper

Energy Technology Data Exchange (ETDEWEB)

Zhu, Aibin, E-mail: abzhu@mail.xjtu.edu.cn; He, Dayong; Luo, Wencheng; Liu, Yangyang

2016-11-15

Highlights: • The role of crystal orientation in cooper CMP by quasi-continuum was studied. • The atom displacement diagrams were obtained and analyzed. • The stress distribution diagrams and load-displacement curves were analyzed. • This research is helpful to revealing the material removal mechanism of CMP. - Abstract: The material removal mechanism of single crystal copper in chemical mechanical polishing (CMP) has not been intensively investigated. And the role of crystal orientation in CMP of single crystal cooper is not quite clear yet. Quasi-continuum method was adopted in this paper to simulate the process of nano-particles grinding on single crystal copper in CMP process. Three different crystal orientations, i.e. x[100]y[001], x[001]y[110] and x[–211]y[111], were chosen for analysis. The atom displacement diagrams, stress distribution diagrams and load-displacement curves were obtained. After analyzing the deformation mechanism, residual stress of the work piece material and cutting force, results showed that, the crystal orientation of work piece has great influence on the deformation characteristics and surface quality of work piece during polishing. In the A(001)[100] orientation, the residual stress distribution after polishing is deeper, and the stress is larger than that in the B(110)[001] and C(111)[–211] orientations. And the average tangential cutting force in the A(001)[100] orientation is much larger than those in the other two crystal orientation. This research is helpful to revealing the material removal mechanism of CMP process.
Different properties exhibited on the two typical crystal faces of hydroxyapatite in a simulated body environment

Energy Technology Data Exchange (ETDEWEB)

Hagio, T; Iwai, K [Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan); Tanase, T [Toho Gas Corporation, 19-18 Sakurada-cho, Atsuta-ku, Nagoya, 456-8511 (Japan); Akiyama, J [Institute for Molecular Science, National Institute of Natural Sciences, 38 Nishigonaka, Myodaiji, Okazaki, 444-8585 (Japan); Asai, S [Innovation Plaza Tokai Japan Science and Technology Agency, 23-1 Ahara-cho, Minami-ku, Nagoya, 457-0063 (Japan)], E-mail: hagio.takeshi@h.mbox.nagoya-u.ac.jp

2009-03-01

Hydroxyapatite is a main mineral constituent of hard tissues and is extensively used as a biomaterial in the medical field. Hydroxyapatite exhibits anisotropic chemical properties on its two typical crystal faces, the a-face and c-face, due to its hexagonal crystal structure. In polycrystalline bodies, such anisotropy can be enhanced by controlling the crystal orientation. Hydroxyapatite nanocrystals that constitute long bones also form a crystal oriented structure. Therefore, clarification of the difference between the properties of a-face and c-face in hydroxyapatite using in vitro experiments is useful to understand the structure and function of actual hard tissues. Hydroxyapatite ceramics with controlled crystal orientation were prepared by a slip casting method under application of a magnetic field. The fabricated hydroxyapatite ceramics had surfaces consisting mainly of a-face, or otherwise c-face hydroxyapatite. These hydroxyapatite ceramics were immersed into simulated body fluids to investigate the difference in bioactivity. The precipitation behavior observed on the surface of each hydroxyapatite ceramic was different. The thickness of the precipitate was increased and formed earlier on the HAp c-face compared to that on the a-face.
Different properties exhibited on the two typical crystal faces of hydroxyapatite in a simulated body environment

International Nuclear Information System (INIS)

Hagio, T; Iwai, K; Tanase, T; Akiyama, J; Asai, S

2009-01-01

Hydroxyapatite is a main mineral constituent of hard tissues and is extensively used as a biomaterial in the medical field. Hydroxyapatite exhibits anisotropic chemical properties on its two typical crystal faces, the a-face and c-face, due to its hexagonal crystal structure. In polycrystalline bodies, such anisotropy can be enhanced by controlling the crystal orientation. Hydroxyapatite nanocrystals that constitute long bones also form a crystal oriented structure. Therefore, clarification of the difference between the properties of a-face and c-face in hydroxyapatite using in vitro experiments is useful to understand the structure and function of actual hard tissues. Hydroxyapatite ceramics with controlled crystal orientation were prepared by a slip casting method under application of a magnetic field. The fabricated hydroxyapatite ceramics had surfaces consisting mainly of a-face, or otherwise c-face hydroxyapatite. These hydroxyapatite ceramics were immersed into simulated body fluids to investigate the difference in bioactivity. The precipitation behavior observed on the surface of each hydroxyapatite ceramic was different. The thickness of the precipitate was increased and formed earlier on the HAp c-face compared to that on the a-face.

A quantum-chemical study of oxygen-vacancy defects in PbTiO{sub 3} crystals

Energy Technology Data Exchange (ETDEWEB)

Stashans, Arvids [Laboratorio de Fisica, Escuela de Electronica y Telecomunicaciones, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador)]. E-mail: arvids@utpl.edu.ec; Serrano, Sheyla [Centro de Investigacion en Fisica de Materia Condensada, Corporacion de Fisica Fundamental y Aplicada, Apartado 17-12-637, Quito (Ecuador); Escuela de Ingenierias, Universidad Politecnica Salesiana, Campus Sur, Rumichaca s/n y Moran Valverde, Apartado 17-12-536, Quito (Ecuador); Medina, Paul [Centro de Investigacion en Fisica de Materia Condensada, Corporacion de Fisica Fundamental y Aplicada, Apartado 17-12-637, Quito (Ecuador)

2006-05-31

Investigation of an oxygen vacancy and F center in the cubic and tetragonal lattices of PbTiO{sub 3} crystals is done by means of quantum-chemical simulations. Displacements of defect-surrounding atoms, electronic and optical properties, lattice relaxation energies and some new effects due to the defects presence are reported and analyzed. A comparison with similar studies is made and conclusions are drawn on the basis of the obtained results.
Hierarchically structured photonic crystals for integrated chemical separation and colorimetric detection.

Science.gov (United States)

Fu, Qianqian; Zhu, Biting; Ge, Jianping

2017-02-16

A SiO 2 colloidal photonic crystal film with a hierarchical porous structure is fabricated to demonstrate an integrated separation and colorimetric detection of chemical species for the first time. This new photonic crystal based thin layer chromatography process requires no dyeing, developing and UV irradiation compared to the traditional TLC. The assembling of mesoporous SiO 2 particles via a supersaturation-induced-precipitation process forms uniform and hierarchical photonic crystals with micron-scale cracks and mesopores, which accelerate the diffusion of developers and intensify the adsorption/desorption between the analytes and silica for efficient separation. Meanwhile, the chemical substances infiltrated to the voids of photonic crystals cause an increase of the refractive index and a large contrast of structural colors towards the unloaded part, so that the sample spots can be directly recognized with the naked eye before and after separation.
Pb1xMnxTe single crystals and their structural properties

Directory of Open Access Journals (Sweden)

NEBOJSA ROMCEVIC

2004-12-01

Full Text Available Pb1-xMnxTe crystals were grown by the vertical Bridgman method. Their structural properties were observed both by optical microscopy after chemical polishing and ething, and by X-ray powder diffraction analysis. A solution of 5 vol. % Br2 in HBr at room temperatur, for an exposure of 2 min was determined for chemical polishing. A solution of 20 g KOH in 1 ml H2O2, 2 ml glycerol (C3H8O3, and 20 ml H2O at room temperature for an exposure for 6 min was found to be a suitable etching solution. The obtained results are discussed and compared with published data.
Synthesis, non-isothermal crystallization and magnetic properties of ...

Indian Academy of Sciences (India)

perties and modifies the physical properties of the matrix considerably. However ... perties and harmlessness to health. PEVA, in their different ..... crystals causing a depression in Tm and Tp. In all the cases, the crystallization enthalpy peak ...
Two-Dimensional Photonic Crystals for Sensitive Microscale Chemical and Biochemical Sensing

Science.gov (United States)

Miller, Benjamin L.

2015-01-01

Photonic crystals – optical devices able to respond to changes in the refractive index of a small volume of space – are an emerging class of label-free chemical-and bio-sensors. This review focuses on one class of photonic crystal, in which light is confined to a patterned planar material layer of sub-wavelength thickness. These devices are small (on the order of tens to 100s of microns square), suitable for incorporation into lab-on-a-chip systems, and in theory can provide exceptional sensitivity. We introduce the defining characteristics and basic operation of two-dimensional photonic crystal sensors, describe variations of their basic design geometry, and summarize reported detection results from chemical and biological sensing experiments. PMID:25563402
Anisotropic surface hole-transport property of triphenylamine-derivative single crystal prepared by solution method

Energy Technology Data Exchange (ETDEWEB)

Umeda, Minoru, E-mail: mumeda@vos.nagaokaut.ac.jp [Nagaoka University of Technology, Kamitomioka, Nagaoka, Niigata 940-2188 (Japan); Katagiri, Mitsuhiko; Shironita, Sayoko [Nagaoka University of Technology, Kamitomioka, Nagaoka, Niigata 940-2188 (Japan); Nagayama, Norio [Nagaoka University of Technology, Kamitomioka, Nagaoka, Niigata 940-2188 (Japan); Ricoh Company, Ltd., Nishisawada, Numazu, Shizuoka 410-0007 (Japan)

2016-12-01

Highlights: • A hole transport molecule was investigated based on its electrochemical redox characteristics. • The solubility and supersolubility curves of the molecule were measured in order to prepare a large crystal. • The polarization micrograph and XRD results revealed that a single crystal was obtained. • An anisotropic surface conduction, in which the long-axis direction exceeds that of the amorphous layer, was observed. • The anisotropic surface conduction was well explained by the molecular stacked structure. - Abstract: This paper reports the anisotropic hole transport at the triphenylamine-derivative single crystal surface prepared by a solution method. Triphenylamine derivatives are commonly used in a hole-transport material for organic photoconductors of laser-beam printers, in which the materials are used as an amorphous form. For developing organic photovoltaics using the photoconductor’s technology, preparation of a single crystal seems to be a specific way by realizing the high mobility of an organic semiconductor. In this study, a single crystal of 4-(2,2-diphenylethenyl)-N,N-bis(4-methylphenyl)-benzenamine (TPA) was prepared and its anisotropic hole-transport property measured. First, the hole-transport property of the TPA was investigated based on its chemical structure and electrochemical redox characteristics. Next, a large-scale single crystal formation at a high rate was developed by employing a solution method based on its solubility and supersolubility curves. The grown TPA was found to be a single crystal based on the polarization micrograph observation and crystallographic analysis. For the TPA single crystal, an anisotropic surface conduction was found, which was well explained by its molecular stack structure. The measured current in the long-axis direction is one order of magnitude greater than that of amorphous TPA.
A novel method of rapidly modeling optical properties of actual photonic crystal fibres

International Nuclear Information System (INIS)

Li-Wen, Wang; Shu-Qin, Lou; Wei-Guo, Chen; Hong-Lei, Li

2010-01-01

The flexible structure of photonic crystal fibre not only offers novel optical properties but also brings some difficulties in keeping the fibre structure in the fabrication process which inevitably cause the optical properties of the resulting fibre to deviate from the designed properties. Therefore, a method of evaluating the optical properties of the actual fibre is necessary for the purpose of application. Up to now, the methods employed to measure the properties of the actual photonic crystal fibre often require long fibre samples or complex expensive equipments. To our knowledge, there are few studies of modeling an actual photonic crystal fibre and evaluating its properties rapidly. In this paper, a novel method, based on the combination model of digital image processing and the finite element method, is proposed to rapidly model the optical properties of the actual photonic crystal fibre. Two kinds of photonic crystal fibres made by Crystal Fiber A/S are modeled. It is confirmed from numerical results that the proposed method is simple, rapid and accurate for evaluating the optical properties of the actual photonic crystal fibre without requiring complex equipment. (rapid communication)
Physical and chemical properties of ice residuals during the 2013 and 2014 CLACE campaigns

Science.gov (United States)

Kupiszewski, Piotr; Weingartner, Ernest; Vochezer, Paul; Hammer, Emanuel; Gysel, Martin; Färber, Raphael; Fuchs, Claudia; Schnaiter, Martin; Baltensperger, Urs; Schmidt, Susan; Schneider, Johannes; Bigi, Alessandro; Toprak, Emre; Linke, Claudia; Klimach, Thomas

2014-05-01

The shortcomings in our understanding and, thus, representation of aerosol-cloud interactions are one of the major sources of uncertainty in climate model projections. Among the poorly understood processes is mixed-phase cloud formation via heterogeneous nucleation, and the subsequent spatial and temporal evolution of such clouds. Cloud glaciation augments precipitation formation, resulting in decreased cloud cover and lifetime, and affects cloud radiative properties. Meanwhile, the physical and chemical properties of atmospherically relevant ice nuclei (IN), the sub-population of aerosol particles which enable heterogeneous nucleation, are not well known. Extraction of ice residuals (IR) in mixed-phase clouds is a difficult task, requiring separation of the few small, freshly formed ice crystals (the IR within such crystals can be deemed representative of the original IN) not only from interstitial particles, but also from the numerous supercooled droplets which have aerodynamic diameters similar to those of the ice crystals. In order to address the difficulties with ice crystal sampling and IR extraction in mixed-phase clouds, the new Ice Selective Inlet (ISI) has been designed and deployed at the Jungfraujoch field site. Small ice crystals are selectively sampled via the inlet with simultaneous counting, sizing and imaging of hydrometeors contained in the cloud by a set of optical particle spectrometers, namely Welas optical particle counters (OPC) and a Particle Phase Discriminator (PPD). The heart of the ISI is a droplet evaporation unit with ice-covered inner walls, resulting in removal of droplets using the Wegener-Bergeron-Findeisen process, while transmitting a relatively high fraction of small ice crystals. The ISI was deployed in the winters of 2013 and 2014 at the high alpine Jungfraujoch site (3580 m.a.s.l) during the intensive CLACE field campaigns. The measurements focused on analysis of the physical and chemical characteristics of IR and the
Effects of Manganese (Ii Sulphate on Structural, Spectral, Optical, Thermal and Mechanical Properties of L-Alanine Sodium Sulphate Single Crystals

Directory of Open Access Journals (Sweden)

F. Praveena

2017-04-01

Full Text Available New Non-linear Optical materials have been attracting in the research world for their potential applications in emerging opto-electronic technology. The dipolar nature of amino acid leads to peculiar physical and chemical properties, thus making a good candidate for NLO applications. Single crystals of manganese(II sulphate doped L-Alanine sodium sulphate(LASS has been synthesized by slow evaporation technique. Structural property of the grown crystals are characterized by X-ray powder diffraction,FT-IR spectral analysis conforms all the functional groups. Thermogravity (TG and differential themogravimetric (DTA analysis have been performed to study the thermal stability of the crystals. The second harmonic generation efficiency was measured by Kurtz-Perry powder technique. The transmission and absorption of electromagnetic radiation is analysed through UV-VIS spectrum. Microhardness was measured at different applied load to understand the mechanical stability of the crystal.
Chemical forms of 35S in KCl crystals doped with elementary 35S. Pt. 1

International Nuclear Information System (INIS)

Maddock, A.G.; Todorovsky, D.S.

1983-01-01

KCl crystals have been doped with 35 S at low chemical concentrations. Upon solution of the doped crystals in cyanide solution and analysis by the method of Kasrai and Maddock, the 35 S appears in the same chemical forms as are found for the 35 S produced in similar crystals by the (n, p) reaction. Reactions are suggested whereby these products may be produced. (orig.)
Spectrometric properties and radiation damage of BGO crystals

Science.gov (United States)

Kim, Gen C.; Gasanov, Eldar M.

1997-07-01

Spectrometric properties, such as light output, energy resolution BGO crystals before and after (superscript 60)Co gamma-ray (dose 10(superscript 4) - 10(superscript 6) R) and neutron irradiation (fluence 10(superscript 14) cm(superscript -2)) are investigated. Condition for degradation of spectrometric properties and their recovering after irradiation are studied. The energy spectrum of the photons emitted from BGO crystals irradiated with neutron fluence contains the long living background peak which is caused by self-irradiation with radioactive isotopes produced in the crystals. The defect production was studied in crystals under the high dose gamma-irradiation with (superscript 60)Co isotope. It was found that after doses above 10(superscript 8) R the color center at 365 nm and doses higher than 10(superscript 9) R a wide absorption band in the region of 300 - 350 nm occur. Comparison of these results with those of reactor irradiation has shown that under the high dose gamma-irradiation the structure defect production takes place.
Linear and nonlinear optical properties of borate crystals as ...

Indian Academy of Sciences (India)

Unknown

crystal series, with an accuracy acceptable for materials development/design, and answer the questions often ... Optical property; nonlinear optical crystals; first principles calculation. 1. ..... system, and is not in concept suitable to excitation pro-.
New crystal-chemical data for marécottite

Czech Academy of Sciences Publication Activity Database

Plášil, Jakub; Škoda, R.

2015-01-01

Roč. 79, č. 3 (2015), s. 649-660 ISSN 0026-461X R&D Projects: GA ČR GP13-31276P Institutional support: RVO:68378271 Keywords : marécottite * uranyl sulfate * zippeite group * crystal structure * chemical composition * hydrogen bonds. Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.212, year: 2015
Photonic crystals: role of architecture and disorder on spectral properties.

Science.gov (United States)

Verma, Rupesh; Audhkhasi, Romil; Thyagarajan, Krishna; Banerjee, Varsha

2018-03-01

Many of the present-day optical devices use photonic crystals. These are multilayers of dielectric media that control the reflection and transmission of light falling on them. In this paper, we study the optical properties of periodic, fractal, and aperiodic photonic crystals and compare them based on their attributes. Our calculations of the band reflectivity and degree of robustness reveal novel features, e.g., fractal photonic crystals are found to reflect the maximum amount of incident light. On the other hand, aperiodic photonic crystals have the largest immunity to disorder. We believe that such properties will be useful in a variety of applications in the field of optical communication.
Crystal growth and properties of novel organic nonlinear optical crystals of 4-Nitrophenol urea

Energy Technology Data Exchange (ETDEWEB)

Mohan, M. Krishna, E-mail: krishnamohan.m@ktr.srmuniv.ac.in; Ponnusamy, S.; Muthamizhchelvan, C.

2017-07-01

Single crystals of 4-Nitrophenol urea have been grown from water using slow evaporation technique at constant temperature, with the vision to improve the properties of the crystals. The unit cell parameters of the grown crystals were determined by single crystal and powder X-Ray diffraction. FTIR studies reveals the presence of different vibrational bands. The Optical studies confirmed that the crystal is transparent up to 360 nm .TGA and DSC studies were carried out to understand the thermal behavior of crystals. The SHG studies show the suitability of the crystals for NLO applications. The etching studies were carried out to study the behavior of the crystals under different conditions.These studies reveal that the crystals of 4-Nitrophenol urea are suitable for device applications. - Highlights: • 4-Nitrophenol urea crystals of dimensions 14 mm × 1 mm were grown. • UV–Visible studies indicate the crystal is transparent in the region of 370–800 nm. • Thermal studies show the crystal starts decomposing at 170 °C. • SHG studies indicate that the crystals have NLO efficiency 3.5 times that of KDP.
Spin dynamics, electronic, and thermal transport properties of two-dimensional CrPS4 single crystal

Science.gov (United States)

Pei, Q. L.; Luo, X.; Lin, G. T.; Song, J. Y.; Hu, L.; Zou, Y. M.; Yu, L.; Tong, W.; Song, W. H.; Lu, W. J.; Sun, Y. P.

2016-01-01

2-Dimensional (2D) CrPS4 single crystals have been grown by the chemical vapor transport method. The crystallographic, magnetic, electronic, and thermal transport properties of the single crystals were investigated by the room-temperature X-ray diffraction, electrical resistivity ρ(T), specific heat CP(T), and the electronic spin response (ESR) measurements. CrPS4 crystals crystallize into a monoclinic structure. The electrical resistivity ρ(T) shows a semiconducting behavior with an energy gap Ea = 0.166 eV. The antiferromagnetic transition temperature is about TN = 36 K. The spin flipping induced by the applied magnetic field is observed along the c axis. The magnetic phase diagram of CrPS4 single crystal has been discussed. The extracted magnetic entropy at TN is about 10.8 J/mol K, which is consistent with the theoretical value R ln(2S + 1) for S = 3/2 of the Cr3+ ion. Based on the mean-field theory, the magnetic exchange constants J1 and Jc corresponding to the interactions of the intralayer and between layers are about 0.143 meV and -0.955 meV are obtained based on the fitting of the susceptibility above TN, which agree with the results obtained from the ESR measurements. With the help of the strain for tuning the magnetic properties, monolayer CrPS4 may be a promising candidate to explore 2D magnetic semiconductors.
Reactive chemically modified piezoelectric crystal detectors: A new class of high-selectivity sensors

International Nuclear Information System (INIS)

Fadeev, A.Yu.; Filatov, A.L.; Lisichkin, G.V.

1994-01-01

A great number of works have focused on the study of properties of modified piezoelectric quartz crystal detectors (PQCDs) coated with sorbing substrates and on applying sensors based on them for the analysis of diluted gas mixtures and solutions. This work offers a new class of gravemetric sensors characterized by a reversible chemical reaction that occurs on their surface. Silica films are proposed as a sorbing coating of quartz detectors, and a chemical modification of a surface is suggested for covalent fixation of the necessary compounds. PQCDs were chemically modified with reactive diene derivatives that can also act as dienophiles. Hexachlorocyclopentadiene (HCCPD, resonater I) and cyclopentadiene (CPD, resonator II) were fixed on a PQCD surface in several stages. After treatment with the resonaters, the PQCD in a CPD gas phase exhibited time dependent frequency shifts from 20-100 Hz. The results suggest that there is a reversible chemical reaction on the electrode surface of resonators I and II when they interact with CPD vapors. Therefore, PQCDs modified with reactive dienes were prepared for the first time and may be employed as selective sensors for CPD
Crystallization evolution, microstructure and properties of sewage sludge-based glass–ceramics prepared by microwave heating

International Nuclear Information System (INIS)

Tian, Yu; Zuo, Wei; Chen, Dongdong

2011-01-01

Highlights: ► A reactor is designed to prepare glass–ceramic from sewage sludge by microwave. ► Microwave process has reduced energy consumption for its low reaction temperature. ► Finer and uniform crystals are observed in microwave glass–ceramics. ► Improved properties of microwave glass–ceramics are found. ► We modeled the crystals growth in microwave field. - Abstract: A Microwave Melting Reactor (MMR) was designed in this study which improved the microwave adsorption of sewage sludge to prepare glass–ceramics. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used for the study of crystallization behavior and microstructure of the developed glass–ceramics. DSC and XRD analysis revealed that crystallization of the nucleated specimen in the region of 900–1000 °C resulted in the formation of two crystalline phases: anorthite and wollastonite. When the crystallization temperature increased from 900 to 1000 °C, the tetragonal wollastonite grains were subjected to tensile microstresses, causing the cracking of crystal. Al ions substituted partially Si ions and occupied tetrahedral sites, giving rise to the formation of anorthite. The relationship between microwave irradiation and crystal growth was studied and the result indicated that the microwave selective heating suppressed the crystal growth, giving apparent improvements in the properties of the glass–ceramics. The glass–ceramics products exhibited bending strength of 86.5–93.4 MPa, Vickers microhardness of 6.12–6.54 GPa and thermal expansion coefficient of 5.29–5.75 × 10 −6 /°C. The best chemical durability in acid and alkali solutions was 1.32–1.61 and 0.41–0.58 mg/cm 2 , respectively, showing excellent durability in alkali solution.
Crystal growth and comparison of vibrational and thermal properties ...

Indian Academy of Sciences (India)

The TGA–DTA studies showed the thermal properties of the crystals. ... impact on laser technology, optical communication and optical storage technology. [1,2]. .... UTHC and UTHS crystals in the temperature range of 25–1100◦C with a heat-.
Synthesis, growth, crystal structure, optical and third order nonlinear optical properties of quinolinium derivative single crystal: PNQI

Science.gov (United States)

Karthigha, S.; Krishnamoorthi, C.

2018-03-01

An organic quinolinium derivative nonlinear optical (NLO) crystal, 1-ethyl-2-[2-(4-nitro-phenyl)-vinyl]-quinolinium iodide (PNQI) was synthesized and successfully grown by slow evaporation solution growth technique. Formation of a crystalline compound was confirmed by single crystal X-ray diffraction. The quinolinium compound PNQI crystallizes in the triclinic crystal system with a centrosymmetric space group of P-1 symmetry. The molecular structure of PNQI was confirmed by 1H NMR and 13C NMR spectral studies. The thermal properties of the crystal have been investigated by thermogravimetric (TG) and differential scanning calorimetry (DSC) studies. The optical characteristics obtained from UV-Vis-NIR spectral data were described and the cut-off wavelength observed at 506 nm. The etching study was performed to analyse the growth features of PNQI single crystal. The third order NLO properties such as nonlinear refractive index (n2), nonlinear absorption coefficient (β) and nonlinear susceptibility (χ (3)) of the crystal were investigated using Z-scan technique at 632.8 nm of Hesbnd Ne laser.

Electronic transport properties of pentacene single crystals upon exposure to air

NARCIS (Netherlands)

Jurchescu, OD; Baas, J; Palstra, TTM; Jurchescu, Oana D.

2005-01-01

We report the effect of air exposure on the electronic properties of pentacene single crystals. Air can diffuse reversibly in and out of the crystals and influences the physical properties. We discern two competing mechanisms that modulate the electronic transport. The presence of oxygen increases
Structural and optical properties of WTe2 single crystals synthesized by DVT technique

Science.gov (United States)

Dixit, Vijay; Vyas, Chirag; Pathak, V. M.; Soalanki, G. K.; Patel, K. D.

2018-05-01

Layered transition metal di-chalcogenide (LTMDCs) crystals have attracted much attention due to their potential in optoelectronic device applications recently due to realization of their monolayer based structures. In the present investigation we report growth of WTe2 single crystals by direct vapor transport (DVT) technique. These crystals are then characterized by energy dispersive analysis of x-rays (EDAX) to study stoichiometric composition after growth. The structural properties are studied by x-ray diffraction (XRD) and selected area electron diffraction (SAED) is used to confirm orthorhombic structure of grown WTe2 crystal. Surface morphological properties of the crystals are also studied by scanning electron microscope (SEM). The optical properties of the grown crystals are studied by UV-Visible spectroscopy which gives direct band gap of 1.44 eV for grown WTe2 single crystals.
Single crystal diamond detectors grown by chemical vapor deposition

International Nuclear Information System (INIS)

Tuve, C.; Angelone, M.; Bellini, V.; Balducci, A.; Donato, M.G.; Faggio, G.; Marinelli, M.; Messina, G.; Milani, E.; Morgada, M.E.; Pillon, M.; Potenza, R.; Pucella, G.; Russo, G.; Santangelo, S.; Scoccia, M.; Sutera, C.; Tucciarone, A.; Verona-Rinati, G.

2007-01-01

The detection properties of heteropitaxial (polycrystalline, pCVD) and homoepitaxial (single crystal, scCVD) diamond films grown by microwave chemical vapor deposition (CVD) in the Laboratories of Roma 'Tor Vergata' University are reported. The pCVD diamond detectors were tested with α-particles from different sources and 12 C ions produced by 15MV Tandem accelerator at Southern National Laboratories (LNS) in Catania (Italy). pCVDs were also used to monitor 14MeV neutrons produced by the D-T plasma at Joint European Torus (JET), Culham, U.K. The limit of pCVDs is the poor energy resolution. To overcome this problem, we developed scCVD diamonds using the same reactor parameters that optimized pCVD diamonds. scCVD were grown on a low cost (100) HPHT single crystal substrate. A detector 110μm thick was tested under α-particles and under 14MeV neutron irradiation. The charge collection efficiency spectrum measured under irradiation with a triple α-particle source shows three clearly resolved peaks, with an energy resolution of about 1.1%. The measured spectra under neutron irradiation show a well separated C(n,α 0 ) 9 Be12 reaction peak with an energy spread of 0.5MeV for 14.8MeV neutrons and 0.3MeV for 14.1MeV neutrons, which are fully compatible with the energy spread of the incident neutron beams
Magneto-optical properties of biogenic photonic crystals in algae

International Nuclear Information System (INIS)

Iwasaka, M.; Mizukawa, Y.

2014-01-01

In the present study, the effects of strong static magnetic fields on the structural colors of the cell covering crystals on a microalgae, coccolithophore, were investigated. The coccolithophore, Emiliania huxleyi, generates a precise assembly of calcite crystals called coccoliths by biomineralization. The coccoliths attached to the cells exhibited structural colors under side light illumination, and the colors underwent dynamic transitions when the magnetic fields were changed between 0 T and 5 T, probably due to diamagnetically induced changes of their inclination under the magnetic fields. The specific light-scattering property of individual coccoliths separated from the cells was also observed. Light scattering from a condensed suspension of coccoliths drastically decreased when magnetic fields of more than 4 T were applied parallel to the direction of observation. The magnetically aligned cell-covering crystals of the coccolithophores exhibited the properties of both a photonic crystal and a minimum micromirror
Influence of encapsulated functional lipids on crystal structure and chemical stability in solid lipid nanoparticles: Towards bioactive-based design of delivery systems.

Science.gov (United States)

Salminen, Hanna; Gömmel, Christina; Leuenberger, Bruno H; Weiss, Jochen

2016-01-01

We investigated the influence of physicochemical properties of encapsulated functional lipids--vitamin A, β-carotene and ω-3 fish oil--on the structural arrangement of solid lipid nanoparticles (SLN). The relationship between the crystal structure and chemical stability of the incorporated bioactive lipids was evaluated with different emulsifier compositions of a saponin-rich, food-grade Quillaja extract alone or combined with high-melting or low-melting lecithins. The major factors influencing the structural arrangement and chemical stability of functional lipids in solid lipid dispersions were their solubility in the aqueous phase and their crystallization temperature in relation to that of the carrier lipid. The results showed that the stabilization of the α-subcell crystals in the lattice of the carrier lipid is a key parameter for forming stable solid lipid dispersions. This study contributes to a better understanding of SLN as a function of the bioactive lipid. Copyright © 2015 Elsevier Ltd. All rights reserved.
Effect of electromagnetic radiation on the physico-chemical properties of minerals

International Nuclear Information System (INIS)

Lopez M, A.; Delgadillo G, J. A.; Vega C, H. R.

2014-08-01

The electromagnetic radiation effect represented by gamma rays was investigated through; chemical analysis, X-ray diffraction (XRD), scanning electron microscopy (Sem) and magnetization when applied at a dose of 0.5704 Gy (0.5704 J/ kg) at a feed relation of 18.40 ± 1.13 mGy/ h., in different minerals; in order to characterize the impact of the same from 137 Cs in the physicochemical properties of these minerals. All the irradiated samples showed chemical stability at this stage undetectable other both in the XRD study and in the images analysis obtained by Sem; and at present almost the same chemical composition as the non-irradiated samples. So the same patterns of X-ray diffraction thereof, show a tendency to slightly lower the intensity of the most representative peaks of each mineral phase, which may be due to a decrease in crystallinity or preferential crystallographic orientation in crystals. In the micrographs analysis obtained by Sem on the irradiated samples, some holes (open pores) present in the particles were observed, mainly chalcopyrite and sphalerite lesser extent, seen this fact may be due to Compton Effect, in the radiation process. In relation to the magnetization property, a variation is obtained in the saturation magnetization (Ms) for the irradiated samples containing iron and more significantly in the chalcopyrite case. Therefore, with the radiation level used; slight changes occurring in the physical properties of minerals, whereas they remained stable chemically. These small changes may represent a signal that electromagnetic radiation applied at higher doses, is a viable option for improving the mineral processing. (author)
Defined PEG smears as an alternative approach to enhance the search for crystallization conditions and crystal-quality improvement in reduced screens

Energy Technology Data Exchange (ETDEWEB)

Chaikuad, Apirat, E-mail: apirat.chaikuad@sgc.ox.ac.uk [University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford OX3 7DQ (United Kingdom); Knapp, Stefan [University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford OX3 7DQ (United Kingdom); Johann Wolfgang Goethe-University, Building N240 Room 3.03, Max-von-Laue-Strasse 9, 60438 Frankfurt am Main (Germany); Delft, Frank von, E-mail: apirat.chaikuad@sgc.ox.ac.uk [University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford OX3 7DQ (United Kingdom)

2015-07-28

An alternative strategy for PEG sampling is suggested through the use of four newly defined PEG smears to enhance chemical space in reduced screens with a benefit towards protein crystallization. The quest for an optimal limited set of effective crystallization conditions remains a challenge in macromolecular crystallography, an issue that is complicated by the large number of chemicals which have been deemed to be suitable for promoting crystal growth. The lack of rational approaches towards the selection of successful chemical space and representative combinations has led to significant overlapping conditions, which are currently present in a multitude of commercially available crystallization screens. Here, an alternative approach to the sampling of widely used PEG precipitants is suggested through the use of PEG smears, which are mixtures of different PEGs with a requirement of either neutral or cooperatively positive effects of each component on crystal growth. Four newly defined smears were classified by molecular-weight groups and enabled the preservation of specific properties related to different polymer sizes. These smears not only allowed a wide coverage of properties of these polymers, but also reduced PEG variables, enabling greater sampling of other parameters such as buffers and additives. The efficiency of the smear-based screens was evaluated on more than 220 diverse recombinant human proteins, which overall revealed a good initial crystallization success rate of nearly 50%. In addition, in several cases successful crystallizations were only obtained using PEG smears, while various commercial screens failed to yield crystals. The defined smears therefore offer an alternative approach towards PEG sampling, which will benefit the design of crystallization screens sampling a wide chemical space of this key precipitant.
Spectrometric properties of crystals for low-energy x-ray diagnostics

International Nuclear Information System (INIS)

Barrus, D.m.; Blake, R.L.; Felthauser, H.; Fenimore, E.E.

1981-01-01

Quantitative diagnostics of fusion and astrophysical plasmas require knowledge of crystal spectrometric properties. To provide more reliable and versatile diagnostics of plasma conditions, increasingly accurate knowledge of crystal spectrometric properties is becoming necessary. A summary is presented of the following accurately measured parameters for the crystals KAP, RbAP, TlAP, NH 4 AP, NaAP, ADP, and EDDT: the interplanar spacing of atoms; the angle correction for normal and anomalous dispersion that is required for application of the Bragg formula; the thermal expansion coefficient near room temperature for commonly used planes; and the integrated coefficient of reflection
A Scanning Hologram Recorded by Phase Conjugate Property of Nonlinear Crystals

DEFF Research Database (Denmark)

Zi-Liang, Ping; Dalsgaard, Erik

1996-01-01

A methode of recording a scanning hologram with phase conjugate property of nonlinear crystal is provided. The principle of recording, setup and experiments are given.......A methode of recording a scanning hologram with phase conjugate property of nonlinear crystal is provided. The principle of recording, setup and experiments are given....
Crystal growth and scintillation properties of Pr-doped SrI2 single crystals

Science.gov (United States)

Yokota, Yuui; Ito, Tomoki; Yoshino, Masao; Yamaji, Akihiro; Ohashi, Yuji; Kurosawa, Shunsuke; Kamada, Kei; Yoshikawa, Akira

2018-04-01

Pr-doped SrI2 (Pr:SrI2) single crystals with various Pr concentrations were grown by the halide-micro-pulling-down (H-μ-PD) method, and the scintillation properties were investigated. Pr1%:SrI2 single crystal with high transparency could be grown by the H-μ-PD method while Pr2, 3 and 5%:SrI2 single crystals included some cracks and opaque parts. In the photoluminescence spectrum of the Pr1%:SrI2 single crystal, an emission peak originated from the Pr3+ ion was observed around 435 nm while the radioluminescence spectra showed an emission peak around 535 nm for the undoped SrI2 and Pr:SrI2 single crystals. Light yields of Pr1, 2, 3 and 5%:SrI2 single crystals under γ-ray irradiation were 7700, 8700, 7200 and 6700 photons/MeV, respectively. Decay times of Pr1 and 2%:SrI2 single crystals under γ-ray irradiation were 55.9 and 35.0 ns of the fast decay component, and 435 and 408 ns of the slow decay component, respectively.
Chemical composition of Chinese palm fruit and chemical properties ...

African Journals Online (AJOL)

... chemical properties and could be used as edible oils and for industrial applications. ... on it, which can provide useful information for Chinese oil palm industry. Key words: Chemical composition, palm fruit, palm oil, palm kernel oil, chemical ...
A study on properties of PbWO4 crystal

International Nuclear Information System (INIS)

He Jingtang; Mao Yufang; Dong Xiaoli

1997-01-01

The experimental results on properties of the PbWO 4 crystal are reported, including the excitation and fluorescence spectra, absolute and relative light yield and decay times. It seems that the PbWO 4 crystal can be used in high energy physics experiments for detecting high energy shower particles
Thorium/uranium mixed oxide nano-crystals: Synthesis, structural characterization and magnetic properties

International Nuclear Information System (INIS)

Hudry, Damien; Griveau, Jean-Christophe; Apostolidis, Christos; Colineau, Eric; Rasmussen, Gert; Walter, Olaf; Wang, Di; Venkata Sai Kiran Chakravadhaluna; Courtois, Eglantine; Kubel, Christian

2014-01-01

One of the primary aims of the actinide community within nano-science is to develop a good understanding similar to what is currently the case for stable elements. As a consequence, efficient, reliable and versatile synthesis techniques dedicated to the formation of new actinide-based nano-objects (e.g., nano-crystals) are necessary. Hence, a 'library' dedicated to the preparation of various actinide based nano-scale building blocks is currently being developed. Nano-scale building blocks with tunable sizes, shapes and compositions are of prime importance. So far, the non-aqueous synthesis method in highly coordinating organic media is the only approach which has demonstrated the capability to provide size and shape control of actinide-based nano-crystals (both for thorium and uranium, and recently extended to neptunium and plutonium). In this paper, we demonstrate that the non-aqueous approach is also well adapted to control the chemical composition of the nano-crystals obtained when mixing two different actinides. Indeed, the controlled hot co-injection of thorium acetylacetonate and uranyl acetate (together with additional capping agents) into benzyl ether can be used to synthesize thorium/uranium mixed oxide nano-crystals covering the full compositional spectrum. Additionally, we found that both size and shape are modified as a function of the thorium/uranium ratio. Finally, the magnetic properties of the different thorium/uranium mixed oxide nano-crystals were investigated. Contrary to several reports, we did not observe any ferromagnetic behavior. As a consequence, ferromagnetism cannot be described as a universal feature of nano-crystals of non-magnetic oxides as recently claimed in the literature. (authors)
Absorption and emission properties of photonic crystals and metamaterials

International Nuclear Information System (INIS)

Peng, Lili

2007-01-01

We study the emission and absorption properties of photonic crystals and metamaterials using Comsol Multiphysics and Ansoft HFSS as simulation tools. We calculate the emission properties of metallic designs using drude model and the results illustrate that an appropriate termination of the surface of the metallic structure can significantly increase the absorption and therefore the thermal emissivity. We investigate the spontaneous emission rate modifications that occur for emitters inside two-dimensional photonic crystals and find the isotropic and directional emissions with respect to different frequencies as we have expected.
Anisotropic surface chemistry properties and adsorption behavior of silicate mineral crystals.

Science.gov (United States)

Xu, Longhua; Tian, Jia; Wu, Houqin; Fang, Shuai; Lu, Zhongyuan; Ma, Caifeng; Sun, Wei; Hu, Yuehua

2018-03-07

Anisotropic surface properties of minerals play an important role in a variety of fields. With a focus on the two most intensively investigated silicate minerals (i.e., phyllosilicate minerals and pegmatite aluminosilicate minerals), this review highlights the research on their anisotropic surface properties based on their crystal structures. Four surface features comprise the anisotropic surface chemistry of minerals: broken bonds, energy, wettability, and charge. Analysis of surface broken bond and energy anisotropy helps to explain the cleavage and growth properties of mineral crystals, and understanding surface wettability and charge anisotropy is critical to the analysis of minerals' solution behavior, such as their flotation performance and rheological properties. In a specific reaction, the anisotropic surface properties of minerals are reflected in the adsorption strengths of reagents on different mineral surfaces. Combined with the knowledge of mineral crushing and grinding, a thorough understanding of the anisotropic surface chemistry properties and the anisotropic adsorption behavior of minerals will lead to the development of effective relational models comprising their crystal structure, surface chemistry properties, and targeted reagent adsorption. Overall, such a comprehensive approach is expected to firmly establish the connection between selective cleavage of mineral crystals for desired surfaces and designing novel reagents selectively adsorbed on the mineral surfaces. As tools to characterize the anisotropic surface chemistry properties of minerals, DLVO theory, atomic force microscopy (AFM), and molecular dynamics (MD) simulations are also reviewed. Copyright © 2017 Elsevier B.V. All rights reserved.
Machine learning for the structure-energy-property landscapes of molecular crystals.

Science.gov (United States)

Musil, Félix; De, Sandip; Yang, Jack; Campbell, Joshua E; Day, Graeme M; Ceriotti, Michele

2018-02-07

Molecular crystals play an important role in several fields of science and technology. They frequently crystallize in different polymorphs with substantially different physical properties. To help guide the synthesis of candidate materials, atomic-scale modelling can be used to enumerate the stable polymorphs and to predict their properties, as well as to propose heuristic rules to rationalize the correlations between crystal structure and materials properties. Here we show how a recently-developed machine-learning (ML) framework can be used to achieve inexpensive and accurate predictions of the stability and properties of polymorphs, and a data-driven classification that is less biased and more flexible than typical heuristic rules. We discuss, as examples, the lattice energy and property landscapes of pentacene and two azapentacene isomers that are of interest as organic semiconductor materials. We show that we can estimate force field or DFT lattice energies with sub-kJ mol -1 accuracy, using only a few hundred reference configurations, and reduce by a factor of ten the computational effort needed to predict charge mobility in the crystal structures. The automatic structural classification of the polymorphs reveals a more detailed picture of molecular packing than that provided by conventional heuristics, and helps disentangle the role of hydrogen bonded and π-stacking interactions in determining molecular self-assembly. This observation demonstrates that ML is not just a black-box scheme to interpolate between reference calculations, but can also be used as a tool to gain intuitive insights into structure-property relations in molecular crystal engineering.
Single particle measurements of the chemical composition of cirrus ice residue during CRYSTAL-FACE

Science.gov (United States)

Cziczo, D. J.; Murphy, D. M.; Hudson, P. K.; Thomson, D. S.

2004-02-01

The first real-time, in situ, investigation of the chemical composition of the residue of cirrus ice crystals was performed during July 2002. This study was undertaken on a NASA WB-57F high-altitude research aircraft as part of CRYSTAL-FACE, a field campaign which sought to further our understanding of the relation of clouds, water vapor, and climate by characterizing, among other parameters, anvil cirrus formed about the Florida peninsula. A counter flow virtual impactor (CVI) was used to separate cirrus ice from the unactivated interstitial aerosol particles and evaporate condensed-phase water. Residual material, on a crystal-by-crystal basis, was subsequently analyzed using the NOAA Aeronomy Laboratory's Particle Analysis by Laser Mass Spectrometry (PALMS) instrument. Sampling was performed from 5 to 15 km altitude and from 12° to 28° north latitude within cirrus originating over land and ocean. Chemical composition measurements provided several important results. Sea salt was often incorporated into cirrus, consistent with homogeneous ice formation by aerosol particles from the marine boundary layer. Size measurements showed that large particles preferentially froze over smaller ones. Meteoritic material was found within ice crystals, indicative of a relation between stratospheric aerosol particles and tropospheric clouds. Mineral dust was the dominant residue observed in clouds formed during a dust transport event from the Sahara, consistent with a heterogeneous freezing mechanism. These results show that chemical composition and size are important determinants of which aerosol particles form cirrus ice crystals.
Crystallization mechanisms of acicular crystals

Science.gov (United States)

Puel, François; Verdurand, Elodie; Taulelle, Pascal; Bebon, Christine; Colson, Didier; Klein, Jean-Paul; Veesler, Stéphane

2008-01-01

In this contribution, we present an experimental investigation of the growth of four different organic molecules produced at industrial scale with a view to understand the crystallization mechanism of acicular or needle-like crystals. For all organic crystals studied in this article, layer-by-layer growth of the lateral faces is very slow and clear, as soon as the supersaturation is high enough, there is competition between growth and surface-activated secondary nucleation. This gives rise to pseudo-twinned crystals composed of several needle individuals aligned along a crystallographic axis; this is explained by regular over- and inter-growths as in the case of twinning. And when supersaturation is even higher, nucleation is fast and random. In an industrial continuous crystallization, the rapid growth of needle-like crystals is to be avoided as it leads to fragile crystals or needles, which can be partly broken or totally detached from the parent crystals especially along structural anisotropic axis corresponding to weaker chemical bonds, thus leading to slower growing faces. When an activated mechanism is involved such as a secondary surface nucleation, it is no longer possible to obtain a steady state. Therefore, the crystal number, size and habit vary significantly with time, leading to troubles in the downstream processing operations and to modifications of the final solid-specific properties. These results provide valuable information on the unique crystallization mechanisms of acicular crystals, and show that it is important to know these threshold and critical values when running a crystallizer in order to obtain easy-to-handle crystals.
Combined crystal structure prediction and high-pressure crystallization in rational pharmaceutical polymorph screening

DEFF Research Database (Denmark)

Neumann, M A; van de Streek, J; Fabbiani, F P A

2015-01-01

Organic molecules, such as pharmaceuticals, agro-chemicals and pigments, frequently form several crystal polymorphs with different physicochemical properties. Finding polymorphs has long been a purely experimental game of trial-and-error. Here we utilize in silico polymorph screening in combination...
Chemical precursor impact on the properties of Cu{sub 2}ZnSnS{sub 4} absorber layer

Energy Technology Data Exchange (ETDEWEB)

Vashistha, Indu B., E-mail: indu-139@yahoo.com; Sharma, S. K. [Department of Physics, Malaviya National Institute of Technology, Jaipur 302017 (India); Sharma, Mahesh C. [National Institute of Solar Energy, Gurgaon 122003 (India)

2016-04-13

In present work impact of different chemical precursor on the deposition of solar absorber layer Cu{sub 2}ZnSnS{sub 4} (CZTS) were studied by Chemical Bath Deposition (CBD) method without using expensive vacuum facilities and followed by annealing. As compared to the other deposition methods, CBD method is interesting one because it is simple, reproducible, non-hazardous, cost effective and well suited for producing large-area thin films at low temperatures, although effect of precursors and concentration plays a vital role in the deposition. So, the central theme of this work is optimizing and controlling of chemical reactions for different chemical precursors. Further Effect of different chemical precursors i.e. sulphate and chloride is analyzed by structural, morphological, optical and electrical properties. The X-ray diffraction (XRD) of annealed CZTS thin film revealed that films were polycrystalline in nature with kestarite tetragonal crystal structure. The Atomic Force micrographs (AFM) images indicated total coverage compact film and as well as growth of crystals. The band gap of annealed CZTS films was found in the range of optimal band gap by absorption spectroscopy.

Effect of sintering on crystallization and structural properties of soda lime silica glass

Directory of Open Access Journals (Sweden)

Zaid Mohd Hafiz Mohd

2017-01-01

Full Text Available The effect of sintering temperatures on crystallization and structural of the soda lime silica (SLS glass was reported. Elemental weight composition of the SLS glass powder was identified through Energy dispersive X-ray fluorescence (EDXRF analysis while the thermal behavior of the glass was determined using Differential thermal analysis (DTA technique. Archimedes’ method and direct geometric measurement were respectively used to determine bulk density and linear shrinkage of the glass samples. Crystallisation behavior of the samples was investigated by X-ray diffraction (XRD analysis and chemical bonds present in the samples were measured using Fourier Transform Infrared (FTIR spectroscopy. Results showed an increase in the density and linear shrinkage of the samples as a function of the sintering temperature. The XRD analysis revealed the formation of α-quartz (SiO2 and a minor amount of devitrite phases in the samples and these were further verified through the detection of chemical bonds by FTIR after sintering at 800ºC. The properties of the glass-ceramics can be explained on the basis of crystal chemistry which indicated that the alkali ions formed as carriers in the random network structure and can be recommended for the manufacture of glass fiber or toughened glass-ceramic insulators.
Magnetic and luminescent properties of vanadium-doped ZnSe crystals

Energy Technology Data Exchange (ETDEWEB)

Radevici, Ivan, E-mail: ivarad@utu.fi [Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., MD-2009 Chisinau (Moldova, Republic of); Nedeoglo, Natalia; Sushkevich, Konstantin [Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., MD-2009 Chisinau (Moldova, Republic of); Huhtinen, Hannu [Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Nedeoglo, Dmitrii [Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., MD-2009 Chisinau (Moldova, Republic of); Paturi, Petriina [Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland)

2016-12-15

Magnetic and photoluminescence properties of vanadium-doped ZnSe crystals with impurity concentrations varied by changing the V amount in the source material from 0.03 to 0.30 at% are studied in 5–300 K temperature range. Investigation of magnetic properties shows that the studied concentrations of vanadium impurity that should not disturb crystal lattice are insignificant for observing ferromagnetic behaviour even at low temperatures. The contribution of V impurity to edge emission and its influence on infra-red emission are discussed. Similarities of magnetic and luminescent properties induced by vanadium and other transition metal impurities are discussed.
Optical properties of mesoporous photonic crystals, filled with dielectrics, ferroelectrics and piezoelectrics

Directory of Open Access Journals (Sweden)

V. S. Gorelik

2017-12-01

Full Text Available At present, it is very important to create new types of mirrors, nonlinear light frequency transformers and optical filters with controlled optical properties. In this connection, it is of great interest to study photonic crystals. Their dielectric permittivity varies periodically in space with a period permitting Bragg diffraction of light. In this paper, we have investigated the optical properties of mesoporous three-dimensional (3D opal-type and one-dimensional (1D anodic alumina photonic crystals, filled with different dielectrics, ferroelectrics and piezoelectrics. We have compared the optical properties of initial mesoporous photonic crystals and filled with different substances. The possibility of mesoporous photonic crystals using selective narrow-band light filters in Raman scattering experiments and nonlinear mirrors has been analyzed. The electromagnetic field enhancing in the case of exciting light frequency close to the stop band edges has been established. The optical harmonics and subharmonics generation in mesoporous crystals, filled with ferroelectrics and piezoelectrics was proposed.
Thermal properties photonic crystal fiber transducers with ferromagnetic nanoparticles

Science.gov (United States)

Przybysz, N.; Marć, P.; Kisielewska, A.; Jaroszewicz, L. R.

2015-12-01

The main aim of the research is to design new types of fiber optic transducers based on filled photonic crystal fibers for sensor applications. In our research we propose to use as a filling material nanoparticles' ferrofluids (Fe3O4 NPs). Optical properties of such transducers are studied by measurements of spectral characteristics' changes when transducers are exposed to temperature and magnetic field changes. From synthesized ferrofluid several mixtures with different NPs' concentrations were prepared. Partially filled commercially available photonic crystal fiber LMA 10 (NKT Photonics) was used to design PCF transducers. Their thermo-optic properties were tested in a temperature chamber. Taking into account magnetic properties of synthetized NPs the patch cords based on a partially filled PM 1550 PCF were measured.
Bi-doped PbO2 anodes: Electrodeposition and physico-chemical properties

International Nuclear Information System (INIS)

Shmychkova, O.; Luk’yanenko, T.; Velichenko, A.; Meda, L.; Amadelli, R.

2013-01-01

The influence of bismuth ions on kinetics of lead dioxide electrodeposition from methanesulfonate electrolytes and physico-chemical properties of obtained coatings were studied. Experimental results are consistent with a mechanism previously proposed in the literature for lead dioxide electrodeposition. The presence of bismuth ions in the electrodeposition solution causes a decrease of rate constants of lead dioxide formation due to co-adsorption phenomena. Deposits from solutions containing bismuth ions appear shiny dark grey, and show good adhesion to metal support. SEM images reveal a compact structure with spindle-shaped submicron and nanosized crystals and X-ray diffractograms demonstrated that incorporation of bismuth diminishes the size of crystal particles. Oxygen evolution was investigated to test electrocatalytic activity. It is shown, that oxygen overpotential on modified electrodes is significantly higher than on non-modified PbO 2 -electrode, which depends on bismuth content in deposit and segregation of bismuth that induces surface heterogeneity due to sites with different electroactivity for water oxidation
Theoretical analysis of static properties of mixed ionic crystal ...

Indian Academy of Sciences (India)

In the present paper, we have investigated the static properties of the mixed ionic crystal NH4Cl1−Br using three-body potential model (TBPM) by the application of Vegard's law. The results for the mixed crystal counterparts are also in fair agreement with the pseudo-experimental data generated from the application of ...
Electrical properties of molecular crystals; Proprietes electriques des cristaux moleculaires

Energy Technology Data Exchange (ETDEWEB)

Barraud, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-07-01

This literature survey summarizes the electrical properties of molecular crystals: molecular crystal structure, transport and excitation mechanisms of charge-carriers, and differences compared to inorganic semi-conductors. The main results concerning the electrical conductivity of the most-studied molecular crystals are presented, together with the optical and photo-electrical properties of these crystals. Finally the different types of electrical measurements used are reviewed, as well as the limits of each method. (author) [French] Cette etude bibliographique resume les proprietes electriques des cristaux moleculaires: structure des cristaux moleculaires, mecanismes de transport et d'excitation des porteurs de charge et differences avec les semiconducteurs mineraux. Les principaux resultats sur la conductibilite electrique des cristaux moleculaires les plus etudies y sont exposes, ainsi que les proprietes optiques et photoelectriques de ces cristaux. Enfin les differents types de mesures electriques utilisees sont passees en revue ainsi que les limites de chaque methode. (auteur)
Electrical properties of molecular crystals; Proprietes electriques des cristaux moleculaires

Energy Technology Data Exchange (ETDEWEB)

Barraud, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-07-01

This literature survey summarizes the electrical properties of molecular crystals: molecular crystal structure, transport and excitation mechanisms of charge-carriers, and differences compared to inorganic semi-conductors. The main results concerning the electrical conductivity of the most-studied molecular crystals are presented, together with the optical and photo-electrical properties of these crystals. Finally the different types of electrical measurements used are reviewed, as well as the limits of each method. (author) [French] Cette etude bibliographique resume les proprietes electriques des cristaux moleculaires: structure des cristaux moleculaires, mecanismes de transport et d'excitation des porteurs de charge et differences avec les semiconducteurs mineraux. Les principaux resultats sur la conductibilite electrique des cristaux moleculaires les plus etudies y sont exposes, ainsi que les proprietes optiques et photoelectriques de ces cristaux. Enfin les differents types de mesures electriques utilisees sont passees en revue ainsi que les limites de chaque methode. (auteur)
A PMMA coated PMN–PT single crystal resonator for sensing chemical agents

International Nuclear Information System (INIS)

Frank, Michael; Kassegne, Sam; Moon, Kee S

2010-01-01

A highly sensitive lead magnesium niobate–lead titanate (PMN–PT) single crystal resonator coated with a thin film of polymethylmethacrylate (PMMA) useful for detecting chemical agents such as acetone, methanol, and isopropyl alcohol is presented. Swelling of the cured PMMA polymer layer in the presence of acetone, methanol, and isopropyl alcohol vapors is sensed as a mass change transduced to an electrical signal by the PMN–PT thickness shear mode sensor. Frequency change in the PMN–PT sensor is demonstrated to vary according to the concentration of the chemical vapor present within the sensing chamber. For acetone, the results indicate a frequency change more than 6000 times greater than that which would be expected from a quartz crystal microbalance coated with PMMA. This study is the first of its kind to demonstrate vapor loading of adsorbed chemical agents onto a polymer coated PMN–PT resonator
Chemical sensors

International Nuclear Information System (INIS)

Hubbard, C.W.; Gordon, R.L.

1987-05-01

The revolution in analytical chemistry promised by recent developments in the field of chemical sensors has potential for significant positive impact on both research and production activities conducted by and for the Department of Energy. Analyses which were, in the past, performed only with a roomful of expensive equipment can now be performed with miniature solid-state electronic devices or small optical probes. Progress in the development of chemical sensors has been rapid, and the field is currently growing at a great rate. In accordance, Pacific Northwest Laboratory initiated a survey of recent literature so that contributors to active programs in research on analytical methods could be made aware of principles and applications of this new technology. This report presents the results of that survey. The sensors discussed here are divided into three types: micro solid-state devices, optical sensors, and piezoelectric crystal devices. The report is divided into three corresponding sections. The first section, ''Micro Solid-State Devices,'' discusses the design, operation, and application of electronic sensors that are produced in much the same way as standard solid-state electronic devices. The second section, ''Optrodes,'' covers the design and operation of chemical sensors that use fiber optics to detect chemically induced changes in optical properties. The final section, ''Piezoelectric Crystal Detectors,'' discusses two types of chemical sensors that depend on the changes in the properties of an oscillating piezoelectric crystal to detect the presence of certain materials. Advantages and disadvantages of each type of sensor are summarized in each section
Co-Crystal Screening of Diclofenac

OpenAIRE

Aaker?y, Christer B.; Grommet, Angela B.; Desper, John

2011-01-01

In the pharmaceutical industry, co-crystals are becoming increasingly valuable as crystalline solids that can offer altered/improved physical properties of an active pharmaceutical ingredient (API) without changing its chemical identity or biological activity. In order to identify new solid forms of diclofenac—an analgesic with extremely poor aqueous solubility for which few co-crystal structures have been determined—a range of pyrazoles, pyridines, and pyrimidines were screened for co-crysta...
Properties of amorphous silicon thin films synthesized by reactive particle beam assisted chemical vapor deposition

International Nuclear Information System (INIS)

Choi, Sun Gyu; Wang, Seok-Joo; Park, Hyeong-Ho; Jang, Jin-Nyoung; Hong, MunPyo; Kwon, Kwang-Ho; Park, Hyung-Ho

2010-01-01

Amorphous silicon thin films were formed by chemical vapor deposition of reactive particle beam assisted inductively coupled plasma type with various reflector bias voltages. During the deposition, the substrate was heated at 150 o C. The effects of reflector bias voltage on the physical and chemical properties of the films were systematically studied. X-ray diffraction and Raman spectroscopy results showed that the deposited films were amorphous and the films under higher reflector voltage had higher internal energy to be easily crystallized. The chemical state of amorphous silicon films was revealed as metallic bonding of Si atoms by using X-ray photoelectron spectroscopy. An increase in reflector voltage induced an increase of surface morphology of films and optical bandgap and a decrease of photoconductivity.
Optical Properties of Small Ice Crystals with Black Carbon Inclusions

Science.gov (United States)

Yang, X.; Geier, M.; Arienti, M.

2013-12-01

The optical properties of ice crystals play a fundamental role in modeling atmospheric radiation and hydrological cycle, which are critical in monitoring climate change. While Black Carbon (BC) is recognized as the dominant absorber with positive radiative forcing (warming) (Ramanathan & Carmichael, 2008), in-situ observations (Cappa, et al, 2012) indicate that the characterization of the mixing state of BC with ice crystals and other non-BC particles in global climate models (Ghan & Schwartz, 2007) needs further investigation. The limitation in the available mixing models is due to the drastically different absorbing properties of BC compared to other aerosols. We explore the scattering properties of ice crystals (in shapes commonly found in cirrus clouds and contrails - Yang, et al. 2012) with the inclusion of BC particles. The Discrete Dipole Approximation (DDA) (Yurkin & Hoekstra, 2011) is utilized to directly calculate the optical properties of the crystals with multiple BC inclusions, modeled as a distribution of spheres. The results are then compared with the most popular models of internal and external mixing (Liou, et al. 2011). The DDA calculations are carried out over a broad range of BC particle sizes and volume fractions within the crystal at the 532 nm wavelength and for ice crystals smaller than 50 μm. The computationally intensive database generated in this study is critical for understanding the effect of different types of BC inclusions on the atmosphere radiative forcing. Examples will be discussed to illustrate the modification of BC optical properties by encapsulation in ice crystals and how the parameterization of the BC mixing state in global climate models can be improved. Acknowledgements Support by Sandia National Laboratories' LDRD (Laboratory Directed Research and Development) is gratefully acknowledged. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of
Lyotropic chromonic liquid crystals: From viscoelastic properties to living liquid crystals

Science.gov (United States)

Zhou, Shuang

Lyotropic chromonic liquid crystal (LCLC) represents a broad range of molecules, from organic dyes and drugs to DNA, that self-assemble into linear aggregates in water through face-to-face stacking. These linear aggregates of high aspect ratio are capable of orientational order, forming, for example nematic phase. Since the microscopic properties (such as length) of the chromonic aggregates are results of subtle balance between energy and entropy, the macroscopic viscoelastic properties of the nematic media are sensitive to change of external factors. In the first part of this thesis, by using dynamic light scattering and magnetic Frederiks transition techniques, we study the Frank elastic moduli and viscosity coefficients of LCLC disodium cromoglycate (DSCG) and sunset yellow (SSY) as functions of concentration c , temperature T and ionic contents. The elastic moduli of splay (K1) and bend (K3) are in the order of 10pN, about 10 times larger than the twist modulus (K2). The splay modulus K1 and the ratio K1/K3 both increase substantially as T decreases or c increases, which we attribute to the elongation of linear aggregates at lower T or higher c . The bend viscosity is comparable to that of thermotropic liquid crystals, while the splay and twist viscosities are several orders of magnitude larger, changing exponentially with T . Additional ionic additives into the system influence the viscoelastic properties of these systems in a dramatic and versatile way. For example, monovalent salt NaCl decreases bend modulus K3 and increases twist viscosity, while an elevated pH decreases all the parameters. We attribute these features to the ion-induced changes in length and flexibility of building units of LCLC, the chromonic aggregates, a property not found in conventional thermotropic and lyotropic liquid crystals form by covalently bound units of fixed length. The second part of the thesis studies a new active bio-mechanical hybrid system called living liquid crystal
Mechanical properties of chemically modified portuguese pinewood

OpenAIRE

Lopes, Duarte B; Mai, Carsten; Militz, Holger

2014-01-01

To turn wood into a construction material with enhanced properties, many methods of chemical modification have been developed in the last few decades. In this work, mechanical properties of pine wood were chemically modified, compared and evaluated. Maritime pine wood (Pinus pinaster) was modified with four chemical processes: 1,3-dimethylol-4,5- dihydroxyethyleneurea, N-methylol melamine formaldehyde, tetra-alkoxysilane and wax. The following mechanical properties were assessed experiment...
Impurities and Electronic Property Variations of Natural MoS 2 Crystal Surfaces

KAUST Repository

Addou, Rafik; McDonnell, Stephen; Barrera, Diego; Guo, Zaibing; Azcatl, Angelica; Wang, Jian; Zhu, Hui; Hinkle, Christopher L.; Quevedo-Lopez, Manuel; Alshareef, Husam N.; Colombo, Luigi; Hsu, Julia W P; Wallace, Robert M.

2015-01-01

Room temperature X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICPMS), high resolution Rutherford backscattering spectrometry (HR-RBS), Kelvin probe method, and scanning tunneling microscopy (STM) are employed to study the properties of a freshly exfoliated surface of geological MoS2 crystals. Our findings reveal that the semiconductor 2H-MoS2 exhibits both n- and p-type behavior, and the work function as measured by the Kelvin probe is found to vary from 4.4 to 5.3 eV. The presence of impurities in parts-per-million (ppm) and a surface defect density of up to 8% of the total area could explain the variation of the Fermi level position. High resolution RBS data also show a large variation in the MoSx composition (1.8 < x < 2.05) at the surface. Thus, the variation in the conductivity, the work function, and stoichiometry across small areas of MoS2 will have to be controlled during crystal growth in order to provide high quality uniform materials for future device fabrication. © 2015 American Chemical Society.
Impurities and Electronic Property Variations of Natural MoS 2 Crystal Surfaces

KAUST Repository

Addou, Rafik

2015-09-22

Room temperature X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICPMS), high resolution Rutherford backscattering spectrometry (HR-RBS), Kelvin probe method, and scanning tunneling microscopy (STM) are employed to study the properties of a freshly exfoliated surface of geological MoS2 crystals. Our findings reveal that the semiconductor 2H-MoS2 exhibits both n- and p-type behavior, and the work function as measured by the Kelvin probe is found to vary from 4.4 to 5.3 eV. The presence of impurities in parts-per-million (ppm) and a surface defect density of up to 8% of the total area could explain the variation of the Fermi level position. High resolution RBS data also show a large variation in the MoSx composition (1.8 < x < 2.05) at the surface. Thus, the variation in the conductivity, the work function, and stoichiometry across small areas of MoS2 will have to be controlled during crystal growth in order to provide high quality uniform materials for future device fabrication. © 2015 American Chemical Society.
Extended model of bond charges and its application in calculation of optical properties of crystals with different types of chemical bonds

International Nuclear Information System (INIS)

Tsirelson, V.G.; Korolkova, O.V.; Rez, I.S.; Ozerov, R.P.

1984-01-01

A method for calculating the optical characteristics of crystals with different types of chemical bonds within the framework of the dielectric theory of chemical bond put forward by Philips and Van Vechten is suggested. The calculating scheme which does not contain adjustable parameters is based on the bond charge model designed by Levine, which is generalized for the case of multiple bonds and modified involving the density functional method data on the spatial distribution of electrons in atoms. The structural elements of the method are: the screened Coulomb potentials and radii of the atomic core, bond lengths and charges, and the distances from the nuclei to the centers of gravity of the latter. The calculated characteristics of the crystals (dielectric permittivity, quadratic and cubic non-linear susceptibilities, electrooptical constants) are in good accordance with experimental findings. An attempt is made to predict the non-linear optical characteristics according to precision X-ray diffraction data on the electron structure of its only representative, lithium formate deuterate LiHCO 2 xD 2 O, whereby a fairly good fit with the experimental data is achieved. (author)
Effect of Ge atoms on crystal structure and optoelectronic properties of hydrogenated Si-Ge films

Science.gov (United States)

Li, Tianwei; Zhang, Jianjun; Ma, Ying; Yu, Yunwu; Zhao, Ying

2017-07-01

Optoelectronic and structural properties of hydrogenated microcrystalline silicon-germanium (μc-Si1-xGex:H) alloys prepared by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) were investigated. When the Ge atoms were predominantly incorporated in amorphous matrix, the dark and photo-conductivity decreased due to the reduced crystalline volume fraction of the Si atoms (XSi-Si) and the increased Ge dangling bond density. The photosensitivity decreased monotonously with Ge incorporation under higher hydrogen dilution condition, which was attributed to the increase in both crystallization of Ge and the defect density.
Reflectance properties of one-dimensional metal-dielectric ternary photonic crystal

Energy Technology Data Exchange (ETDEWEB)

Pandey, G. N., E-mail: gnpandey2009@gmail.com [Department of Physics, Amity Institute of Applied Sciences, AmityUniversity, Noida (U.P.) (India); Kumar, Narendra [Department of Physics (CASH), Modi University of Science and Technology, Lakshmangarh, Sikar, Rajsthan (India); Thapa, Khem B. [Department of Physics, U I E T, ChhatrapatiShahu Ji Maharaj University, Kanpur- (UP) (India); Ojha, S. P. [Department of Physics IIT, Banaras Hindu University (India)

2016-05-06

Metallic photonic crystal has a very important application in absorption enhancement in solar cells. It has been found that an ultra-thin metallic layer becomes transparent due to internal scattering of light through the each interface of the dielectric and metal surfaces. The metal has absorption due to their surface plasmon and the plasmon has important parameters for changing optical properties of the metal. We consider ternary metallic-dielectric photonic crystal (MDPC) for having large probabilities to change the optical properties of the MDPC and the photonic crystals may be changed by changing dimensionality, symmetry, lattice parameters, Filling fraction and effective refractive index refractive index contrast. In this present communication, we try to show that the photonic band gap in ternary metal-dielectric photonic crystal can be significantly enlarged when air dielectric constant is considered. All the theoretical analyses are made based on the transfer matrix method together with the Drude model of metal.

Co-Crystal Screening of Diclofenac

Directory of Open Access Journals (Sweden)

John Desper

2011-08-01

Full Text Available In the pharmaceutical industry, co-crystals are becoming increasingly valuable as crystalline solids that can offer altered/improved physical properties of an active pharmaceutical ingredient (API without changing its chemical identity or biological activity. In order to identify new solid forms of diclofenac—an analgesic with extremely poor aqueous solubility for which few co-crystal structures have been determined—a range of pyrazoles, pyridines, and pyrimidines were screened for co-crystal formation using solvent assisted grinding and infrared spectroscopy with an overall success rate of 50%. The crystal structures of three new diclofenac co-crystals are reported herein: (diclofenac∙(2-aminopyrimidine, (diclofenac∙(2-amino-4,6-dimethylpyrimidine, and (diclofenac∙(2-amino-4-chloro-6-methylpyrimidine.
Co-crystal screening of diclofenac.

Science.gov (United States)

Aakeröy, Christer B; Grommet, Angela B; Desper, John

2011-08-31

In the pharmaceutical industry, co-crystals are becoming increasingly valuable as crystalline solids that can offer altered/improved physical properties of an active pharmaceutical ingredient (API) without changing its chemical identity or biological activity. In order to identify new solid forms of diclofenac-an analgesic with extremely poor aqueous solubility for which few co-crystal structures have been determined-a range of pyrazoles, pyridines, and pyrimidines were screened for co-crystal formation using solvent assisted grinding and infrared spectroscopy with an overall success rate of 50%. The crystal structures of three new diclofenac co-crystals are reported herein: (diclofenac)∙(2-aminopyrimidine), (diclofenac)∙(2-amino-4,6-dimethylpyrimidine), and (diclofenac)∙(2-amino-4-chloro-6-methylpyrimidine).
Properties and Crystallization Phenomena in Li2Si2O5–Ca5(PO4)3F and Li2Si2O5–Sr5(PO4)3F Glass–Ceramics Via Twofold Internal Crystallization

Science.gov (United States)

Rampf, Markus; Dittmer, Marc; Ritzberger, Christian; Schweiger, Marcel; Höland, Wolfram

2015-01-01

The combination of specific mechanical, esthetic, and chemical properties is decisive for the application of materials in prosthodontics. Controlled twofold crystallization provides a powerful tool to produce special property combinations for glass–ceramic materials. The present study outlines the potential of precipitating Ca5(PO4)3F as well as Sr5(PO4)3F as minor crystal phases in Li2Si2O5 glass–ceramics. Base glasses with different contents of CaO/SrO, P2O5, and F− were prepared within the glasses of the SiO2–Li2O–K2O–CaO/SrO–Al2O3–P2O5–F system. Preliminary studies of nucleation by means of XRD and scanning electron microscopy (SEM) of the nucleated base glasses revealed X-ray amorphous phase separation phenomena. Qualitative and quantitative crystal phase analyses after crystallization were conducted using XRD in combination with Rietveld refinement. As a main result, a direct proportional relationship between the content of apatite-forming components in the base glasses and the content of apatite in the glass–ceramics was established. The microstructures of the glass–ceramics were investigated using SEM. Microstructural and mechanical properties were found to be dominated by Li2Si2O5 crystals and quite independent of the content of the apatite present in the glass–ceramics. Biaxial strengths of up to 540 MPa were detected. Ca5(PO4)3F and Sr5(PO4)3F influence the translucency of the glass–ceramics and, hence, help to precisely tailor the properties of Li2Si2O5 glass–ceramics. The authors conclude that the twofold crystallization of Li2Si2O5–Ca5(PO4)3F or Li2Si2O5–Sr5(PO4)3F glass–ceramics involves independent solid-state reactions, which can be controlled via the chemical composition of the base glasses. The influence of the minor apatite phase on the optical properties helps to achieve new combinations of features of the glass–ceramics and, hence, displays new potential for dental applications. PMID:26389112
A multistep single-crystal-to-single-crystal bromodiacetylene dimerization

Science.gov (United States)

Hoheisel, Tobias N.; Schrettl, Stephen; Marty, Roman; Todorova, Tanya K.; Corminboeuf, Clémence; Sienkiewicz, Andrzej; Scopelliti, Rosario; Schweizer, W. Bernd; Frauenrath, Holger

2013-04-01

Packing constraints and precise placement of functional groups are the reason that organic molecules in the crystalline state often display unusual physical or chemical properties not observed in solution. Here we report a single-crystal-to-single-crystal dimerization of a bromodiacetylene that involves unusually large atom displacements as well as the cleavage and formation of several bonds. Density functional theory computations support a mechanism in which the dimerization is initiated by a [2 + 1] photocycloaddition favoured by the nature of carbon-carbon short contacts in the crystal structure. The reaction proceeded up to the theoretical degree of conversion without loss of crystallinity, and it was also performed on a preparative scale with good yield. Moreover, it represents the first synthetic pathway to (E)-1,2-dibromo-1,2-diethynylethenes, which could serve as synthetic intermediates for the preparation of molecular carbon scaffolds. Our findings both extend the scope of single-crystal-to-single-crystal reactions and highlight their potential as a synthetic tool for complex transformations.
Synthesis, crystal structures and properties of new quinolinium derivatives

Science.gov (United States)

Zhang, Xinyuan; Jiang, Xingxing; Li, Yin; Lin, Zheshuai; Zhang, Guochun; Wu, Yicheng

2015-11-01

Four phenyl-substituted quinolinium salts with different counter anions, C27H27NO4S, C26H25NO5S, C25H22NO5SCl, and C25H22NO5SBr, were synthesized and their single crystals were successfully grown from methanol solution by slow evaporation. Single crystal X-ray diffraction analyses showed that C27H27NO4S crystal belongs to the noncentrosymmetric orthorhombic space group Pna21, and the other three crystals belong to centrosymmetric monoclinic space group P21/n. Their first order hyperpolarization and macroscopic nonlinearity were analyzed and physical properties were characterized by UV-vis absorption spectroscopy, and differential scanning calorimetric and thermal gravimetric analysis.
Growth and Characterization of Tetraphenylphosphonium Bromide Crystal

Directory of Open Access Journals (Sweden)

Guangqiang Wang

2017-05-01

Full Text Available Multiple-phenyl phosphorous compounds are a group of chemical materials that have been used as reactants, pharmaceutical intermediates, extractants, and catalysts in organic synthetic reactions. However, the crystal growth of bulk crystals of multiple-phenyl phosphorous compounds, which may expand their applications in photonics technology, have been largely overlooked. In this article, the crystal growth of tetraphenylphosphonium bromide (TPPB has been studied in organic solvents and water. The crystal structures and crystallization features are analyzed by X-ray diffraction data. By a slow temperature-lowering method, a single-crystal of TPPB (2H2O with the size of 27 × 20 × 20 mm3 has been obtained in water. The basic thermal and optical properties were characterized. We find that the TPPB (2H2O crystal shows excellent transparent property in the near-IR region. Large Raman shifts and strong Raman scattering intensity indicate that TPPB is a potential candidate in Raman-scattering-based nonlinearity applications.
Frictional properties of single crystals HMX, RDX and PETN explosives

International Nuclear Information System (INIS)

Wu, Y.Q.; Huang, F.L.

2010-01-01

The frictional properties of single crystals of cyclotetramethylene tetranitramine (HMX), cyclotrimethylene trinitramine (RDX) and pentaerythritol tetranitrate (PETN) secondary explosives are examined using a sensitive friction machine. The explosive crystals used for the measurements are at least 3.5 mm wide. The friction coefficients between crystals of the same explosive (i.e., HMX on HMX, etc.), crystals of different explosives (i.e., HMX on RDX, etc.), and each explosive and a well-polished gauge steel surface are determined. The frictional surfaces are also studied under an environmental scanning electron microscope (ESEM) to analyze surface microstructural changes under increasing loading forces. The friction coefficients vary considerably with increasing normal loading forces and are particularly sensitive to slider shapes, crystal roughness and the mechanical properties of both the slider and the sample. With increasing loading forces, most friction experiments show surface damage, consisting of grooves, debris, and nano-particles, on both the slider and sample. In some cases, a strong evidence of a localized molten state is found in the central region of the friction track. Possible mechanisms that affect the friction coefficient are discussed based on microscopic observations.
Computerized crystal-chemical classification of silicates and related materials with CRYSTANA and formula notation for classified structures

International Nuclear Information System (INIS)

Klein, Hans-Joachim; Liebau, Friedrich

2008-01-01

The computer program CRYSTANA is described which implements a method for the crystal-chemical classification of silicates and related materials. This method is mainly based upon the topological structure of the connected units of a compound and can be applied when the units are built from tetrahedra as coordination polyhedra. The classification parameters and the rules which have to be applied for their determination are summarized and a formalization of the method is provided based upon a finite graph representation of the units. A description of how CRYSTANA can be used and which kind of output it produces is included. From this output crystal-chemical formulas can be derived, which differ slightly from an existing notation in order to meet recommendations of the International Union of Crystallography. - The computer program CRYSTANA is described which implements a method for the crystal-chemical classification of silicates and related materials. The implementation is based upon a graph-theoretical formalization of the classification method. An extended notation of crystal-chemical formulas is introduced. The formulas can be derived from the output of the program
Spin dynamics, electronic, and thermal transport properties of two-dimensional CrPS{sub 4} single crystal

Energy Technology Data Exchange (ETDEWEB)

Pei, Q. L.; Luo, X., E-mail: xluo@issp.ac.cn, E-mail: ypsun@issp.ac.cn; Lin, G. T.; Song, J. Y.; Hu, L.; Song, W. H.; Lu, W. J. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Zou, Y. M.; Yu, L.; Tong, W. [High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031 (China); Sun, Y. P., E-mail: xluo@issp.ac.cn, E-mail: ypsun@issp.ac.cn [High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031 (China); Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

2016-01-28

2-Dimensional (2D) CrPS{sub 4} single crystals have been grown by the chemical vapor transport method. The crystallographic, magnetic, electronic, and thermal transport properties of the single crystals were investigated by the room-temperature X-ray diffraction, electrical resistivity ρ(T), specific heat C{sub P}(T), and the electronic spin response (ESR) measurements. CrPS{sub 4} crystals crystallize into a monoclinic structure. The electrical resistivity ρ(T) shows a semiconducting behavior with an energy gap E{sub a} = 0.166 eV. The antiferromagnetic transition temperature is about T{sub N} = 36 K. The spin flipping induced by the applied magnetic field is observed along the c axis. The magnetic phase diagram of CrPS{sub 4} single crystal has been discussed. The extracted magnetic entropy at T{sub N} is about 10.8 J/mol K, which is consistent with the theoretical value R ln(2S + 1) for S = 3/2 of the Cr{sup 3+} ion. Based on the mean-field theory, the magnetic exchange constants J{sub 1} and J{sub c} corresponding to the interactions of the intralayer and between layers are about 0.143 meV and −0.955 meV are obtained based on the fitting of the susceptibility above T{sub N}, which agree with the results obtained from the ESR measurements. With the help of the strain for tuning the magnetic properties, monolayer CrPS{sub 4} may be a promising candidate to explore 2D magnetic semiconductors.
Crystal structure, Raman scattering and magnetic properties of CuCr2-xZrxSe4 and CuCr2-xSnxSe4 selenospinels

Science.gov (United States)

Pinto, C.; Galdámez, A.; Barahona, P.; Moris, S.; Peña, O.

2018-06-01

Selenospinels, CuCr2-xMxSe4 (M = Zr and Sn), were synthesized via conventional solid-state reactions. The crystal structure of CuCr1.5Sn0.5Se4, CuCr1.7Sn0.3Se4, CuCr1.5Zr0.5Se4, and CuCr1.8Zr0.2Se4 were determined using single-crystal X-ray diffraction. All the phases crystallized in a cubic spinel-type structure. The chemical compositions of the single-crystals were examined using energy-dispersive X-ray analysis (EDS). Powder X-ray diffraction patterns of CuCr1.3Sn0.7Se4 and CuCr1.7Sn0.3Se4 were consistent with phases belonging to the Fd 3 bar m Space group. An analysis of the vibrational properties on the single-crystals was performed using Raman scattering measurements. The magnetic properties showed a spin glass behavior with increasing Sn content and ferromagnetic order for CuCr1.7Sn0.3Se4.
Characteristic properties of crystals. Their demonstration; Proprietes caracteristiques des cristaux. Mise en evidence

Energy Technology Data Exchange (ETDEWEB)

Lesueur, C

1951-03-01

The characteristic properties of scintillation crystals discussed are the photon spectrum emitted by passage of a particle, number of these photons, transparence of the crystal to its own fluorescence radiation, and decay period of the fluorescence. The experimental apparatus, consisting of photomultiplier tube, preamplifier, amplifier, discriminator, and scaler, is described, and the experimental evaluation of the characteristic properties is discussed. Results of tests on various crystals with {alpha} and {beta} radiations are reported graphically.
Computing Properties Of Chemical Mixtures At Equilibrium

Science.gov (United States)

Mcbride, B. J.; Gordon, S.

1995-01-01

Scientists and engineers need data on chemical equilibrium compositions to calculate theoretical thermodynamic properties of chemical systems. Information essential in design and analysis of such equipment as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical-processing equipment. CET93 is general program that calculates chemical equilibrium compositions and properties of mixtures for any chemical system for which thermodynamic data are available. Includes thermodynamic data for more than 1,300 gaseous and condensed species and thermal-transport data for 151 gases. Written in FORTRAN 77.
Structure and properties of diamond and diamond-like films

Energy Technology Data Exchange (ETDEWEB)

Clausing, R.E. [Oak Ridge National Lab., TN (United States)

1993-01-01

This section is broken into four parts: (1) introduction, (2) natural IIa diamond, (3) importance of structure and composition, and (4) control of structure and properties. Conclusions of this discussion are that properties of chemical vapor deposited diamond films can compare favorably with natural diamond, that properties are anisotropic and are a strong function of structure and crystal perfection, that crystal perfection and morphology are functions of growth conditions and can be controlled, and that the manipulation of texture and thereby surface morphology and internal crystal perfection is an important step in optimizing chemically deposited diamond films for applications.
Crystal structure and thermal property of polyethylene glycol octadecyl ether

International Nuclear Information System (INIS)

Meng, Jie-yun; Tang, Xiao-fen; Li, Wei; Shi, Hai-feng; Zhang, Xing-xiang

2013-01-01

Highlights: ► The crystal structure of C18En for n ≥ 20 is a monoclinic system. ► Polyethylene glycol octadecyl ether crystallizes perfectly. ► The number of repeat units has significant effect on the melting, crystallizing temperature and enthalpy. ► The thermal stable temperature increases rapidly with increasing the number of repeat unit. - Abstract: The crystal structure, phase change property and thermal stable temperature (T d ) of polyethylene glycol octadecyl ether [HO(CH 2 CH 2 O) n C 18 H 37 , C18En] with various numbers of repeat units (n = 2, 10, 20 and 100) as phase change materials (PCMs) were investigated using temperature variable Fourier transformed infrared spectroscopy (FTIR), wide-angle X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TG). C18En crystallizes perfectly at 0 °C; and the crystal structure for n ≥ 20 is a monoclinic system. The number of repeat units has great effect on the phase change properties of C18En. The thermal stable temperature increases rapidly with increasing the number of repeat units. They approach to that of PEG-2000 as the number of repeat units is more than 10. T d increases rapidly with increasing the number of repeat units. C18En are a series of promising polymeric PCMs
Ab initio study of single-crystalline and polycrystalline elastic properties of Mg-substituted calcite crystals.

Science.gov (United States)

Zhu, L-F; Friák, M; Lymperakis, L; Titrian, H; Aydin, U; Janus, A M; Fabritius, H-O; Ziegler, A; Nikolov, S; Hemzalová, P; Raabe, D; Neugebauer, J

2013-04-01

We employ ab initio calculations and investigate the single-crystalline elastic properties of (Ca,Mg)CO3 crystals covering the whole range of concentrations from pure calcite CaCO3 to pure magnesite MgCO3. Studying different distributions of Ca and Mg atoms within 30-atom supercells, our theoretical results show that the energetically most favorable configurations are characterized by elastic constants that nearly monotonously increase with the Mg content. Based on the first principles-derived single-crystalline elastic anisotropy, the integral elastic response of (Ca,Mg)CO3 polycrystals is determined employing a mean-field self-consistent homogenization method. As in case of single-crystalline elastic properties, the computed polycrystalline elastic parameters sensitively depend on the chemical composition and show a significant stiffening impact of Mg atoms on calcite crystals in agreement with the experimental findings. Our analysis also shows that it is not advantageous to use a higher-scale two-phase mix of stoichiometric calcite and magnesite instead of substituting Ca atoms by Mg ones on the atomic scale. Such two-phase composites are not significantly thermodynamically favorable and do not provide any strong additional stiffening effect. Copyright © 2013 Elsevier Ltd. All rights reserved.
Synthesis, crystal structure, physicochemical properties of hydrogen bonded supramolecular assembly of N,N-diethylanilinium-3, 5-dinitrosalicylate crystal

Science.gov (United States)

Rajkumar, M.; Chandramohan, A.

2017-12-01

An organic salt, N,N-diethylanilinium 3,5-dinitrosalicylate was synthesized and single crystals grown by employing the slow solvent evaporation solution growth technique in methanol-acetone (1:1) mixture. The electronic transitions of the salt crystal were studied by UV-Visible spectrum. The optical transmittance window and lower wavelength cut-off of grown crystal have been identified by UV-Vis-NIR studies. The FT-IR spectrum was recorded to confirm the presence of various functional groups in the grown crystal. 1H and 13C NMR spectrum were recorded to establish the molecular structure of the title crystal. Single crystal X-ray diffraction data indicated that the crystal belongs to monoclinic crystal system with P21/n space group. The thermal stability of the crystal was established by TG/DTA studies. The mechanical properties of the grown crystal were studied by Vickers' microhardness technique. The dielectric studies indicated that the dielectric constant and dielectric loss decrease exponentially with frequency at different temperatures.
The importance of proper crystal-chemical and geometrical reasoning demonstrated using layered single and double hydroxides

International Nuclear Information System (INIS)

Richardson, Ian G.

2013-01-01

The importance and utility of proper crystal-chemical and geometrical reasoning in structural studies is demonstrated through the consideration of layered single and double hydroxides. New yet fundamental information is provided and it is evident that the crystal chemistry of the double hydroxide phases is much more straightforward than is apparent from the literature. Atomistic modelling techniques and Rietveld refinement of X-ray powder diffraction data are widely used but often result in crystal structures that are not realistic, presumably because the authors neglect to check the crystal-chemical plausibility of their structure. The purpose of this paper is to reinforce the importance and utility of proper crystal-chemical and geometrical reasoning in structural studies. It is achieved by using such reasoning to generate new yet fundamental information about layered double hydroxides (LDH), a large, much-studied family of compounds. LDH phases are derived from layered single hydroxides by the substitution of a fraction (x) of the divalent cations by trivalent. Equations are derived that enable calculation of x from the a parameter of the unit cell and vice versa, which can be expected to be of widespread utility as a sanity test for extant and future structure determinations and computer simulation studies. The phase at x = 0 is shown to be an α form of divalent metal hydroxide rather than the β polymorph. Crystal-chemically sensible model structures are provided for β-Zn(OH) 2 and Ni- and Mg-based carbonate LDH phases that have any trivalent cation and any value of x, including x = 0 [i.e. for α-M(OH) 2 ·mH 2 O phases
Phase relations, crystal structures and physical properties of nuclear fuels

International Nuclear Information System (INIS)

Tagawa, Hiroaki; Fujino, Takeo; Tateno, Jun

1975-07-01

Phase relations, crystal structures and physical properties of the compounds for nuclear fuels are presented, including melting point, thermal expansion, diffusion and magnetic and electric properties. Emphasis is on oxides, carbides and nitrides of thorium, uranium and plutonium. (auth.)
Folding two dimensional crystals by swift heavy ion irradiation

International Nuclear Information System (INIS)

Ochedowski, Oliver; Bukowska, Hanna; Freire Soler, Victor M.; Brökers, Lara; Ban-d'Etat, Brigitte; Lebius, Henning; Schleberger, Marika

2014-01-01

Ion irradiation of graphene, the showcase model of two dimensional crystals, has been successfully applied to induce various modifications in the graphene crystal. One of these modifications is the formation of origami like foldings in graphene which are created by swift heavy ion irradiation under glancing incidence angle. These foldings can be applied to locally alter the physical properties of graphene like mechanical strength or chemical reactivity. In this work we show that the formation of foldings in two dimensional crystals is not restricted to graphene but can be applied for other materials like MoS 2 and hexagonal BN as well. Further we show that chemical vapour deposited graphene forms foldings after swift heavy ion irradiation while chemical vapour deposited MoS 2 does not
Thermal, defects, mechanical and spectral properties of Nd-doped GdNbO{sub 4} laser crystal

Energy Technology Data Exchange (ETDEWEB)

Ding, Shoujun [Chinese Academy of Sciences, Anhui Institute of Optics and Fine Mechanics, Hefei, Anhui Province (China); University of Science and Technology of China, Hefei (China); Zhang, Qingli; Luo, Jianqiao; Liu, Wenpeng; Wang, Xiaofei; Sun, Guihua; Li, Xiuli; Sun, Dunlu [Chinese Academy of Sciences, Anhui Institute of Optics and Fine Mechanics, Hefei, Anhui Province (China)

2017-05-15

A Nd-doped GdNbO{sub 4} crystal was grown successfully by Czochralski method. Its monoclinic structure was determined by X-ray diffraction; the unit-cell parameters are a = 5.38 Aa, b = 11.09 Aa, c = 5.11 Aa, and β = 94.56 . The morphological defects of Nd:GdNbO{sub 4} crystal were investigated using the chemical etching with the phosphoric acid etchant. For a new crystal, the physical properties are of great importance. The hardness and density of Nd:GdNbO{sub 4} were investigated first. Thermal properties of Nd:GdNbO{sub 4}, including thermal expansion coefficient and specific heat, were measured along a-, b-, and c-crystalline axes. Thermal properties indicate that the Nd:GdNbO{sub 4} pumped along c-axis can reduce the thermal lensing effect effectively. The specific heat is 0.53 J g{sup -1} K{sup -1} at 300 K, indicating a relatively high damage threshold of Nd:GdNbO{sub 4}. The transmission and emission spectrum of Nd:GdNbO{sub 4} were measured, and the absorption peaks were assigned. The strongest emission peak of Nd:GdNbO{sub 4} is located at 1065.3 nm in the spectral range of 850-1420 nm excited by 808 nm laser. The refractive index of Nd:GdNbO{sub 4} was calculated with the transmission spectrum and fitted with Sellmeier equation. All these obtained results is of great significance for the further research of Nd:GdNbO{sub 4}. (orig.)

Influences of chemical aging on the surface morphology and crystallization behavior of basaltic glass fibers

DEFF Research Database (Denmark)

Lund, Majbritt Deichgræber; Yue, Yuanzheng

2008-01-01

The impact of aging in high humidity and water on the surface morphology and crystallization behavior of basaltic glass fibers has been studied using scanning electron microscopy, transmission electron microscopy, calorimetry and X-ray diffraction. The results show that interaction between...... the fibers and the surrounding media (high humidity or water at 70 C) leads to chemical changes strongly affecting the surface morphology. The crystallization peak temperature of the basaltic glass fibers are increased without changing the onset temperature, this may be caused by a chemical depletion...
Tensile properties of electron-beam-welded single crystals of molybdenum

International Nuclear Information System (INIS)

Hiraoka, Yutaka; Okada, Masatoshi; Irie, Hirosada; Fujii, Tadayuki.

1987-01-01

The purpose of this study is to investigate the macro- and microstructures and the tensile properties of electron-beam-welded single crystals of molybdenum. The single-crystal sheets were prepared by means of secondary recrystallization. The welding was carried out by a melt-run technique. The weld metal had the same crystallographic orientation as the base metal, and no grain boundary was observed. However, many large weld pores were formed mostly along the weld bond. The strength and ductility of the welded joints of single crystals were almost the same as those of the base metal (''annealed'' single crystals). It is concluded that the joint efficiency of molybdenum single crystals at room temperature or above was excellent and nearly 100 %. (author)
Effect of cobalt on microstructural parameters and mechanical properties of Ni-base single crystal superalloys

International Nuclear Information System (INIS)

Suzuki, Takanobu; Imai, Hachiro; Yokokawa, Tadaharu; Kobayashi, Toshiharu; Koizumi, Yutaka; Harada, Hiroshi

2007-01-01

The alloying effect of Cobalt (Co) to microstructural parameters and mechanical properties, such as partitioning ratios of alloying elements and creep strength, of Re-bearing Ni-base single crystal superalloys have been investigated. The second generation single crystal superalloys, TMS-82+, Ni-7.8Co-4.9Cr-1.9Mo-8.7W-5.3Al-6.0Ta-2.4Re-0.1Hf, in mass% (8Co) was compared to a Co-free (0Co) and 15 mass% Co (15Co) alloy which had the same chemical composition as TMS-82+ except that Co was changed. It was shown that the partitioning ratios of alloying elements trend to k(=X γ /X' γ )=1, as the content of Co was increased. Furthermore, it was found that there was suitable content of Co for the creep strength under various temperature-stress conditions. (author)
Crystallization and mechanical properties of biodegradable poly(p ...

Indian Academy of Sciences (India)

Effect of ome-POSS on the isothermal melt crystallization and dynamic mechanical properties of PPDO in the ... attracting more and more attention in recent times.12–14 Blen- ..... spent at Ts is enough to erase the crystalline memory of the.
Linear, non-linear and thermal properties of single crystal of LHMHCl

Science.gov (United States)

Kulshrestha, Shobha; Shrivastava, A. K.

2018-05-01

The single crystal of amino acid of L-histidine monohydrochloride was grown by slow evaporation technique at room temperature. High optical quality and appropriate size of crystals were grown under optimized growth conditions. The grown crystals were transparent. Crystals are characterized with different characterizations such as Solubility test, UV-Visible, optical band gap (Eg). With the help of optical data to be calculate absorption coefficient (α), extinction coefficient (k), refractive index (n), dielectric constant (ɛ). These optical constants are shows favorable conditions for photonics devices. Second harmonic generation (NLO) test show the green light emission which is confirm that crystal have properties for laser application. Thermal stability of grown crystal is confirmed by TG/DTA.
Influence of dislocations in solid-phase crystal lattices on structure and properties of an WC-9Co alloy

International Nuclear Information System (INIS)

Grewe, H.

1976-01-01

After theoretical considerations about evaluation of degree of dislocation concentration in crystal lattices two tungsten-carbide-powders are characterized by chemical reaction behaviour. The hard metal grades produced from the two carbide powders are tested by material and tool life investigation. The tungsten carbide powder with lower level of dislocation-concentration leads to a hardmetall-alloy with an equal microstructure and with favourable properties, especially with a good toughness and with an interesting tool life. (orig.) [de
Crystallization and properties of a spodumene-willemite glass ceramic

International Nuclear Information System (INIS)

Hu, A.M.; Li, M.; Dali, D.L. Mao; Liang, K.M.

2005-01-01

Spodumene-willemite glass ceramics were produced by replacement of Al 2 O 3 in lithium aluminium silicate by ZnO. With replacement of Al 2 O 3 by ZnO, the batch melting temperature, glass transition temperature (T g ) and crystallization temperature (T p ) all decreased. The main crystalline phases precipitated were eucriptite, β-spodumene and willemite (Zn 2 SiO 4 ). All compositions of glass ceramics showed bulk crystallization. As ZnO content increased, the grain sizes and thermal expansion coefficients increased, while the flexural strength and fracture toughness of the glass-ceramics increased first, and then decreased. The mechanical properties were correlated with crystallization and morphology of glass ceramics
Properties of magnetized Coulomb crystals of ions with polarizable electron background

Science.gov (United States)

Kozhberov, A. A.

2018-06-01

We have studied phonon and thermodynamic properties of a body-centered cubic (bcc) Coulomb crystal of ions with weakly polarized electron background in a uniform magnetic field B. At B = 0, the difference between phonon moments calculated using the Thomas-Fermi (TF) and random phase approximations is always less than 1% and for description of phonon properties of a crystal, TF formalism was used. This formalism was successfully applied to investigate thermodynamic properties of magnetized Coulomb crystals. It was shown that the influence of the polarization of the electron background is significant only at κ TF a > 0.1 and T ≪ T p ( 1 + h2 ) - 1 / 2 , where κTF is the Thomas-Fermi wavenumber, a is the ion sphere radius, T p ≡ ℏ ω p is the ion plasma temperature, h ≡ ω B / ω p , ωB is the ion cyclotron frequency, and ωp is the ion plasma frequency.
Determination of structure and properties of molecular crystals from first principles.

Science.gov (United States)

Szalewicz, Krzysztof

2014-11-18

CONSPECTUS: Until recently, it had been impossible to predict structures of molecular crystals just from the knowledge of the chemical formula for the constituent molecule(s). A solution of this problem has been achieved using intermolecular force fields computed from first principles. These fields were developed by calculating interaction energies of molecular dimers and trimers using an ab initio method called symmetry-adapted perturbation theory (SAPT) based on density-functional theory (DFT) description of monomers [SAPT(DFT)]. For clusters containing up to a dozen or so atoms, interaction energies computed using SAPT(DFT) are comparable in accuracy to the results of the best wave function-based methods, whereas the former approach can be applied to systems an order of magnitude larger than the latter. In fact, for monomers with a couple dozen atoms, SAPT(DFT) is about equally time-consuming as the supermolecular DFT approach. To develop a force field, SAPT(DFT) calculations are performed for a large number of dimer and possibly also trimer configurations (grid points in intermolecular coordinates), and the interaction energies are then fitted by analytic functions. The resulting force fields can be used to determine crystal structures and properties by applying them in molecular packing, lattice energy minimization, and molecular dynamics calculations. In this way, some of the first successful determinations of crystal structures were achieved from first principles, with crystal densities and lattice parameters agreeing with experimental values to within about 1%. Crystal properties obtained using similar procedures but empirical force fields fitted to crystal data have typical errors of several percent due to low sensitivity of empirical fits to interactions beyond those of the nearest neighbors. The first-principles approach has additional advantages over the empirical approach for notional crystals and cocrystals since empirical force fields can only be
A new series of two-dimensional silicon crystals with versatile electronic properties

Science.gov (United States)

Chae, Kisung; Kim, Duck Young; Son, Young-Woo

2018-04-01

Silicon (Si) is one of the most extensively studied materials owing to its significance to semiconductor science and technology. While efforts to find a new three-dimensional (3D) Si crystal with unusual properties have made some progress, its two-dimensional (2D) phases have not yet been explored as much. Here, based on a newly developed systematic ab initio materials searching strategy, we report a series of novel 2D Si crystals with unprecedented structural and electronic properties. The new structures exhibit perfectly planar outermost surface layers of a distorted hexagonal network with their thicknesses varying with the atomic arrangement inside. Dramatic changes in electronic properties ranging from semimetal to semiconducting with indirect energy gaps and even to one with direct energy gaps are realized by varying thickness as well as by surface oxidation. Our predicted 2D Si crystals with flat surfaces and tunable electronic properties will shed light on the development of silicon-based 2D electronics technology.
Asymmetric flavone-based liquid crystals: synthesis and properties

Energy Technology Data Exchange (ETDEWEB)

Timmons, Daren J. [Department of Chemistry, Virginia Military Institute, Lexington, VA, USA; Jordan, Abraham J. [Department of Chemistry, Virginia Military Institute, Lexington, VA, USA; Kirchon, Angelo A. [Department of Chemistry, Virginia Military Institute, Lexington, VA, USA; Murthy, N. Sanjeeva [New Jersey Center for Biomaterials, Rutgers, The State University of New Jersey, Piscataway, NJ, USA; Siemers, Troy J. [Department of Applied Mathematics, Virginia Military Institute, Lexington, VA, USA; Harrison, Daniel P. [Department of Chemistry, Virginia Military Institute, Lexington, VA, USA; Slebodnick, Carla [Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA

2017-02-01

A series of flavones (n-F) substituted at the 4', and 6 positions was prepared, characterised by NMR (1H,13C), HRMS, and studied for liquid crystal properties. The 4'-alkoxy,6-methoxyflavones (4-F–16-F) exhibit varying ranges of nematic and smectic A phases as evidenced by polarised optical microscopy and differential scanning calorimetry (DSC). As the tail length is increased, the smectic phase becomes more prevalent. Smectic phases for (8-F–16-F) were further analysed by powder X-ray diffraction (XRD), and the rate of structural transformations was explored by combined DSC/XRD studies. Flavonol 6-F–OH was also prepared but no mesogenic behaviour was observed. The molecular structures of 6-F and 6-F–OH were determined by single-crystal XRD and help to explain the differences in material properties. Additionally, fluorescence and electrochemical studies were conducted on solutions of n-F.
40 CFR 716.50 - Reporting physical and chemical properties.

Science.gov (United States)

2010-07-01

... chemical properties. Studies of physical and chemical properties must be reported under this subpart if... they investigated one or more of the following properties: (a) Water solubility. (b) Adsorption... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Reporting physical and chemical...
Crystal Structure, Optical, and Electrical Properties of SnSe and SnS Semiconductor Thin Films Prepared by Vacuum Evaporation Techniques for Solar Cell Applications

Science.gov (United States)

Ariswan; Sutrisno, H.; Prasetyawati, R.

2017-05-01

Thin films of SnSe and SnS semiconductors had been prepared by vacuum evaporation techniques. All prepared samples were characterized on their structure, optical, and electrical properties in order to know their application in technology. The crystal structure of SnSe and SnS was determined by X-Ray Diffraction (XRD) instrument. The morphology and chemical composition were obtained by Scanning Electron Microscopy (SEM) coupled with Energy Dispersive of X-Ray Analysis (EDAX). The optical property such as band gap was determined by DR-UV-Vis (Diffuse Reflectance-Ultra Violet-Visible) spectroscopy, while the electrical properties were determined by measuring the conductivity by four probes method. The characterization results indicated that both SnSe and SnS thin films were polycrystalline. SnSe crystallized in an orthorhombic crystal system with the lattice parameters of a = 11.47 Å, b = 4.152 Å and c = 4.439 Å, while SnS had an orthorhombic crystal system with lattice parameters of a = 4.317 Å, b = 11.647 Å and c = 3.981 Å. Band gaps (Eg) of SnSe and SnS were 1.63 eV and 1.35 eV, respectively. Chemical compositions of both thin films were non-stoichiometric. Molar ratio of Sn : S was close to ideal which was 1 : 0.96, while molar ratio of Sn : S was 1 : 0.84. The surface morphology described the arrangement of the grains on the surface of the thin film with sizes ranging from 0.2 to 0.5 microns. Color similarity on the surface of the SEM images proved a homogenous thin layer.
Superconducting selenides intercalated with organic molecules: synthesis, crystal structure, electric and magnetic properties, superconducting properties, and phase separation in iron based-chalcogenides and hybrid organic-inorganic superconductors

Science.gov (United States)

Krzton-Maziopa, Anna; Pesko, Edyta; Puzniak, Roman

2018-06-01

Layered iron-based superconducting chalcogenides intercalated with molecular species are the subject of intensive studies, especially in the field of solid state chemistry and condensed matter physics, because of their intriguing chemistry and tunable electric and magnetic properties. Considerable progress in the research, revealing superconducting inorganic–organic hybrid materials with transition temperatures to superconducting state, T c, up to 46 K, has been brought in recent years. These novel materials are synthesized by low-temperature intercalation of molecular species, such as solvates of alkali metals and nitrogen-containing donor compounds, into layered FeSe-type structure. Both the chemical nature as well as orientation of organic molecules between the layers of inorganic host, play an important role in structural modifications and may be used for fine tuning of superconducting properties. Furthermore, a variety of donor species compatible with alkali metals, as well as the possibility of doping also in the host structure (either on Fe or Se sites), makes this system quite flexible and gives a vast array of new materials with tunable electric and magnetic properties. In this review, the main aspects of intercalation chemistry are discussed with a particular attention paid to the influence of the unique nature of intercalating species on the crystal structure and physical properties of the hybrid inorganic–organic materials. To get a full picture of these materials, a comprehensive description of the most effective chemical and electrochemical methods, utilized for synthesis of intercalated species, with critical evaluation of their strong and weak points, related to feasibility of synthesis, phase purity, crystal size and morphology of final products, is included as well.
A chemical library to screen protein and protein-ligand crystallization using a versatile microfluidic platform

OpenAIRE

Gerard , Charline ,; Ferry , Gilles; Vuillard , Laurent ,; Boutin , Jean ,; Ferte , Nathalie ,; Grossier , Romain ,; Candoni , Nadine ,; Veesler , Stéphane ,

2018-01-01

Here, we describe a plug-and-play microfluidic platform, suitable for protein crystallization. The droplet factory is designed to generate hundreds of droplets as small as a few nanoliters (2 to 10nL) for screening and optimization of crystallization conditions. Commercially-available microfluidic junctions and tubing are combined to create the appropriate geometry. In addition, a " chemical library " is produced in tubing. The microfluidic geometry for a " crystallization agent-based chemica...
Electrical properties of zirconium diselenide single crystals grown by iodine transport method

International Nuclear Information System (INIS)

Patel, S.G.; Agarwal, M.K.; Batra, N.M.; Lakshminarayana, D.

1998-01-01

Single crystals of zirconium diselenide (ZrSe 2 ) were grown by chemical vapour transport method using iodine as the transporting agent. The crystals were found to exhibit metallic behaviour in the temperature range 77-300 K and semiconducting nature in 300-443 K range. The measurements of thermoelectric power and conductivity enabled the determination of both carrier mobility and carrier concentration. The variation of carrier mobility and carrier concentration with temperature indicates the presence of deep trapping centres and their reduction with temperature in these crystals. (author)
Folding two dimensional crystals by swift heavy ion irradiation

Energy Technology Data Exchange (ETDEWEB)

Ochedowski, Oliver; Bukowska, Hanna [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany); Freire Soler, Victor M. [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany); Departament de Fisica Aplicada i Optica, Universitat de Barcelona, E08028 Barcelona (Spain); Brökers, Lara [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany); Ban-d' Etat, Brigitte; Lebius, Henning [CIMAP (CEA-CNRS-ENSICAEN-UCBN), 14070 Caen Cedex 5 (France); Schleberger, Marika, E-mail: marika.schleberger@uni-due.de [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany)

2014-12-01

Ion irradiation of graphene, the showcase model of two dimensional crystals, has been successfully applied to induce various modifications in the graphene crystal. One of these modifications is the formation of origami like foldings in graphene which are created by swift heavy ion irradiation under glancing incidence angle. These foldings can be applied to locally alter the physical properties of graphene like mechanical strength or chemical reactivity. In this work we show that the formation of foldings in two dimensional crystals is not restricted to graphene but can be applied for other materials like MoS{sub 2} and hexagonal BN as well. Further we show that chemical vapour deposited graphene forms foldings after swift heavy ion irradiation while chemical vapour deposited MoS{sub 2} does not.
Self-assembled tunable photonic hyper-crystals.

Science.gov (United States)

Smolyaninova, Vera N; Yost, Bradley; Lahneman, David; Narimanov, Evgenii E; Smolyaninov, Igor I

2014-07-16

We demonstrate a novel artificial optical material, the "photonic hyper-crystal", which combines the most interesting features of hyperbolic metamaterials and photonic crystals. Similar to hyperbolic metamaterials, photonic hyper-crystals exhibit broadband divergence in their photonic density of states due to the lack of usual diffraction limit on the photon wave vector. On the other hand, similar to photonic crystals, hyperbolic dispersion law of extraordinary photons is modulated by forbidden gaps near the boundaries of photonic Brillouin zones. Three dimensional self-assembly of photonic hyper-crystals has been achieved by application of external magnetic field to a cobalt nanoparticle-based ferrofluid. Unique spectral properties of photonic hyper-crystals lead to extreme sensitivity of the material to monolayer coatings of cobalt nanoparticles, which should find numerous applications in biological and chemical sensing.
Static and dynamic properties of three-dimensional dot-type magnonic crystals

International Nuclear Information System (INIS)

Maksymov, Artur; Spinu, Leonard

2016-01-01

The static and dynamic magnetization of three-dimensional magnonic metamaterials has been investigated. By numerical means it was analyzed the impact of space dimensionality on the properties of magnonic crystal with unit cell consisting of four dots. It is find out the possibility of multi-vortex core formation which is related to the increasing of the crystal height by three-dimensional periodicity of single crystal layer. Additionally is provided the analysis of ferromagnetic resonance phenomenon for two-dimensional and three-dimensional structures. For the unsaturated magnetization of three-dimensional crystal the several pronounced resonance frequencies were detected.
Static and dynamic properties of three-dimensional dot-type magnonic crystals

Energy Technology Data Exchange (ETDEWEB)

Maksymov, Artur, E-mail: maxyartur@gmail.com [Advanced Materials Research Institute, University of New Orleans, LA 70148 (United States); Department of General Physics, Chernivtsi National University, Chernivtsi 58012 (Ukraine); Spinu, Leonard [Advanced Materials Research Institute, University of New Orleans, LA 70148 (United States); Department of Physics, University of New Orleans, New Orleans, LA 70148 (United States)

2016-04-01

The static and dynamic magnetization of three-dimensional magnonic metamaterials has been investigated. By numerical means it was analyzed the impact of space dimensionality on the properties of magnonic crystal with unit cell consisting of four dots. It is find out the possibility of multi-vortex core formation which is related to the increasing of the crystal height by three-dimensional periodicity of single crystal layer. Additionally is provided the analysis of ferromagnetic resonance phenomenon for two-dimensional and three-dimensional structures. For the unsaturated magnetization of three-dimensional crystal the several pronounced resonance frequencies were detected.

UV response on dielectric properties of nano nematic liquid crystal

Directory of Open Access Journals (Sweden)

Kamal Kumar Pandey

2018-03-01

Full Text Available In this work, we investigate the effect of UV light irradiation on the dielectric parameters of nematic liquid crystal (5CB and ZnO nanoparticles dispersed liquid crystal. With addition of nanoparticles in nematic LC are promising new materials for a variety of application in energy harvesting, displays and photonics including the liquid crystal laser. To realize many applications, however we optimize the properties of liquid crystal and understand how the UV light irradiation interact the nanoparticles and LC molecules in dispersed/doped LC. The dielectric permittivity and loss factor have discussed the pure nematic LC and dispersed/doped system after, during and before UV light exposure. The dielectric relaxation spectroscopy was carried out in the frequency range 100 Hz–10 MHz in the nematic mesophase range. Keywords: Dielectric permittivity, Relaxation frequency, Nematic liquid crystal, UV light irradiation
Luminescent properties of Y3Al5−xGaxO12:Ce crystals

International Nuclear Information System (INIS)

Zorenko, Yu.; Zorenko, T.; Malinowski, P.; Sidletskiy, O.; Neicheva, S.

2014-01-01

Absorption, luminescent and scintillation properties of Ce 3+ doped Y 3 Al 5−x Ga x O 12 crystals with Ga content in the x=1–5 range were investigated in this work and compared with the properties of YAG:Ce crystals. Apart from the traditional spectral methods (absorption, cathodoluminescence and light yield measurements), the intrinsic and Ce 3+ related luminescence of Y 3 Al 5−x Ga x O 12 :Ce solid-solution were also investigated using the luminescent spectroscopy under excitation by synchrotron radiation in the 3.7–25 eV range. We show that the optical properties Y 3 Al 5−x Ga x O 12 :Ce garnets monotonically change with increasing the Ga content in the x=0–3 range due to preferable localization of Ga ions in the tetrahedral position of the garnet lattice. At the highest Ga concentration (x>3) the deviation of the optical properties of Y 3 Al 5−x Ga x O 12 :Ce garnets is observed from the respective properties of these crystals with Ga content in the x=0–3 range due to occupation by Ga ions of the octahedral position in the garnet host. - Highlights: • Different dependence of optical properties of Y 3 Al 5−x Ga x O 12 :Ce crystals on Ga content in x=0–3 and 3–5 ranges. • Elimination of the luminescence of Y Al antisite defects in Y 3 Al 5−x Ga x O 12 :Ce crystals at x>2. • Significant improvement of the scintillation properties of Y 3 Al 5−x Ga x O 12 :Ce crystals at x=2 and 3 in comparison with YAG:Ce
A Study of the Optical Properties of Ice Crystals with Black Carbon Inclusions

Energy Technology Data Exchange (ETDEWEB)

Arienti, Marco [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Yang, Xiaoyuan [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Kopacz, Adrian M [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Geier, Manfred [Sandia National Laboratories (SNL-CA), Livermore, CA (United States)

2015-09-01

The report focu ses on the modification of the optical properties of ice crystals due to atmospheric black car bon (BC) contamination : the objective is to advance the predictive capabilities of climate models through an improved understanding of the radiative properties of compound particles . The shape of the ice crystal (as commonly found in cirrus clouds and cont rails) , the volume fraction of the BC inclusion , and its location inside the crystal are the three factors examined in this study. In the multiscale description of this problem, where a small absorbing inclusion modifies the optical properties of a much la rger non - absorbing particle, state - of - the - art discretization techniques are combined to provide the best compromise of flexibility and accuracy over a broad range of sizes .
Optical properties of a defective one-dimensional photonic crystal containing graphene nanaolayers

International Nuclear Information System (INIS)

Entezar, S. Roshan; Saleki, Z.; Madani, A.

2015-01-01

The transmission properties of a defective one-dimensional photonic crystal containing graphene nanolayers have been investigated using the transfer matrix method. It is shown that two kinds of the defect modes can be found in the band gaps of the structure. One kind is the traditional defect mode which is created in the Bragg gaps of the structure and is due to the breaking of the periodicity of the dielectric lattice. The other one is created in the graphene induced band gap. Such a defect mode which we call it the graphene induced defect mode is due to the breaking of the periodicity of the graphene lattice. However, our investigations reveal that only in the case of wide defect layers one can obtain the graphene induced defect modes. The effects of many parameters such as the incident angle, the state of polarization and the chemical potential of the graphene nanolayers on the properties of the graphene induced defect modes are discussed. Moreover, the possibility of external control of the graphene induced defect modes using a gate voltage is shown.
Chemical composition, crystal size and lattice structural changes after incorporation of strontium into biomimetic apatite.

Science.gov (United States)

Li, Z Y; Lam, W M; Yang, C; Xu, B; Ni, G X; Abbah, S A; Cheung, K M C; Luk, K D K; Lu, W W

2007-03-01

Recently, strontium (Sr) as ranelate compound has become increasingly popular in the treatment of osteoporosis. However, the lattice structure of bone crystal after Sr incorporation is yet to be extensively reported. In this study, we synthesized strontium-substituted hydroxyapatite (Sr-HA) with different Sr content (0.3%, 1.5% and 15% Sr-HA in mole ratio) to simulate bone crystals incorporated with Sr. The changes in chemical composition and lattice structure of apetite after synthetic incorporation of Sr were evaluated to gain insight into bone crystal changes after incorporation of Sr. X-ray diffraction (XRD) patterns revealed that 0.3% and 1.5% Sr-HA exhibited single phase spectrum, which was similar to that of HA. However, 15% Sr-HA induced the incorporation of HPO4(2-) and more CO3(2-), the crystallinity reduced dramatically. Transmission electron microscopy (TEM) images showed that the crystal length and width of 0.3% and 1.5% Sr-HA increased slightly. Meanwhile, the length and width distribution were broadened and the aspect ratio decreased from 10.68+/-4.00 to 7.28+/-2.80. The crystal size and crystallinity of 15% Sr-HA dropped rapidly, which may suggest that the fundamental crystal structure is changed. The findings from this work indicate that current clinical dosage which usually results in Sr incorporation of below 1.5% may not change chemical composition and lattice structure of bone, while it will broaden the bone crystal size distribution and strengthen the bone.
Determining the diffraction properties of a cylindrically bent KAP(001) crystal from 1 to 5 keV

Energy Technology Data Exchange (ETDEWEB)

Haugh, Michael [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Lee, Joshua [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Jacoby, Kenneth [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Christensen, C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Loisel, G. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States), Livermore Operations

2015-08-31

Various crystals are used for the dispersive component of X-ray spectrometers. The crystals are usually bent to meet the desired measurement needs, such as focusing. The bending can change the crystal diffraction properties, thus altering the spectrometer throughput and resolving power. This work concerns measuring the diffraction properties of a potassium acid phthalate (001) [KAP(001)] crystal bent into a circular cylinder segment. The measurement methods using a diode source and a synchrotron source are described. The multi-lamellar model for calculating the diffraction properties of a bent crystal is described. The measurement results are compared to the multi-lamellar model and show qualitative agreement. The measurements show how to make the multi-lamellar calculations a useful estimate. A method is given to make useful estimates of the diffraction properties of the KAP(001) crystal bent into a circular cylinder segment.
CET89 - CHEMICAL EQUILIBRIUM WITH TRANSPORT PROPERTIES, 1989

Science.gov (United States)

Mcbride, B.

1994-01-01

Scientists and engineers need chemical equilibrium composition data to calculate the theoretical thermodynamic properties of a chemical system. This information is essential in the design and analysis of equipment such as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical processing equipment. The substantial amount of numerical computation required to obtain equilibrium compositions and transport properties for complex chemical systems led scientists at NASA's Lewis Research Center to develop CET89, a program designed to calculate the thermodynamic and transport properties of these systems. CET89 is a general program which will calculate chemical equilibrium compositions and mixture properties for any chemical system with available thermodynamic data. Generally, mixtures may include condensed and gaseous products. CET89 performs the following operations: it 1) obtains chemical equilibrium compositions for assigned thermodynamic states, 2) calculates dilute-gas transport properties of complex chemical mixtures, 3) obtains Chapman-Jouguet detonation properties for gaseous species, 4) calculates incident and reflected shock properties in terms of assigned velocities, and 5) calculates theoretical rocket performance for both equilibrium and frozen compositions during expansion. The rocket performance function allows the option of assuming either a finite area or an infinite area combustor. CET89 accommodates problems involving up to 24 reactants, 20 elements, and 600 products (400 of which may be condensed). The program includes a library of thermodynamic and transport properties in the form of least squares coefficients for possible reaction products. It includes thermodynamic data for over 1300 gaseous and condensed species and transport data for 151 gases. The subroutines UTHERM and UTRAN convert thermodynamic and transport data to unformatted form for faster processing. The program conforms to the FORTRAN 77 standard, except for
Chemical and structural properties of polymorphous silicon thin films grown from dichlorosilane

Energy Technology Data Exchange (ETDEWEB)

Álvarez-Macías, C.; Monroy, B.M.; Huerta, L.; Canseco-Martínez, M.A. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, A.P. 70-360, Coyoacán, C.P. 04510 México, D.F. (Mexico); Picquart, M. [Departamento de Física, Universidad Autónoma Metropolitana, Iztapalapa, A.P. 55-534, 09340 México, D.F. (Mexico); Santoyo-Salazar, J. [Departamento de Física, CINVESTAV-IPN, A.P. 14-740, C.P. 07000 México, D.F. (Mexico); Sánchez, M.F. García [Unidad Profesional Interdisciplinaria en Ingeniería y Tecnologías Avanzadas, Instituto Politécnico Nacional, Av. I.P.N. 2580, Gustavo A. Madero, 07340 México .D.F. (Mexico); Santana, G., E-mail: gsantana@iim.unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, A.P. 70-360, Coyoacán, C.P. 04510 México, D.F. (Mexico)

2013-11-15

We have examined the effects of hydrogen dilution (R{sub H}) and deposition pressure on the morphological, structural and chemical properties of polymorphous silicon thin films (pm-Si:H), using dichlorosilane as silicon precursor in the plasma enhanced chemical vapor deposition (PECVD) process. The use of silicon chlorinated precursors enhances the crystallization process in as grown pm-Si:H samples, obtaining crystalline fractions from Raman spectra in the range of 65–95%. Atomic Force Microscopy results show the morphological differences obtained when the chlorine chemistry dominates the growth process and when the plasma–surface interactions become more prominent. Augmenting R{sub H} causes a considerable reduction in both roughness and topography, demonstrating an enhancement of ion bombardment and attack of the growing surface. X-ray Photoelectron Spectroscopy results show that, after ambient exposure, there is low concentration of oxygen inside the films grown at low R{sub H}, present in the form of Si-O, which can be considered as structural defects. Instead, oxidation increases with deposition pressure and dilution, along with film porosity, generating a secondary SiO{sub x} phase. For higher pressure and dilution, the amount of chlorine incorporated to the film decreases congruently with HCl chlorine extraction processes involving atomic hydrogen interactions with the surface. In all cases, weak silicon hydride (Si-H) bonds were not detected by infrared spectroscopy, while bonding configurations associated to the silicon nanocrystal surface were clearly observed. Since these films are generally used in photovoltaic devices, analyzing their chemical and structural properties such as oxygen incorporation to the films, along with chlorine and hydrogen, is fundamental in order to understand and optimize their electrical and optical properties.
On the tungsten single crystal coatings achieved by chemical vapor transportation deposition

Energy Technology Data Exchange (ETDEWEB)

Shi, J.Q.; Shen, Y.B.; Yao, S.Y.; Zhang, P.J.; Zhou, Q.; Guo, Y.Z. [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Tan, C.W., E-mail: tanchengwen@bit.edu.cn [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); China Astronaut Research and Training Center, Beijing 100094 (China); Yu, X.D. [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); China Astronaut Research and Training Center, Beijing 100094 (China); Nie, Z.H. [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Ma, H.L. [China Astronaut Research and Training Center, Beijing 100094 (China); Cai, H.N. [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)

2016-12-15

The tungsten single crystal has many excellent properties, namely a high melting point, high anti-creeping strength. Chemical vapor transportation deposition (CVTD) is a possible approach to achieve large-sized W single crystals for high-temperature application such as the cathode of a thermionic energy converter. In this work, CVTD W coatings were deposited on the monocrystalline molybdenum substrate (a tube with < 111 > axial crystalline orientation) using WCl{sub 6} as a transport medium. The microstructures of the coatings were investigated by a scanning electron microscope (SEM) and electron backscatter diffraction (EBSD). The as-deposited coatings are hexagonal prisms—rough surfaces perpendicular to < 110 > with alternating hill-like bulges and pits at the side edges of the prisms, and flat surfaces perpendicular to < 112 > with arc-shaped terraces at the side faces. This can be explained by two-dimensional nucleation -mediated lateral growth model. Some parts of the coatings contain hillocks of an exotic morphology (noted as “abnormal growth”). The authors hypothesize that the abnormal growth is likely caused by the defects of the Mo substrate, which facilitate W nucleation sites, cause orientation difference, and may even form boundaries in the coatings. A dislocation density of 10{sup 6} to 10{sup 7} (counts/cm{sup 2}) was revealed by an etch-pit method and synchrotron X-ray diffraction. As the depositing temperature rises, the dislocation density decreases, and no sub-boundaries are found on samples deposited over 1300 °C, as a result of atom diffusion and dislocation climbing. - Highlights: •The varied growth rate causes the different morphologies of different planes. •The W coating is a single crystal when only single hillocks appear. •The (110) plane tends to have the lowest dislocation density. •The dislocation density tends to decrease as the temperature increases.
On the tungsten single crystal coatings achieved by chemical vapor transportation deposition

International Nuclear Information System (INIS)

Shi, J.Q.; Shen, Y.B.; Yao, S.Y.; Zhang, P.J.; Zhou, Q.; Guo, Y.Z.; Tan, C.W.; Yu, X.D.; Nie, Z.H.; Ma, H.L.; Cai, H.N.

2016-01-01

The tungsten single crystal has many excellent properties, namely a high melting point, high anti-creeping strength. Chemical vapor transportation deposition (CVTD) is a possible approach to achieve large-sized W single crystals for high-temperature application such as the cathode of a thermionic energy converter. In this work, CVTD W coatings were deposited on the monocrystalline molybdenum substrate (a tube with < 111 > axial crystalline orientation) using WCl 6 as a transport medium. The microstructures of the coatings were investigated by a scanning electron microscope (SEM) and electron backscatter diffraction (EBSD). The as-deposited coatings are hexagonal prisms—rough surfaces perpendicular to < 110 > with alternating hill-like bulges and pits at the side edges of the prisms, and flat surfaces perpendicular to < 112 > with arc-shaped terraces at the side faces. This can be explained by two-dimensional nucleation -mediated lateral growth model. Some parts of the coatings contain hillocks of an exotic morphology (noted as “abnormal growth”). The authors hypothesize that the abnormal growth is likely caused by the defects of the Mo substrate, which facilitate W nucleation sites, cause orientation difference, and may even form boundaries in the coatings. A dislocation density of 10 6 to 10 7 (counts/cm 2 ) was revealed by an etch-pit method and synchrotron X-ray diffraction. As the depositing temperature rises, the dislocation density decreases, and no sub-boundaries are found on samples deposited over 1300 °C, as a result of atom diffusion and dislocation climbing. - Highlights: •The varied growth rate causes the different morphologies of different planes. •The W coating is a single crystal when only single hillocks appear. •The (110) plane tends to have the lowest dislocation density. •The dislocation density tends to decrease as the temperature increases.
CHEMICAL PROPERTIES STUDYS OF PEATLANDON VARIOUS LANDUSE

Directory of Open Access Journals (Sweden)

Yondra Yondra

2017-12-01

Full Text Available Natural peat swamp forests converted can alter the soil chemical properties. This study aims to determine the extent to which changes in soil chemical properties that occur after the conversion of land from peat swamp forest to palm oil plantation, HTI Acacia crasicarpa, and sago plantation and to know which types of plants are sustainable on peatlands. The results showed that soil pH increased after the change of land function. While the water content decreased. Chemical properties such as C-organic, ash content, CEC, alkaline saturation, macro nutrients (NPK and bases can be changed also undergo changes after undergoing landuse changes, but no violations based on the law made by the government in pp No 25 of 2000 on the criteria of peatland damage and government regulation no. 150 of 2000 on the control of soil damage for biomass production. Sago is the most sustainable plant compared to others due to changes in soil chemical properties not too much different from other landuse although planted in the long term.
Direct growth of large grain polycrystalline silicon films on aluminum-induced crystallization seed layer using hot-wire chemical vapor deposition

International Nuclear Information System (INIS)

Wu, Bing-Rui; Lo, Shih-Yung; Wuu, Dong-Sing; Ou, Sin-Liang; Mao, Hsin-Yuan; Wang, Jui-Hao; Horng, Ray-Hua

2012-01-01

Large grain polycrystalline silicon (poly-Si) films on glass substrates have been deposited on an aluminum-induced crystallization (AIC) seed layer using hot-wire chemical vapor deposition (HWCVD). A poly-Si seed layer was first formed by the AIC process and a thicker poly-Si film was subsequently deposited upon the seed layer using HWCVD. The effects of AIC annealing parameters on the structural and electrical properties of the poly-Si seed layers were characterized by Raman scattering spectroscopy, field-emission scanning electron microscopy, and Hall measurements. It was found that the crystallinity of seed layer was enhanced with increasing the annealing duration and temperature. The poly-Si seed layer formed at optimum annealing parameters can reach a grain size of 700 nm, hole concentration of 3.5 × 10 18 cm −3 , and Hall mobility of 22 cm 2 /Vs. After forming the seed layer, poly-Si films with good crystalline quality and high growth rate (> 1 nm/s) can be obtained using HWCVD. These results indicated that the HWCVD-deposited poly-Si film on an AIC seed layer could be a promising candidate for thin-film Si photovoltaic applications. - Highlights: ►Poly-Si seed layers are formed by aluminum-induced crystallization (AIC) process. ►Poly-Si on AIC seed layers are prepared by hot-wire chemical vapor deposition. ►AIC process parameters affect structural properties of poly-Si films. ►Increasing the annealing duration and temperature increases the film crystallinity.
Mechanical properties of hydroxyapatite single crystals from nanoindentation data

Science.gov (United States)

Zamiri, A.; De, S.

2011-01-01

In this paper we compute elasto-plastic properties of hydroxyapatite single crystals from nanindentation data using a two-step algorithm. In the first step the yield stress is obtained using hardness and Young’s modulus data, followed by the computation of the flow parameters. The computational approach is first validated with data from existing literature. It is observed that hydroxyapatite single crystals exhibit anisotropic mechanical response with a lower yield stress along the [1010] crystallographic direction compared to the [0001] direction. Both work hardening rate and work hardening exponent are found to be higher for indentation along the [0001] crystallographic direction. The stress-strain curves extracted here could be used for developing constitutive models for hydroxyapatite single crystals. PMID:21262492
Elastic properties of Ti-24Nb-4Zr-8Sn single crystals with bcc crystal structure

International Nuclear Information System (INIS)

Zhang, Y.W.; Li, S.J.; Obbard, E.G.; Wang, H.; Wang, S.C.; Hao, Y.L.; Yang, R.

2011-01-01

Research highlights: → The single crystals of Ti2448 alloy with the bcc crystal structure were prepared. → The elastic moduli and constants were measured by several resonant methods. → The crystal shows significant elastic asymmetry in tension and compression. → The crystal exhibits weak nonlinear elasticity with large elastic strain ∼2.5%. → The crystal has weak atomic interactions against crystal distortion to low symmetry. - Abstract: Single crystals of Ti2448 alloy (Ti-24Nb-4Zr-8Sn in wt.%) were grown successfully using an optical floating-zone furnace. Several kinds of resonant methods gave consistent Young's moduli of 27.1, 56.3 and 88.1 GPa and shear moduli of 34.8, 11.0 and 14.6 GPa for the , and oriented single crystals, and C 11 , C 12 and C 44 of 57.2, 36.1 and 35.9 GPa respectively. Uniaxial testing revealed asymmetrical elastic behaviors of the crystals: tension caused elastic softening with a large reversible strain of ∼4% and a stress plateau of ∼250 MPa, whereas compression resulted in gradual elastic stiffening with much smaller reversible strain. The crystals exhibited weak nonlinear elasticity with a large elastic strain of ∼2.5% and a high strength, approaching ∼20% and ∼30% of its ideal shear and ideal tensile strength respectively. The crystals showed linear elasticity with a small elastic strain of ∼1%. These elastic deformation characteristics have been interpreted in terms of weakened atomic interactions against crystal distortion to low crystal symmetry under external applied stresses. These results are consistent with the properties of polycrystalline Ti2448, including high strength, low elastic modulus, large recoverable strain and weak strengthening effect due to grain refinement.
Gold Nanoparticles in Photonic Crystals Applications: A Review.

Science.gov (United States)

Venditti, Iole

2017-01-24

This review concerns the recently emerged class of composite colloidal photonic crystals (PCs), in which gold nanoparticles (AuNPs) are included in the photonic structure. The use of composites allows achieving a strong modification of the optical properties of photonic crystals by involving the light scattering with electronic excitations of the gold component (surface plasmon resonance, SPR) realizing a combination of absorption bands with the diffraction resonances occurring in the body of the photonic crystals. Considering different preparations of composite plasmonic-photonic crystals, based on 3D-PCs in presence of AuNPs, different resonance phenomena determine the optical response of hybrid crystals leading to a broadly tunable functionality of these crystals. Several chemical methods for fabrication of opals and inverse opals are presented together with preparations of composites plasmonic-photonic crystals: the influence of SPR on the optical properties of PCs is also discussed. Main applications of this new class of composite materials are illustrated with the aim to offer the reader an overview of the recent advances in this field.
Gold Nanoparticles in Photonic Crystals Applications: A Review

Directory of Open Access Journals (Sweden)

Iole Venditti

2017-01-01

Full Text Available This review concerns the recently emerged class of composite colloidal photonic crystals (PCs, in which gold nanoparticles (AuNPs are included in the photonic structure. The use of composites allows achieving a strong modification of the optical properties of photonic crystals by involving the light scattering with electronic excitations of the gold component (surface plasmon resonance, SPR realizing a combination of absorption bands with the diffraction resonances occurring in the body of the photonic crystals. Considering different preparations of composite plasmonic-photonic crystals, based on 3D-PCs in presence of AuNPs, different resonance phenomena determine the optical response of hybrid crystals leading to a broadly tunable functionality of these crystals. Several chemical methods for fabrication of opals and inverse opals are presented together with preparations of composites plasmonic-photonic crystals: the influence of SPR on the optical properties of PCs is also discussed. Main applications of this new class of composite materials are illustrated with the aim to offer the reader an overview of the recent advances in this field.
Crystal-Chemical Analysis Martian Minerals in Gale Crater

Science.gov (United States)

Morrison, S. M.; Downs, R. T.; Blake, D. F.; Bish, D. L.; Ming, D. W.; Morris, R. V.; Yen, A. S.; Chipera, S. J.; Treiman, A. H.; Vaniman, D. T.;

2015-01-01

The CheMin instrument on the Mars Science Laboratory rover Curiosity performed X-ray diffraction analyses on scooped soil at Rocknest and on drilled rock fines at Yellowknife Bay (John Klein and Cumberland samples), The Kimberley (Windjana sample), and Pahrump (Confidence Hills sample) in Gale crater, Mars. Samples were analyzed with the Rietveld method to determine the unit-cell parameters and abundance of each observed crystalline phase. Unit-cell parameters were used to estimate compositions of the major crystalline phases using crystal-chemical techniques. These phases include olivine, plagioclase and clinopyroxene minerals. Comparison of the CheMin sample unit-cell parameters with those in the literature provides an estimate of the chemical compositions of the major crystalline phases. Preliminary unit-cell parameters, abundances and compositions of crystalline phases found in Rocknest and Yellowknife Bay samples were reported in. Further instrument calibration, development of 2D-to- 1D pattern conversion corrections, and refinement of corrected data allows presentation of improved compositions for the above samples.

Interactions of molecules and the properties of crystals

Science.gov (United States)

McConnell, Thomas Daniel Leigh

In this thesis the basic theory of the lattice dynamics of molecular crystals is considered, with particular reference to the specific case of linear molecules. The objective is to carry out a critical investigation of a number of empirical potentials as models for real systems. Suitable coordinates are introduced, in particular vibrational coordinates which are used to describe the translational and rotational modes of the free molecule. The Taylor expansion of the intermolecular potential is introduced and its terms considered, in particular the (first-order) equilibrium conditions for such a system and the (second-order) lattice vibrations. The elastic properties are also considered, in particular with reference to the specific case of rhombohedral crystals. The compressibility and a number of conditions for elastic stability are introduced. The total intermolecular interaction potential is divided into three components using perturbation methods, the electrostatic energy, the repulsion energy and the dispersion energy. A number of models are introduced for these various components. The induction energy is neglected. The electrostatic interaction is represented by atomic multipole and molecular multipole models. The repulsion and dispersion energies are modelled together in a central interaction potential, either the Lennard-Jones atom-atom potential or the anisotropic Berne-Pechukas molecule-molecule potential. In each case, the Taylor expansion coefficients, used to calculate the various molecular properties, are determined. An algorithm is described which provides a relatively simple method for calculating cartesian tensors, which are found in the Taylor expansion coefficients of the multipolar potentials. This proves to be particularly useful from a computational viewpoint, both in terms of programming and calculating efficiency. The model system carbonyl sulphide is introduced and its lattice properties are described. Suitable parameters for potentials used
Physicochemical properties of dimethylammonium p-nitrophenolate– p-nitrophenol: A nonlinear optical crystal

International Nuclear Information System (INIS)

Rathika, A.; Prasad, L. Guru; Raman, R. Ganapathi

2016-01-01

Single crystals of Dimethylammonium p-nitrophenolate–p-nitrophenol have been grown from aqueous solution by slow evaporation solution growth technique. Unit cell parameters of the grown crystal were confirmed by single crystal X-ray diffraction analysis and the synthesized compound is crystallized in monoclinic system. Various functional groups and their vibrational frequencies were recognized from the FT-IR and FT-Raman spectrum. Thermal stability of the crystal was examined by recording the TGA/DTA curve. The grown crystal has wider transparency nature in the visible region and the lower cut-off wavelength is found at 465 nm. Mechanical property of the crystal was studied by analyzing the Vicker's microhardness measurements. The fluorescence emission from the crystal is observed at 350 nm which arise due to the presence of aromatic ring. Relative SHG conversion efficiency of the grown crystal is about 0.59 times that of KDP.
Physicochemical properties of dimethylammonium p-nitrophenolate– p-nitrophenol: A nonlinear optical crystal

Energy Technology Data Exchange (ETDEWEB)

Rathika, A. [Department of Physics, Noorul Islam Centre for Higher Education, Noorul Islam University, Kumaracoil 629 180 (India); Prasad, L. Guru [Departemnt of Science & Humanities, M. Kumarasamy College of Engineering, Karur (India); Raman, R. Ganapathi, E-mail: ganapathiraman83@gmail.com [Department of Physics, Noorul Islam Centre for Higher Education, Noorul Islam University, Kumaracoil 629 180 (India)

2016-03-15

Single crystals of Dimethylammonium p-nitrophenolate–p-nitrophenol have been grown from aqueous solution by slow evaporation solution growth technique. Unit cell parameters of the grown crystal were confirmed by single crystal X-ray diffraction analysis and the synthesized compound is crystallized in monoclinic system. Various functional groups and their vibrational frequencies were recognized from the FT-IR and FT-Raman spectrum. Thermal stability of the crystal was examined by recording the TGA/DTA curve. The grown crystal has wider transparency nature in the visible region and the lower cut-off wavelength is found at 465 nm. Mechanical property of the crystal was studied by analyzing the Vicker's microhardness measurements. The fluorescence emission from the crystal is observed at 350 nm which arise due to the presence of aromatic ring. Relative SHG conversion efficiency of the grown crystal is about 0.59 times that of KDP.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. YIN ZHOU. Articles written in Journal of Chemical Sciences. Volume 130 Issue 2 February 2018 pp 19. Polynuclear and one-dimensional cyanide-bridged heterobimetallic complexes: synthesis, crystal structures and magnetic properties · JINGWEN SHI WENLONG LAN YIN ...
Anisotropy of the Mechanical Properties of TbF3 Crystals

Science.gov (United States)

Karimov, D. N.; Lisovenko, D. S.; Sizova, N. L.; Sobolev, B. P.

2018-01-01

TbF3 (sp. gr. Pnma) crystals up to 40 mm in diameter have been grown from melt by a Bridgman technique. The anisotropy of their mechanical properties is studied for the first time. the technical elasticity constants are calculated, and room-temperature values of Vickers microhardness for the (010) and (100) planes are measured. The shape of indentation impressions is found to correlate with Young's modulus anisotropy for TbF3 crystals.
Layered Growth and Crystallization in Calcareous Biominerals: Impact of Structural and Chemical Evidence on Two Major Concepts in Invertebrate Biomineralization Studies

Directory of Open Access Journals (Sweden)

Jean-Pierre Cuif

2012-02-01

Full Text Available In several recent models of invertebrate skeletogenesis, Ca-carbonate crystallization occurs within a liquid-filled chamber. No explanation is given neither for the simultaneous occurrence of distinct polymorphs of Ca-carbonate within these liquid volumes, nor for the spatial arrangement of the mineral units which are always organized in species-specific structural sequences. Results of a series of physical characterizations applied to reference skeletal materials reveal the inadequacy of this liquid-filled chamber model to account for structural and chemical properties of the shell building units. Simultaneously, these data provide convergent pieces of evidence for a specific mode of crystallization developed throughout various invertebrate phyla, supporting the hypothesized “common strategy” based on a multi-scaled control exerted on formation of their calcareous hard parts.
Preliminary laboratory studies of the optical scattering properties of the crystal clouds

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C. Saunders

Full Text Available Ice crystal clouds have an influence on the radiative budget of the earth; however, the exact size and nature of this influence has yet to be determined. A laboratory cloud chamber experiment has been set up to provide data on the optical scattering behaviour of ice crystals at a visible wavelength in order to gain information which can be used in climate models concerning the radiative characteristics of cirrus clouds. A PMS grey-scale probe is used to monitor simultaneously the cloud microphysical properties in order to correlate these closely with the observed radiative properties. Preliminary results show that ice crystals scatter considerably more at 90° than do water droplets, and that the halo effects are visible in a laboratory-generated cloud when the ice crystal concentration is sufficiently small to prevent masking from multiple scattering.

Key words. Meteorology and atmosphere dynamics · Climatology · Radiative process · Atmospheric composition and structure · Cloud physics and chemistry
Protein Crystals as Novel Catalytic Materials.

Science.gov (United States)

Margolin, Alexey L.; Navia, Manuel A.

2001-06-18

In this era of molecular biology, protein crystallization is often considered to be a necessary first step in obtaining structural information through X-ray diffraction analysis. In a different light, protein crystals can also be thought of as materials, whose chemical and physical properties make them broadly attractive and useful across a larger spectrum of disciplines. The full potential of these protein crystalline materials has been severely restricted in practice, however, both by their inherent fragility, and by strongly held skepticism concerning their routine and predictable growth, formulation, and practical application. Fortunately, these problems have turned out to be solvable. A systematic exploration of the biophysics and biochemistry of protein crystallization has shown that one can dependably create new protein crystalline materials more or less at will. In turn, these crystals can be readily strengthened, both chemically and mechanically, to make them suitable for practical commercialization. Today, these novel materials are used as industrial catalysts on a commercial scale, in bioremediation and "green chemistry" applications, and in enantioselective chromatography of pharmaceuticals and fine chemicals. In the near future, their utility will expand, to include the purification of protein drugs, formulation of direct protein therapeutics, and development of adjuvant-less vaccines.
Transistor properties of exfoliated single crystals of 2 H -Mo (Se1-xT ex ) 2(0 ≤x ≤1 )

Science.gov (United States)

Uesugi, Eri; Miao, Xiao; Ota, Hiromi; Goto, Hidenori; Kubozono, Yoshihiro

2017-06-01

Field-effect transistors (FETs) were fabricated using exfoliated single crystals of Mo (Se1-xT ex) 2 with an x range of 0 to 1, and the transistor properties fully investigated at 295 K in four-terminal measurement mode. The chemical composition and crystal structure of exfoliated single crystals were identified by energy-dispersive x-ray spectroscopy (EDX), single-crystal x-ray diffraction, and Raman scattering, suggesting the 2 H - structure in all Mo (Se1-xT ex) 2 . The lattice constants of a and c increase monotonically with increasing x , indicating the substitution of Se by Te. When x 0.4 . In contrast, the polarity of a thick single-crystal Mo (Se1-xT ex) 2 FET did not change despite an increase in x . The change of polarity in a thin single-crystal FET was well explained by the variation of electronic structure. The absence of such change in the thick single-crystal FET can be reasonably interpreted based on the large bulk conduction due to naturally accumulated electrons. The μ value in the thin single-crystal FET showed a parabolic variation, with a minimum μ at around x =0.4 , which probably originates from the disorder of the single crystal caused by the partial replacement of Se by Te, i.e., a disorder that may be due to ionic size difference of Se and Te.
Study of the growth and pyroelectric properties of TGS crystals doped with aniline-family dipolar molecules

Science.gov (United States)

Zhang, Kecong; Song, Jiancheng; Wang, Min; Fang, Changshui; Lu, Mengkai

1987-04-01

TGS crystals doped with aniline-family dipolar molecules (aniline, 2-aminobenzoic acid, 3-aminobenzoic acid, 3-aminobenzene-sulphonic acid, 4-aminobenzenesulphonic acid and 4-nitroraniline) have been grown by the slow-cooling solution method. The influence of these dopants on the growth habits, crystal morphology pyroelectric properties, and structure parameters of TGS crystals has been systematically investigated. The effects of the domain structure of the seed crystal on the pyroelectric properties of the doped crystals have been studied. It is found that the spontaneous polarization (P), pyroelectric coefficient (lambda), and internal bias field of the doped crystals are slightly higher than those of the pure TGS, and the larger the dipole moment of the dopant molecule, the higher the P and lambda of the doped TGS crystal.
Physical-chemical property based sequence motifs and methods regarding same

Science.gov (United States)

Braun, Werner [Friendswood, TX; Mathura, Venkatarajan S [Sarasota, FL; Schein, Catherine H [Friendswood, TX

2008-09-09

A data analysis system, program, and/or method, e.g., a data mining/data exploration method, using physical-chemical property motifs. For example, a sequence database may be searched for identifying segments thereof having physical-chemical properties similar to the physical-chemical property motifs.
Structural and electrical properties of organic stilbazolium single crystal of DSCHS

Science.gov (United States)

Sundaram, S. John; Raj, A. Antony; Ramaclus, Jerald V.; Sagayaraj, P.

2016-05-01

Organic nonlinear optical crystal 4-N, N-Dimethyl Amino-4'N'-Methyl-Stilbazolium 3-Carboxy-4-Hydroxy benzenesulfonate (DSCHS) has been successfully grown from aqueous methanol solution by adopting slow solvent evaporation technique. Chemical composition of the sample was confirmed by CHN analysis. Powder X-ray diffraction analysis was carried out and it shows that DSCHS crystal belongs to triclinic structure with Pl space group. It is found that this material exhibits positive photoconductivity. Dielectric studies were also carried out for different temperature by varying the frequency.
Crystal structure and magnetic properties of Tb6FeSb2

International Nuclear Information System (INIS)

Cai Gemei; Zhang Jiliang; He Wei; Qin Pingli; Zeng Lingmin

2006-01-01

The crystal structure and magnetic properties of Tb 6 FeSb 2 has been investigated for the first time. The compound crystallizes in the hexagonal, space group P6-bar 2m (No. 189) with the Ho 6 FeSb 2 structure type and lattice parameters a=8.1942(5)A, c=4.1758(3)A, z=1 and D calc =8.564g/cm 3 . Its magnetic properties were measured between 85 and 420K. The Curie temperature T c =256K was obtained using the method of intersecting tangents, and the effective paramagnetic moment was μ eff =9.32μ B per Tb atom
Conductive properties of switchable photoluminescence thermosetting systems based on liquid crystals.

Science.gov (United States)

Tercjak, Agnieszka; Gutierrez, Junkal; Ocando, Connie; Mondragon, Iñaki

2010-03-16

Conductive properties of different thermosetting materials modified with nematic 4'-(hexyl)-4-biphenyl-carbonitrile (HBC) liquid crystal and rutile TiO(2) nanoparticles were successfully studied by means of tunneling atomic force miscroscopy (TUNA). Taking into account the liquid crystal state of the HBC at room temperature, depending on both the HBC content and the presence of TiO(2) nanoparticles, designed materials showed different TUNA currents passed through the sample. The addition of TiO(2) nanoparticles into the systems multiply the detected current if compared to the thermosetting systems without TiO(2) nanoparticles and simultaneously stabilized the current passed through the sample, making the process reversible since the absolute current values were almost the same applying both negative and positive voltage. Moreover, thermosetting systems modified with liquid crystals with and without TiO(2) nanoparticles are photoluminescence switchable materials as a function of temperature gradient during repeatable heating/cooling cycle. Conductive properties of switchable photoluminescence thermosetting systems based on liquid crystals can allow them to find potential application in the field of photoresponsive devices, with a high contrast ratio between transparent and opaque states.
Rare-Earth Tantalates and Niobates Single Crystals: Promising Scintillators and Laser Materials

Directory of Open Access Journals (Sweden)

Renqin Dou

2018-01-01

Full Text Available Rare-earth tantalates, with high density and monoclinic structure, and niobates with monoclinic structure have been paid great attention as potential optical materials. In the last decade, we focused on the crystal growth technology of rare-earth tantalates and niobates and studied their luminescence and physical properties. A series of rare-earth tantalates and niobates crystals have been grown by the Czochralski method successfully. In this work, we summarize the research results on the crystal growth, scintillation, and laser properties of them, including the absorption and emission spectra, spectral parameters, energy levels structure, and so on. Most of the tantalates and niobates exhibit excellent luminescent properties, rich physical properties, and good chemical stability, indicating that they are potential outstanding scintillators and laser materials.
Mechanical properties and crystallization behavior of hydroxyapatite/poly(butylenes succinate) composites.

Science.gov (United States)

Guo, Wenmin; Zhang, Yihe; Zhang, Wei

2013-09-01

Biodegradable synthetic polymers have attracted much attention nowadays, and more and more researches have been done on biodegradable polymers due to their excellent mechanical properties, biocompatibility, and biodegradability. In this work, hydroxyapatite (HA) particles were melt-mixing with poly (butylenes succinate) (PBS) to prepare the material, which could be used in the biomedical industry. To develop high-performance PBS for cryogenic engineering applications, it is necessary to investigate the cryogenic mechanical properties and crystallization behavior of HA/PBS composites. Cryogenic mechanical behaviors of the composites were studied in terms of tensile and impact strength at the glass transition temperature (-30°C) and compared to their corresponding behaviors at room temperature. With the increase of HA content, the crystallization of HA/PBS composites decreased and crystallization onset temperature shifted to a lower temperature. The diameter of spherulites increased at first and decreased with a further HA content. At the same time, the crystallization rate became slow when the HA content was no more than 15wt% and increased when HA content reached 20wt%. In all, the results we obtained demonstrate that HA/PBS composites reveal a better tensile strength at -30°C in contrast to the strength at room temperature. HA particles with different amount affect the crystallization of PBS in different ways. Copyright © 2013 Wiley Periodicals, Inc.
Crystals in light.

Science.gov (United States)

Kahr, Bart; Freudenthal, John; Gunn, Erica

2010-05-18

We have made images of crystals illuminated with polarized light for almost two decades. Early on, we abandoned photosensitive chemicals in favor of digital electrophotometry with all of the attendant advantages of quantitative intensity data. Accurate intensities are a boon because they can be used to analytically discriminate small effects in the presence of larger ones. The change in the form of our data followed camera technology that transformed picture taking the world over. Ironically, exposures in early photographs were presumed to correlate simply with light intensity, raising the hope that photography would replace sensorial interpretation with mechanical objectivity and supplant the art of visual photometry. This was only true in part. Quantitative imaging accurate enough to render the separation of crystalloptical quantities had to await the invention of the solid-state camera. Many pioneers in crystal optics were also major figures in the early history of photography. We draw out the union of optical crystallography and photography because the tree that connects the inventors of photography is a structure unmatched for organizing our work during the past 20 years, not to mention that silver halide crystallites used in chemical photography are among the most consequential "crystals in light", underscoring our title. We emphasize crystals that have acquired optical properties such as linear birefringence, linear dichroism, circular birefringence, and circular dichroism, during growth from solution. Other crystalloptical effects were discovered that are unique to curiously dissymmetric crystals containing embedded oscillators. In the aggregate, dyed crystals constitute a generalization of single crystal matrix isolation. Simple crystals provided kinetic stability to include guests such as proteins or molecules in excited states. Molecular lifetimes were extended for the preparation of laser gain media and for the study of the photodynamics of single
The importance of proper crystal-chemical and geometrical reasoning demonstrated using layered single and double hydroxides

Science.gov (United States)

Richardson, Ian G.

2013-01-01

Atomistic modelling techniques and Rietveld refinement of X-ray powder diffraction data are widely used but often result in crystal structures that are not realistic, presumably because the authors neglect to check the crystal-chemical plausibility of their structure. The purpose of this paper is to reinforce the importance and utility of proper crystal-chemical and geometrical reasoning in structural studies. It is achieved by using such reasoning to generate new yet fundamental information about layered double hydroxides (LDH), a large, much-studied family of compounds. LDH phases are derived from layered single hydroxides by the substitution of a fraction (x) of the divalent cations by trivalent. Equations are derived that enable calculation of x from the a parameter of the unit cell and vice versa, which can be expected to be of widespread utility as a sanity test for extant and future structure determinations and computer simulation studies. The phase at x = 0 is shown to be an α form of divalent metal hydroxide rather than the β polymorph. Crystal-chemically sensible model structures are provided for β-Zn(OH)2 and Ni- and Mg-based carbonate LDH phases that have any trivalent cation and any value of x, including x = 0 [i.e. for α-M(OH)2·mH2O phases]. PMID:23719702
Mechanical, thermodynamic and electronic properties of wurtzite and zinc-blende GaN crystals

NARCIS (Netherlands)

Qin, Hongbo; Luan, Xinghe; Feng, Chuang; Yang, Daoguo; Zhang, G.Q.

2017-01-01

For the limitation of experimental methods in crystal characterization, in this study, the mechanical, thermodynamic and electronic properties of wurtzite and zinc-blende GaN crystals were investigated by first-principles calculations based on density functional theory. Firstly, bulk moduli,
Structural and electrical properties of organic stilbazolium single crystal of DSCHS

International Nuclear Information System (INIS)

Sundaram, S. John; Ramaclus, Jerald V.; Sagayaraj, P.; Raj, A. Antony

2016-01-01

Organic nonlinear optical crystal 4-N, N-Dimethyl Amino-4’N’-Methyl-Stilbazolium 3-Carboxy-4-Hydroxy benzenesulfonate (DSCHS) has been successfully grown from aqueous methanol solution by adopting slow solvent evaporation technique. Chemical composition of the sample was confirmed by CHN analysis. Powder X-ray diffraction analysis was carried out and it shows that DSCHS crystal belongs to triclinic structure with Pl space group. It is found that this material exhibits positive photoconductivity. Dielectric studies were also carried out for different temperature by varying the frequency.
Damage and recovery of skin barrier function after glycolic acid chemical peeling and crystal microdermabrasion.

Science.gov (United States)

Song, Ji Youn; Kang, Hyun A; Kim, Mi-Yeon; Park, Young Min; Kim, Hyung Ok

2004-03-01

Superficial chemical peeling and microdermabrasion have become increasingly popular methods for producing facial rejuvenation. However, there are few studies reporting the skin barrier function changes after these procedures. To evaluate objectively the degree of damage visually and the time needed for the skin barrier function to recover after glycolic acid peeling and aluminum oxide crystal microdermabrasion using noninvasive bioengineering methods. Superficial chemical peeling using 30%, 50%, and 70% glycolic acid and aluminum oxide crystal microdermabrasion were used on the volar forearm of 13 healthy women. The skin response was measured by a visual observation and using an evaporimeter, corneometer, and colorimeter before and after peeling at set time intervals. Both glycolic acid peeling and aluminum oxide crystal microdermabrasion induced significant damage to the skin barrier function immediately after the procedure, and the degree of damage was less severe after the aluminum oxide crystal microdermabrasion compared with glycolic acid peeling. The damaged skin barrier function had recovered within 24 hours after both procedures. The degree of erythema induction was less severe after the aluminum oxide crystal microdermabrasion compared with the glycolic acid peeling procedure. The degree of erythema induced after the glycolic acid peeling procedure was not proportional to the peeling solution concentration used. The erythema subsided within 1 day after the aluminum oxide crystal microdermabrasion procedure and within 4 days after the glycolic acid peeling procedure. These results suggest that the skin barrier function is damaged after the glycolic acid peeling and aluminum oxide crystal microdermabrasion procedure but recovers within 1 to 4 days. Therefore, repeating the superficial peeling procedure at 2-week intervals will allow sufficient time for the damaged skin to recover its barrier function.
Structural, Linear, and Nonlinear Optical and Mechanical Properties of New Organic L-Serine Crystal

Directory of Open Access Journals (Sweden)

K. Rajesh

2014-01-01

Full Text Available Nonlinear optical single crystal of organic amino acid L-Serine (LS was grown by slow evaporation technique. Solubility study of the compound was measured and metastable zone width was found. Single crystal X-ray diffraction study was carried out for the grown crystal. The linear and nonlinear optical properties of the crystal were confirmed by UV-Vis analysis and powder SHG tester. FT-IR spectrum was recorded and functional groups were analyzed. Vickers’ microhardness studies showed the mechanical strength of the grown crystal. Laser damage threshold value of the crystal was calculated. Photoconductivity studies reveal the conductivity of the crystal.
Ferromagnetism in CVT grown tungsten diselenide single crystals with nickel doping

Science.gov (United States)

Habib, Muhammad; Muhammad, Zahir; Khan, Rashid; Wu, Chuanqiang; Rehman, Zia ur; Zhou, Yu; Liu, Hengjie; Song, Li

2018-03-01

Two dimensional (2D) single crystal layered transition materials have had extensive consideration owing to their interesting magnetic properties, originating from their lattices and strong spin-orbit coupling, which make them of vital importance for spintronic applications. Herein, we present synthesis of a highly crystalline tungsten diselenide layered single crystal grown by chemical vapor transport technique and doped with nickel (Ni) to tailor its magnetic properties. The pristine WSe2 single crystal and Ni-doped crystal were characterized and analyzed for magnetic properties using both experimental and computational aspects. It was found that the magnetic behavior of the 2D layered WSe2 crystal changed from diamagnetic to ferromagnetic after Ni-doping at all tested temperatures. Moreover, first principle density functional theory (DFT) calculations further confirmed the origin of room temperature ferromagnetism of Ni-doped WSe2, where the d-orbitals of the doped Ni atom promoted the spin moment and thus largely contributed to the magnetism change in the 2D layered material.

Density functional theory for calculation of elastic properties of orthorhombic crystals: Application to TiSi2

International Nuclear Information System (INIS)

Ravindran, P.; Fast, L.; Korzhavyi, P.A.; Johansson, B.; Wills, J.; Eriksson, O.

1998-01-01

A theoretical formalism to calculate the single crystal elastic constants for orthorhombic crystals from first principle calculations is described. This is applied for TiSi 2 and we calculate the elastic constants using a full potential linear muffin-tin orbital method using the local density approximation (LDA) and generalized gradient approximation (GGA). The calculated values compare favorably with recent experimental results. An expression to calculate the bulk modulus along crystallographic axes of single crystals, using elastic constants, has been derived. From this the calculated linear bulk moduli are found to be in good agreement with the experiments. The shear modulus, Young's modulus, and Poisson's ratio for ideal polycrystalline TiSi 2 are also calculated and compared with corresponding experimental values. The directional bulk modulus and the Young's modulus for single crystal TiSi 2 are estimated from the elastic constants obtained from LDA as well as GGA calculations and are compared with the experimental results. The shear anisotropic factors and anisotropy in the linear bulk modulus are obtained from the single crystal elastic constants. From the site and angular momentum decomposed density of states combined with a charge density analysis and the elastic anisotropies, the chemical bonding nature between the constituents in TiSi 2 is analyzed. The Debye temperature is calculated from the average elastic wave velocity obtained from shear and bulk modulus as well as the integration of elastic wave velocities in different directions of the single crystal. The calculated elastic properties are found to be in good agreement with experimental values when the generalized gradient approximation is used for the exchange and correlation potential. copyright 1998 American Institute of Physics
Phase-change materials: vibrational softening upon crystallization and its impact on thermal properties

Energy Technology Data Exchange (ETDEWEB)

Matsunaga, Toshiyuki [Materials Science and Analysis Technology Centre, Panasonic Corporation, Osaka (Japan); Japan Synchrotron Radiation Research Institute Hyogo (Japan); Yamada, Noboru [Digital and Network Technology Development Centre, Panasonic Corporation, Osaka (Japan); Japan Synchrotron Radiation Research Institute Hyogo (Japan); Kojima, Rie [Digital and Network Technology Development Centre, Panasonic Corporation, Osaka (Japan); Shamoto, Shinichi [Neutron Science Research Centre, Japan Atomic Energy Research Institute, Ibaraki (Japan); Sato, Masugu; Tanida, Hajime; Uruga, Tomoya; Kohara, Shinji [Japan Synchrotron Radiation Research Institute, Hyogo (Japan); Takata, Masaki [SPring-8/RIKEN, Hyogo, Japan, Department of Advanced Materials Science, School of Frontier Sciences, The University of Tokyo, Chiba (Japan); Zalden, Peter; Bruns, Gunnar; Wuttig, Matthias [I. Physikalisches Institut und JARA-FIT, RWTH Aachen Univ. (Germany); Sergueev, Ilya [European Synchrotron Radiation Facility, Grenoble (France); Wille, Hans Christian [Deutsches Elektronen-Synchrotron, Hamburg (Germany); Hermann, Raphael Pierre [Juelich Centre for Neutron Science JCNS and Peter Gruenberg, Institut PGI, JARA-FIT, Forschungszentrum Juelich GmbH (Germany); Faculte des Sciences, Universite de Liege (Belgium)

2011-06-21

Crystallization of an amorphous solid is usually accompanied by a significant change of transport properties, such as an increase in thermal and electrical conductivity. This fact underlines the importance of crystalline order for the transport of charge and heat. Phase-change materials, however, reveal a remarkably low thermal conductivity in the crystalline state. The small change in this conductivity upon crystallization points to unique lattice properties. The present investigation reveals that the thermal properties of the amorphous and crystalline state of phase-change materials show remarkable differences such as higher thermal displacements and a more pronounced anharmonic behavior in the crystalline phase. These findings are related to the change of bonding upon crystallization, which leads to an increase of the sound velocity and a softening of the optical phonon modes at the same time. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Chemical hydrogen storage material property guidelines for automotive applications

Science.gov (United States)

Semelsberger, Troy A.; Brooks, Kriston P.

2015-04-01

Chemical hydrogen storage is the sought after hydrogen storage media for automotive applications because of the expected low pressure operation (0.05 kg H2/kgsystem), and system volumetric capacities (>0.05 kg H2/Lsystem). Currently, the primary shortcomings of chemical hydrogen storage are regeneration efficiency, fuel cost and fuel phase (i.e., solid or slurry phase). Understanding the required material properties to meet the DOE Technical Targets for Onboard Hydrogen Storage Systems is a critical knowledge gap in the hydrogen storage research community. This study presents a set of fluid-phase chemical hydrogen storage material property guidelines for automotive applications meeting the 2017 DOE technical targets. Viable material properties were determined using a boiler-plate automotive system design. The fluid-phase chemical hydrogen storage media considered in this study were neat liquids, solutions, and non-settling homogeneous slurries. Material properties examined include kinetics, heats of reaction, fuel-cell impurities, gravimetric and volumetric hydrogen storage capacities, and regeneration efficiency. The material properties, although not exhaustive, are an essential first step in identifying viable chemical hydrogen storage material properties-and most important, their implications on system mass, system volume and system performance.
Pyroelectric properties of phosphoric acid-doped TGS single crystals

International Nuclear Information System (INIS)

Saxena, Aparna; Fahim, M; Gupta, Vinay; Sreenivas, K

2003-01-01

Pyroelectric properties of phosphoric acid (H 3 PO 4 )-doped triglycine sulfate (TGSP) single crystals grown from solutions containing 0.1-0.5 mol of H 3 PO 4 have been studied. Incorporation of H 3 PO 4 into the crystal lattice is found to induce an internal bias field (E b ) and is observed through the presence of a sustained polarization and pyroelectricity beyond the transition temperature. The internal bias field has been estimated theoretically by fitting the experimentally measured data on temperature dependence of the pyroelectric coefficient (λ), dielectric constant (ε') and polarization (P). A high E b value in the range 9 x 10 3 -15.5 x 10 4 V m -1 is obtained for crystals grown with 0.1-0.5 mol of H 3 PO 4 in the solution, and a specific concentration of 0.2-0.25 mol of H 3 PO 4 in the solution during crystal growth is found to be optimum for a high figure of merit for detectivity, F d = 428 μC m -2 K -1
Defect formation and magnetic properties of Co-doped GaN crystal and nanowire

International Nuclear Information System (INIS)

Shi, Li-Bin; Liu, Jing-Jing; Fei, Ying

2013-01-01

Theoretical calculation based on density functional theory (DFT) and generalized gradient approximation (GGA) has been carried out in studying defect formation and magnetic properties of Co doped GaN crystal and nanowire (NW). Co does not exhibit site preference in GaN crystal. However, Co occupies preferably surface sites in GaN NW. Transition level of the defect is also investigated in GaN crystal. We also find that Co Ga (S) in NW does not produce spin polarization and Co Ga (B) produces spontaneous spin polarization. Ferromagnetic (FM) and antiferromagnetic (AFM) couplings are analyzed by six different configurations. The results show that AFM coupling is more stable than FM coupling for Co doped GaN crystal. It is also found from Co doped GaN NW calculation that the system remains FM stability for majority of the configurations. Magnetic properties in Co doped GaN crystal can be mediated by N and Ga vacancies. The FM and AFM stability can be explained by Co 3d energy level coupling
Influence of smectite crystal chemistry on the organization of interlayer water and cations

International Nuclear Information System (INIS)

Dazas, Baptiste

2014-01-01

Swelling clay minerals such as smectites are ubiquitous at the Earth surface and possess major hydration ability and contaminant uptake/retention capacity. As a consequence smectites exert a pivotal influence on elemental transfers in surficial environments. These properties are especially relevant also when smectites are used as sealant in engineered or geological barriers for waste disposal facilities. As interlayer H_2O molecules account for more than 80% of smectite water in under-saturated conditions, characterization of H_2O organization and dynamics in smectites interlayers is essential to determining the geometrical and dynamical properties of clay barriers for waste disposal and to predicting the mobility of contaminant whose principal vector is water. Within this general framework, the present works describe, in a first time, the structuration of interlayer water/cations in saturated conditions. Then, in a second time, review the influence of structural parameters such as the amount and location of layer charge deficit and the chemical composition (and more especially the presence of structural fluorine/hydroxyl) on smectite hydration properties. A set of samples covering the whole compositional range of swelling phyllosilicates has thus been synthesized and characterized chemically and structurally. Special attention was paid to determining the amount (water vapor sorption isotherms) and the distribution (X-ray diffraction) of interlayer water. Molecular modeling allowed unraveling the origin of the contrasting behaviors observed experimentally and to determine the influence of the different crystal-chemical parameters on smectite hydration. This step is essential for the prediction of smectite reactivity in the environment from a limited number of crystal-chemical parameters. Molecular modeling allowed unraveling the origin of the contrasting behaviors observed experimentally and to determine the influence of the different crystal-chemical parameters on
Photoluminescence properties of boron doped InSe single crystals

International Nuclear Information System (INIS)

Ertap, H.; Bacıoğlu, A.; Karabulut, M.

2015-01-01

Undoped and boron doped InSe single crystals were grown by Bridgman–Stockbarger technique. The PL properties of undoped, 0.1% and 0.5% boron doped InSe single crystals have been investigated at different temperatures. PL measurements revealed four emission bands labeled as A, B, C and D in all the single crystals studied. These emission bands were associated with the radiative recombination of direct free excitons (n=1), impurity-band transitions, donor–acceptor recombinations and structural defect related band (impurity atoms, defects, defect complexes, impurity-vacancy complex etc.), respectively. The direct free exciton (A) bands of undoped, 0.1% and 0.5% boron doped InSe single crystals were observed at 1.337 eV, 1.335 eV and 1.330 eV in the PL spectra measured at 12 K, respectively. Energy positions and PL intensities of the emission bands varied with boron addition. The FWHM of direct free exciton band increases while the FWHM of the D emission band decreases with boron doping. Band gap energies of undoped and boron doped InSe single crystals were calculated from the PL measurements. It was found that the band gap energies of InSe single crystals decreased with increasing boron content. - Highlights: • PL spectra of InSe crystals have been studied as a function of temperature. • Four emission bands were observed in the PL spectra at low temperatures. • PL intensity and position of free exciton band vary with doping and temperature. • Temperature dependences of the bands observed in the PL spectra were analyzed

Thermo- and electro-optical properties of photonic liquid crystal fibers doped with gold nanoparticles

Directory of Open Access Journals (Sweden)

Agata Siarkowska

2017-12-01

Full Text Available Thermo- and electro-optical properties of a photonic liquid crystal fiber (PLCF enhanced by the use of dopants have been investigated. A 6CHBT nematic liquid crystal was doped with four different concentrations of gold nanoparticles (NPs, 0.1, 0.3, 0.5 and 1.0 wt %, for direct comparison of the influence of the dopant on the properties of the PLCF. The thermo-optical effects of the liquid crystal doped with gold NPs were compared in three setups, an LC cell, a microcapillary and within the PLCF, to determine if the observed responses to external factors are caused by the properties of the infiltration material or due to the setup configuration. The results obtained indicated that with increasing NP doping a significant reduction of the rise time under an external electric field occurs with a simultaneous decrease in the nematic–isotropic phase transition temperature, thus improving the thermo- and electro-optical properties of the PLCF.

Thermo- and electro-optical properties of photonic liquid crystal fibers doped with gold nanoparticles.

Science.gov (United States)

Siarkowska, Agata; Chychłowski, Miłosz; Budaszewski, Daniel; Jankiewicz, Bartłomiej; Bartosewicz, Bartosz; Woliński, Tomasz R

2017-01-01

Thermo- and electro-optical properties of a photonic liquid crystal fiber (PLCF) enhanced by the use of dopants have been investigated. A 6CHBT nematic liquid crystal was doped with four different concentrations of gold nanoparticles (NPs), 0.1, 0.3, 0.5 and 1.0 wt %, for direct comparison of the influence of the dopant on the properties of the PLCF. The thermo-optical effects of the liquid crystal doped with gold NPs were compared in three setups, an LC cell, a microcapillary and within the PLCF, to determine if the observed responses to external factors are caused by the properties of the infiltration material or due to the setup configuration. The results obtained indicated that with increasing NP doping a significant reduction of the rise time under an external electric field occurs with a simultaneous decrease in the nematic-isotropic phase transition temperature, thus improving the thermo- and electro-optical properties of the PLCF.

Single crystal growth and nonlinear optical properties of Nd3+ doped STGS crystal for self-frequency-doubling application

Science.gov (United States)

Chen, Feifei; Wang, Lijuan; Wang, Xinle; Cheng, Xiufeng; Yu, Fapeng; Wang, Zhengping; Zhao, Xian

2017-11-01

The self-frequency-doubling crystal is an important kind of multi-functional crystal materials. In this work, Nd3+ doped Sr3TaGa3Si2O14 (Nd:STGS) single crystals were successfully grown by using Czochralski pulling method, in addition, the nonlinear and laser-frequency-doubling properties of Nd:STGS crystals were studied. The continuous-wave laser at 1064 nm was demonstrated along different physical axes, where the maximum output power was obtained to be 295 mW for the Z-cut samples, much higher than the Y-cut (242 mW) and X-cut (217 mW) samples. Based on the measured refractive indexes, the phase matching directions were discussed and determined for type I (42.5°, 30°) and type II (69.5°, 0°) crystal cuts. As expected, self-frequency-doubling green laser at 529 nm was achieved with output powers being around 16 mW and 12 mW for type I and type II configurations, respectively.

Studying the properties of photonic quasi-crystals by the scaling convergence method

International Nuclear Information System (INIS)

Ho, I-Lin; Ng, Ming-Yaw; Mai, Chien Chin; Ko, Peng Yu; Chang, Yia-Chung

2013-01-01

This work introduces the iterative scaling (or inflation) method to systematically approach and analyse the infinite structure of quasi-crystals. The resulting structures preserve local geometric orderings in order to prevent artificial disclination across the boundaries of super-cells, with realistic quasi-crystals coming out under high iteration (infinite super-cell). The method provides an easy way for decorations of quasi-crystalline lattices, and for compact reliefs with a quasi-periodic arrangement to underlying applications. Numerical examples for in-plane and off-plane properties of square-triangle quasi-crystals show fast convergence during iteratively geometric scaling, revealing characteristics that do not appear on regular crystals. (paper)

Properties of laser-crystallized polycrystalline SiGe thin films

Energy Technology Data Exchange (ETDEWEB)

Weizman, Moshe

2008-06-06

In this thesis, structural, electrical, and optical properties of laser-crystallized polycrystalline Si{sub 1-x}Ge{sub x} thin films with 0crystallization of amorphous Si{sub 1-x}Ge{sub x} thin films with 0.3crystallized poly-Si{sub 1-x}Ge{sub x} thin films with 0crystallization method and Ge content. The defect density for solid-phase crystallized SiGe films was lower and amounted to N{sub s}=7 x 10{sup 17} cm{sup -3}. - Germanium-rich laser-crystallized poly-SiGe thin films exhibited mostly a broad atypical electric dipole spin resonance (EDSR) signal that was accompanied by a nearly temperature-independent electrical conductivity in the range 20-100 K. - Most likely, the origin of the grain boundary conductance is due to dangling-bond defects and not impurities. Metallic-like conductance occurs when the dangling-bond defect density is above a critical value of about N{sub C} {approx} 10{sup 18} cm{sup -3}. - Laser crystallized poly-Si{sub 1-x}Ge{sub x} thin films with x{>=}0.5 exhibit optical absorption behavior that is characteristic for disordered SiGe, implying that the absorption occurs primarily at the grain boundaries. A sub-band-gap absorption peak was found for

Massive photon properties in 3D photonic crystals, filled by dielectrics or metals

International Nuclear Information System (INIS)

Gorelik, V S

2009-01-01

The optical properties of 3D photonic crystals-artificial opals, consisting of monosized silica globules-have been investigated. The volume between globules was filled by various dielectrics or metals. The dispersion law of electromagnetic waves of this type of crystal has been obtained. It was shown that the sign of photonic mass in globular photonic crystals may be positive or negative for different points on dispersion curves. The value of the effective mass of photons depends on the refractive index of the substance infiltrated into the globular photonic crystal.

Mechanical, electronic, chemical bonding and optical properties of cubic BaHfO3: First-principles calculations

International Nuclear Information System (INIS)

Liu Qijun; Liu Zhengtang; Feng Liping; Tian Hao

2010-01-01

We have performed ab-initio total energy calculations using the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory (DFT) to study structural parameters, mechanical, electronic, chemical bonding and optical properties of cubic BaHfO 3 . The calculated lattice parameter and independent elastic constants are in good agreement with previous theoretical and experimental work. The bulk, shear and Young's modulus, Poisson coefficient, compressibility and Lame constants are obtained using Voigt-Reuss-Hill method and the Debye temperature is estimated using Debye-Grueneisen model, which are consistent with previous results. Electronic and chemical bonding properties have been studied from the calculations of band structure, density of states and charge densities. Furthermore, in order to clarify the mechanism of optical transitions of cubic BaHfO 3 , the complex dielectric function, refractive index, extinction coefficient, reflectivity, absorption efficient, loss function and complex conductivity function are calculated. Then, we have explained the origins of spectral peaks on the basis of the theory of crystal-field and molecular-orbital bonding.

Physico-Chemical Properties of Kaolin-Organic Acid

Directory of Open Access Journals (Sweden)

Yeo S.W.

2017-01-01

Full Text Available Soil with more than 20% of organic content is classified as organic soil in Malaysia. Contents of organic soil consist of different types of organic and inorganic matter. Each type of organic matter has its own characteristic and its effect on the properties of the soil is different. Hence, a good understanding on the effect of specific organic and inorganic matter on the physico-chemical characteristic of organic soils can serve as a guide for predicting the properties of organic soils. The main objective is to unveil the effect of organic acid on the physico-chemical properties of soil. Artificial organic soil (kaolin mixed with organic acid was utilized in order to minimize the geochemical variability of studied soil. The organic acid which consists of humic acid and fulvic acid was extracted from highly humificated plant–based compost. The effect of organic acid on the physico-chemical properties of soil was determined by varying the concentration of organic acid. The specific gravity, Atterberg limits, pH, bulk chemical composition and the functional group of kaolin-organic acid were determined. It was found that the plasticity index, specific gravity and pH value were decreased with lowered concentration of organic acid. However, the liquid limits and plastic limits were found to be increased with the concentration decrement of organic acid. The analysis of XRF on the bulk chemical composition and analysis of FTIR spectra on the functional group of artificial organic soils with different concentration have confirmed little geochemical variability between samples.

Physical and Chemical Properties of Soils under Contrasting Land ...

African Journals Online (AJOL)

Physical and Chemical Properties of Soils under Contrasting Land Use ... the aim of understanding the response of the soil to different management practices over time. ... The soil chemical properties studied were soil pH, organic carbon, total ...

Chemical vapor deposition diamond based multilayered radiation detector: Physical analysis of detection properties

International Nuclear Information System (INIS)

Almaviva, S.; Marinelli, Marco; Milani, E.; Prestopino, G.; Tucciarone, A.; Verona, C.; Verona-Rinati, G.; Angelone, M.; Pillon, M.; Dolbnya, I.; Sawhney, K.; Tartoni, N.

2010-01-01

Recently, solid state photovoltaic Schottky diodes, able to detect ionizing radiation, in particular, x-ray and ultraviolet radiation, have been developed at the University of Rome 'Tor Vergata'. We report on a physical and electrical properties analysis of the device and a detailed study of its detection capabilities as determined by its electrical properties. The design of the device is based on a metal/nominally intrinsic/p-type diamond layered structure obtained by microwave plasma chemical vapor deposition of homoepitaxial single crystal diamond followed by thermal evaporation of a metallic contact. The device can operate in an unbiased mode by using the built-in potential arising from the electrode-diamond junction. We compare the expected response of the device to photons of various energies calculated through Monte Carlo simulation with experimental data collected in a well controlled experimental setup i.e., monochromatic high flux x-ray beams from 6 to 20 keV, available at the Diamond Light Source synchrotron in Harwell (U.K.).

Crystal orientation dependent thermoelectric properties of highly oriented aluminum-doped zinc oxide thin films

KAUST Repository

Abutaha, Anas I.; Sarath Kumar, S. R.; Alshareef, Husam N.

2013-01-01

We demonstrate that the thermoelectric properties of highly oriented Al-doped zinc oxide (AZO) thin films can be improved by controlling their crystal orientation. The crystal orientation of the AZO films was changed by changing the temperature

Dielectric properties of lanthanum gallate (LaGaO3) crystal

Science.gov (United States)

Dube, D. C.; Scheel, H. J.; Reaney, I.; Daglish, M.; Setter, N.

1994-04-01

Dielectric properties of single crystals of LaGaO3 have been measured at low frequencies as well as in the microwave region over a wide temperature range. Measurements performed on two crystal orientations, viz. (001) and (110), show dielectric anomalies at a transition near 145 °C. Dielectric anisotropy below, but not above, 145 °C confirm the previously reported orthorhombic symmetry at room temperature and rhombohedral symmetry above 145 °C. Domain wall motion which arises as a result of a phase transition has been observed around 145 °C.

Properties of melt-grown single crystals of 'YB/sub 68/'

Energy Technology Data Exchange (ETDEWEB)

Slack, G A; Oliver, D W; Brower, G D; Young, J D [General Electric Co., Schenectady, N.Y. (USA). Research and Development Center

1977-01-01

Single crystals of yttrium boride YB/sub n/ with n = 61 +- 3 were grown from the melt. Precision density and lattice parameter measurements indicate a congruent melting point at n = 61.7 and a stoichiometric composition at n = 68. Measurements of elastic constants, acoustic attenuation, electrical resistivity and optical absorption are presented. High resolution transmission electron microscopy reveals a complex crystal structure similar to that found by using X-rays. A comparison of the properties of YB/sub n/ with those of ..beta..-boron show that there are many similarities.

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Crystal-chemical features of the solid solutions

Energy Technology Data Exchange (ETDEWEB)

Titov, V.V.; Kesler, Ya.A.; Gordeev, I.V.; Mozhaev, A.P.

1988-04-01

The unusual magnetic properties of the solid solutions of CuCr/sub 2/S/sub 4/ in Cu/sub 0.5/Mo/sub 0.5/Cr/sub 2/S/sub 4/ (M = Al, Ga, In) are closely related to the crystal chemistry of these compounds. Specimens for structural investigation were obtained by solid-phase synthesis in evacuated quartz capsules. X-ray phase analysis of all the compounds was made by the powder method in a DRON-1 diffractometer with Cu K..cap alpha.. filtered radiation. The experimental confirmation of the ordering of the cations in the tetrahedral sublattice of the investigated spinels was obtained by the authors from their IR absorption spectra taken in the range 400-33 cm/sup /minus/1/. The presence of seven intense absorption bands in the spectra of the specimens indicates that these materials belong to the space group F/anti/43m, i.e., that there is ordering in the A sublattice. Their investigation led them to the conclusion that in a number of cases the vibrational spectra of the crystals are more sensitive in the investigation of atomic ordering than the spectra of x-ray and neutron diffraction, in agreement with the theoretical predictions.

Modification of mechanical properties of Si crystal irradiated by Kr-beam

International Nuclear Information System (INIS)

Guo, Xiaowei; Momota, Sadao; Nitta, Noriko; Yamaguchi, Takaharu; Sato, Noriyuki; Tokaji, Hideto

2015-01-01

Graphical abstract: - Highlights: • Modification of mechanical properties of silicon crystal irradiated by Kr-beam was observed by means of continuous measurements of nano-indentation technique. • Modified mechanical properties show fluence-dependence. • Young's modulus is more sensitive to crystal to amorphous phase transition while hardness is more sensitive to damage induced by ion beam irradiation. • The depth profile of modified mechanical properties have a potential application of determining the longitudinal size of phase transition region induced by nanoindentation. - Abstract: The application of ion-beam irradiation in fabrication of structures with micro-/nanometer scale has achieved striking improvement. However, an inevitable damage results in the change of mechanical properties in irradiated materials. To investigate the relation between mechanical properties and ion-irradiation damages, nanoindentation was performed on crystalline silicon irradiated by Kr-beam with an energy of 240 keV. Modified Young's modulus and nanohardness, provided from the indentation, indicated fluence dependence. Stopping and range of ions in matter (SRIM) calculation, transmission electron microscopy (TEM) observation, and Rutherford backscattering-channeling (RBS-C) measurement were utilized to understand the irradiation effect on mechanical properties. In addition, the longitudinal size of the phase transition region induced by indentation was firstly evaluated based on the depth profile of modified nanohardness

Crystallization kinetics and magnetic properties of FeSiCr amorphous alloy powder cores

Energy Technology Data Exchange (ETDEWEB)

Xu, Hu-ping [School of Logistics Engineering, Wuhan University of Technology, Wuhan 430063 (China); Wang, Ru-wu, E-mail: ruwuwang@hotmail.com [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China); College of Materials Science and Metallurgical Engineering, Wuhan University of Science and Technology, Wuhan 430081 (China); Wei, Ding [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China); Zeng, Chun [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China)

2015-07-01

The crystallization kinetics of FeSiCr amorphous alloy, characterized by the crystallization activation energy, Avrami exponent and frequency factor, was studied by non-isothermal differential scanning calorimetric (DSC) measurements. The crystallization activation energy and frequency factor of amorphous alloy calculated from Augis–Bennett model were 476 kJ/mol and 5.5×10{sup 18} s{sup −1}, respectively. The Avrami exponent n was calculated to be 2.2 from the Johnson–Mehl–Avrami (JMA) equation. Toroid-shaped Fe-base amorphous powder cores were prepared from the commercial FeSiCr amorphous alloy powder and subsequent cold pressing using binder and insulation. The characteristics of FeSiCr amorphous alloy powder and the effects of compaction pressure and insulation content on the magnetic properties, i.e., effective permeability μ{sub e}, quality factor Q and DC-bias properties of FeSiCr amorphous alloy powder cores, were investigated. The FeSiCr amorphous alloy powder cores exhibit a high value of quality factor and a stable permeability in the frequency range up to 1 MHz, showing superior DC-bias properties with a “percent permeability” of more than 82% at H=100 Oe. - Highlights: • The crystallization kinetics of FeSiCr amorphous alloy was investigated. • The FeSiCr powder cores exhibit a high value of Q and a stable permeability. • The FeSiCr powder cores exhibit superior DC-bias properties.

Physical and chemical properties of gels. Application to protein nucleation control in the gel acupuncture technique

Science.gov (United States)

Moreno, Abel; Juárez-Martínez, Gabriela; Hernández-Pérez, Tomás; Batina, Nikola; Mundo, Manuel; McPherson, Alexander

1999-09-01

In this work, we present a new approach using analytical and optical techniques in order to determine the physical and chemical properties of silica gel, as well as the measurement of the pore size in the network of the gel by scanning electron microscopy. The gel acupuncture technique developed by García-Ruiz et al. (Mater. Res. Bull 28 (1993) 541) García-Ruiz and Moreno (Acta Crystallogr. D 50 (1994) 484) was used throughout the history of crystal growth. Several experiments were done in order to evaluate the nucleation control of model proteins (thaumatin I from Thaumatococcus daniellii, lysozyme from hen egg white and catalase from bovine liver) by the porous network of the gel. Finally, it is shown how the number and the size of the crystals obtained inside X-ray capillaries is controlled by the size of the porous structure of the gel.

Antisolvent crystallization of a cardiotonic drug in ionic liquids: Effect of mixing on the crystal properties

Science.gov (United States)

de Azevedo Jacqueline, Resende; Fabienne, Espitalier; Jean-Jacques, Letourneau; Inês, Ré Maria

2017-08-01

LASSBio-294 (3,4-methylenedioxybenzoyl-2-thienylhydrazon) is a poorly soluble drug which has been proposed to have major advantages over other cardiotonic drugs. Poorly water soluble drugs present limited bioavailability due to their low solubility and dissolution rate. An antisolvent crystallization processing can improve the dissolution rate by decreasing the crystals particle size. However, LASSBio-294 is also poorly soluble in organic solvents and this operation is limited. In order to open new perspectives to improve dissolution rate, this work has investigated LASSBio-294 in terms of its antisolvent crystallization in 1-ethyl-3-methylimidazolium methyl phosphonate [emim][CH3O(H)PO2] as solvent and water as antisolvent. Two modes of mixing are tested in stirred vessel with different pre-mixers (Roughton or T-mixers) in order to investigate the mixing effect on the crystal properties (crystalline structure, particle size distribution, residual solvent and in vitro dissolution rate). Smaller drug particles with unchanged crystalline structure were obtained. Despite the decrease of the elementary particles size, the recrystallized particles did not achieve a better dissolution profile. However, this study was able to highlight a certain number of findings such as the impact of the hydrodynamic conditions on the crystals formation and the presence of a gel phase limiting the dissolution rate.

Pyroelectric properties of phosphoric acid-doped TGS single crystals

Energy Technology Data Exchange (ETDEWEB)

Saxena, Aparna; Fahim, M; Gupta, Vinay; Sreenivas, K [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

2003-12-21

Pyroelectric properties of phosphoric acid (H{sub 3}PO{sub 4})-doped triglycine sulfate (TGSP) single crystals grown from solutions containing 0.1-0.5 mol of H{sub 3}PO{sub 4} have been studied. Incorporation of H{sub 3}PO{sub 4} into the crystal lattice is found to induce an internal bias field (E{sub b}) and is observed through the presence of a sustained polarization and pyroelectricity beyond the transition temperature. The internal bias field has been estimated theoretically by fitting the experimentally measured data on temperature dependence of the pyroelectric coefficient ({lambda}), dielectric constant ({epsilon}') and polarization (P). A high E{sub b} value in the range 9 x 10{sup 3}-15.5 x 10{sup 4} V m{sup -1} is obtained for crystals grown with 0.1-0.5 mol of H{sub 3}PO{sub 4} in the solution, and a specific concentration of 0.2-0.25 mol of H{sub 3}PO{sub 4} in the solution during crystal growth is found to be optimum for a high figure of merit for detectivity, F{sub d} = 428 {mu}C m{sup -2} K{sup -1}.

In situ Spectroscopy of Solid-State Chemical Reaction in PbBr2-Deposited CsBr Crystals

Science.gov (United States)

Kondo, Shin-ichi; Matsunaga, Toshihiro; Saito, Tadaaki; Asada, Hiroshi

2003-09-01

It is possible to measure the fundamental optical absorption spectra of CsPbBr3 and Cs4PbBr6, whose stability is predicted by the study of phase diagram in the binary system CsBr-PbBr2, by means of in situ optical absorption and reflection spectroscopy of thermally induced solid-state chemical reaction in PbBr2-deposited CsBr crystals. On heavy annealing of the crystals, the Pb2+ ions are uniformly dispersed in the crystal matrix. The present experiment provides a novel method for measuring intrinsic optical absorption of ternary metal halides and also for in situ monitoring of doping metal halide crystal with impurities (metal ions or halogen ions).

Crystal growth and magnetic properties of equiatomic CeAl

Science.gov (United States)

Das, Pranab Kumar; Thamizhavel, A.

2015-03-01

Single crystal of CeAl has been grown by flux method using Ce-Al self-flux. Several needle like single crystals were obtained and the length of the needle corresponds to the [001] crystallographic direction. Powder x-ray diffraction revealed that CeAl crystallizes in orthorhombic CrB-type structure with space group Cmcm (no. 63). The magnetic properties have been investigated by means of magnetic susceptibility, isothermal magnetization, electrical transport, and heat capacity measurements. CeAl is found to order antiferromagnetically with a Neel temperature TN = 10 K. The magnetization data below the ordering temperature reveals two metamagentic transitions for fields less than 20 kOe. From the inverse magnetic susceptibility an effective moment of 2.66 μB/Ce has been estimated, which indicates that Ce is in its trivalent state. Electrical resistivity data clearly shows a sharp drop at 10 K due to the reduction of spin disorder scattering of conduction electrons thus confirming the magnetic ordering. The estimated residual resistivity ratio (RRR) is 33, thus indicating a good quality of the single crystal. The bulk nature of the magnetic ordering is also confirmed by heat capacity data. From the Schottky anomaly of the heat capacity we have estimated the crystal field level splitting energies of the (2J + 1) degenerate ground state as 25 K and 175 K respectively for the fist and second excited states.

Optical and scintillating properties of Ce:Li(Y,Lu)F4 single crystals

International Nuclear Information System (INIS)

Yokota, Yuui; Kurosawa, Shunsuke; Chani, Valery; Kamada, Kei; Yoshikawa, Akira

2014-01-01

We have investigated the optical and scintillating properties of Lu co-doped Ce:LiYF 4 single crystals with various Lu content. In the transmittance and absorption spectra, the absorption peaks at 243 nm get systematically red shifted in contrast to the peaks at 197 and 200 nm which get blue shifted with the increase in Lu content. At the same time, emission peaks at 306 nm and 200 nm under 295 nm excitation also get red shifted. The decay time of Ce:Li(Y,Lu)F 4 crystals under 295 nm excitation is found to be faster than that of Ce:LiYF 4 and Ce:LiLuF 4 crystals. The alpha-peak positions in the pulse-height spectra and decay times of crystals under alpha-ray irradiation are found to vary with the Lu content. - Highlights: • Optical and scintillation properties of Ce:Li(Y 1-x Lu x )F 4 crystals were inspected. • Increase of Lu content resulted change of the position of four absorption peaks. • Admixing of Y and Lu decreased the light yield and increased the decay time. • The Ce:LiLuF 4 crystal indicated the largest light yield in the pulse-height spectra. • Li[(Y 0.8 Lu 0.2 ) 0.98 Ce 0.02 ]F 4 indicated larger light yield than Ce:LiYF 4 crystal

Structural and morphological properties of electroceramics for chemical sensors

International Nuclear Information System (INIS)

Tor Vergata, Via della Ricerca Scientifica, Roma (Italy). Dipartimento di Scienze e Tecnologie Chimiche)" data-affiliation=" (Universita' di Roma Tor Vergata, Via della Ricerca Scientifica, Roma (Italy). Dipartimento di Scienze e Tecnologie Chimiche)" >Enrico Traversa

1996-01-01

Ceramic materials possess a unique structure consisting of grains, grain boundaries, surfaces and pores, which makes them suitable for chemical sensors. The control of the chemical composition and microstructure of electrochemicals is fundamental for controlling their properties. Ceramics with a given composition and microstructure can be produced by controlling the different steps of their processing. The chemical processing of ceramics offer many advantages in terms of control and reproducibility, with respect to the conventional ceramics processing. Results are reported about the chemical processing of perovskite-type oxides for gas sensors and about the novel humidity-sensitive electrical properties of sol-gel processed alkali-doped titania films. The structural and morphological characterization of these materials permits the understanding of the sensitive electrical properties of the ceramics (71 refs.)

Electrical properties of the n-ZnO/c-Si heterojunction prepared by chemical spray pyrolysis

International Nuclear Information System (INIS)

Romero, R.; Lopez, M.C.; Leinen, D.; Martin, F.; Ramos-Barrado, J.R.

2004-01-01

Electrical, structural and compositional properties of n-ZnO/c-Si heterojunctions prepared by chemical spray pyrolysis on single-crystal n-type and p-type monocrystalline silicon(1 0 0) substrates are examined with the C-V method and admittance spectroscopy at temperature ranges between 223 and 373 K. The n-ZnO/c-Si heterojunctions show a height barrier consistent with the difference in energy of the work functions of Si and ZnO; however, the n-ZnO:Al/c-Si heterojunctions present a more complex behavior due to the defects at or near the n-ZnO:Al/c-Si interface, causing a Fermi energy pinning

Fractal and mechanical micro- and nanorange properties of sylvite and halite crystals

Directory of Open Access Journals (Sweden)

Valery N. Aptukov

2017-09-01

Full Text Available This article involves the treatment of micro- and nanorange scanning and indentation data for salt rock crystals obtained with help of the scanning microscope Dimension Icon using the mathematical models. It also describes the basic methods of fractal analysis. It shows the effectiveness of the method of minimal covering which is chosen to research the fractal properties of salt rock crystal surfaces. The article includes the algorithm of this method and the description of its generalization for the two-dimensional case. The values of fractal index and multifractal parameters have been calculated on the basis of the minimal covering method. The article also involves the anisotropy effects for fractal properties, comparison of fractal behavior on different scale levels. It gives the values of hardness for different parts of the crystals and studies the correlation between hardness and fractal index and describes the character of the influence of fractal dimension on roughness.

Electromagnetic absorbing property of the flaky carbonyl iron particles by chemical corrosion process

Energy Technology Data Exchange (ETDEWEB)

Zheng, Dianliang, E-mail: 272895980@qq.com [College of Aeronautical Engineering, Jilin Institute of Chemical Technology, Jilin 132022 (China); Liu, Ting; Zhou, Li [College of Aeronautical Engineering, Jilin Institute of Chemical Technology, Jilin 132022 (China); Xu, Yonggang [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai 200438 (China)

2016-12-01

The flaky carbonyl iron particles (CIPs) were prepared using a milling process at the first step, then the chemical corrosion process was done to optimize the particle shape. The particle morphology was characterized by the scanning electron microscopy, the static magnetic property was evaluated on a vibrating sample magnetometer and X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability were measured using a vector network analyzer in the frequency range of 2–18 GHz and the reflection loss (RL) was calculated. The results showed that the saturation magnetization value of the CIPs decreased as the CIPs was corroded to the small flakes in chemical corrosion process. The diffraction peaks of the single α-Fe existed in the XRD pattern of CIPs, and the characteristic peaks was more obvious and the intensity of the diffraction pattern was lower by corrosion. The permittivity and the permeability of the corroded milling CIPs was a little larger than the milling CIPs, it was due to the larger aspect ratio based on the fitting calculation process. At thickness 0.6 mm and 0.8 mm, the corroded milling CIPs composite had the better absorbing property than the other two samples. The frequency band (RL<−5 dB) could be widened to 8.96–18 GHz at 0.6 mm and 5.92–18 GHz at 0.8 mm, and RL less than −8 dB began to exist in 8.96–14.72 GHz at 0.8 mm. - Graphical abstract: The property of absorber using corrosion process could be enhanced. - Highlights: • The chemical corrosion process was done to optimize the particle shape. • The permittivity and permeability of corroded milling CIPs increased. • The aspect ratio of flaky CIPs increased in the corrosion process. • The corroded milling CIPs composite had the better absorbing property.

Magnetic, transport, and optical properties of Ca0.85Eu0.15MnO3 single crystal

International Nuclear Information System (INIS)

Naumov, S.V.; Loshkareva, N.N.; Mostovshchikova, E.V.; Solin, N.I.; Korolev, A.V.; Arbuzova, T.I.; Telegin, S.V.; Patrakov, E.I.

2013-01-01

Magnetic, transport and optical properties of the Ca 0.85 Eu 0.15 MnO 3 single crystal are studied and discussed in comparison with the properties of polycrystalline sample. The magnetic data show existence the two magnetic phase transitions under cooling: the transition near 150 K occurs from the paramagnetic orthorhombic to C-type antiferromagnetic monoclinic phase with the charge/orbital ordering in some part of the crystal; and at 90 K the transition from the paramagnetic to G-type antiferromagnetic phase takes place in another part of the crystal with the orthorhombic structure. The magnetoresistance of the Ca 0.85 Eu 0.15 MnO 3 single crystal has features at temperatures of these phase transitions. Differences in the properties of single crystal and polycrystalline sample with the same content of Eu are associated with the ordering of oxygen vacancies that appear under the crystal growth. The reflection spectra in infrared range confirm the existence of the electron conductivity in a narrow band at room temperature.

Utilization of High-Temperature Slags From Metallurgy Based on Crystallization Behaviors

Science.gov (United States)

Sun, Yongqi; Zhang, Zuotai

2018-05-01

Here, following the principle of modifying crystallization behaviors, including avoidance and optimization, we review recent research on the utilization of hot slags. Because of the high-temperature property (1450-1650°C), the utilization of hot slags are much different from that of other wastes. We approach this issue from two main directions, namely, material recycling and heat utilization. From the respect of material recycling, the utilization of slags mainly follows total utilization and partial utilization, whereas the heat recovery from slags follows two main paths, namely, physical granulation and chemical reaction. The effective disposal of hot slags greatly depends on clarifying the crystallization behaviors, and thus, we discuss some optical techniques and their applicable scientific insights. For the purpose of crystallization avoidance, characterizing the glass-forming ability of slags is of great significance, whereas for crystallization modification, the selection of chemical additives and control of crystallization conditions comprise the central routes.

Crystal structure, characterization and magnetic properties of a 1D ...

Indian Academy of Sciences (India)

Crystal structure, characterization and magnetic properties of a 1D copper(II) polymer incorporating a Schiff base with carboxylate side arm. SHYAMAPADA SHIT MADHUSUDAN NANDY CORRADO RIZZOLI CÉDRIC DESPLANCHES SAMIRAN MITRA. Regular Article Volume 128 Issue 6 June 2016 pp 913-920 ...

Dataset on photonic crystal fiber based chemical sensor.

Science.gov (United States)

Ahmed, Kawsar; Paul, Bikash Kumar; Chowdhury, Sawrab; Islam, Md Shadidul; Sen, Shuvo; Islam, Md Ibadul; Asaduzzaman, Sayed; Bahar, Ali Newaz; Miah, Mohammad Badrul Alam

2017-06-01

This article represents the data set of micro porous core photonic crystal fiber based chemical sensor. The suggested structure is folded cladding porous shaped with circular air hole. Here is investigated four distinctive parameters including relative sensitivity, confinement loss, numerical aperture (NA), and effective area ( A eff). The numerical outcomes are computed over the E+S+C+L+U communication band. The useable sensed chemicals are methanol, ethanol, propanol, butanol, and pentanol whose are lies in the alcohol series (Paul et al., 2017) [1]. Furthermore, V -parameter ( V ), Marcuse spot size (MSS), and beam divergence (BD) are also investigated rigorously. All examined results have been obtained using finite element method based simulation software COMSOL Multiphysics 4.2 versions with anisotropic circular perfectly matched layer (A-CPML). The proposed PCF shows the high NA from 0.35 to 0.36; the low CL from ~10 -11 to ~10 -7 dB/m; the high A eff from 5.50 to 5.66 µm 2 ; the MSS from 1.0 to 1.08 µm; the BD from 0.43 to 0.46 rad at the controlling wavelength λ = 1.55 µm for employing alcohol series respectively.

One- and two-dimensional fluids properties of smectic, lamellar and columnar liquid crystals

CERN Document Server

Jakli, Antal

2006-01-01

Smectic and lamellar liquid crystals are three-dimensional layered structures in which each layer behaves as a two-dimensional fluid. Because of their reduced dimensionality they have unique physical properties and challenging theoretical descriptions, and are the subject of much current research. One- and Two-Dimensional Fluids: Properties of Smectic, Lamellar and Columnar Liquid Crystals offers a comprehensive review of these phases and their applications. The book details the basic structures and properties of one- and two-dimensional fluids and the nature of phase transitions. The later chapters consider the optical, magnetic, and electrical properties of special structures, including uniformly and non-uniformly aligned anisotropic films, lyotropic lamellar systems, helical and chiral structures, and organic anisotropic materials. Topics also include typical and defective features, magnetic susceptibility, and electrical conductivity. The book concludes with a review of current and potential applications ...

Single crystal growth and surface chemical stability of KPb2Br5

Science.gov (United States)

Atuchin, V. V.; Isaenko, L. I.; Kesler, V. G.; Tarasova, A. Yu.

2011-03-01

Single crystal of KPb2Br5 has been grown using the Bridgman technique. Initially the synthesis of stoichiometric KPb2Br5 compound was performed from high purity bromide salts. Electronic structure of KPb2Br5 has been determined with X-ray photoelectron spectroscopy for powdered sample fabricated by grinding in air. Drastic chemical interaction of KPb2Br5 with atmosphere has not been detected. Chemical bonding in potassium- and lead-containing bromides is considered using binding energy differences ΔK=(BE K 2p3/2-BE Br 3d) and ΔPb=(BE Pb 4f7/2-BE Br 3d), respectively, as representative parameters.

The influence of mineralogical, chemical and physical properties on grindability of commercial clinkers with high MgO level

International Nuclear Information System (INIS)

Souza, Vladia Cristina G. de; Koppe, Jair Carlos; Costa, Joao F.C.L.; Vargas, Andre Luis Marin; Blando, Eduardo; Huebler, Roberto

2008-01-01

This research investigates various methods able to identify possible mineralogical, physical and chemical influences on the grindability of commercial clinkers with high MgO level. The aim of the study is to evaluate the hardness and elastic modulus of the clinker mineral phases and their fracture strength during the comminution processes, comparing samples from clinkers with low MgO level (0.5%) and clinkers with elevated MgO levels (> 5.0%). The study of the influence of mineralogical, chemical and physical properties was carried out using several analytical techniques, such as: optical microscopy, X-ray diffraction with Rietveld refinement (XRD) and X-ray fluorescence (XRF). These techniques were useful in qualifying the different clinker samples. The drop weight test (DWT) and the Bond ball mill grindability test were performed to characterize the mechanical properties of clinkers. Nanoindentation tests were also carried out. Results from the Bond ball mill grindability test were found to be related to the hardness of the mineral phase and to mineralogical characteristics, such as type and amount of inclusions in silicates, belite and alite crystals shape, or microcracked alites. In contrast, the results obtained by the DWT were associated to the macro characteristics of clinkers, such as porosity, as well as to the hardness and mineralogical characteristics of belite crystals in clusters. Hardness instrumented tests helped to determine the Vickers hardness and elastic modulus from the mineral phases in commercial clinkers and produced different values for the pure phases compared to previous publications

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Band structures and localization properties of aperiodic layered phononic crystals

Energy Technology Data Exchange (ETDEWEB)

Yan Zhizhong, E-mail: zzyan@bit.edu.cn [Department of Applied Mathematics, Beijing Institute of Technology, Beijing 100081 (China); Zhang Chuanzeng [Department of Civil Engineering, University of Siegen, D-57078 Siegen (Germany)

2012-03-15

The band structures and localization properties of in-plane elastic waves with coupling of longitudinal and transverse modes oblique propagating in aperiodic phononic crystals based on Thue-Morse and Rudin-Shapiro sequences are studied. Using transfer matrix method, the concept of the localization factor is introduced and the correctness is testified through the Rytov dispersion relation. For comparison, the perfect periodic structure and the quasi-periodic Fibonacci system are also considered. In addition, the influences of the random disorder, local resonance, translational and/or mirror symmetries on the band structures of the aperiodic phononic crystals are analyzed in this paper.

Chemical and Physical Properties of Hi-Cal-2

Science.gov (United States)

Spakowski, A. E.; Allen, Harrison, Jr.; Caves, Robert M.

1955-01-01

As part of the Navy Project Zip to consider various boron-containing materials as possible high-energy fuels, the chemical and physical properties of Hi-Cal-2 prepared by the Callery Chemical Company were evaluated at the NACA Lewis laboratory. Elemental chemical analysis, heat of combustion, vapor pressure and decomposition, freezing point, density, self ignition temperature, flash point, and blow-out velocity were determined for the fuel. Although the precision of measurement of these properties was not equal to that obtained for hydrocarbons, this special release research memorandum was prepared to make the data available as soon as possible.

Tuning the dielectric properties of thiourea analog crystals for efficient nonlinear optical applications

International Nuclear Information System (INIS)

Sabari Girisun, T.C.; Dhanuskodi, S.

2010-01-01

Materials with low dielectric constant have attracted a great deal of interest in the field of nonlinear applications and microelectronic industry. Metal complexes of thiourea with group II transition metals (Zn, Cd) as central atom and period III elements (S, Cl) were synthesized by chemical reaction method and single crystals were grown from aqueous solution by slow evaporation method. By parallel plate capacitor technique, the dielectric response, dissipation factor, ac conductivity and impedance of virgin and metal complexes have been studied in the frequency (100 Hz to 5 MHz) and temperature (303-423 K) ranges. Metal complexes of thiourea with cadmium substitute have a low dielectric constant less than 10. Also the presence of chlorine in the metal complex induces noncentro symmetric structure. Hence the role of group II transition metals and period III elements in tuning the dielectric properties for efficient nonlinear applications has been studied.

Prospects for the synthesis of large single-crystal diamonds

International Nuclear Information System (INIS)

Khmelnitskiy, R A

2015-01-01

The unique properties of diamond have stimulated the study of and search for its applications in many fields, including optics, optoelectronics, electronics, biology, and electrochemistry. Whereas chemical vapor deposition allows the growth of polycrystalline diamond plates more than 200 mm in diameter, most current diamond application technologies require large-size (25 mm and more) single-crystal diamond substrates or films suitable for the photolithography process. This is quite a challenge, because the largest diamond crystals currently available are 10 mm or less in size. This review examines three promising approaches to fabricating large-size diamond single crystals: growing large-size single crystals, the deposition of heteroepitaxial diamond films on single-crystal substrates, and the preparation of composite diamond substrates. (reviews of topical problems)

Physico-chemical properties and sensory evaluation of jam made ...

African Journals Online (AJOL)

This study was carried out to investigate the possibility of producing jam from black-plum and to evaluate the physico-chemical properties, nutritional properties and consumer acceptability of the product. Black-plum jam was produced using traditional openkettle method. The physico-chemical analyses of black-plum fruit ...

Growth and spectroscopic properties of Tm3+:NaBi(MoO4)2 single crystal

Science.gov (United States)

Gusakova, N. V.; Mudryi, A. V.; Demesh, M. P.; Yasukevich, A. S.; Pavlyuk, A. A.; Kornienko, A. A.; Dunina, E. B.; Khodasevich, I. A.; Orlovich, V. A.; Kuleshov, N. V.

2018-06-01

In this work we report the spectroscopic properties of Tm3+:NaBi(MoO4)2 crystals with the dopant concentrations of 0.7 at.% and 3 at.%. The energy levels of the Tm3+ in the NaBi(MoO4)2 host were determined from polarized optical absorption and photoluminescence spectra measured at 77.4 K. Radiative properties of the crystals were calculated in context of Judd-Ofelt theory. Raman spectra of the crystal were studied. The concentration dependences of emission decay times of 3H4 and 3F4 levels were analyzed. The potential of the crystal for building tunable and ultrafast pulse lasers is shown on the base of cross sections and gain coefficient in the range of 1.9 μm.

A crystal chemistry approach for high-power ytterbium doped solid-state lasers: diffusion-bonded crystals and new crystalline hosts

International Nuclear Information System (INIS)

Gaume, R.

2002-11-01

This work deals with ytterbium based crystals for high-power laser applications. In particular, we focus our interest in reducing crystal heating and its consequences during laser operation following two different ways. First, we review the specific properties of ytterbium doped solid-state lasers in order to define a figure-of-merit which gives the evaluation of laser performances, thermo-mechanical and thermo-optical properties. Bearing in mind this analysis, we propose a set of theoretical tools, based on the crystallographic structure of the crystal and its chemical composition, to predict thermo-mechanical and optical potentials. This approach, used for the seek of new Yb 3+ -doped materials for high-power laser applications, shows that simple oxides containing rare-earths are favorable. Therefore, the spectroscopic properties of six new materials Yb 3+ :GdVO 4 , Yb 3+ :GdAlO 3 , Yb 3+ :Gd 2 O 3 , Yb 3+ :Sc 2 SiO 5 , Yb 3+ :CaSc 2 O 4 and Yb 3+ :SrSc 2 O 4 are described. The second aspect developed in this work deals with thermal properties enhancement of already well characterized laser materials. Two different ways are explored: a) elaboration by diffusion bonding of end-caps lasers with undoped crystals (composite crystals). Thus, different composites were obtained and a fairly lowering of thermal lensing effect was observed during laser operation. b) strengthening of crystalline structures by ionic substitution of one of its constituents. We demonstrate how crystal growth ability can be improved by a cationic substitution in the case of Yb 3+ :BOYS, a largely-tunable laser material which is of great interest for femtosecond pulses generation. (author)

Crystal growth, structural, optical, thermal, mechanical, laser damage threshold and electrical properties of triphenylphosphine oxide 4-nitrophenol (TP4N) single crystals for nonlinear optical applications

Science.gov (United States)

Karuppasamy, P.; Senthil Pandian, Muthu; Ramasamy, P.; Verma, Sunil

2018-05-01

The optically good quality single crystals of triphenylphosphine oxide 4-nitrophenol (TP4N) with maximum dimension of 15 × 10 × 5 mm3 were grown by slow evaporation solution technique (SEST) at room temperature. The cell dimensions of the grown TP4N crystal were confirmed by single crystal X-ray diffraction (SXRD) and the crystalline purity was confirmed and planes were indexed by powder X-ray diffraction (PXRD) analysis. Functional groups of TP4N crystal were confirmed by Fourier transform infrared (FTIR) spectral analysis. The optical transmittance of the grown crystal was determined by the UV-Vis NIR spectral analysis and it has good optical transparency in the entire visible region. The band tail (Urbach) energy of the grown crystal was analyzed and it appears to be minimum, which indicates that the TP4N has good crystallinity. The position of valence band (Ev) and conduction band (Ec) of the TP4N have been determined from the electron affinity energy (EA) and the ionization energy (EI) of its elements and using the optical band gap. The thermal behaviour of the grown crystal was investigated by thermogravimetric and differential thermal analysis (TG-DTA). Vickers microhardness analysis was carried out to identify the mechanical stability of the grown crystal and their indentation size effect (ISE) was explained by the Meyer's law (ML), Hays-Kendall's (HK) approach, proportional specimen resistance (PSR) model, modified PSR model (MPSR), elastic/plastic deformation (EPD) model and indentation induced cracking (IIC) model. Chemical etching study was carried out to find the etch pit density (EPD) of the grown crystal. Laser damage threshold (LDT) value was measured by using Nd:YAG laser (1064 nm). The dielectric permittivity (ε՛) and dielectric loss (tan δ) as a function of frequency was measured. The electronic polarizability (α) of the TP4N crystal was calculated. It is well matched to the value which was calculated from Clausius-Mossotti relation

Unique Reversible Crystal-to-Crystal Phase Transition – Structural and Functional Properties of Fused Ladder Thienoarenes

KAUST Repository

Abe, Yuichiro

2017-08-15

Donor-acceptor type molecules based on fused ladder thienoarenes, indacenodithiophene (IDT) and dithienocyclopenta-thienothiophene (DTCTT), coupled with benzothiadiazole, are prepared and their solid-state structures are investigated. They display a rich variety of solid phases ranging from amorphous glass states to crystalline states, upon changes in the central aromatic core and side group structures. Most notably, the DTCTT-based derivatives showed reversible crystal-to-crystal phase transitions in heating and cooling cycles. Unlike what has been seen in π−conjugated molecules variable temperature XRD revealed that structural change occurs continuously during the transition. A columnar self-assembled structure with slip-stacked π−π interaction is proposed to be involved in the solid-state. This research provides the evidence of unique structural behavior of the DTCTT-based molecules through the detailed structural analysis. This unique structural transition paves the way for these materials to have self-healing of crystal defects, leading to improved optoelectronic properties.

Unique Reversible Crystal-to-Crystal Phase Transition – Structural and Functional Properties of Fused Ladder Thienoarenes

KAUST Repository

Abe, Yuichiro; Savikhin, Victoria; Yin, Jun; Grimsdale, Andrew C.; Soci, Cesare; Toney, Michael F.; Lam, Yeng Ming

2017-01-01

Donor-acceptor type molecules based on fused ladder thienoarenes, indacenodithiophene (IDT) and dithienocyclopenta-thienothiophene (DTCTT), coupled with benzothiadiazole, are prepared and their solid-state structures are investigated. They display a rich variety of solid phases ranging from amorphous glass states to crystalline states, upon changes in the central aromatic core and side group structures. Most notably, the DTCTT-based derivatives showed reversible crystal-to-crystal phase transitions in heating and cooling cycles. Unlike what has been seen in π−conjugated molecules variable temperature XRD revealed that structural change occurs continuously during the transition. A columnar self-assembled structure with slip-stacked π−π interaction is proposed to be involved in the solid-state. This research provides the evidence of unique structural behavior of the DTCTT-based molecules through the detailed structural analysis. This unique structural transition paves the way for these materials to have self-healing of crystal defects, leading to improved optoelectronic properties.

The formation and optical properties of planar waveguide in laser crystal Nd:YGG by carbon ion implantation

Science.gov (United States)

Zhao, Jin-Hua; Qin, Xi-Feng; Wang, Feng-Xiang; Jiao, Yang; Guan, Jing; Fu, Gang

2017-10-01

As one kind of prominent laser crystal, Nd:Y3Ga5O12 (Nd:YGG) crystal has outstanding performance on laser excitation at multi-wavelength which have shown promising applications in optical communication field. In addition, Nd:YGG crystal has potential applications in medical field due to its ability of emit the laser at 1110 nm. Optical waveguide structure with high quality could improve the efficiency of laser emission. In this work, we fabricated the optical planar waveguide on Nd:YGG crystal by medium mass ion implantation which was convinced an effective method to realize a waveguide structure with superior optical properties. The sample is implanted by C ions at energy of 5.0 MeV with the fluence of 1 × 1015 ions/cm2. We researched the optical propagation properties in the Nd:YGG waveguide by end-face coupling and prism coupling method. The Nd ions fluorescent properties are obtained by a confocal micro-luminescence measurement. The fluorescent properties of Nd ions obtained good reservation after C ion implantation. Our work has reference value for the application of Nd:YGG crystal in the field of optical communication.

Influence of MgSO{sub 4} doping on the properties of zinc tris–thiourea sulphate (ZTS) single crystals

Energy Technology Data Exchange (ETDEWEB)

Selvapandiyan, M., E-mail: mselvapandiyan@rediffmail.com [Department of Physics, Sri Vidya Mandir Arts and Science College, Uthangarai 635 207 (India); Arumugam, J. [Department of Physics, Sri Vidya Mandir Arts and Science College, Uthangarai 635 207 (India); Sundaramoorthi, P. [Department of Physics, Thiruvalluvar Government Arts College, Rasipuram 637 401 (India); Sudhakar, S. [CSIR–National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110 012 (India)

2013-12-15

Highlights: •The influence of MgSO{sub 4} doping on the properties of ZTS single crystals grown at room temperature. •Thermal stability of the crystals increased with incorporation of Mg atom. •Energy band gap was estimated from UV–vis spectra. •ZTS is a potential material for frequency conversion. •Both pure and doped ZTS crystals are belonging to category of typical insulating materials. -- Abstract: The influence of MgSO{sub 4} doping on the properties of zinc tris–thiourea sulphate single crystals grown at room temperature by slow evaporation solution growth technique was studied. Powder XRD analysis confirmed the orthorhombic crystal structure with noncentrosymmetric space group Pca2{sub 1}. The mechanical properties of the grown crystals were analysed by Vicker’s microhardness method. Functional groups present in the materials were identified by FTIR spectral analysis in the range between 4000 and 400 cm{sup −1}. The UV–Vis spectrum indicates that the UV cut-off wavelength of the crystals has less than 297 nm. The thermal stability of the grown crystals was determined with the aid of thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Second order nonlinear optical behaviour of the grown crystals have been confirmed by Kurtz powder second harmonic generation (SHG) test.

Controlled synthesis of thorium and uranium oxide nano-crystals

International Nuclear Information System (INIS)

Hudry, Damien; Apostolidis, Christos; Walter, Olaf; Gouder, Thomas; Courtois, Eglantine; Kubel, Christian; Meyer, Daniel

2013-01-01

Very little is known about the size and shape effects on the properties of actinide compounds. As a consequence, the controlled synthesis of well-defined actinide-based nano-crystals constitutes a fundamental step before studying their corresponding properties. In this paper, we report on the non-aqueous surfactant-assisted synthesis of thorium and uranium oxide nano-crystals. The final characteristics of thorium and uranium oxide nano-crystals can be easily tuned by controlling a few experimental parameters such as the nature of the actinide precursor and the composition of the organic system (e.g., the chemical nature of the surfactants and their relative concentrations). Additionally, the influence of these parameters on the outcome of the synthesis is highly dependent on the nature of the actinide element (thorium versus uranium). By using optimised experimental conditions, monodisperse isotropic uranium oxide nano-crystals with different sizes (4.5 and 10.7 nm) as well as branched nano-crystals (overall size ca. 5 nm), nano-dots (ca. 4 nm) and nano-rods (with ultra-small diameters of 1 nm) of thorium oxide were synthesised. (authors)

Anomalous property of coherent bremsstrahlung linear polarization of relativistic electrons in a crystal

International Nuclear Information System (INIS)

Lapko, V.P.; Nasonov, N.N.; Truten', V.I.

1993-01-01

Polarization and spectral-and-angular properties of γ-radiation of the relativistic electron flux moving in a crystal under uncorrelated collisions with crystal atomic chains, are studied theoretically. Direction of linear polarization of radiation is shown to vary with energy of emitted photon. Reasons of occurrence of this effect are discussed. The results of numerical calculations demonstrating the possibility to form an intensive source of polarized γ-quanta on the basis of coherent radiation of relativistic electrons during low-angular scattering at crystal atom chains, are given

Topological Characterization of Carbon Graphite and Crystal Cubic Carbon Structures.

Science.gov (United States)

Siddiqui, Wei Gao Muhammad Kamran; Naeem, Muhammad; Rehman, Najma Abdul

2017-09-07

Graph theory is used for modeling, designing, analysis and understanding chemical structures or chemical networks and their properties. The molecular graph is a graph consisting of atoms called vertices and the chemical bond between atoms called edges. In this article, we study the chemical graphs of carbon graphite and crystal structure of cubic carbon. Moreover, we compute and give closed formulas of degree based additive topological indices, namely hyper-Zagreb index, first multiple and second multiple Zagreb indices, and first and second Zagreb polynomials.

Growth and physicochemical properties of second-order nonlinear optical 2-amino-5-chloropyridinium trichloroacetate single crystals

Science.gov (United States)

Renugadevi, R.; Kesavasamy, R.

2015-09-01

The growth of organic nonlinear optical (NLO) crystal 2-amino-5-chloropyridinium trichloroacetate (2A5CPTCA) has been synthesized and single crystals have been grown from methanol solvent by slow evaporation technique. The grown crystals were subjected to various characterization analyses in order to find out the suitability for device fabrication. Single crystal X-ray diffraction analysis reveals that 2A5CPTCA crystallizes in monoclinic system with the space group Cc. The grown crystal was further characterized by Fourier transform infrared spectral analysis to find out the functional groups. The nuclear magnetic resonance spectroscopy is a research technique that exploits the magnetic properties of certain atomic nuclei. The optical transparency window in the visible and near-IR (200--1100 nm) regions was found to be good for NLO applications. Thermogravimetric analysis and differential thermal analysis were used to study its thermal properties. The powder second harmonic generation efficiency measurement with Nd:YAG laser (1064 nm) radiation shows that the highest value when compared with the standard potassium dihydrogen phosphate crystal.

Rare earth separations by selective borate crystallization

Science.gov (United States)

Yin, Xuemiao; Wang, Yaxing; Bai, Xiaojing; Wang, Yumin; Chen, Lanhua; Xiao, Chengliang; Diwu, Juan; Du, Shiyu; Chai, Zhifang; Albrecht-Schmitt, Thomas E.; Wang, Shuao

2017-03-01

Lanthanides possess similar chemical properties rendering their separation from one another a challenge of fundamental chemical and global importance given their incorporation into many advanced technologies. New separation strategies combining green chemistry with low cost and high efficiency remain highly desirable. We demonstrate that the subtle bonding differences among trivalent lanthanides can be amplified during the crystallization of borates, providing chemical recognition of specific lanthanides that originates from Ln3+ coordination alterations, borate polymerization diversity and soft ligand coordination selectivity. Six distinct phases are obtained under identical reaction conditions across lanthanide series, further leading to an efficient and cost-effective separation strategy via selective crystallization. As proof of concept, Nd/Sm and Nd/Dy are used as binary models to demonstrate solid/aqueous and solid/solid separation processes. Controlling the reaction kinetics gives rise to enhanced separation efficiency of Nd/Sm system and a one-step quantitative separation of Nd/Dy with the aid of selective density-based flotation.

First principles study of structural, electronic and optical properties of KCl crystal

International Nuclear Information System (INIS)

Chen, Z.J.; Xiao, H.Y.; Zu, X.T.

2006-01-01

The structural, electronic and optical properties of KCl crystal in B1, B2, B3 and T1 structures have been systematically studied using first-principle pseudopotential calculations. In addition, pressure-induced phase transition has also been investigated. It was found that when the pressure is below 2.8 GPa, the B1 structure is the most stable. Above 2.8 GPa KCl crystal will undergo a structural phase transition from the relatively open NaCl structure into the more dense CsCl atomic arrangement. Our results also suggested that at about 1.2 GPa structural phase transition from B3 to T1 will occur. When the pressure arrives at 39.9 GPa, the phase transition will occur from B2 to T1. In addition, we found KCl Crystal has indirect band gap in B2 structure and direct band gap in B1, B3 and T1 structures. The band gap value is the smallest in the T1 structure and is the largest in the B1 and B3 structures. Our calculations are found to be in good agreement with available experimental and theoretical results. The dielectric function and energy loss function of KCl crystal in four structures (B1, B2, B3 and T1) have been calculated as well as the anisotropy of the optical properties of KCl crystal in T1 structure

Optical Properties and Wave Propagation in Semiconductor-Based Two-Dimensional Photonic Crystals

International Nuclear Information System (INIS)

Mario Agio

2002-01-01

This work is a theoretical investigation on the physical properties of semiconductor-based two-dimensional photonic crystals, in particular for what concerns systems embedded in planar dielectric waveguides (GaAs/AlGaAs, GaInAsP/InP heterostructures, and self-standing membranes) or based on macro-porous silicon. The photonic-band structure of photonic crystals and photonic-crystal slabs is numerically computed and the associated light-line problem is discussed, which points to the issue of intrinsic out-of-lane diffraction losses for the photonic bands lying above the light line. The photonic states are then classified by the group theory formalism: each mode is related to an irreducible representation of the corresponding small point group. The optical properties are investigated by means of the scattering matrix method, which numerically implements a variable-angle-reflectance experiment; comparison with experiments is also provided. The analysis of surface reflectance proves the existence of selection rules for coupling an external wave to a certain photonic mode. Such rules can be directly derived from symmetry considerations. Lastly, the control of wave propagation in weak-index contrast photonic-crystal slabs is tackled in view of designing building blocks for photonic integrated circuits. The proposed designs are found to comply with the major requirements of low-loss propagation, high and single-mode transmission. These notions are then collected to model a photonic-crystal combiner for an integrated multi-wavelength-source laser

Optical Properties and Wave Propagation in Semiconductor-Based Two-Dimensional Photonic Crystals

Energy Technology Data Exchange (ETDEWEB)

Agio, Mario [Iowa State Univ., Ames, IA (United States)

2002-12-31

This work is a theoretical investigation on the physical properties of semiconductor-based two-dimensional photonic crystals, in particular for what concerns systems embedded in planar dielectric waveguides (GaAs/AlGaAs, GaInAsP/InP heterostructures, and self-standing membranes) or based on macro-porous silicon. The photonic-band structure of photonic crystals and photonic-crystal slabs is numerically computed and the associated light-line problem is discussed, which points to the issue of intrinsic out-of-lane diffraction losses for the photonic bands lying above the light line. The photonic states are then classified by the group theory formalism: each mode is related to an irreducible representation of the corresponding small point group. The optical properties are investigated by means of the scattering matrix method, which numerically implements a variable-angle-reflectance experiment; comparison with experiments is also provided. The analysis of surface reflectance proves the existence of selection rules for coupling an external wave to a certain photonic mode. Such rules can be directly derived from symmetry considerations. Lastly, the control of wave propagation in weak-index contrast photonic-crystal slabs is tackled in view of designing building blocks for photonic integrated circuits. The proposed designs are found to comply with the major requirements of low-loss propagation, high and single-mode transmission. These notions are then collected to model a photonic-crystal combiner for an integrated multi-wavelength-source laser.

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Near-equilibrium chemical vapor deposition of high-quality single-crystal graphene directly on various dielectric substrates.

Science.gov (United States)

Chen, Jianyi; Guo, Yunlong; Jiang, Lili; Xu, Zhiping; Huang, Liping; Xue, Yunzhou; Geng, Dechao; Wu, Bin; Hu, Wenping; Yu, Gui; Liu, Yunqi

2014-03-05

By using near-equilibrium chemical vapor deposition, it is demonstrated that high-quality single-crystal graphene can be grown on dielectric substrates. The maximum size is about 11 μm. The carrier mobility can reach about 5650 cm(2) V(-1) s(-1) , which is comparable to those of some metal-catalyzed graphene crystals, reflecting the good quality of the graphene lattice. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Computational chemical product design problems under property uncertainties

DEFF Research Database (Denmark)

Frutiger, Jerome; Cignitti, Stefano; Abildskov, Jens

2017-01-01

Three different strategies of how to combine computational chemical product design with Monte Carlo based methods for uncertainty analysis of chemical properties are outlined. One method consists of a computer-aided molecular design (CAMD) solution and a post-processing property uncertainty...... fluid design. While the higher end of the uncertainty range of the process model output is similar for the best performing fluids, the lower end of the uncertainty range differs largely....

Controlling single and few-layer graphene crystals growth in a solid carbon source based chemical vapor deposition

International Nuclear Information System (INIS)

Papon, Remi; Sharma, Subash; Shinde, Sachin M.; Vishwakarma, Riteshkumar; Tanemura, Masaki; Kalita, Golap

2014-01-01

Here, we reveal the growth process of single and few-layer graphene crystals in the solid carbon source based chemical vapor deposition (CVD) technique. Nucleation and growth of graphene crystals on a polycrystalline Cu foil are significantly affected by the injection of carbon atoms with pyrolysis rate of the carbon source. We observe micron length ribbons like growth front as well as saturated growth edges of graphene crystals depending on growth conditions. Controlling the pyrolysis rate of carbon source, monolayer and few-layer crystals and corresponding continuous films are obtained. In a controlled process, we observed growth of large monolayer graphene crystals, which interconnect and merge together to form a continuous film. On the other hand, adlayer growth is observed with an increased pyrolysis rate, resulting few-layer graphene crystal structure and merged continuous film. The understanding of monolayer and few-layer crystals growth in the developed CVD process can be significant to grow graphene with controlled layer numbers.

Supramolecular Liquid Crystal Displays Construction and Applications

OpenAIRE

Hoogboom, J.T.V.

2004-01-01

This thesis describes chemical methodologies, which can be ued to construct alignment layers for liquid crystal display purposes in a non-clean room environment, by making use of supramolecular chemistry. These techniques are subsequently used to attain control over LCD-properties, both pre- and post-LCD construction. In addition, the thesis describes the application of LCD technology in biosensors.

Optical properties of Sulfur doped InP single crystals

Science.gov (United States)

El-Nahass, M. M.; Youssef, S. B.; Ali, H. A. M.

2014-05-01

Optical properties of InP:S single crystals were investigated using spectrophotometric measurements in the spectral range of 200-2500 nm. The absorption coefficient and refractive index were calculated. It was found that InP:S crystals exhibit allowed and forbidden direct transitions with energy gaps of 1.578 and 1.528 eV, respectively. Analysis of the refractive index in the normal dispersion region was discussed in terms of the single oscillator model. Some optical dispersion parameters namely: the dispersion energy (Ed), single oscillator energy (Eo), high frequency dielectric constant (ɛ∞), and lattice dielectric constant (ɛL) were determined. The volume and the surface energy loss functions (VELF & SELF) were estimated. Also, the real and imaginary parts of the complex conductivity were calculated.

Status on PWO crystals from Bogoroditsk after one year of preproduction for CMS-ECAL

CERN Document Server

Auffray, Etiennette; Lecoq, P; Marcos, R; Sempere-Roldan, P; Schneegans, M; Annenkov, A N; Korzhik, M V

2000-01-01

In September 1998, the CMS electromagnetic calorimeter entered into its construction phase. Since that time, more than 2000 crystals have been produced by Bogoroditsk Techno-Chemical Plant (BTCP) in Russia and analysed at CERN. An overview about mechanical and optical properties as well as radiation hardness characteristics of these crystals will be presented. (8 refs).

Sublimation Properties of Pentaerythritol Tetranitrate Single Crystals Doped with Its Homologs

Energy Technology Data Exchange (ETDEWEB)

Bhattacharia, Sanjoy K.; Maiti, Amitesh; Gee, Richard H.; Weeks, Brandon L.

2012-07-20

Pentaerythritol tetranitrate (PETN) is a secondary explosive used extensively in military and commercial applications. Coarsening of PETN during long-term storage changes the physical properties such as surface area and particle morphology which are important factors in initiation and performance. Doping of impurities was proposed to slow the coarsening process since impurities were shown to modify both the kinetic and thermodynamic properties. In this paper, we discuss how doping of PETN with its homologs of dipentaerythritol hexanitrate (diPEHN) and tripentaerytritol octanitrate (triPEON) affect kinetic and thermodynamic parameters. Pure and homolog doped PETN single crystals were prepared by solvent evaporation in acetone at room temperature. Doping concentrations for this study were 1000 ppm, 5000 ppm, and 10000 ppm. Activation energy and vapor pressure of pure and doped PETN single crystals were obtained from thermogravimetric analysis data.

71Ga Chemical Shielding and Quadrupole Coupling Tensors of the Garnet Y(3)Ga(5)O(12) from Single-Crystal (71)Ga NMR

DEFF Research Database (Denmark)

Vosegaard, Thomas; Massiot, Dominique; Gautier, Nathalie

1997-01-01

A single-crystal (71)Ga NMR study of the garnet Y(3)Ga(5)O(12) (YGG) has resulted in the determination of the first chemical shielding tensors reported for the (71)Ga quadrupole. The single-crystal spectra are analyzed in terms of the combined effect of quadrupole coupling and chemical shielding ...

Emergent Low-Symmetry Phases and Large Property Enhancements in Ferroelectric KNbO ₃ Bulk Crystals

Energy Technology Data Exchange (ETDEWEB)

Lummen, Tom T. A. [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 USA; Leung, J. [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 USA; Kumar, Amit [School of Mathematics and Physics, Queen' s University Belfast, University Road, Belfast BT71NN Northern Ireland UK; Wu, X. [Department of Physics, University of Texas at Austin, Austin TX 78712 USA; Ren, Y. [Department of Physics, University of Texas at Austin, Austin TX 78712 USA; VanLeeuwen, Brian K. [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 USA; Haislmaier, Ryan C. [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 USA; Holt, Martin [Center for Nanoscale Materials, Argonne National Laboratory, Argonne IL 60439 USA; Lai, Keji [Department of Physics, University of Texas at Austin, Austin TX 78712 USA; Kalinin, Sergei V. [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge TN 37831 USA; Gopalan, Venkatraman [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 USA

2017-06-19

The design of new or enhanced functionality in materials is traditionally viewed as requiring the discovery of new chemical compositions through synthesis. Large property enhancements may however also be hidden within already well-known materials, when their structural symmetry is deviated from equilibrium through a small local strain or field. Here, the discovery of enhanced material properties associated with a new metastable phase of monoclinic symmetry within bulk KNbO3 is reported. This phase is found to coexist with the nominal orthorhombic phase at room temperature, and is both induced by and stabilized with local strains generated by a network of ferroelectric domain walls. While the local microstructural shear strain involved is only approximate to 0.017%, the concurrent symmetry reduction results in an optical second harmonic generation response that is over 550% higher at room temperature. Moreover, the meandering walls of the low-symmetry domains also exhibit enhanced electrical conductivity on the order of 1 S m(-1). This discovery reveals a potential new route to local engineering of significant property enhancements and conductivity through symmetry lowering in ferroelectric crystals.

Polarized spectroscopic properties of Nd3+-doped KGd(WO4)2 single crystal

International Nuclear Information System (INIS)

Chen Yujin; Lin Yanfu; Gong Xinghong; Tan Qiguang; Zhuang Jian; Luo Zundu; Huang Yidong

2007-01-01

The polarized absorption spectra, infrared fluorescence spectra, upconversion visible fluorescence spectra, and fluorescence decay curve of orientated Nd 3+ :KGd(WO 4 ) 2 crystal were measured at room-temperature. Some important spectroscopic parameters were investigated in detail in the framework of the Judd-Ofelt theory and the Fuchtbauer-Ladenburg formula. The effect of the crystal structure on the spectroscopic properties of the Nd 3+ ions was analyzed. The relation among the spectroscopic parameters and the laser performances of the Nd 3+ :KGd(WO 4 ) 2 crystal was discussed

Polarized spectral properties of Sm3+:LiYF4 crystal

International Nuclear Information System (INIS)

Wang, G.Q.; Lin, Y.F.; Gong, X.H.; Chen, Y.J.; Huang, J.H.; Luo, Z.D.; Huang, Y.D.

2014-01-01

A trivalent samarium-doped LiYF 4 single crystal was grown by the vertical Bridgman technique. Its polarized absorption and fluorescence spectra and fluorescence decay curves were recorded at room temperature. On the basis of the Judd–Ofelt theory, the spectral parameters of the Sm 3+ :LiYF 4 crystal were calculated. The emission cross sections for the 4 G 5/2 → 6 H J (J=5/2, 7/2. 9/2, and 11/2) transitions of special interest for visible laser application were obtained by the Fuchtbauer–Ladenburg formula. -- Highlights: • Polarized spectral properties of Sm 3+ :LiYF 4 crystal at room temperature were analyzed in detail. • The emission cross sections for the transitions of special interest for visible laser application are calculated. • Sm 3+ :LiYF 4 is a promising laser material for 401 nm GaN LD pumped 605 nm visible laser

Fundamental problems on immiscibility, crystallization, and chemical interaction between stainless steel 304 and glasses for radioactivewaste glasses

International Nuclear Information System (INIS)

Inoue, Tadashi; Yokoyama, Hayaichi

1982-01-01

Immiscibility and crystallization, and chemical interaction with stainless steel, SUS 304, which is designed as a canister material, were investigated on non-radioactive glasses with simulated waste of 26.4 wt%. Although glasses whose initial color was black changed to yellow or yellow-brown by heat-treatment at 600 0 C, the change of color was hardly observed by the treatment at 850 0 C. Molybdenum oxide and molybdate were detected in all heat-treated glasses. It was deduced that the compounds were existing as meta-stable particle corresponding to immiscibility particle at 600 0 C and as stable crystallized particle at 850 0 C. The chemical interaction occurred at the interface between glasses and SUS 304, whose surface was attacked by boundary corrosion proceeding to uniform corrosion with increasing temperature and time. Chromium oxide layer was mainly formed in the region suffered chemical interaction. It was deduced that the chemical interaction was moderated due to the formation of protective layer, which mainly consisted of nickel oxide, at the same time as the formation of Cr 2 O 3 layer. (author)

Structural elucidation and physicochemical properties of an organic NLO crystal: 4-Nitrotoluene-2-sulphonic acid dihydrate

Science.gov (United States)

Sangeetha, K.; Guru Prasad, L.; Mathammal, R.

2018-03-01

4-nitrotoluene-2-sulphonic acid dihydrate single crystals have been developed using slow evaporation technique in methanol. Lattice parameters of the NTSAD crystal have been calculated and it confirms the grown material. The intermolecular interactions are studied from the 3D Hirshfeld surface analysis and 2D fingerprint plots. The NMR spectral analysis has been carried out to confirm the molecular structure of the grown material. Optical properties have been obtained from UV-VIS spectral analysis and photoluminescence studies. Frequency conversion property of the NTSAD crystal was investigated with the aid of Kurtz and Perry method.

Synthesis, growth, physicochemical properties and DFT calculations of 2-naphthol substituted Mannich base 1-(morpholino(phenyl) methyl) naphthalen-2-ol: A non linear optical single crystal

Science.gov (United States)

Dennis Raj, A.; Jeeva, M.; Shankar, M.; Venkatesa Prabhu, G.; Vimalan, M.; Vetha Potheher, I.

2017-11-01

2-Naphthol substituted Mannich base 1-morpholino(phenyl)methyl)naphthalen-2-ol (MPMN), a potential NLO active organic single crystal was developed using acetonitrile as a solvent by slow evaporation method. The experimental and theoretical analysis made towards the exploitation in the field of electro-optic and NLO applications. The cubic structure with non-centrosymmetric space group Cc was confirmed and cell dimensions of the grown crystal were obtained from single crystal X-ray diffraction (XRD) study. The formation of the Csbnd Nsbnd C vibrational band at 1115 cm-1 in Fourier Transform Infra-Red (FTIR) analysis confirms the formation of MPMN compound. The placement of protons and carbons of MPMN were identified from Nuclear Magnetic Resonance Spectroscopy (NMR) analysis. The wide optical absorption window and the lower cutoff wavelength of MPMN show the suitability of the material for the various laser related applications. The presence of dislocations and growth pattern of crystal were analyzed using chemical etching technique. The Second Harmonic Generation (SHG) of MPMN was found to be 1.57 times greater than the standard KDP crystal. The laser damage threshold was measured by using Nd: YAG laser beam passed through the sample and it was found to be 1.006 GW/cm2. The electronic structure of the molecular system and the optical properties were also studied from quantum chemical calculations using Density Functional Theory (DFT) and reported for the first time.

Synthesis, crystal structure refinement, and nonlinear-optical properties of CaB3O5(OH): Comparative crystal chemistry of calcium triborates

International Nuclear Information System (INIS)

Yamnova, N. A.; Aksenov, S. M.; Stefanovich, S. Yu.; Volkov, A. S.; Dimitrova, O. V.

2015-01-01

Calcium triborate CaB 3 O5(OH) obtained by hydrothermal synthesis in the Ca(OH) 2 –H 3 BO 3 –Na 2 CO 3 –KCl system is studied by single-crystal X-ray diffraction. The parameters of the orthorhombic unit cell are as follows: a = 13.490(1), b = 6.9576(3), and c = 4.3930(2) Å; V = 412.32(3) Å 3 and space group Pna2 1 . The structure is refined in the anisotropic approximation of the atomic displacement parameters to R = 4.28% using 972 vertical bar F vertical bar > 4σ(F). It is confirmed that the crystal structure of Ca triborate CaB 3 O 5 (OH) is identical to that described earlier. The hydrogen atom is localized. An SHG signal stronger than that of the quartz standard is registered. The phase transition of calcium triborate into calciborite is found on heating. The comparative crystal-chemical analysis of a series of borates with the general chemical formula 2CaO · 3B 2 O 3 · nH 2 O (n = 0–13) with the constant CaO: B 2 O 3 = 2: 3 ratio and variable content of water is performed

Dataset on photonic crystal fiber based chemical sensor

Directory of Open Access Journals (Sweden)

Kawsar Ahmed

2017-06-01

Full Text Available This article represents the data set of micro porous core photonic crystal fiber based chemical sensor. The suggested structure is folded cladding porous shaped with circular air hole. Here is investigated four distinctive parameters including relative sensitivity, confinement loss, numerical aperture (NA, and effective area (Aeff. The numerical outcomes are computed over the E+S+C+L+U communication band. The useable sensed chemicals are methanol, ethanol, propanol, butanol, and pentanol whose are lies in the alcohol series (Paul et al., 2017 [1]. Furthermore, V-parameter (V, Marcuse spot size (MSS, and beam divergence (BD are also investigated rigorously. All examined results have been obtained using finite element method based simulation software COMSOL Multiphysics 4.2 versions with anisotropic circular perfectly matched layer (A-CPML. The proposed PCF shows the high NA from 0.35 to 0.36; the low CL from ~10–11 to ~10−7 dB/m; the high Aeff from 5.50 to 5.66 µm2; the MSS from 1.0 to 1.08 µm; the BD from 0.43 to 0.46 rad at the controlling wavelength λ = 1.55 µm for employing alcohol series respectively.

Spectral properties of a two dimensional photonic crystal with quasi-integrable geometry

International Nuclear Information System (INIS)

Cruz-Bueno, J J; Méndez-Bermúdez, J A; Arriaga, J

2013-01-01

In this paper we study the statistical properties of the allowed frequencies for electromagnetic waves propagating in two-dimensional photonic crystals with quasi-integrable geometry. We compute the level spacing, group velocity, and curvature distributions (P(s), P(v), and P(c), respectively) and compare them with the corresponding random matrix theory predictions. Due to the quasi-integrability of the crystal we observe signatures of intermediate statistics in P(s) and P(c) for high refractive index contrasts

Crystal-Size-Dependent Structural Transitions in Nanoporous Crystals: Adsorption-Induced Transitions in ZIF-8

KAUST Repository

Zhang, Chen

2014-09-04

© 2014 American Chemical Society. Understanding the crystal-size dependence of both guest adsorption and structural transitions of nanoporous solids is crucial to the development of these materials. We find that nano-sized metal-organic framework (MOF) crystals have significantly different guest adsorption properties compared to the bulk material. A new methodology is developed to simulate the adsorption and transition behavior of entire MOF nanoparticles. Our simulations predict that the transition pressure significantly increases with decreasing particle size, in agreement with crystal-size-dependent experimental measurements of the N2-ZIF-8 system. We also propose a simple core-shell model to examine this effect on length scales that are inaccessible to simulations and again find good agreement with experiments. This study is the first to examine particle size effects on structural transitions in ZIFs and provides a thermodynamic framework for understanding the underlying mechanism.

Molecular packing and magnetic properties of lithium naphthalocyanine crystals: hollow channels enabling permeability and paramagnetic sensitivity to molecular oxygen

Science.gov (United States)

Pandian, Ramasamy P.; Dolgos, Michelle; Marginean, Camelia; Woodward, Patrick M.; Hammel, P. Chris; Manoharan, Periakaruppan T.; Kuppusamy, Periannan

2009-01-01

The synthesis, structural framework, magnetic and oxygen-sensing properties of a lithium naphthalocyanine (LiNc) radical probe are presented. LiNc was synthesized in the form of a microcrystalline powder using a chemical method and characterized by electron paramagnetic resonance (EPR) spectroscopy, magnetic susceptibility, powder X-ray diffraction analysis, and mass spectrometry. X-Ray powder diffraction studies revealed a structural framework that possesses long, hollow channels running parallel to the packing direction. The channels measured approximately 5.0 × 5.4 Å2 in the two-dimensional plane perpendicular to the length of the channel, enabling diffusion of oxygen molecules (2.9 × 3.9 Å2) through the channel. The powdered LiNc exhibited a single, sharp EPR line under anoxic conditions, with a peak-to-peak linewidth of 630 mG at room temperature. The linewidth was sensitive to surrounding molecular oxygen, showing a linear increase in pO2 with an oxygen sensitivity of 31.2 mG per mmHg. The LiNc microcrystals can be further prepared as nano-sized crystals without the loss of its high oxygen-sensing properties. The thermal variation of the magnetic properties of LiNc, such as the EPR linewidth, EPR intensity and magnetic susceptibility revealed the existence of two different temperature regimes of magnetic coupling and hence differing columnar packing, both being one-dimensional antiferromagnetic chains but with differing magnitudes of exchange coupling constants. At a temperature of ∼50 K, LiNc crystals undergo a reversible phase transition. The high degree of oxygen-sensitivity of micro- and nano-sized crystals of LiNc, combined with excellent stability, should enable precise and accurate measurements of oxygen concentration in biological systems using EPR spectroscopy. PMID:19809598

Scintillation properties of pure and Ca-doped ZnWO4 crystals

International Nuclear Information System (INIS)

Danevich, F.A.; Shkulkova, O.G.; Henry, S.; Kraus, H.; McGowan, R.; Mikhailik, V.B.; Telfer, J.

2008-01-01

Following the investigations of the structure and scintillation properties of Ca-doped zinc tungstate powder [phys. stat. sol. (a) 204, 730 (2007)] a single-crystal of ZnWO 4 -Ca (0.5 mol%) was grown and characterised. The relative light output, energy resolution and decay characteristics were measured for pure and Ca-doped ZnWO 4 scintillators. An increase in the light yield of ∝40% compared with the undoped crystal, and an energy resolution 9.6% ( 137 Cs) were obtained for Ca-doped ZnWO 4 . The observed improvement is attributed to the reduction of self-absorption (bleaching) of the crystal. The cause of bleaching as well as the possible contribution of scattering is discussed. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

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Effect of temperature on the morphology and electro-optical properties of liquid crystal physical gel

International Nuclear Information System (INIS)

Leaw, W.L.; Mamat, C.R.; Triwahyono, S.; Jalil, A.A.; Bidin, N.

2016-01-01

Liquid crystal physical gels were (thermally) prepared with cholesteryl stearate as a gelator in nematic liquid crystal, 4-cyano-4′-pentylbiphenyl. The electro-optical performance of liquid crystal physical gels is almost entirely dependent on the gels' inherent morphology. This study involved an empirical investigation of the relationships among all of the gelation temperature, morphology, and electro-optical properties. Besides continuous cooling at room temperature, isothermal cooling was also performed at both 18 and 0 °C, corresponding to near-solid and solid phases of 4-cyano-4′-pentylbiphenyl respectively. Nevertheless, the liquid crystal physical gel was also isothermally rapidly cooled using liquid nitrogen. Polarizing optical microscopy showed that the gel structure became thinner when isothermal cooling was carried out. These thinner gel aggregates then interconnected to form larger liquid crystal domains. Moreover, it was also revealed that the gel networks were randomized. Electron spin resonance results showed that the liquid crystal director orientation was severely randomized in the presence of gel networks. Conversely, isothermal cooling using liquid nitrogen generated a higher liquid crystal director orientation order. The 6.0 wt% cholesteryl stearate/4-cyano-4′-pentylbiphenyl physical gel that was isothermally cooled using liquid nitrogen showed the lowest response time in a twisted nematic mode optical cell. - Graphical abstract: Liquid crystal physical gel was prepared using nematic liquid crystal, 4-cyano-4′-pentylbiphenyl and cholesteryl stearate as gelator. Isothermal cooling at lower temperature produced thinner gel network and larger liquid crystal domain. - Highlights: • 5CB nematic liquid crystal was successfully gelled by cholesteryl stearate gelator. • The morphology of gel network was controlled by different cooling conditions. • Thinner gel network was formed by the rapid cooling using liquid nitrogen. • Enhanced

Effect of temperature on the morphology and electro-optical properties of liquid crystal physical gel

Energy Technology Data Exchange (ETDEWEB)

Leaw, W.L. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Mamat, C.R., E-mail: che@kimia.fs.utm.my [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Triwahyono, S. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Jalil, A.A. [Department of Chemical Engineering, Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Centre of Hydrogen Energy, Institute of Future Energy, Univerisiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Bidin, N. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia)

2016-12-01

Liquid crystal physical gels were (thermally) prepared with cholesteryl stearate as a gelator in nematic liquid crystal, 4-cyano-4′-pentylbiphenyl. The electro-optical performance of liquid crystal physical gels is almost entirely dependent on the gels' inherent morphology. This study involved an empirical investigation of the relationships among all of the gelation temperature, morphology, and electro-optical properties. Besides continuous cooling at room temperature, isothermal cooling was also performed at both 18 and 0 °C, corresponding to near-solid and solid phases of 4-cyano-4′-pentylbiphenyl respectively. Nevertheless, the liquid crystal physical gel was also isothermally rapidly cooled using liquid nitrogen. Polarizing optical microscopy showed that the gel structure became thinner when isothermal cooling was carried out. These thinner gel aggregates then interconnected to form larger liquid crystal domains. Moreover, it was also revealed that the gel networks were randomized. Electron spin resonance results showed that the liquid crystal director orientation was severely randomized in the presence of gel networks. Conversely, isothermal cooling using liquid nitrogen generated a higher liquid crystal director orientation order. The 6.0 wt% cholesteryl stearate/4-cyano-4′-pentylbiphenyl physical gel that was isothermally cooled using liquid nitrogen showed the lowest response time in a twisted nematic mode optical cell. - Graphical abstract: Liquid crystal physical gel was prepared using nematic liquid crystal, 4-cyano-4′-pentylbiphenyl and cholesteryl stearate as gelator. Isothermal cooling at lower temperature produced thinner gel network and larger liquid crystal domain. - Highlights: • 5CB nematic liquid crystal was successfully gelled by cholesteryl stearate gelator. • The morphology of gel network was controlled by different cooling conditions. • Thinner gel network was formed by the rapid cooling using liquid nitrogen. �

Optical Properties of the Fresnoite Ba2TiSi2O8 Single Crystal

Directory of Open Access Journals (Sweden)

Chuanying Shen

2017-02-01

Full Text Available In this work, using large-sized single crystals of high optical quality, the optical properties of Ba2TiSi2O8 were systematically investigated, including transmission spectra, refractive indices and nonlinear absorption properties. The crystal exhibits a high transmittance (>84% over a wide wavelength range from 340 to 2500 nm. The refractive indices in the range from 0.31256 to 1.01398 μm were measured, and Sellmeier’s equations were fitted by the least squares method. The nonlinear absorption properties were studied by using the open-aperture Z-scan technique, with a nonlinear absorption coefficient measured to be on the order of 0.257 cm/GW at the peak power density of 16.4 GW/cm2. Such high transmittance and wide transparency indicate that optical devices using the Ba2TiSi2O8crystal can be applied over a wide wavelength range. Furthermore, the small nonlinear absorption observed in Ba2TiSi2O8 will effectively increase the optical conversion efficiency, decreasing the generation of laser damage of the optical device.

Properties and applications of chemically functionalized graphene

International Nuclear Information System (INIS)

Craciun, M F; Khrapach, I; Barnes, M D; Russo, S

2013-01-01

The vast and yet largely unexplored family of graphene materials has great potential for future electronic devices with novel functionalities. The ability to engineer the electrical and optical properties in graphene by chemically functionalizing it with a molecule or adatom is widening considerably the potential applications targeted by graphene. Indeed, functionalized graphene has been found to be the best known transparent conductor or a wide gap semiconductor. At the same time, understanding the mechanisms driving the functionalization of graphene with hydrogen is proving to be of fundamental interest for energy storage devices. Here we discuss recent advances on the properties and applications of chemically functionalized graphene. (topical review)

Photoluminescent properties of single crystal diamond microneedles

Science.gov (United States)

Malykhin, Sergey A.; Ismagilov, Rinat R.; Tuyakova, Feruza T.; Obraztsova, Ekaterina A.; Fedotov, Pavel V.; Ermakova, Anna; Siyushev, Petr; Katamadze, Konstantin G.; Jelezko, Fedor; Rakovich, Yury P.; Obraztsov, Alexander N.

2018-01-01

Single crystal needle-like diamonds shaped as rectangular pyramids were produced by combination of chemical vapor deposition and selective oxidation with dimensions and geometrical characteristics depending on the deposition process parameters. Photoluminescence spectra and their dependencies on wavelength of excitation radiation reveal presence of nitrogen- and silicon-vacancy color centers in the diamond crystallites. Photoluminescence spectra, intensity mapping, and fluorescence lifetime imaging microscopy indicate that silicon-vacancy centers are concentrated at the crystallites apex while nitrogen-vacancy centers are distributed over the whole crystallite. Dependence of the photoluminescence on excitation radiation intensity demonstrates saturation and allows estimation of the color centers density. The combination of structural parameters, geometry and photoluminescent characteristics are prospective for advantageous applications of these diamond crystallites in quantum information processing and optical sensing.

Dislocation-defect interactions and mechanical properties of crystals

International Nuclear Information System (INIS)

Granato, A.V.

1975-01-01

The influence of dislocation-defect interactions on mechanical properties of crystals is reviewed. Interactions are separated into those producing pinning and those producing viscous drag. Deformation behavior is classified according to the strength of the drag. For small drag, inertial effects become important. For intermediate drag, traditional theories resting on rate theory treatments become applicable. For large drag, viscoelastic behavior is obtained. Measurements are examined for information concerning the basic nature of different sources of short and long range pinning and of drag

Chemical conversion of cisplatin and carboplatin with histidine in a model protein crystallized under sodium iodide conditions

Energy Technology Data Exchange (ETDEWEB)

Tanley, Simon W. M.; Helliwell, John R., E-mail: john.helliwell@manchester.ac.uk [University of Manchester, Brunswick Street, Manchester M13 9PL (United Kingdom)

2014-08-29

Crystals of HEWL with cisplatin and HEWL with carboplatin grown in sodium iodide conditions both show a partial chemical transformation of cisplatin or carboplatin to a transiodoplatin (PtI{sub 2}X{sub 2}) form. The binding is only at the N{sup δ} atom of His15. A further Pt species (PtI{sub 3}X) is also seen, in both cases bound in a crevice between symmetry-related protein molecules. Cisplatin and carboplatin are platinum anticancer agents that are used to treat a variety of cancers. Previous X-ray crystallographic studies of carboplatin binding to histidine in hen egg-white lysozyme (HEWL) showed a partial chemical conversion of carboplatin to cisplatin owing to the high sodium chloride concentration used in the crystallization conditions. Also, the co-crystallization of HEWL with carboplatin in sodium bromide conditions resulted in the partial conversion of carboplatin to the transbromoplatin form, with a portion of the cyclobutanedicarboxylate (CBDC) moiety still present. The results of the co-crystallization of HEWL with cisplatin or carboplatin in sodium iodide conditions are now reported in order to determine whether the cisplatin and carboplatin converted to the iodo form, and whether this took place in a similar way to the partial conversion of carboplatin to cisplatin in NaCl conditions or to transbromoplatin in NaBr conditions as seen previously. It is reported here that a partial chemical transformation has taken place to a transplatin form for both ligands. The NaI-grown crystals belonged to the monoclinic space group P2{sub 1} with two molecules in the asymmetric unit. The chemically transformed cisplatin and carboplatin bind to both His15 residues, i.e. in each asymmetric unit. The binding is only at the N{sup δ} atom of His15. A third platinum species is also seen in both conditions bound in a crevice between symmetry-related molecules. Here, the platinum is bound to three I atoms identified based on their anomalous difference electron densities

Thermodynamic properties of a liquid crystal carbosilane dendrimer

Science.gov (United States)

Samosudova, Ya. S.; Markin, A. V.; Smirnova, N. N.; Ogurtsov, T. G.; Boiko, N. I.; Shibaev, V. P.

2016-11-01

The temperature dependence of the heat capacity of a first-generation liquid crystal carbosilane dendrimer with methoxyphenyl benzoate end groups is studied for the first time in the region of 6-370 K by means of precision adiabatic vacuum calorimetry. Physical transformations are observed in this interval of temperatures, and their standard thermodynamic characteristics are determined and discussed. Standard thermodynamic functions C p ° ( T), H°( T) - H°(0), S°( T) - S°(0), and G°( T) - H°(0) are calculated from the obtained experimental data for the region of T → 0 to 370 K. The standard entropy of formation of the dendrimer in the partially crystalline state at T = 298.15 K is calculated, and the standard entropy of the hypothetic reaction of its synthesis at this temperature is estimated. The thermodynamic properties of the studied dendrimer are compared to those of second- and fourth-generation liquid crystal carbosilane dendrimers with the same end groups studied earlier.

Effects of heat treatment temperature on morphology and properties of opal crystal

International Nuclear Information System (INIS)

Duan Tao; China Academy of Engineering Physics, Mianyang; Peng Tongjiang; Chen Jiming; Tang Yongjian

2008-01-01

The monodispersed SiO 2 microspheres were synthesized by reactant mixed equally. The colloid crystal templates were assemblied by vertical sedimentation method in ethanol at certain temperatures, and the effects of the heat treatment temperature on the morphology and the properties of opal colloid crystals were investigated. SEM, TCr-DSC results indicate SiO 2 colloid templates should be heat treated at 700-800 degree C, enhancing the conglutination and mechanistic intensity of opal templates. UV-Vis analysis result indicates that the heat treatment process can remove the photonic band gap location of the opal colloid crystals, and with the heat treatment temperature increasing gradually, blue shift occurs and the gap narrows. (authors)

Effect of antimony incorporation on structural properties of CuInS2 crystals

International Nuclear Information System (INIS)

Ben Rabeh, M.; Chaglabou, N.; Kanzari, M.

2010-01-01

CuInS 2 (CIS) single crystals doped with 1, 2, 3 and 4 atomic percent (at.%) of antimony (Sb) were grown by the horizontal Bridgman method. The effect of Sb doping on the structural properties of CIS crystal was studied by means of X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM) and PL measurements. X-ray diffraction data suggests that the doping of Sb in the CIS single crystals does not affect the tetragonal (chalcopyrite) crystal structure and exhibited a (1 1 2) preferred orientation. In addition, with increasing Sb concentration, the X-ray diffraction analysis show that Sb doped CIS crystals are more crystallized and the diffraction peaks of the CuInS 2 phase were more pronounced in particular the (1 1 2) plane. EDAX study revealed that Sb atoms can occupy the indium site and/or occupying the sulfur site to make an acceptor. PL spectra of undoped and Sb doped CIS crystals show two emission peaks at 1.52 and 1.62 eV, respectively which decreased with increasing atomic percent antimony. Sb doped CIS crystals show p-type conductivity.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences; Volume 130; Issue 2. Polynuclear and one-dimensional cyanide-bridged heterobimetallic complexes: synthesis, crystal structures and magnetic properties. JINGWEN SHI WENLONG LAN YIN ZHOU CHONGCHONG XUE QINGYUN LIU DAOPENG ZHANG. Volume 130 Issue ...

Effect of ozone gas processing on physical and chemical properties ...

African Journals Online (AJOL)

Purpose: To investigate the effects of ozone treatment on chemical and physical properties of wheat (Triticum aestivum L.) gluten, glutenin and gliadin. Methods: Wheat proteins isolated from wheat flour were treated with ozone gas. The physical and chemical properties of gluten proteins were investigated after treatment ...

Anisotropic surface physicochemical properties of spodumene and albite crystals: Implications for flotation separation

Science.gov (United States)

Xu, Longhua; Peng, Tiefeng; Tian, Jia; Lu, Zhongyuan; Hu, Yuehua; Sun, Wei

2017-12-01

Aluminosilicate minerals (e.g., spodumene, albite) have complex crystal structures and similar surface chemistries, but they have poor selectivity compared to traditional fatty acid collectors, making flotation separation difficult. Previous research has mainly considered the mineral crystal structure as a whole. In contrast, the surface characteristics at the atomic level and the effects of different crystal interfaces on the flotation behavior have rarely been investigated. This study focuses on investigating the surface anisotropy quantitatively, including the chemical bond characteristics, surface energies, and broken bond densities, using density functional theory and classical theoretical calculations. In addition, the anisotropy of the surface wettability and adsorption characteristics were examined using contact angle, zeta potential, and Fourier-transform infrared measurements. Finally, these surface anisotropies with different flotation behaviors were investigated and interpreted using molecular dynamics simulations, scanning electron microscopy, and X-ray photoelectron spectroscopy. This systematic research offers new ideas concerning the selective grinding and stage flotation of aluminosilicate minerals based on the crystal characteristics.

Can pharmaceutical co-crystals provide an opportunity to modify the biological properties of drugs?

Science.gov (United States)

Dalpiaz, Alessandro; Pavan, Barbara; Ferretti, Valeria

2017-08-01

Poorly soluble and/or permeable molecules jeopardize the discovery and development of innovative medicines. Pharmaceutical co-crystals, formed by an active pharmaceutical substance (API) and a co-crystal former, can show enhanced dissolution and permeation values compared with those of the parent crystalline pure phases. It is currently assumed that co-crystallization with pharmaceutical excipients does not affect the pharmacological activity of an API or, indeed, might even improve physical properties such as solubility and permeability. However, as we highlight here, the biological behavior of co-crystals can differ drastically with respect to that of their parent physical mixtures. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chemical structure, network topology, and porosity effects on the mechanical properties of Zeolitic Imidazolate Frameworks

OpenAIRE

Tan, J. C.; Bennett, T. D.; Cheetham, A. K.

2010-01-01

The mechanical properties of seven zeolitic imidazolate frameworks (ZIFs) based on five unique network topologies have been systematically characterized by single-crystal nanoindentation studies. We demonstrate that the elastic properties of ZIF crystal structures are strongly correlated to the framework density and the underlying porosity. For the systems considered here, the elastic modulus was found to range from 3 to 10 GPa, whereas the hardness property lies between 300 MPa and 1.1 GPa. ...

The effect of linear imperfection in [001] direction on the thermal properties of silver crystal

Directory of Open Access Journals (Sweden)

J Davoodi

2013-09-01

Full Text Available The aim of this investigation was to calculate the thermal properties of silver crystal in the presence of linear imperfection. The simulations were performed by molecular dynamics simulation technique in NPT as well as NVT ensemble based on quantum Sutton-Chen many body potential. The thermal properties including cohesive energy, melting temperature, isobaric heat capacity and thermal expansion of imperfect silver crystal were calculated and compared to those of the perfect crystal. Moreover, the quantities such as radial distribution function, order parameter and lindemann index were calculated in order to obtain information on crystal structure and disorder in atoms. All calculations were done both with liner imperfection in [001] direction and without imperfection at different temperature. The simulation results show that cohesive energy, linear thermal expansion coefficient increase and melting temperature, latent heat of fusion decrease with increasing linear imperfection. Also, the results show that linear imperfection has no effect on the heat capacity.

Chemical properties of mendelevium

International Nuclear Information System (INIS)

Hulet, E.K.

1980-01-01

The isotope 256 Md is nearly always employed for chemical studies of this element. This nuclide can be made by bombardment of fractions of a microgram of 254 Es with intense alpha-particle beams which will produce about 10 6 atoms of 256 Md with a half-life of 77 minutes. Even with the most intense ion beams and the largest available quantities of target isotope, about 10 6 atoms at a time is all the Md that can be produced for chemical studies. This lack of sufficient sample size coupled with the very short lifetimes of the few atoms produced has severly restricted the gathering and broadening of our knowledge concerning the properties of Md and the heavier elements. To illustrate, the literature contains a mere eleven references to the chemical studies of Md, and none of these deal with bulk properties associated with element found in solid phases. Some of these findings are: Md was found to be more volatile than other actinide metals which lead to the belief that it is divalent in the metallic state; separation of Md from the other actinides can be accomplished either by reduction of Md to the divalent state or by chromatographic separations with Md remaining in the tripositive state; extraction of Md with bis(2-ethylhexyl)phosphoric acid is much poorer than the extraction of the neighboring tripositive actinides; attempts to oxidize Md wih sodium bismuthate failed to show any evidence of Md 4+ ; standard reduction potential of Md 3+ was found to be close to -0.1 volt; Md 3+ can be reduced to Md(Hg) by sodium amalgams and by electrolysis; the electrochemical behavior of Md is very similar to that of Fm and can be summarized in the equation, Md 2+ + 2e - = Md(Hg), and E 0 = 1.5 V

Ethanol vapor-induced fabrication of colloidal crystals with controllable layers and photonic properties.

Science.gov (United States)

Zhou, Chuanqiang; Gong, Xiangxiang; Han, Jie; Guo, Rong

2015-04-07

A novel fabrication method for colloidal crystals has been proposed for the first time in this research. In this method, a suspension droplet containing colloidal particles was first spread onto a glass substrate placed in an ethanol vapor environment, and then the droplet was extracted from its center. In that case, the contact angle of the droplet reduced and the contact line receded toward the center, during which the colloidal particles self-assembled and immobilized forming a 2D colloidal crystal film on the substrate upon drying the liquid film. Alternately spreading and drying of suspension films could construct fine multi-layers of colloidal crystals, while the ethanol fraction in the suspension would be used to control roughly but rapidly the layer numbers of colloidal crystals. It was also found that the photonic properties of resultant colloidal crystal films were elevated by increasing their thickness.

Effects of crystal size on the mechanical properties of a lithium disilicate glass-ceramic

Energy Technology Data Exchange (ETDEWEB)

Li, D. [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, 28 West Xianning Road, Xi’an 710049 (China); Guo, J.W.; Wang, X.S; Zhang, S.F. [State Key Laboratory of Military Stomatology, Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, 145 West Changle Road, Xi’an 710032 (China); He, L., E-mail: helin@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, 28 West Xianning Road, Xi’an 710049 (China)

2016-07-04

Crystal size of lithium disilicate (LD) phase in a LD glass-ceramic was changed by thermally controlled crystallization of a precursory LD glass at different temperatures. Effects of the crystal size on the mechanical properties of the glass-ceramic were investigated. It was found that the flexural strength presented a hump-like variation trend with increasing the crystal size, the hardness monotonously decreased at the same time. It was further confirmed that micro residual compressive stresses existed inside the LD crystals due to the thermal expansion mismatch between the glass matrix and the crystalline phase. The levels of the residual stresses increased with increasing the crystal size. The crystal size performed dual effects on the flexural strength of the glass-ceramic: an “interlocking effect” caused by larger-sized LD crystals and a “micro residual stress effect” related to the balancing tensile stresses in the glass matrix. Higher residual tensile stresses in the glass matrix induced by larger-sized LD crystals would counteract the “interlocking effect” of the crystals, causing the strength degradation. The hardness of the glass-ceramic was mainly controlled by the “micro residual stress effect”.

Improvement of several properties of lead tungstate crystals with different doping ions

CERN Document Server

Auffray, Etiennette; Baccaro, Stefania; Cecilia, Angelica; Dafinei, Ioan; Diemoz, Marcella; Jarolímek, O; Korzhik, Mikhail; Lecoq, Paul; Nikl, M

1998-01-01

A very good radiation resistance of Lead Tungstate crystals is mandatory for their use in the high precision electromagnetic calorimeter of the CMS experiment at LHC. Since the beginning of 1996 we have organised systematic investigations of the parameters influencing the radiation hardness of this crystal. Two classes of parameters have been particularly studied, the first one related to the control of the stoichiometry and structure associated defects, the second one connected with the suppression and the charge compensation of existing defects with different kinds of doping ions. This paper reports about the second part of this study and complements a first paper where the role of the stoichiometry was already discussed. Results of tests are given on a significant statistical sample of full size crystals ( 23cm) which show a considerable improvement in the optical properties and the radiation resistance of appropriately doped crystals.

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Relationship between mechanical properties and crystal structure in cocrystals and salt of paracetamol.

Science.gov (United States)

Ahmed, Hamzah; Shimpi, Manishkumar R; Velaga, Sitaram P

2017-01-01

Objectives were to study mechanical properties of various solid forms of paracetamol and relate to their crystal structures. Paracetamol form I (PRA), its cocrystals with oxalic acid (PRA-OXA) and 4,4-bipyridine (PRA-BPY) and hydrochloride salt (PRA-HCL) were selected. Cocrystals and salt were scaled-up using rational crystallization methods. The resulting materials were subjected to different solid-state characterizations. The powders were sieved and 90-360 µm sieve fraction was considered. These powders were examined by scanning electron microscopy (SEM) and densities were determined. Tablets were made at applied pressures of 35-180 MPa under controlled conditions and the tablet height, diameter and hardness were measured. Tensile strength and porosity of the tablets were estimated using well known models. Crystal structures of these systems were visualized and slip planes were identified. Cocrystal and salt of PRA were physically pure. Sieved powders had comparable morphologies and particle size. The apparent and theoretical densities of powders were similar, but no clear trends were observed. The tensile strengths of these compacts were increased with increasing pressure whereas tabletability decreased in the order oxalic acid > PRA-HCL ≈ PRA-OXA > BPY > PRA-BPY. Tablet tensile strength decreases exponentially with increasing porosity with the exception of PRY-BPY and BPY. Slip plane prediction based on attachment energies may not be independently considered. However, it was possible to explain the improved mechanical properties of powders based on the crystal structure. Cocrystallization and salt formation have introduced structural features that are responsible for improved tableting properties of PRA.

Crystal growth, spectral and laser properties of Nd:LSAT single crystal

Science.gov (United States)

Hu, P. C.; Yin, J. G.; Zhao, C. C.; Gong, J.; He, X. M.; Zhang, L. H.; Liang, X. Y.; Hang, Y.

2011-10-01

Nd:(La, Sr)(Al, Ta)O3 (Nd:LSAT) crystal was grown by the Czochralski method. The absorption and fluorescence spectra of Nd:LSAT crystal at room temperature were investigated. With a fiber-coupled diode laser as pump source, the continuous-wave (CW) laser action of Nd:LSAT crystal was demonstrated. The result of diode-pumped laser operation of Nd:LSAT crystal single crystal is reported for what is to our knowledge the first time. The maximum output power at 1064 nm was obtained to be 165 mW under the incident pump power of 3 W, with the slope efficiency 10.9%.

Effects of crystal refining on wear behaviors and mechanical properties of lithium disilicate glass-ceramics.

Science.gov (United States)

Zhang, Zhenzhen; Guo, Jiawen; Sun, Yali; Tian, Beimin; Zheng, Xiaojuan; Zhou, Ming; He, Lin; Zhang, Shaofeng

2018-05-01

The purpose of this study is to improve wear resistance and mechanical properties of lithium disilicate glass-ceramics by refining their crystal sizes. After lithium disilicate glass-ceramics (LD) were melted to form precursory glass blocks, bar (N = 40, n = 10) and plate (N = 32, n = 8) specimens were prepared. According to the differential scanning calorimetry (DSC) of precursory glass, specimens G1-G4 were designed to form lithium disilicate glass-ceramics with different crystal sizes using a two-step thermal treatment. In the meantime, heat-pressed lithium disilicate glass-ceramics (GC-P) and original ingots (GC-O) were used as control groups. Glass-ceramics were characterized using X-ray diffraction (XRD) and were tested using flexural strength test, nanoindentation test and toughness measurements. The plate specimens were dynamically loaded in a chewing simulator with 350 N up to 2.4 × 10 6 loading cycles. The wear analysis of glass-ceramics was performed using a 3D profilometer after every 300,000 wear cycles. Wear morphologies and microstructures were analyzed by scanning electron microscopy (SEM). One-way analysis of variance (ANOVA) was used to analyze the data. Multiple pairwise comparisons of means were performed by Tukey's post-hoc test. Materials with different crystal sizes (p properties. Specifically, G3 with medium-sized crystals presented the highest flexural strength, hardness, elastic modulus and fracture toughness. G1 and G2 with small-sized crystals showed lower flexural strength, whereas G4, GC-P, and GC-O with large-sized crystals exhibited lower hardness and elastic modulus. The wear behaviors of all six groups showed running-in wear stage and steady wear stage. G3 showed the best wear resistance while GC-P and GC-O exhibited the highest wear volume loss. After crystal refining, lithium disilicate glass-ceramic with medium-sized crystals showed the highest wear resistance and mechanical properties. Copyright © 2018

Crystal chemistry, properties and synthesis of microporous silicates containing transition elements

International Nuclear Information System (INIS)

Chukanov, Nikita V; Pekov, Igor V; Rastsvetaeva, Ramiza K

2004-01-01

The review surveys and generalises recent data on synthesis methods, physicochemical properties and crystal chemistry of silicate microporous materials containing transition elements (amphoterosilicates). The frameworks of these materials, unlike those of usual aluminosilicate zeolites, are built from tetrahedrally coordinated atoms along with atoms of various elements (Ti, Nb, Zr, Ta, Sn, W, Fe, Mn, Zn, etc.) with coordination numbers of 6 or 5. Many amphoterosilicates possess ion-exchange properties and can serve as catalysts for redox reactions, sorbents, etc. The structural diversity of synthetic and natural amphoterosilicates provides the basis for the preparation of microporous materials with different properties.

Comparative study of the chemical properties of palm oil extracted ...

African Journals Online (AJOL)

The chemical properties of oil samples determined were free fatty acid, acid value, saponification value, peroxide value, iodine value and moisture content. The experimental design adopted was 3 x 2 x 2 factorial randomized complete block design in three replicates. The data of chemical properties of extracted palm oil ...

XRD- and infrared-probed anisotropic thermal expansion properties of an organic semiconducting single crystal.

Science.gov (United States)

Mohanraj, J; Capria, E; Benevoli, L; Perucchi, A; Demitri, N; Fraleoni-Morgera, A

2018-01-17

The anisotropic thermal expansion properties of an organic semiconducting single crystal constituted by 4-hydroxycyanobenzene (4HCB) have been probed by XRD in the range 120-300 K. The anisotropic thermal expansion coefficients for the three crystallographic axes and for the crystal volume have been determined. A careful analysis of the crystal structure revealed that the two different H-bonds stemming from the two independent, differently oriented 4HCB molecules composing the unit cell have different rearrangement patterns upon temperature variations, in terms of both bond length and bond angle. Linearly Polarized Mid InfraRed (LP-MIR) measurements carried out in the same temperature range, focused on the O-H bond spectral region, confirm this finding. The same LP-MIR measurements, on the basis of a semi-empirical relation and of geometrical considerations and assumptions, allowed calculation of the -CNH-O- hydrogen bond length along the a and b axes of the crystal. In turn, the so-calculated -CNH-O- bond lengths were used to derive the thermal expansion coefficients along the corresponding crystal axes, as well as the volumetric one, using just the LP-MIR data. Reasonable to good agreement with the same values obtained from XRD measurements was obtained. This proof-of-principle opens interesting perspectives about the possible development of a rapid, low cost and industry-friendly assessment of the thermal expansion properties of organic semiconducting single crystals (OSSCs) involving hydrogen bonds.

High-purity germanium crystal growing

International Nuclear Information System (INIS)

Hansen, W.L.; Haller, E.E.

1982-10-01

The germanium crystals used for the fabrication of nuclear radiation detectors are required to have a purity and crystalline perfection which is unsurpassed by any other solid material. These crystals should not have a net electrically active impurity concentration greater than 10 10 cm - 3 and be essentially free of charge trapping defects. Such perfect crystals of germanium can be grown only because of the highly favorable chemical and physical properties of this element. However, ten years of laboratory scale and commercial experience has still not made the production of such crystals routine. The origin and control of many impurities and electrically active defect complexes is now fairly well understood but regular production is often interrupted for long periods due to the difficulty of achieving the required high purity or to charge trapping in detectors made from crystals seemingly grown under the required conditions. The compromises involved in the selection of zone refining and crystal grower parts and ambients is discussed and the difficulty in controlling the purity of key elements in the process is emphasized. The consequences of growing in a hydrogen ambient are discussed in detail and it is shown how complexes of neutral defects produce electrically active centers

On The Importance of Connecting Laboratory Measurements of Ice Crystal Growth with Model Parameterizations: Predicting Ice Particle Properties

Science.gov (United States)

Harrington, J. Y.

2017-12-01

Parameterizing the growth of ice particles in numerical models is at an interesting cross-roads. Most parameterizations developed in the past, including some that I have developed, parse model ice into numerous categories based primarily on the growth mode of the particle. Models routinely possess smaller ice, snow crystals, aggregates, graupel, and hail. The snow and ice categories in some models are further split into subcategories to account for the various shapes of ice. There has been a relatively recent shift towards a new class of microphysical models that predict the properties of ice particles instead of using multiple categories and subcategories. Particle property models predict the physical characteristics of ice, such as aspect ratio, maximum dimension, effective density, rime density, effective area, and so forth. These models are attractive in the sense that particle characteristics evolve naturally in time and space without the need for numerous (and somewhat artificial) transitions among pre-defined classes. However, particle property models often require fundamental parameters that are typically derived from laboratory measurements. For instance, the evolution of particle shape during vapor depositional growth requires knowledge of the growth efficiencies for the various axis of the crystals, which in turn depends on surface parameters that can only be determined in the laboratory. The evolution of particle shapes and density during riming, aggregation, and melting require data on the redistribution of mass across a crystals axis as that crystal collects water drops, ice crystals, or melts. Predicting the evolution of particle properties based on laboratory-determined parameters has a substantial influence on the evolution of some cloud systems. Radiatively-driven cirrus clouds show a broader range of competition between heterogeneous nucleation and homogeneous freezing when ice crystal properties are predicted. Even strongly convective squall

Studies on various properties of pure and Li-doped Barium Hydrogen Phosphate (BHP) single crystals

Energy Technology Data Exchange (ETDEWEB)

Nallamuthu, D. [Department of Physics, Aditanar College of Arts and Science, Tiruchendur 628216, Tamil Nadu (India); Selvarajan, P., E-mail: pselvarajanphy@yahoo.co.i [Department of Physics, Aditanar College of Arts and Science, Tiruchendur 628216, Tamil Nadu (India); Freeda, T.H. [Physics Research Centre, S.T. Hindu College, Nagercoil 629002 (India)

2010-12-15

Single crystals of pure and Li-doped barium hydrogen phosphate (BHP) were grown by solution method with gel technique. Various properties of the harvested crystals were studied by carrying out single crystal and powder XRD, FTIR, TG/DTA, microhardness and dielectric studies. Atomic absorption study was carried out for Li-doped BHP crystal to check the presence of Li dopants. Unit cell dimensions and diffracting planes of the grown crystals have been identified from XRD studies. Functional groups of the title compounds have been identified from FTIR studies. Density of the grown crystals was calculated using the XRD data. Thermal stability of the samples was checked by TG/DTA studies. Mechanical and dielectric characterizations of the harvested pure and Li-doped BHP crystals reveal the mechanical strength and ferroelectric transition. The observed results are reported and discussed.

Piezoelectric Ca{sub 3}NbGa{sub 3}Si{sub 2}O{sub 14} crystal: crystal growth, piezoelectric and acoustic properties

Energy Technology Data Exchange (ETDEWEB)

Roshchupkin, Dmitry; Emelin, Evgenii [Russian Academy of Sciences, Institute of Microelectronics Technology and High-Purity Materials, Chernogolovka, Moscow District (Russian Federation); National University of Science and Technology MISiS, Moscow (Russian Federation); Ortega, Luc [Univ. Paris-Sud, CNRS, UMR 8502, Laboratoire de Physique des Solides, Orsay Cedex (France); Plotitcyna, Olga; Irzhak, Dmitry [Russian Academy of Sciences, Institute of Microelectronics Technology and High-Purity Materials, Chernogolovka, Moscow District (Russian Federation); Erko, Alexei; Zizak, Ivo; Vadilonga, Simone [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Institute for Nanometre Optics and Technology, Berlin (Germany); Buzanov, Oleg [FOMOS Materials Co., Moscow (Russian Federation); Leitenberger, Wolfram [Universitaet Potsdam Institut fuer Physik, Potsdam (Germany)

2016-08-15

Ca{sub 3}NbGa{sub 3}Si{sub 2}O{sub 14} (CNGS), a five-component crystal of lanthanum-gallium silicate group, was grown by the Czochralski method. The parameters of the elementary unit cell of the crystal were measured by powder diffraction. The independent piezoelectric strain coefficients d{sub 11} and d{sub 14} were determined by the triple-axis X-ray diffraction in the Bragg and Laue geometries. Excitation and propagation of surface acoustic waves (SAW) were studied by high-resolution X-ray diffraction at BESSY II synchrotron radiation source. The velocity of SAW propagation and power flow angles in the Y-, X- and yxl/+36 {sup circle} -cuts of the CNGS crystal were determined from the analysis of the diffraction spectra. The CNGS crystal was found practically isotropic by its acoustic properties. (orig.)

The structure and properties of vacancies in Si nano-crystals calculated by real space pseudopotential methods

International Nuclear Information System (INIS)

Beckman, S.P.; Chelikowsky, James R.

2007-01-01

The structure and properties of vacancies in a 2 nm Si nano-crystal are studied using a real space density functional theory/pseudopotential method. It is observed that a vacancy's electronic properties and energy of formation are directly related to the local symmetry of the vacancy site. The formation energy for vacancies and Frenkel pair are calculated. It is found that both defects have lower energy in smaller crystals. In a 2 nm nano-crystal the energy to form a Frenkel pair is 1.7 eV and the energy to form a vacancy is no larger than 2.3 eV. The energy barrier for vacancy diffusion is examined via a nudged elastic band algorithm

Optical power limiting and transmitting properties of cadmium iodide single crystals: Temperature dependence

Energy Technology Data Exchange (ETDEWEB)

Miah, M. Idrish, E-mail: m.miah@griffith.edu.a [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)] [Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)] [Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

2009-09-14

Optical limiting properties of the single crystals of cadmium iodide are investigated using ns laser pulses. It is found that the transmissions in the crystals increase with increasing temperature. However, they limit the transmissions at high input powers. The limiting power is found to be higher at higher temperature. From the measured transmission data, the photon absorption coefficients are estimated. The temperature dependence of the coefficients shows a decrease in magnitude with increasing temperature. This might be due to the temperature-dependent bandgap shift of the material. The results demonstrate that the cadmium iodide single crystals are promising materials for applications in optical power limiting devices.

Optical power limiting and transmitting properties of cadmium iodide single crystals: Temperature dependence

International Nuclear Information System (INIS)

Miah, M. Idrish

2009-01-01

Optical limiting properties of the single crystals of cadmium iodide are investigated using ns laser pulses. It is found that the transmissions in the crystals increase with increasing temperature. However, they limit the transmissions at high input powers. The limiting power is found to be higher at higher temperature. From the measured transmission data, the photon absorption coefficients are estimated. The temperature dependence of the coefficients shows a decrease in magnitude with increasing temperature. This might be due to the temperature-dependent bandgap shift of the material. The results demonstrate that the cadmium iodide single crystals are promising materials for applications in optical power limiting devices.

Palm-based diacylglycerol fat dry fractionation: effect of crystallisation temperature, cooling rate and agitation speed on physical and chemical properties of fractions

Directory of Open Access Journals (Sweden)

Razam Ab Latip

2013-05-01

Full Text Available Fractionation which separates the olein (liquid and stearin (solid fractions of oil is used to modify the physicochemical properties of fats in order to extend its applications. Studies showed that the properties of fractionated end products can be affected by fractionation processing conditions. In the present study, dry fractionation of palm-based diacylglycerol (PDAG was performed at different: cooling rates (0.05, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0°C/min, end-crystallisation temperatures (30, 35, 40, 45 and 50°C and agitation speeds (30, 50, 70, 90 and 110 rpm to determine the effect of these parameters on the properties and yield of the solid and liquid portions. To determine the physicochemical properties of olein and stearin fraction: Iodine value (IV, fatty acid composition (FAC, acylglycerol composition, slip melting point (SMP, solid fat content (SFC, thermal behaviour tests were carried out. Fractionation of PDAG fat changes the chemical composition of liquid and solid fractions. In terms of FAC, the major fatty acid in olein and stearin fractions were oleic (C18:1 and palmitic (C16:0 respectively. Acylglycerol composition showed that olein and stearin fractions is concentrated with TAG and DAG respectively. Crystallization temperature, cooling rate and agitation speed does not affect the IV, SFC, melting and cooling properties of the stearin fraction. The stearin fraction was only affected by cooling rate which changes its SMP. On the other hand, olein fraction was affected by crystallization temperature and cooling rate but not agitation speed which caused changes in IV, SMP, SFC, melting and crystallization behavior. Increase in both the crystallization temperature and cooling rate caused a reduction of IV, increment of the SFC, SMP, melting and crystallization behaviour of olein fraction and vice versa. The fractionated stearin part melted above 65°C while the olein melted at 40°C. SMP in olein fraction also reduced to a range of

Crystallization and sintering characteristics of CaO-Al2O3-SiO2 glasses in the presence of TiO2, CaF2 and ZrO2

International Nuclear Information System (INIS)

Banijamali, S.; Eftekhari Yekta, B.; Rezaie, H.R.; Marghussian, V.K.

2009-01-01

In this study, the effects of different amounts of TiO 2 , ZrO 2 and CaF 2 nucleating agents on sinterability, crystallization, mechanical properties and chemical resistance of glass-ceramics belonging to the CaO-Al 2 O 3 -SiO 2 system were investigated, using differential thermal analysis (DTA), X-ray diffractometry (XRD), scanning electron microscopy (SEM), mechanical and chemical resistance measurements. It was found that in CaF 2 containing samples, the sinterability, crystallization and mechanical properties were improved by increasing of CaF 2 amount. However, addition of ZrO 2 and TiO 2 increases the firing temperature required for complete densification of specimens. Our experiments showed that fluctuations of chemical composition of the residual glass phases during sintering were responsible for these dissimilar trends and greatly influenced mechanical and chemical properties. According to the obtained results, appropriate sinterability, acceptable mechanical and chemical properties, as well as desirable whiteness of the most promising specimens make them suitable choices for floor tile applications. The main crystallization phases in all fully sintered glass-ceramics were wollastonite, anorthite and calcium aluminum silicate.

Optical properties and radiation response of Ce3+-doped GdScO3 crystals

International Nuclear Information System (INIS)

Yamaji, Akihiro; Fujimoto, Yutaka; Futami, Yoshisuke; Yokota, Yuui; Kurosawa, Shunsuke; Kochurikhin, Vladimir; Yanagida, Takayuki; Yoshikawa, Akira

2012-01-01

10%-Ce doped GdScO 3 perovskite type single crystal was grown by the Czochralski process. The Ce concentration in the crystal was measured. No impurity phases were observed by powder X-ray diffraction analysis. We evaluated the optical and radiation properties of the grown crystal. Ce:GdScO 3 crystal showed photo- and radio-luminescence peaks due to Ce 3+ of 5d-4f transition and colour centre. The photoluminescence decay time was sub-ns order. The relative light yield under 5.5 MeV alpha-ray excitation was calculated to be approximately 9% of BGO. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Development of Single Crystal Chemical Vapor Deposition Diamonds for Detector Applications

International Nuclear Information System (INIS)

Kagan, Harris; Gan, K.K.; Kass, Richard

2009-01-01

Diamond was studied as a possible radiation hard technology for use in future high radiation environments. With the commissioning of the LHC expected in 2009, and the LHC upgrades expected in 2013, all LHC experiments are planning for detector upgrades which require radiation hard technologies. Chemical Vapor Deposition (CVD) diamond has now been used extensively in beam conditions monitors as the innermost detectors in the highest radiation areas of BaBar, Belle and CDF and is installed in all LHC experiments. As a result, this material is now being discussed as an alternative sensor material for tracking very close to the interaction region of the super-LHC where the most extreme radiation conditions will exist. Our work addressed the further development of the new material, single-crystal Chemical Vapor Deposition diamond, towards reliable industrial production of large pieces and new geometries needed for detector applications.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences; Volume 128; Issue 1. Synthesis, spectral properties and DNA binding and nuclease activity of lanthanide (III) complexes of 2-benzoylpyridine benzhydrazone: X-ray crystal structure, Hirshfeld studies and nitrate- interactions of cerium(III) complex. Karreddula Raja Akkili ...

Gamma radiation effects on photorefractive and photoelectric properties of lithium niobate crystals

Energy Technology Data Exchange (ETDEWEB)

Vartanyan, Eh.S.; Ovsepyan, R.K.; Pogosyan, A.R.; Timofeev, A.L.

1984-08-01

Investigations into the gamma radiation effect on the photorefractive aned photoelectric properties of lithium niobate crystals have been carried out for the first time. Gamma irradiation has been found to lead to an increase in the photorefractive sensitivity. The effect of optical decoloration has been discovered for the first time along with photorelaxation currents resulting from radiation center decay under the action of light. It has been shown that an increase of photorefractive sensitivity in gamma-irradiated lithium niobate crystals is caused by a new photorefraction mechanism - photorelaxation currents.

Optical properties of GaS:Ho3+ and GaS:Tm3+ single crystals

International Nuclear Information System (INIS)

Jin, Moon-Seog; Kim, Chang-Dae; Kim, Wha-Tek

2004-01-01

GaS:Ho 3+ and GaS:Tm 3+ single crystals were grown by using the chemical transport reaction method. We measured the optical absorption, the infra-red absorption, and the photoluminescence spectra of the single crystals. The direct and the indirect energy band gaps of the single crystals at 13 K were identified. Infra-red absorption peaks at 6 K appeared in the single crystals. Broad emission bands at 6 K were observed at 464 nm and 580 nm for GaS:Ho 3+ and 462 nm and 581 nm for GaS:Tm 3+ . These broad emission bands were identified as originating from donor-acceptor pair recombinations. Sharp emission peak groups were observed near 435 nm, 495 nm, and 660 nm for GaS:Ho 3+ and near 672 nm for GaS:Tm 3+ . These sharp emission peak groups were identified as being due to the electron transitions between the energy levels of Ho 3+ and Tm 3+ . Especially, white photoluminescence was obtained in the GaS:Ho 3+ single crystal.

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Liquid crystals: high technology materials for potential applications

International Nuclear Information System (INIS)

Saeed, M.A.; Badaruddin; Rizvi, T.Z.

1993-01-01

Liquid crystals have very rapidly emerged as a basis of many high technology fields within the last few decades. These materials because of their intriguing physical properties are regarded as the fourth state of matter. At present the applications of liquid crystals are established in digital display devices, electro-optical switches, optical computing, acousto-optics, thermo-indicators, laser thermo-recording, photo-chemical image recording and optical communication networks. More recently due to the concept of molecularly based electronics (MBE): the logical extreme for miniaturization of electronic device, liquid crystals are foreseen to play a vital role in the future optics based technologies. This paper gives a brief introduction to liquid crystals, the types of meso phases found in these materials together with their applications in research and industry. Some technical details of the construction liquid crystal cells for some typical applications in digital displays and other electro optical devices have also been discussed with special emphasis on relevant physical processes occurring at molecular level. (author)

Crystallization process and magnetic properties of amorphous iron oxide nanoparticles

International Nuclear Information System (INIS)

Phu, N D; Luong, N H; Chau, N; Hai, N H; Ngo, D T; Hoang, L H

2011-01-01

This paper studied the crystallization process, phase transition and magnetic properties of amorphous iron oxide nanoparticles prepared by the microwave heating technique. Thermal analysis and magnetodynamics studies revealed many interesting aspects of the amorphous iron oxide nanoparticles. The as-prepared sample was amorphous. Crystallization of the maghemite γ-Fe 2 O 3 (with an activation energy of 0.71 eV) and the hematite α-Fe 2 O 3 (with an activation energy of 0.97 eV) phase occurred at around 300 deg. C and 350 deg. C, respectively. A transition from the maghemite to the hematite occurred at 500 deg. C with an activation energy of 1.32 eV. A study of the temperature dependence of magnetization supported the crystallization and the phase transformation. Raman shift at 660 cm -1 and absorption band in the infrared spectra at 690 cm -1 showed the presence of disorder in the hematite phase on the nanoscale which is supposed to be the origin of the ferromagnetic behaviour of that antiferromagnetic phase.

Crystal growth and scintillation properties of multi-component oxide single crystals: Ce:GGAG and Ce:La-GPS

Energy Technology Data Exchange (ETDEWEB)

Yoshikawa, A., E-mail: yoshikawa@imr.tohoku.ac.jp [Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai 980-8579 (Japan); C& A Corporation, 6-6-40 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan); Kamada, K. [New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai 980-8579 (Japan); C& A Corporation, 6-6-40 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan); Kurosawa, S. [Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai 980-8579 (Japan); Shoji, Y. [Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan); C& A Corporation, 6-6-40 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan); Yokota, Y. [New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai 980-8579 (Japan); Chani, V.I. [Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan); Nikl, M. [Institute of Physics, AS CR, Cukrovarnická 10, 162 53 Prague (Czech Republic)

2016-01-15

Crystal growth by micro-pulling-down, Czochralski, and floating zone methods and scintillation properties of Ce:Gd{sub 3}(Ga,Al){sub 5}O{sub 12} (Ce:GGAG) multi-component oxide garnets, and Ce:Gd{sub 2}Si{sub 2}O{sub 7} (Ce:GPS) or Ce:(La,Gd){sub 2}Si{sub 2}O{sub 7} (Ce:La-GPS) pyro-silicates are reviewed. GGAG crystals demonstrated practically linear dependences of some of the parameters including lattice constant, emission wavelength, and band gap on Ga content. However, emission intensity, light yield and energy resolution showed maxima for intermediate compositions. GGAG crystals had the highest light yield of 56,000 photon/MeV for Ga content of 2.7 atoms per garnet formula unit. Similarly the light yield and energy resolution of La-GPS showed the highest values of 40,000 photon/MeV and 4.4%@662 keV, respectively, for La-GPS containing 10% of La. Moreover, La-GPS demonstrated stable scintillation performance up to 200 °C.

Properties of horizontally oriented ice crystals observed by polarization lidar over summit, Greenland

Directory of Open Access Journals (Sweden)

Neely Ryan R.

2018-01-01

Full Text Available A source of error in microphysical retrievals and model simulations is the assumption that clouds are composed of only randomly oriented ice crystals. This assumption is frequently not true, as evidenced by optical phenomena such as parhelia. Here, observations from the Cloud, Aerosol and Polarization Backscatter Lidar at Summit, Greenland are utilized along with other sensors and beam imaging to examine the properties of horizontally oriented ice crystals and the environment conditions in which they occur.

Effect of substrate bias voltage on tensile properties of single crystal silicon microstructure fully coated with plasma CVD diamond-like carbon film

Science.gov (United States)

Zhang, Wenlei; Hirai, Yoshikazu; Tsuchiya, Toshiyuki; Tabata, Osamu

2018-06-01

Tensile strength and strength distribution in a microstructure of single crystal silicon (SCS) were improved significantly by coating the surface with a diamond-like carbon (DLC) film. To explore the influence of coating parameters and the mechanism of film fracture, SCS microstructure surfaces (120 × 4 × 5 μm3) were fully coated by plasma enhanced chemical vapor deposition (PECVD) of a DLC at five different bias voltages. After the depositions, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermal desorption spectrometry (TDS), surface profilometry, atomic force microscope (AFM) measurement, and nanoindentation methods were used to study the chemical and mechanical properties of the deposited DLC films. Tensile test indicated that the average strength of coated samples was 13.2-29.6% higher than that of the SCS sample, and samples fabricated with a -400 V bias voltage were strongest. The fracture toughness of the DLC film was the dominant factor in the observed tensile strength. Deviations in strength were reduced with increasingly negative bias voltage. The effect of residual stress on the tensile properties is discussed in detail.

Optical properties of opal photonic crystals

Science.gov (United States)

Eradat-Oskouei, Nayer

2001-10-01

Photonic crystals (PC) are a class of artificial structures with a periodic dielectric function in one, two, or three dimensions, in which the propagation of electromagnetic waves within a certain frequency band is forbidden. This forbidden frequency band has been dubbed photonic band gap (PBG). The position, width, depth, and shape of the PBG strongly depend on the periodicity, symmetry properties, dielectric constant contrast, and internal lattice structure of the unit cell. There is a common belief that PCs will perform many functions with light that ordinary crystals do with electrons. At the same time, PCs are of great promise to become a laboratory for testing fundamental processes involving interactions of radiation with matter in novel conditions. We have studied the optical properties of opal PCs that are infiltrated with metals, laser dyes, π-conjugated polymers, and J-aggregates. Opals are self-assembled structures of silica (SiO2) spheres mostly packed in a face centered cubic (fcc) lattice. Our research is summarized in the following six chapters. Chapter 1 is a review on the concepts related to PBG and PC, eigenvalue problem of electromagnetism, material systems that exhibit PBG. Chapter 2 covers all the fabrication and measurement techniques including angle resolved reflectivity, transmission, photoluminescence, photo-induced absorption, and coherent backscattering. Chapter 3 focuses on the relationship between a polaritonic gap and a photonic stop-band when they resonantly coexist in the same structure. Infiltration of opal with polarizable molecules combines the polaritonic and Bragg diffractive effects. The experimental results on reflectivity and its dependence on the impinging angle and concentration of the polarizable medium are in agreement with the theoretical calculations. In Chapter 4, the optical studies of three-dimensional metallic mesh composites are reported. Photonic and electronic properties of these PCs strongly depend on their

Temperature-Induced Lattice Relaxation of Perovskite Crystal Enhances Optoelectronic Properties and Solar Cell Performance

KAUST Repository

Banavoth, Murali

2016-12-14

Hybrid organic-inorganic perovskite crystals have recently become one of the most important classes of photoactive materials in the solar cell and optoelectronic communities. Albeit improvements have focused on state-of-the-art technology including various fabrication methods, device architectures, and surface passivation, progress is yet to be made in understanding the actual operational temperature on the electronic properties and the device performances. Therefore, the substantial effect of temperature on the optoelectronic properties, charge separation, charge recombination dynamics, and photoconversion efficiency are explored. The results clearly demonstrated a significant enhancement in the carrier mobility, photocurrent, charge carrier lifetime, and solar cell performance in the 60 ± 5 °C temperature range. In this temperature range, perovskite crystal exhibits a highly symmetrical relaxed cubic structure with well-aligned domains that are perpendicular to a principal axis, thereby remarkably improving the device operation. This finding provides a new key variable component and paves the way toward using perovskite crystals in highly efficient photovoltaic cells.

Third-order nonlinear optical properties of ADP crystal

Science.gov (United States)

Wang, Mengxia; Wang, Zhengping; Chai, Xiangxu; Sun, Yuxiang; Sui, Tingting; Sun, Xun; Xu, Xinguang

2018-05-01

By using the Z-scan method, we investigated the third-order nonlinear optical (NLO) properties of ADP crystal at different wavelengths (355, 532, and 1064 nm) and different orientations ([001], [100], [110], I and II). The experimental data were fitted by NLO theory, to give out the two photon absorption (TPA) coefficient β 2 and the nonlinear refractive index n 2. When the light source changed from a 40 ps, 1064 nm fundamental laser to a 30 ps, 355 nm third-harmonic-generation (THG) laser, the β 2 value increased about 5 times (0.2 × 10‑2 → 1 × 10‑2 cm GW‑1), and the n 2 value increased about 1.5 times (1.5 × 10‑16 → 2.2 × 10‑16 cm2 W‑1). Among all of the orientations, the [110] sample exhibits the smallest β 2, and the second smallest n 2. It indicates that this orientation and its surroundings will be the preferred directions for high-power laser applications of ADP crystal.

Property Modelling for Applications in Chemical Product and Process Design

DEFF Research Database (Denmark)

Gani, Rafiqul

such as database, property model library, model parameter regression, and, property-model based product-process design will be presented. The database contains pure component and mixture data for a wide range of organic chemicals. The property models are based on the combined group contribution and atom...... is missing, the atom connectivity based model is employed to predict the missing group interaction. In this way, a wide application range of the property modeling tool is ensured. Based on the property models, targeted computer-aided techniques have been developed for design and analysis of organic chemicals......, polymers, mixtures as well as separation processes. The presentation will highlight the framework (ICAS software) for property modeling, the property models and issues such as prediction accuracy, flexibility, maintenance and updating of the database. Also, application issues related to the use of property...

Thermodynamic properties of tert-butylbenzene and 1,4-di-tert-butylbenzene

International Nuclear Information System (INIS)

Chirico, Robert D.; Steele, William V.

2009-01-01

Heat capacities, enthalpies of phase transitions, and derived thermodynamic properties over the temperature range 5 < (T/K) < 442 were determined with adiabatic calorimetry for tert-butylbenzene (TBB) {Chemical Abstracts Service registry number (CASRN) [98-06-6]} and 1,4-di-tert-butylbenzene (DTBB) {CASRN [1012-72-2]}. A crystal to plastic crystal transition very near the triple-point temperature of DTBB was observed. New vapor pressures near the triple-point temperature are also reported for DTBB for the liquid and crystal states. These new measurements, when combined with published results, allow calculation of the thermodynamic properties for the ideal gas state for both compounds. The contribution of the tert-butyl group to the entropy of the ideal gas is determined quantitatively here for the first time based on the calorimetric results over the temperature range 298.15 < (T/K) < 600. Comparisons with literature values are shown for all measured and derived properties, including entropies for the ideal gas derived from quantum chemical calculations

Synthesis, Crystal Structure, and Chemical-Bonding Analysis of BaZn(NCN2

Directory of Open Access Journals (Sweden)

Alex J. Corkett

2017-12-01

Full Text Available The ternary carbodiimide BaZn(NCN2 was prepared by a solid-state metathesis reaction between BaF2, ZnF2, and Li2NCN in a 1:1:2 molar ratio, and its crystal structure was determined from Rietveld refinement of X-ray data. BaZn(NCN2 represents the aristotype of the LiBa2Al(NCN4 structure which is unique to carbodiimide/cyanamide chemistry and is well regarded as being constructed from ZnN4 tetrahedra, sharing edges and vertices through NCN2− units to form corrugated layers with Ba2+ in the interlayer voids. Structural anomalies in the shape of the cyanamide units are addressed via IR spectrometry and DFT calculations, which suggest the presence of slightly bent N=C=N2− carbodiimide units with C2v symmetry. Moreover, chemical-bonding analysis within the framework of crystal orbital Hamilton population (COHP reveals striking similarities between the bonding interactions in BaZn(NCN2 and SrZn(NCN2 despite their contrasting crystal structures. BaZn(NCN2 is only the second example of a ternary post-transition metal carbodiimide, and its realization paves the way for the preparation of analogues featuring divalent transition metals at the tetrahedral Zn2+ site.

Characterization of chemically synthesized CdS nanoparticles

Indian Academy of Sciences (India)

Similar to the effects of charge carriers on optical properties, confinement of optical and acoustic phonons leads to interesting changes in the phonon spectra. In the present work, we have synthesized nanoparticles of CdS using chemical precipitation technique. The crystal structure and grain size of the particles are studied ...

Synthesis, spectral analysis, optical and thermal properties of new organic NLO crystal: N,N";-Diphenylguanidinium Nitrate (DPGN)

Science.gov (United States)

Saravana Kumar, G.; Murugakoothan, P.

2014-10-01

A new organic NLO material N,N";-Diphenylguanidinium Nitrate (DPGN) single crystal was grown by slow evaporation technique using methanol as solvent. Single crystal X-ray diffraction and powder X-ray diffraction experiments were carried out in order to confirm the structure and crystalline nature of DPGN crystal. Wide band gap of 3.9 eV with transmittance of 57% up to 800 nm is observed for the grown crystal using UV-vis spectral analysis. The chemical bonding and presence of various functional groups were confirmed by the FT-IR and FT-Raman spectral studies. The thermal behavior of DPGN crystal was analyzed by simultaneous TG-DTA studies. The second harmonic generation (SHG) nonlinearity of the grown crystal was measured by Kurtz and Perry powder technique and was found to be comparable with that of the standard reference material potassium dihydrogen phosphate (KDP) crystal.

Application of Bottlebrush Block Copolymers as Photonic Crystals.

Science.gov (United States)

Liberman-Martin, Allegra L; Chu, Crystal K; Grubbs, Robert H

2017-07-01

Brush block copolymers are a class of comb polymers that feature polymeric side chains densely grafted to a linear backbone. These polymers display interesting properties due to their dense functionality, low entanglement, and ability to rapidly self-assemble to highly ordered nanostructures. The ability to prepare brush polymers with precise structures has been enabled by advancements in controlled polymerization techniques. This Feature Article highlights the development of brush block copolymers as photonic crystals that can reflect visible to near-infrared wavelengths of light. Fabrication of these materials relies on polymer self-assembly processes to achieve nanoscale ordering, which allows for the rapid preparation of photonic crystals from common organic chemical feedstocks. The characteristic physical properties of brush block copolymers are discussed, along with methods for their preparation. Strategies to induce self-assembly at ambient temperatures and the use of blending techniques to tune photonic properties are emphasized. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Crystal phase transition in LixNa1-xGdF4 solid solution nanocrystals - Tuning of optical properties

KAUST Repository

Bański, Mateusz

2014-01-01

The influence of precursor composition on the crystallization of LixNa1-xGdF4 is investigated and discussed. Nanocrystals are prepared from the thermal decomposition of trifluoroacetates in the presence of trioctylphosphine oxide to provide control over particle size. A crystal phase transition from hexagonal to cubic and to tetragonal is observed by increasing lithium trifluoroacetate (Li-TFA) in the solution. Controlling the composition of LixNa1-xGdF4 nanocrystals results in modified crystal field symmetry and emission properties from doped europium (Eu3+) ions. We report that for lithium (Li+) substitution <15%, the hexagonal crystal field is preferred, while the Eu3+ emission is already tuned, whereas at higher Li+ substitution, a phase change takes place and the number of crystalline matrix defects increases which is reflected in the optical properties of Eu3+. From Eu3+ emission properties, the optimum Li+ content is determined to be ∼6.2% in the prepared LixNa1-xGdF4 nanocrystals.

Effect of antimony incorporation on structural properties of CuInS{sub 2} crystals

Energy Technology Data Exchange (ETDEWEB)

Ben Rabeh, M., E-mail: mohamedbenrabeh@yahoo.f [Laboratoire de Photovoltaique et Materiaux Semi-Conducteurs - ENIT BP 37, Le belvedere, 1002 Tunis (Tunisia); Chaglabou, N., E-mail: nadia_chaglabou@yahoo.f [Laboratoire de Photovoltaique et Materiaux Semi-Conducteurs - ENIT BP 37, Le belvedere, 1002 Tunis (Tunisia); Kanzari, M., E-mail: Mounir.Kanzari@ipeit.rnu.t [Laboratoire de Photovoltaique et Materiaux Semi-Conducteurs - ENIT BP 37, Le belvedere, 1002 Tunis (Tunisia)

2010-02-15

CuInS{sub 2} (CIS) single crystals doped with 1, 2, 3 and 4 atomic percent (at.%) of antimony (Sb) were grown by the horizontal Bridgman method. The effect of Sb doping on the structural properties of CIS crystal was studied by means of X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM) and PL measurements. X-ray diffraction data suggests that the doping of Sb in the CIS single crystals does not affect the tetragonal (chalcopyrite) crystal structure and exhibited a (1 1 2) preferred orientation. In addition, with increasing Sb concentration, the X-ray diffraction analysis show that Sb doped CIS crystals are more crystallized and the diffraction peaks of the CuInS{sub 2} phase were more pronounced in particular the (1 1 2) plane. EDAX study revealed that Sb atoms can occupy the indium site and/or occupying the sulfur site to make an acceptor. PL spectra of undoped and Sb doped CIS crystals show two emission peaks at 1.52 and 1.62 eV, respectively which decreased with increasing atomic percent antimony. Sb doped CIS crystals show p-type conductivity.

The study of thermodynamic properties and transport properties of multicomponent systems with chemical reactions

Directory of Open Access Journals (Sweden)

Samujlov E.

2013-04-01

Full Text Available In case of system with chemical reaction the most important properties are heat conductivity and heat capacity. In this work we have considered the equation for estimate the component of these properties caused by chemical reaction and ionization processes. We have evaluated the contribution of this part in heat conductivity and heat capacity too. At the high temperatures contribution in heat conductivity from ionization begins to play an important role. We have created a model, which describe partial and full ionization of gases and gas mixtures. In addition, in this work we present the comparison of our result with experimental data and data from numerical simulation. We was used the data about transport properties of middle composition of Russian coals and the data of thermophysical properties of natural gas for comparison.

Improving the chemical compatibility of sealing glass for solid oxide fuel cells: Blocking the reactive species by controlled crystallization

Science.gov (United States)

Zhang, Teng; Zou, Qi; Zeng, Fanrong; Wang, Shaorong; Tang, Dian; Yang, Hiswen

2012-10-01

The chemical compatibility of sealing glass is of great importance for Solid oxide fuel cell (SOFC). In this work, the interfacial reaction between sealing glass and Cr-containing interconnect alloy is characterized by reacting Cr2O3 powders with a representative SrO-containing glass crystallized by different heat-treatment schedules. The crystalline structure and crystalline content of sealing glass are determined by X-ray diffraction. The results show that the fraction of Cr6+ decreases from 39.8 ± 1.9% for quenched glass to 8.2 ± 0.4% for glass crystallized at 900 °C for 2 h. In addition, the interfacial reaction can be further reduced with increasing crystallization temperature and time as well as the addition of nucleation agent (TiO2). The formation of some Sr-containing crystalline phases, Sr2SiO4 and Sr(TiO3), contributes to the improvement of chemical compatibility of sealing glass, in agreement with the results of thermodynamic calculations.

Crystal chemical substitutions and doping of YBa2Cu3Ox and related superconductors

International Nuclear Information System (INIS)

Skakle, J.M.S.

1998-01-01

This review covers the literature on cationic and anionic substitutions and their effect on the properties of YBCO. Reported solubility limits are given, together with crystal symmetry and trends in unit cell parameters with dopant concentration. The dopant site is considered; this is additionally complex in the case of copper substitution because of the two distinct copper sites in the crystal structure. The effect of the dopant on the critical temperature, T c , is reviewed; the literature is often contradictory due to the dual effects of variable oxygen content and the nature of the dopant. Preparation methods appear to have an effect on solubility limits, crystal symmetry and T c . Also, the methods used to determine solubility limits are often imprecise which can lead to contradictions. The magnetic properties of doped materials are reviewed; for some dopants, particularly the magnetic lanthanides, antiferromagnetism and superconductivity co-exist. The related RBa 2 Cu 3 O δ phases (R=lanthanide), their structure, properties and behaviour on doping are reviewed in a similar way. For the larger rare earths, the related systems R 1+x Ba 2-x Cu 3 O δ are reviewed; as x increases, the transition temperature decreases and compositions R 1.5 Ba 1.5 Cu 3 O δ are semiconducting. The upper and lower solubility limit changes with R, and for R=Dy, the upper limit is 2 Cu 3 O δ , cannot be prepared in air since substitution of La onto the Ba site occurs, forming the Ba-deficient solid solutions. (orig.)

Study on Physical Properties and Chemical Composition of Some Myanmar Gems

International Nuclear Information System (INIS)

Kyaw Myint Htoo; Tun Khin; Sein Htoon

2004-05-01

Physical properties of some Myanmar gems were studied by using refractometer, dichroscope, polariscope, SG test, UV test and microscope. Then, chemical composition were investigated by XRF-technique. After that, gem identification, evaluation, colour improvement were studied according to these physical properties and chemical composition

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Calculation of dynamic and electronic properties of perfect and defect crystals by semiempirical quantum mechanical methods

International Nuclear Information System (INIS)

Zunger, A.

1975-07-01

Semiempirical all-valence-electron LCAO methods, that were previously used to study the electronic structure of molecules are applied to three problems in solid state physics: the electronic band structure of covalent crystals, point defect problems in solids and lattice dynamical study of molecular crystals. Calculation methods for the electronic band structure of regular solids are introduced and problems regarding the computation of the density matrix in solids are discussed. Three models for treating the electronic eigenvalue problem in the solid, within the proposed calculation schemes, are discussed and the proposed models and calculation schemes are applied to the calculation of the electronic structure of several solids belonging to different crystal types. The calculation models also describe electronic properties of deep defects in covalent insulating crystals. The possible usefulness of the semieipirical LCAO methods in determining the first order intermolecular interaction potential in solids and an improved model for treating the lattice dynamics and related thermodynamical properties of molecular solids are presented. The improved lattice dynamical is used to compute phonon dispersion curves, phonon density of states, stable unit cell structure, lattice heat capacity and thermal crystal parameters, in α and γ-N 2 crystals, using the N 2 -N 2 intermolecular interaction potential that has been computed from the semiempirical LCAO methods. (B.G.)

Optical and magneto-optical properties of the electron-doped and hole-doped C{sub 82} crystal

Energy Technology Data Exchange (ETDEWEB)

Rostampour, E., E-mail: el_rostampour@yahoo.com [Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Koohi, A. [Plasma Physics and Nuclear Fusion Research School, Nuclear Science and Technology Research Institute, AEOI, Tehran (Iran, Islamic Republic of)

2015-01-15

The optical and magnetic properties of the doped C{sub 82} crystal have been investigated by Su–Schrieffer–Heeger (SSH) model, which is based on the Ewald method. When the C{sub 82} molecule is doped with one electron (or hole), a single electron is remained in the energy level that affects the optical and magnetic properties of the C{sub 82} crystal. The lattice and electronic structures of C{sub 82} changed with doping electron (or hole) in the molecule of C{sub 82}. Therefore, polarons are predicted in doped fullerenes. The obtained results showed that the dielectric tensor of the C{sub 82} crystal increased with doping electron (or hole) in the molecule of C{sub 82}. The spectral shapes of the dielectric tensor, circular dichroism and birefringence coefficient of the C{sub 82} crystal turn out to be determined mainly by the geometrical distributions of the pentagons in the fullerene structures.

Piezoelectric and ferroelectric properties of lead-free niobium-rich potassium lithium tantalate niobate single crystals

Energy Technology Data Exchange (ETDEWEB)

Li, Jun, E-mail: lijuna@hit.edu.cn [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Li, Yang [Department of chemistry, Harbin Institute of Technology, Harbin 150001 (China); Zhou, Zhongxiang [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Guo, Ruyan; Bhalla, Amar S. [Multifunctional Electronic Materials and Device Research Lab, Department of Electrical and Computer Engineering, The University of Texas at San Antonio, San Antonio 78249 (United States)

2014-01-01

Graphical abstract: - Highlights: • Lead-free K{sub 0.95}Li{sub 0.05}Ta{sub 1−x}Nb{sub x}O{sub 3} single crystals were grown using the top-seeded melt growth method. • The piezoelectric and ferroelectric properties of as-grown crystals were systematically investigated. • The piezoelectric properties are very attractive, e.g. for x = 0.60 composition, k{sub t} ≈ 70%, k{sub 31} ≈ 70%, k{sub 33} ≈ 77%, d{sub 31} ≈ 230 pC/N, d{sub 33} ≈ 600 pC/N. • The coercive fields of P–E hysteresis loops are quite small, about or less than 1 kV/mm. - Abstract: Lead-free potassium lithium tantalate niobate single crystals with the composition of K{sub 0.95}Li{sub 0.05}Ta{sub 1−x}Nb{sub x}O{sub 3} (abbreviated as KLTN, x = 0.51, 0.60, 0.69, 0.78) were grown using the top-seeded melt growth method. Their piezoelectric and ferroelectric properties in as-grown crystals have been systematically investigated. The phase transitions and Curie temperatures were determined from dielectric and pyroelectric measurements. Piezoelectric coefficients and electromechanical coupling factors in thickness mode, length-extensional mode and longitudinal mode were obtained. The piezoelectric properties are very attractive, e.g. for x = 0.60 composition, k{sub t} ≈ 70%, k{sub 31} ≈ 70%, k{sub 33} ≈ 77%, d{sub 31} ≈ 230 pC/N, d{sub 33} ≈ 600 pC/N are comparable to the lead-based PZT composition. The polarization versus electric field hysteresis loops show saturated shapes. In short, lead-free niobium-rich KLTN system possesses comparable properties to those in important lead-based piezoelectric material nowadays.

Thermo-chemical properties and electrical resistivity of Zr-based arsenide chalcogenides

OpenAIRE

A. Schlechte, R. Niewa, M. Schmidt, G. Auffermann, Yu. Prots, W. Schnelle, D. Gnida, T. Cichorek, F. Steglich and R. Kniep

2007-01-01

Ternary phases in the systems Zr–As–Se and Zr–As–Te were studied using single crystals of ZrAs1.40(1)Se0.50(1) and ZrAs1.60(2)Te0.40(1) (PbFCl-type of structure, space group P4/nmm) as well as ZrAs0.70(1)Se1.30(1) and ZrAs0.75(1)Te1.25(1) (NbPS-type of structure, space group Immm). The characterization covers chemical compositions, crystal structures, homogeneity ranges and electrical resistivities. At 1223 K, the Te-containing phases can be described with the general formula ZrAsxTe2−x, with...

Crystal growth and magnetic property of YFeO3 crystal

Indian Academy of Sciences (India)

2Department of Physics, Shanghai University, Shanghai 200444, China. 3School ... YFeO3 and other rare earth substituted crystals with distorted orthorhombic pervoskite-like struc- .... gen, with rotation rates of 30 rpm for the growing crystal or.

Short review of high-pressure crystal growth and magnetic and electrical properties of solid-state osmium oxides

Energy Technology Data Exchange (ETDEWEB)

Yamaura, Kazunari, E-mail: YAMAURA.Kazunari@nims.go.jp [Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, North 10 West 8, Kita-ku, Sapporo, Hokkaido 060-0810 (Japan)

2016-04-15

High-pressure crystal growth and synthesis of selected solid-state osmium oxides, many of which are perovskite-related types, are briefly reviewed, and their magnetic and electrical properties are introduced. Crystals of the osmium oxides, including NaOsO{sub 3}, LiOsO{sub 3}, and Na{sub 2}OsO{sub 4}, were successfully grown under high-pressure and high-temperature conditions at 6 GPa in the presence of an appropriate amount of flux in a belt-type apparatus. The unexpected discovery of a magnetic metal–insulator transition in NaOsO{sub 3}, a ferroelectric-like transition in LiOsO{sub 3}, and high-temperature ferrimagnetism driven by a local structural distortion in Ca{sub 2}FeOsO{sub 6} may represent unique features of the osmium oxides. The high-pressure and high-temperature synthesis and crystal growth has played a central role in the development of solid-state osmium oxides and the elucidation of their magnetic and electronic properties toward possible use in multifunctional devices. - Graphical Abstract: Flux-grown crystals of NaOsO{sub 3} under high-pressure and high-temperature conditions in a belt-type apparatus. The crystal shows a magnetically driven metal–insulator transition at a temperature of 410 K. - Highlights: • Short review of high-pressure crystal growth of solid-state osmium oxides. • Wide variety of magnetic properties of solid-state osmium oxides. • Perovskite and related dense structures stabilized at 3–17 GPa.

The melt growth of large LuAP single crystals for PET scanners

International Nuclear Information System (INIS)

Petrosyan, Ashot; Ovanesyan, Karine; Shirinyan, Grigory; Butaeva, Tatyana; Derdzyan, Marina; Pedrini, Christian; Dujardin, Christophe; Garnier, Nicolas; Kamenskikh, Irina

2005-01-01

Performance properties of LuAP, a material of highly promising potential for future PET scanners, are presented, as they relate to crystal growth and composition. The light yield measured in 2x2x10 mm 3 elements with 0.4-0.5% Ce and cut from large size crystals (100 mm long and 15 mm in diameter) grown by the Bridgman technique is improved to 40% LSO. The ratio between light yield measured in vertical and horizontal arrangements in the best crystals is near 90%. The role of chemical purity in respect to divalent impurities is studied

Calculations of electronic structure of UF6 molecule and crystal UO2 with relativistic pseudopotential

International Nuclear Information System (INIS)

Ehvarestov, R.A.; Panin, A.I.; Bandura, A.V.

2008-01-01

Account of relativistic effects on the properties of uranium hexafluoride is testified. Detailed comparison of single electron energies spectrum revealed in nonrelativistic (by Hartree-Fock method), relativistic (by Dirac-Fock method), and scalar-relativistic (using relativistic potential of atomic uranium frame) has been conducted. Optimization procedures of atomic basis in LCAO calculations of molecules and crystals permissive taking into account distortion of atomic orbitals when chemical bonding are discussed, and optimization effect of atomic basis on the results of scalar-relativistic calculations of UF 6 molecule properties is analyzed. Calculations of electronic structure and properties of UO 2 crystal having relativistic and nonrelativistic pseudopotentials have been realized [ru

Magnetic, transport, and optical properties of Ca{sub 0.85}Eu{sub 0.15}MnO{sub 3} single crystal

Energy Technology Data Exchange (ETDEWEB)

Naumov, S.V., E-mail: naumov@imp.uran.ru [Institute of Metal Physics, Ural Branch of RAS, Kovalevskaya Street 18, Ekaterinburg 620990 (Russian Federation); Loshkareva, N.N.; Mostovshchikova, E.V.; Solin, N.I.; Korolev, A.V.; Arbuzova, T.I.; Telegin, S.V.; Patrakov, E.I. [Institute of Metal Physics, Ural Branch of RAS, Kovalevskaya Street 18, Ekaterinburg 620990 (Russian Federation)

2013-01-01

Magnetic, transport and optical properties of the Ca{sub 0.85}Eu{sub 0.15}MnO{sub 3} single crystal are studied and discussed in comparison with the properties of polycrystalline sample. The magnetic data show existence the two magnetic phase transitions under cooling: the transition near 150 K occurs from the paramagnetic orthorhombic to C-type antiferromagnetic monoclinic phase with the charge/orbital ordering in some part of the crystal; and at 90 K the transition from the paramagnetic to G-type antiferromagnetic phase takes place in another part of the crystal with the orthorhombic structure. The magnetoresistance of the Ca{sub 0.85}Eu{sub 0.15}MnO{sub 3} single crystal has features at temperatures of these phase transitions. Differences in the properties of single crystal and polycrystalline sample with the same content of Eu are associated with the ordering of oxygen vacancies that appear under the crystal growth. The reflection spectra in infrared range confirm the existence of the electron conductivity in a narrow band at room temperature.

Tensometrical properties of volumetric crystals of germanium-silicon solid solutions irradiated by fast electrons

International Nuclear Information System (INIS)

Abbasov, Sh.M.

2002-01-01

Full Text: In the present work the tensometrical properties of Ge1-xSix solid solution monocrystal contended of up to 15 at. % Si were investigated. The radiation-proof strain gauges of researched crystals were made. For this purpose the site was cutted out from a sample, perpendicularly or in parallel of a crystal axes. After polishing the samples had thickness of 30-40 microns, and length of 2 mm

Systematic Modelling and Crystal Size Distribution Control for Batch Crystallization Processes

DEFF Research Database (Denmark)

Abdul Samad, Noor Asma Fazli; Singh, Ravendra; Sin, Gürkan

Crystallization processes form an important class of separation methods that are frequently used in the chemical, the pharmaceutical and the food industry. The specifications of the crystal product are usually given in terms of crystal size, shape and purity. In order to predict the desired cryst...

Cracking a chemical conundrum

Energy Technology Data Exchange (ETDEWEB)

Adams, James M.; Ivanov, Alexandre S.; Johnson, Mark R.; Stride, John A

2004-07-15

An everyday laboratory chemical, hexamethylbenzene (HMB) has assumed an important role in the history of molecular structure and crystallography. It was one of the first organic crystal structures to be solved and provided direct experimental proof for the hypothesis of planarity in aromatic systems. Very soon after this, HMB was found to undergo a phase transition at 117 K, resulting in crystal shattering. Since then, many attempts have been made to obtain the low-temperature structure, but none have succeeded until now. Making use of the unique properties of the neutron, we have performed powder diffraction measurements to obtain the low-temperature crystal structure and inelastic measurements to determine the dynamics of the system. These experiments have been augmented by the use of ab initio calculations and molecular modelling to obtain a complete picture of HMB in the solid state.

Cracking a chemical conundrum

International Nuclear Information System (INIS)

Adams, James M.; Ivanov, Alexandre S.; Johnson, Mark R.; Stride, John A.

2004-01-01

An everyday laboratory chemical, hexamethylbenzene (HMB) has assumed an important role in the history of molecular structure and crystallography. It was one of the first organic crystal structures to be solved and provided direct experimental proof for the hypothesis of planarity in aromatic systems. Very soon after this, HMB was found to undergo a phase transition at 117 K, resulting in crystal shattering. Since then, many attempts have been made to obtain the low-temperature structure, but none have succeeded until now. Making use of the unique properties of the neutron, we have performed powder diffraction measurements to obtain the low-temperature crystal structure and inelastic measurements to determine the dynamics of the system. These experiments have been augmented by the use of ab initio calculations and molecular modelling to obtain a complete picture of HMB in the solid state

Chemical etching of a GaSb crystal incorporated with Mn grown by the Bridgman method under microgravity conditions

International Nuclear Information System (INIS)

Chen Xiaofeng; Chen Nuofu; Wu Jinliang; Zhang Xiulan; Chai Chunlin; Yu Yude

2009-01-01

A GaSb crystal incorporated with Mn has been grown by the Bridgman method on the Polizon facility onboard the FOTON-M3 spacecraft. Structural defects and growth striations have been successfully revealed by the chemical etching method. By calculating various parameters of the convection, the striation patterns can be explained, and the critical value of the Taylor number, which characterizes the convective condition of the rotating magnetic field induced azimuthal flow, was shown. The stresses generated during crystal growth can be reflected by the observations of etch pit distribution and other structural defects. Suggestions for improving the space experiment to improve the quality of the crystal are given. (semiconductor materials)

Chemical etching of a GaSb crystal incorporated with Mn grown by the Bridgman method under microgravity conditions

Energy Technology Data Exchange (ETDEWEB)

Chen Xiaofeng; Chen Nuofu; Wu Jinliang; Zhang Xiulan; Chai Chunlin; Yu Yude, E-mail: xfchen@semi.ac.c, E-mail: nfchen@semi.ac.c [Key Laboratory of Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

2009-08-15

A GaSb crystal incorporated with Mn has been grown by the Bridgman method on the Polizon facility onboard the FOTON-M3 spacecraft. Structural defects and growth striations have been successfully revealed by the chemical etching method. By calculating various parameters of the convection, the striation patterns can be explained, and the critical value of the Taylor number, which characterizes the convective condition of the rotating magnetic field induced azimuthal flow, was shown. The stresses generated during crystal growth can be reflected by the observations of etch pit distribution and other structural defects. Suggestions for improving the space experiment to improve the quality of the crystal are given. (semiconductor materials)

Thermopower, electrical and Hall conductivity of undoped and doped iron disilicide single crystals

Energy Technology Data Exchange (ETDEWEB)

Heinrich, A; Behr, G; Griessmann, H; Teichert, S; Lange, H

1997-07-01

The electrical transport properties of {beta}-FeSi{sub 2} single crystals have been investigated in dependence on the purity of the source material and on doping with 3d transition metals. The transport properties included are electrical conductivity, Hall conductivity and thermopower mainly in the temperature range from 4K to 300K. The single crystals have been prepared by chemical transport reaction in a closed system with iodine as transport agent. In undoped single crystals prepared with 5N Fe both electrical conductivity and thermopower depend on the composition within the homogeneity range of {beta}-FeSi{sub 2} which is explained by different intrinsic defects at the Si-rich and Fe-rich phase boundaries. In both undoped and doped single crystals impurity band conduction is observed at low temperatures but above 100K extrinsic behavior determined by shallow impurity states. The thermopower shows between 100K and 200K a significant phonon drag contribution which depends on intrinsic defects and additional doping. The Hall resistivity is considered mainly with respect to an anomalous contribution found in p-type and n-type single crystals and thin films. In addition doped single crystals show at temperatures below about 130K an hysteresis of the Hall voltage. These results make former mobility data uncertain. Comparison will be made between the transport properties of single crystals and polycrystalline material.

Symmetry of crystals and molecules

CERN Document Server

Ladd, Mark

2014-01-01

This book successfully combines a thorough treatment of molecular and crystalline symmetry with a simple and informal writing style. By means of familiar examples the author helps to provide the reader with those conceptual tools necessary for the development of a clear understanding of what are often regarded as 'difficult' topics. Christopher Hammond, University of Leeds This book should tell you everything you need to know about crystal and molecular symmetry. Ladd adopts an integrated approach so that the relationships between crystal symmetry, molecular symmetry and features of chemical interest are maintained and reinforced. The theoretical aspects of bonding and symmetry are also well represented, as are symmetry-dependent physical properties and the applications of group theory. The comprehensive coverage will make this book a valuable resource for a broad range of readers.

Structural and optical properties of nano-structured CdS thin films prepared by chemical bath deposition

Energy Technology Data Exchange (ETDEWEB)

Bai, Rekha, E-mail: rekha.mittal07@gmail.com; Kumar, Dinesh; Chaudhary, Sujeet; Pandya, Dinesh K. [Thin Film Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi-110016 (India)

2016-05-06

Cadmium sulfide (CdS) thin films have been deposited on conducting glass substrates by chemical bath deposition (CBD) technique. The effect of precursor concentration on the structural, morphological, compositional, and optical properties of the CdS films has been studied. Crystal structure of these CdS films is characterized by X-ray diffraction (XRD) and it reveals polycrystalline structure with mixture of cubic and wurtzite phases with grain size decreasing as precursor concentration is increased. Optical studies reveal that the CdS thin films have high transmittance in visible spectral region reaching 90% and the films possess direct optical band gap that decreases from 2.46 to 2.39 eV with decreasing bath concentration. Our study suggests that growth is nucleation controlled.

Structural and optical properties of nano-structured CdS thin films prepared by chemical bath deposition

International Nuclear Information System (INIS)

Bai, Rekha; Kumar, Dinesh; Chaudhary, Sujeet; Pandya, Dinesh K.

2016-01-01

Cadmium sulfide (CdS) thin films have been deposited on conducting glass substrates by chemical bath deposition (CBD) technique. The effect of precursor concentration on the structural, morphological, compositional, and optical properties of the CdS films has been studied. Crystal structure of these CdS films is characterized by X-ray diffraction (XRD) and it reveals polycrystalline structure with mixture of cubic and wurtzite phases with grain size decreasing as precursor concentration is increased. Optical studies reveal that the CdS thin films have high transmittance in visible spectral region reaching 90% and the films possess direct optical band gap that decreases from 2.46 to 2.39 eV with decreasing bath concentration. Our study suggests that growth is nucleation controlled.

Method for solid state crystal growth

Science.gov (United States)

Nolas, George S.; Beekman, Matthew K.

2013-04-09

A novel method for high quality crystal growth of intermetallic clathrates is presented. The synthesis of high quality pure phase crystals has been complicated by the simultaneous formation of both clathrate type-I and clathrate type-II structures. It was found that selective, phase pure, single-crystal growth of type-I and type-II clathrates can be achieved by maintaining sufficient partial pressure of a chemical constituent during slow, controlled deprivation of the chemical constituent from the primary reactant. The chemical constituent is slowly removed from the primary reactant by the reaction of the chemical constituent vapor with a secondary reactant, spatially separated from the primary reactant, in a closed volume under uniaxial pressure and heat to form the single phase pure crystals.

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Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences; Volume 127; Issue 9. Three silver (I) supramolecular compounds constructed from pyridinium or methylimidazolium polycations: Synthesis, crystal structure and properties. Yao Li Wen Li Zhang Hai Juan Du Chao-Hai Wang Ya Bin Lu Yun-Yin Niu. Volume 127 Issue 9 ...

Some chemical and physico-mechanical properties of pear cultivars

African Journals Online (AJOL)

STORAGESEVER

2009-02-18

Feb 18, 2009 ... carried out at the Biological Material Laboratory in Agricultural. Machinery Department and Fruit Science Laboratory in Horticulture. Department of Ataturk University, Erzurum, Turkey. Chemical analysis. All chemical properties of the pear cultivars were investigated on randomly selected fifty fruit samples.

On the topography of sputtered or chemically etched crystals: surface energies minimised

International Nuclear Information System (INIS)

Chadderton, L.T.; Cope, J.O.

1984-01-01

The sputtering of single or polycrystalline metal surfaces by heavy ions gives rise to the characteristic topographical features of etch pits, ripples, and cones (pyramids). For cones and pyramids, in particular, no completely satisfactory explanation exists as to the origin of the basic geometry. Scanning electron micrographs are shown. It is proposed that for topographical features of both chemical etch and ion beam origin on single crystal surfaces, the presence of facets on cones and pyramids in particular, is due to the minimization of surface energy. (U.K.)

Luminescent properties of Y{sub 3}Al{sub 5−x}Ga{sub x}O{sub 12}:Ce crystals

Energy Technology Data Exchange (ETDEWEB)

Zorenko, Yu., E-mail: zorenko@ukw.edu.pl [Institute of Physics, Kazimierz Wielki University in Bydgoszcz, Powstańców Wielkopolskich No 2, 85-090 Bydgoszcz (Poland); Zorenko, T. [Institute of Physics, Kazimierz Wielki University in Bydgoszcz, Powstańców Wielkopolskich No 2, 85-090 Bydgoszcz (Poland); Department of Electronics, Ivan Franko National University of Lviv, Gen. Tarnavskyj str. 107, 70017 Lviv (Ukraine); Malinowski, P. [Institute of Physics, Kazimierz Wielki University in Bydgoszcz, Powstańców Wielkopolskich No 2, 85-090 Bydgoszcz (Poland); Sidletskiy, O.; Neicheva, S. [Institute for Scintillation Materials, National Academy of Sciences of Ukraine, Lenina pr. 60, 61001 Kharkiv (Ukraine)

2014-12-15

Absorption, luminescent and scintillation properties of Ce{sup 3+} doped Y{sub 3}Al{sub 5−x}Ga{sub x}O{sub 12} crystals with Ga content in the x=1–5 range were investigated in this work and compared with the properties of YAG:Ce crystals. Apart from the traditional spectral methods (absorption, cathodoluminescence and light yield measurements), the intrinsic and Ce{sup 3+} related luminescence of Y{sub 3}Al{sub 5−x}Ga{sub x}O{sub 12}:Ce solid-solution were also investigated using the luminescent spectroscopy under excitation by synchrotron radiation in the 3.7–25 eV range. We show that the optical properties Y{sub 3}Al{sub 5−x}Ga{sub x}O{sub 12}:Ce garnets monotonically change with increasing the Ga content in the x=0–3 range due to preferable localization of Ga ions in the tetrahedral position of the garnet lattice. At the highest Ga concentration (x>3) the deviation of the optical properties of Y{sub 3}Al{sub 5−x}Ga{sub x}O{sub 12}:Ce garnets is observed from the respective properties of these crystals with Ga content in the x=0–3 range due to occupation by Ga ions of the octahedral position in the garnet host. - Highlights: • Different dependence of optical properties of Y{sub 3}Al{sub 5−x}Ga{sub x}O{sub 12}:Ce crystals on Ga content in x=0–3 and 3–5 ranges. • Elimination of the luminescence of Y{sub Al} antisite defects in Y{sub 3}Al{sub 5−x}Ga{sub x}O{sub 12}:Ce crystals at x>2. • Significant improvement of the scintillation properties of Y{sub 3}Al{sub 5−x}Ga{sub x}O{sub 12}:Ce crystals at x=2 and 3 in comparison with YAG:Ce.

Crystal structure mediates mode of cell death in TiO2 nanotoxicity

International Nuclear Information System (INIS)

Braydich-Stolle, Laura K.; Schaeublin, Nicole M.; Murdock, Richard C.; Jiang, Jingkun; Biswas, Pratim; Schlager, John J.; Hussain, Saber M.

2009-01-01

Certain properties that nanoparticles possess differentiate them from their bulk counterparts, and these characteristics must be evaluated prior to nanoparticle studies and include: size, shape, dispersion, physical and chemical properties, surface area, and surface chemistry. Early nanotoxicity studies evaluating TiO 2 have yielded conflicting data which identify either size or crystal structure as the mediating property for nano-TiO 2 toxicity. However, it is important to note that none of these studies examined size with the crystal structure composition controlled for or examined crystal structure while controlling the nanoparticle size. The goal of this study was to evaluate the role of size and crystal structure in TiO 2 nanotoxicity while controlling for as many other nanoproperties as possible using the HEL-30 mouse keratinocyte cell line as a model for dermal exposure. In the size-dependent studies, all the nanoparticles are 100% anatase, and aggregate sizes were determined in order to take into account the effect of agglomeration on size-dependent toxicity. In addition, varying crystal structures were assessed while the size of the nanoparticles was controlled. We were able to identify that both size and crystal structure contribute to cytotoxicity and that the mechanism of cell death varies based on crystal structure. The 100% anatase TiO 2 nanoparticles, regardless of size, induced cell necrosis, while the rutile TiO 2 nanoparticles initiated apoptosis through formation of reactive oxygen species (ROS).

A Rare Case of Anal and Perianal Chemical Burn in a Child due to Potassium Permanganate Crystals.

Science.gov (United States)

Dash, Suvashis; Bhojani, Jatin; Sharma, Sharadendu

2018-02-09

Many chemicals used as medical treatments can cause chemical burns as an untoward side effect. One of such chemicals is potassium permanganate. It is a caustic chemical used as a disinfectant. The most common sites of burn by potassium permanganate are exposed sites like the face and hands. Chemical burns in the perianal and anal region are rare in clinical practice and even sparser in the pediatric age group. In this article, we report a case of perianal and anal chemical burn in an 18-month-old, male child, caused by potassium permanganate crystal applied wrongly for the treatment of pinworm infestation. As a chemical burn in this region can have serious complications, it is necessary to be vigilant when using such chemicals in these cases. Early and timely management in such cases leads to good outcomes. This is the first of such cases of chemical burn caused by potassium permanganate in the anal and perianal region.

Micromechanical properties of C70 single crystals in the temperature range 77-350 K

International Nuclear Information System (INIS)

Lubenets, S.V.; Natsik, V.D.; Fomenko, L.S.; Rusakova, A.V.; Natsik, V.D.; Osip'yan, Yu.A.; Orlov, V.I.; Sidorov, N.S.; Izotov, A.N.

2012-01-01

Hexagonal single crystals of C 70 up to a size down to 1-2 mm were grown which allowed for the first time to investigate their low-temperature mechanical properties. Morphology, microplasticity anisotropy and the temperature dependence of Vickers microhardness HV (T) of the C 70 crystals in the temperature range 77-350 K involving all known phase transitions have been studied with the aid of optical microscopy and microindentation. The association of the features of HV (T) dependence with orientation phase transformations has been analyzed. It is suggested that anisotropy of microplasticity in the C 70 crystals correlates with the active slip systems.

Relation between photochromic properties and molecular structures in salicylideneaniline crystals.

Science.gov (United States)

Johmoto, Kohei; Ishida, Takashi; Sekine, Akiko; Uekusa, Hidehiro; Ohashi, Yuji

2012-06-01

The crystal structures of the salicylideneaniline derivatives N-salicylidene-4-tert-butyl-aniline (1), N-3,5-di-tert-butyl-salicylidene-3-methoxyaniline (2), N-3,5-di-tert-butyl-salicylidene-3-bromoaniline (3), N-3,5-di-tert-butyl-salicylidene-3-chloroaniline (4), N-3,5-di-tert-butyl-salicylidene-4-bromoaniline (5), N-3,5-di-tert-butyl-salicylidene-aniline (6), N-3,5-di-tert-butyl-salicylidene-4-carboxyaniline (7) and N-salicylidene-2-chloroaniline (8) were analyzed by X-ray diffraction analysis at ambient temperature to investigate the relationship between their photochromic properties and molecular structures. A clear correlation between photochromism and the dihedral angle of the two benzene rings in the salicylideneaniline derivatives was observed. Crystals with dihedral angles less than 20° were non-photochromic, whereas those with dihedral angles greater than 30° were photochromic. Crystals with dihedral angles between 20 and 30° could be either photochromic or non-photochromic. Inhibition of the pedal motion by intra- or intermolecular steric hindrance, however, can result in non-photochromic behaviour even if the dihedral angle is larger than 30°.

Gold nanoparticles on MoS2 layered crystal flakes

International Nuclear Information System (INIS)

Cao, Wei; Pankratov, Vladimir; Huttula, Marko; Shi, Xinying; Saukko, Sami; Huang, Zhongjia; Zhang, Meng

2015-01-01

Inorganic layered crystal MoS 2 is considered as one of the most promising and efficient semiconductor materials for future transistors, photoelectronics, and electrocatalysis. To boost MoS 2 -based material applications, one direction is to grow physically and chemically reactive nanoparticles onto MoS 2 . Here we report on a simple route to synthesis crystalized MoS 2 –Au complexes. The gold nanoparticles were grown on MoS 2 flakes through a wet method in the oxygen free environment at room temperature. Nanoparticles with diameters varying from 9 nm to 429 nm were controlled by the molar ratios of MoS 2 and HAuCl 4 precursors. MoS 2 host flakes keep intrinsic honeycomb layered structures and the Au nanoparticles cubic-center crystal microstructures. From product chemical states analysis, the synthesis was found driven by redox reactions between the sulphide and the chloroauric acid. Photoluminescence measurement showed that introducing Au nanoparticles onto MoS 2 stacks substantially prompted excitonic transitions of stacks, as an analogy for doping Si wafers with dopants. Such composites may have potential applications in wide ranges similar as the doped Si. - Highlights: • The Au nanoparticles were decorated on MoS 2 in oxygen free ambiences via a wet method. • The Au nanoparticles are size-controllable and crystalized. • Chemical reaction scheme was clarified. • The MoS 2 –Au complexes have strong photoluminescent properties

Simulation of diffusion time of small molecules in protein crystals.

Science.gov (United States)

Geremia, Silvano; Campagnolo, Mara; Demitri, Nicola; Johnson, Louise N

2006-03-01

A simple model for evaluation of diffusion times of small molecule into protein crystals has been developed, which takes into account the physical and chemical properties both of protein crystal and the diffusing molecules. The model also includes consideration of binding and the binding affinity of a ligand to the protein. The model has been validated by simulation of experimental set-ups of several examples found in the literature. These experiments cover a wide range of situations: from small to relatively large diffusing molecules, crystals having low, medium, or high protein density, and different size. The reproduced experiments include ligand exchange in protein crystals by soaking techniques. Despite the simplifying assumptions of the model, theoretical and experimental data are in agreement with available data, with experimental diffusion times ranging from a few seconds to several hours. The method has been used successfully for planning intermediate cryotrapping experiments in maltodextrin phosphorylase crystals.

Electrical and thermoluminescence properties of γ-irradiated La2CuO4 crystals

Science.gov (United States)

El-Kolaly, M. A.; Abd El-Kader, H. I.; Kassem, M. E.

1994-12-01

Measurements of the electrical properties of unirradiated as well as ?-irradiated La2CuO4 crystals were carried out at different temperatures in the frequency range of 0.1-100 kHz. Thermoluminescence (TL) studies were also performed on such crystals in the temperature range of 300-600K. The conductivity of the unirradiated La2CuO4 crystals were found to obey the power law frequency dependence at each measured temperature below the transition temperature (Tc = 450K). The activation energies for conduction and dielectric relaxation time have been calculated. The TL response and the dc resistance were found to increase with ?-irradiation dose up to 9-10 kGy. The results showed that the ferroelastic domain walls of La2CuO4 crystal as well as its TL traps are sensitive to ?-raditaion. This material can be used in radiation measurements in the range 225 Gy-10 kGy.

Effect of Co-60 gamma radiation on optical, dielectric and mechanical properties of strontium L-ascorbate hexahydrate NLO crystal

Science.gov (United States)

Dileep, M. S.; Suresh Kumar, H. M.

2018-04-01

A potentially useful nonlinear optical semi-organic single crystal of strontium L-ascorbate hexahydrate (SLAH) was grown by solution growth slow evaporation technique at room temperature. The grown crystal is semi transparent, yellowish in color with monoclinic crystal system having space group P21 and is stable up to 198 °C. Further, SLAH crystals were irradiated with gamma rays produced by 60Co with different doses of 10 KGy, 30 KGy and 50 KGy at room temperature and then studied the effect of gamma-rays on dielectric properties, optical absorption, microhardness and SHG efficiency. The absorption study reveals that the absorbance of the grown crystal is appeared to be low throughout the visible region with a lower cutoff wavelength of 277 nm and these parameters are not affected upon gamma irradiation. The luminescence intensity of the crystal is also not affected by the irradiation. There is noticeable changes were observed in dielectric properties and hardness of the materials for different doses of gamma irradiation. The second harmonic generation (SHG) efficiency of the grown crystal is 0.54 times that of the KDP crystal and is decreased moderately by increasing the dosage of gamma irradiation.

Extrinsic and intrinsic properties in metal–insulator transition of hydrothermally prepared vanadium dioxide crystals

International Nuclear Information System (INIS)

Lee, Myeongsoon; Kim, Don

2014-01-01

The clear insulator (monoclinic-VO 2 ) to metal (rutile-VO 2 ) transition (IMT) was observed in electrical conductivity and differential scanning calorimeter (DSC) measurements at around 340 K, which is IMT temperature (T H ), in the hydrothermally prepared VO 2 crystals. The occurrence of metal to insulator transition (MIT) temperature (T C ) was observed below 333 K during the first resistance measurement cycle in the most of cases. The sudden jump of the electrical resistance at IMT and MIT points was amplified several times than that of the first cycle during the repeated successive thermal cycles (heating and cooling across the IMT and MIT temperatures). T C and T H shifted to higher temperature by the repeated successive thermal cycles. This shift and the amplified jump might be related to the mechanical stress between the VO 2 crystals, i.e. extrinsic properties. However, the starting point of MIT, T CS = ∼ 336 K, and the starting point of IMT, T HS = ∼ 338 K, kept almost constant during the repeated thermal cycles (< 10 times). These two temperatures may be related to the intrinsic properties of the VO 2 : the phase transitions initiated at these temperatures regardless of the number of the repeated thermal cycles. The neat surface of the VO 2 crystals was severely damaged and the average size of particles reduced from 110 nm to 70–90 nm after extensively repeated thermal cycles (> 70 times). The damaged surface and the smaller particles, which would be originated from the mechanical stress caused by crystal volume change during the first order transition of the VO 2 , would weaken the electrical conduction path (loosen grain boundaries) between the VO 2 single crystals and would result in the amplified jump at the following MIT. This report may boost the study for the improved stability and lifetime of the VO 2 based electronic devices. - Highlights: • The sharp phase transition in cluster of VO 2 crystals depends on repeated thermal cycles. �

Luminescent and structural properties of Zn_xMg_1_-_xWO_4 mixed crystals

International Nuclear Information System (INIS)

Krutyak, N.; Nagirnyi, V.; Spassky, D.; Tupitsyna, I.; Dubovik, A.; Belsky, A.

2016-01-01

The structural and luminescent properties of perspective scintillating Zn_xMg_1_-_xWO_4 mixed crystals were studied. The following characteristics were found to depend linearly on x value: the energy of several vibrational modes detected by Raman spectroscopy, the bandgap width deduced from the shift of the excitation spectrum onset of a self-trapped exciton (STE) emission, the position of thermally stimulated luminescence peaks. It is also shown that the thermal stability of the STE luminescence decreases gradually when x decreases. These data indicate that each Zn_xMg_1_-_xWO_4 mixed crystal is not a mixture of two constituents, but possesses its original crystalline structure, as well as optical and luminescent properties. - Highlights: • The structural and luminescent properties of Zn_xMg_1_-_xWO_4 were studied. • The energy of Raman modes, the bandgap width, TSL peak position linearly depend on x. • Each Zn_xMg_1_-_xWO_4 possesses its original crystalline structure.

Wetting of cholesteric liquid crystals.

Science.gov (United States)

Silvestre, Nuno M; Figueirinhas Pereira, Maria Carolina; Bernardino, Nelson R; Telo da Gama, Margarida M

2016-02-01

We investigate theoretically the wetting properties of cholesteric liquid crystals at a planar substrate. If the properties of substrate and of the interface are such that the cholesteric layers are not distorted, the wetting properties are similar to those of a nematic liquid crystal. If, on the other hand, the anchoring conditions force the distortion of the liquid crystal layers the wetting properties are altered, the free cholesteric-isotropic interface is non-planar and there is a layer of topological defects close to the substrate. These deformations can either promote or hinder the wetting of the substrate by a cholesteric, depending on the properties of the cholesteric liquid crystal.

Synthesis, crystal structure refinement, and nonlinear-optical properties of CaB{sub 3}O{sub 5}(OH): Comparative crystal chemistry of calcium triborates

Energy Technology Data Exchange (ETDEWEB)

Yamnova, N. A., E-mail: aks.crys@gmail.com; Aksenov, S. M. [Moscow State University, Faculty of Geology (Russian Federation); Stefanovich, S. Yu. [Moscow State University, Faculty of Chemistry (Russian Federation); Volkov, A. S.; Dimitrova, O. V. [Moscow State University, Faculty of Geology (Russian Federation)

2015-09-15

Calcium triborate CaB{sub 3}O5(OH) obtained by hydrothermal synthesis in the Ca(OH){sub 2}–H{sub 3}BO{sub 3}–Na{sub 2}CO{sub 3}–KCl system is studied by single-crystal X-ray diffraction. The parameters of the orthorhombic unit cell are as follows: a = 13.490(1), b = 6.9576(3), and c = 4.3930(2) Å; V = 412.32(3) Å{sup 3} and space group Pna2{sub 1}. The structure is refined in the anisotropic approximation of the atomic displacement parameters to R = 4.28% using 972 vertical bar F vertical bar > 4σ(F). It is confirmed that the crystal structure of Ca triborate CaB{sub 3}O{sub 5}(OH) is identical to that described earlier. The hydrogen atom is localized. An SHG signal stronger than that of the quartz standard is registered. The phase transition of calcium triborate into calciborite is found on heating. The comparative crystal-chemical analysis of a series of borates with the general chemical formula 2CaO · 3B{sub 2}O{sub 3} · nH{sub 2}O (n = 0–13) with the constant CaO: B{sub 2}O{sub 3}= 2: 3 ratio and variable content of water is performed.

Luminescence and scintillation properties of YAG:Ce single crystal and optical ceramics

CERN Document Server

Mihóková, E; Mareš, J A; Beitlerová, A; Vedda, A; Nejezchleb, K; Blažek, K; D’Ambrosio, C

2007-01-01

We use various techniques to study optical and scintillation properties of Ce-doped yttrium aluminum garnet, Y3Al5O12 (YAG:Ce), in the form of a high-quality industrial single crystal. This was compared to optical ceramics prepared from YAG:Ce nanopowders. We present experimental data in the areas of optical absorption, radioluminescence, scintillation decay, photoelectron yield, thermally stimulated luminescence and radiation-induced absorption. The results point to an interesting feature—the absence of antisite (YAl, i.e. Y at the Al site) defects in optical ceramics. The scintillation decay of the ceramics is faster than that of the single crystal, but its photoelectron yield (measured with 1 μs integration time) is about 30–40% lower. Apart from the photoelectron yield value the YAG:Ce optical ceramic is fully comparable to a high quality industrial YAG:Ce single crystal and can become a competitive scintillator material.

Crystal growth, spectral and laser properties of Nd:LuAG single crystal

International Nuclear Information System (INIS)

Xu, X D; Meng, J Q; Cheng, Y; Li, D Z; Cheng, S S; Wu, F; Zhao, Z W; Wang, X D; Xu, J

2009-01-01

Nd:LuAG (Nd:Lu 3 Al 5 O 12 ) crystal was grown by the Czochralski method. X-ray powder diffraction experiments show that the Nd:LuAG crystal crystallizes in the cubic with space group Ia3d and has the cell parameter: a = 1.1907 nm, V = 1.6882 nm 3 . The absorption and fluorescence spectra of Nd:LuAG crystal at room temperature were investigated. With a fiber-coupled diode laser as pump source, the continuous-wave (CW) laser action of Nd:LuAG crystal was demonstrated. The maximum output power at 1064 nm was obtained to be 3.8 W under the incident pump power of 17.3 W, with the optical conversion efficiency 22.0% and the slope efficiency 25.7%

Crystal growth, spectral and laser properties of Nd:LuAG single crystal

Science.gov (United States)

Xu, X. D.; Wang, X. D.; Meng, J. Q.; Cheng, Y.; Li, D. Z.; Cheng, S. S.; Wu, F.; Zhao, Z. W.; Xu, J.

2009-09-01

Nd:LuAG (Nd:Lu3Al5O12) crystal was grown by the Czochralski method. X-ray powder diffraction experiments show that the Nd:LuAG crystal crystallizes in the cubic with space group Ia3d and has the cell parameter: a = 1.1907 nm, V = 1.6882 nm3. The absorption and fluorescence spectra of Nd:LuAG crystal at room temperature were investigated. With a fiber-coupled diode laser as pump source, the continuous-wave (CW) laser action of Nd:LuAG crystal was demonstrated. The maximum output power at 1064 nm was obtained to be 3.8 W under the incident pump power of 17.3 W, with the optical conversion efficiency 22.0% and the slope efficiency 25.7%.

Enhanced photorefractive properties in Hf, Ce and Cu co-doped LiNbO{sub 3} crystals for holographic application

Energy Technology Data Exchange (ETDEWEB)

Zhang, Tao, E-mail: tzhang_hit02@yahoo.com [Key Laboratory of In-fiber Integrated Optics, Ministry of Education of China, Harbin Engineering University, Harbin 150001 (China); College of Science, Harbin Engineering University, Harbin 150001 (China); Postdoctoral Research Station of Mechanical Engineering, College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin 150001 (China); Wang, Xin; Geng, Tao; Tong, Chengguo [Key Laboratory of In-fiber Integrated Optics, Ministry of Education of China, Harbin Engineering University, Harbin 150001 (China); College of Science, Harbin Engineering University, Harbin 150001 (China); Kang, Chong [Key Laboratory of In-fiber Integrated Optics, Ministry of Education of China, Harbin Engineering University, Harbin 150001 (China); College of Science, Harbin Engineering University, Harbin 150001 (China); Postdoctoral Research Station of Mechanical Engineering, College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin 150001 (China)

2015-04-25

Graphical abstract: Correlation spots of 200 holograms in a Hf, Ce and Cu co-doped LiNbO{sub 3}. - Highlights: • Several doped LiNbO{sub 3} crystals with various level of Hf doping were grown by Cz method. • IR peak shift is attributed to the complex defect change at different level of Hf. • Enhanced photorefractive properties have been got with higher Hf-doping level. • Reduced defect and increased photoconductivity are responsible for optical properties. • 200 holograms’ experiment is realized in a coherent volume 0.073 cm{sup 3}. - Abstract: Hf, Ce and Cu co-doped LiNbO{sub 3} crystals with various level of Hf doping were grown in air by a conventional Cz method. The infrared spectra were measured to discuss the defect structures and the mechanism of the absorption peak shift in these crystals. The light-induced scattering of the crystals was evaluated by the transmitted light method. The influence of the Hf-doping level on the photorefractive properties of Hf, Ce and Cu co-doped LiNbO{sub 3} crystals was studied via two-beam coupling. It is found that proper doping Hf is an efficient method to enhance the comprehensive photorefractive properties of the LiNbO{sub 3}. Using one of these crystals as medium, 200 holograms storage and correlation experiments based on angle fractal multiplexing have been realized in a coherent volume 0.073 cm{sup 3}. Moreover the diffraction efficiency is uniform and the storage density has reached 2.2 Gb/cm{sup 3}.

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Monolayer atomic crystal molecular superlattices

Science.gov (United States)

Wang, Chen; He, Qiyuan; Halim, Udayabagya; Liu, Yuanyue; Zhu, Enbo; Lin, Zhaoyang; Xiao, Hai; Duan, Xidong; Feng, Ziying; Cheng, Rui; Weiss, Nathan O.; Ye, Guojun; Huang, Yun-Chiao; Wu, Hao; Cheng, Hung-Chieh; Shakir, Imran; Liao, Lei; Chen, Xianhui; Goddard, William A., III; Huang, Yu; Duan, Xiangfeng

2018-03-01

Artificial superlattices, based on van der Waals heterostructures of two-dimensional atomic crystals such as graphene or molybdenum disulfide, offer technological opportunities beyond the reach of existing materials. Typical strategies for creating such artificial superlattices rely on arduous layer-by-layer exfoliation and restacking, with limited yield and reproducibility. The bottom-up approach of using chemical-vapour deposition produces high-quality heterostructures but becomes increasingly difficult for high-order superlattices. The intercalation of selected two-dimensional atomic crystals with alkali metal ions offers an alternative way to superlattice structures, but these usually have poor stability and seriously altered electronic properties. Here we report an electrochemical molecular intercalation approach to a new class of stable superlattices in which monolayer atomic crystals alternate with molecular layers. Using black phosphorus as a model system, we show that intercalation with cetyl-trimethylammonium bromide produces monolayer phosphorene molecular superlattices in which the interlayer distance is more than double that in black phosphorus, effectively isolating the phosphorene monolayers. Electrical transport studies of transistors fabricated from the monolayer phosphorene molecular superlattice show an on/off current ratio exceeding 107, along with excellent mobility and superior stability. We further show that several different two-dimensional atomic crystals, such as molybdenum disulfide and tungsten diselenide, can be intercalated with quaternary ammonium molecules of varying sizes and symmetries to produce a broad class of superlattices with tailored molecular structures, interlayer distances, phase compositions, electronic and optical properties. These studies define a versatile material platform for fundamental studies and potential technological applications.

Effect of loading orientations on the microstructure and property of Al−Cu single crystal during stress aging

Energy Technology Data Exchange (ETDEWEB)

Chen, Jiqiang [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Chen, Zhiguo, E-mail: zgchen@mail.csu.edu.cn [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Hunan University of Humanities, Science and Technology, Loudi 417000 (China); Deng, Yunlai [School of Material Science and Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of High Performance and Complex Manufacturing, Central South University, Changsha 410083 (China); Guo, Xiaobin; Ren, Jieke [School of Material Science and Engineering, Central South University, Changsha 410083 (China)

2016-07-15

The precipitation behavior and property of Al−Cu alloy during stress aging under various loading orientations were investigated using single crystals. The resulting microstructures and the strength property were examined by transmission electron microscope (TEM) and compression test, respectively, and the effect of the distribution of θ′-plates on strength property were discussed. The results show that the precipitation distribution of θ′ was significantly affected by the loading orientation during stress aging of Al−Cu single crystals. Loading along close to 〈011〉{sub Al} directions provided more uniform precipitation distribution of θ′ as compared to loading along close to 〈001〉{sub Al} directions, and therefore provided higher strengthening stress of the θ′-plates for the stress aging sample. The results suggested that regulating the distribution of θ′ and therefore improving strength property are possible via controlling the loading orientation during stress aging. - Highlights: • We studied the effect of loading directions on stress aging of Al−Cu single crystal. • Precipitation distribution of θ′ was noticeably affected by the loading direction. • Loading along close to 〈011〉{sub Al} directions reduced the stress-orienting effect. • The strength property is closely related to the precipitation distribution of θ′. • It is possible to regulate the distribution of θ′ and improve strength property.

Optimal numerical methods for determining the orientation averages of single-scattering properties of atmospheric ice crystals

International Nuclear Information System (INIS)

Um, Junshik; McFarquhar, Greg M.

2013-01-01

The optimal orientation averaging scheme (regular lattice grid scheme or quasi Monte Carlo (QMC) method), the minimum number of orientations, and the corresponding computing time required to calculate the average single-scattering properties (i.e., asymmetry parameter (g), single-scattering albedo (ω o ), extinction efficiency (Q ext ), scattering efficiency (Q sca ), absorption efficiency (Q abs ), and scattering phase function at scattering angles of 90° (P 11 (90°)), and 180° (P 11 (180°))) within a predefined accuracy level (i.e., 1.0%) were determined for four different nonspherical atmospheric ice crystal models (Gaussian random sphere, droxtal, budding Bucky ball, and column) with maximum dimension D=10μm using the Amsterdam discrete dipole approximation at λ=0.55, 3.78, and 11.0μm. The QMC required fewer orientations and less computing time than the lattice grid. The calculations of P 11 (90°) and P 11 (180°) required more orientations than the calculations of integrated scattering properties (i.e., g, ω o , Q ext , Q sca , and Q abs ) regardless of the orientation average scheme. The fewest orientations were required for calculating g and ω o . The minimum number of orientations and the corresponding computing time for single-scattering calculations decreased with an increase of wavelength, whereas they increased with the surface-area ratio that defines particle nonsphericity. -- Highlights: •The number of orientations required to calculate the average single-scattering properties of nonspherical ice crystals is investigated. •Single-scattering properties of ice crystals are calculated using ADDA. •Quasi Monte Carlo method is more efficient than lattice grid method for scattering calculations. •Single-scattering properties of ice crystals depend on a newly defined parameter called surface area ratio

Effect of different crystal faces on experimental interaction force and aggregation of hematite

NARCIS (Netherlands)

Hiemstra, T.; Riemsdijk, van W.H.

1999-01-01

Charging is a basic property of the solid/solution interface of minerals. The charging at different crystal faces depends on the surface chemical composition, that is, the type and number of proton-reactive surface groups. Atomic force microscopy has provided direct information on the pH-dependent

Chemical consequences of compaction within the freezing front of a crystallizing magma ocean

Science.gov (United States)

Hier-Majumder, S.; Hirschmann, M. M.

2013-12-01

develop a simple 1-D model of melt retention in the freezing front of a crystallizing magma ocean, and apply it to the thermal and chemical evolution of the early Earth.

Improving the electrical properties of graphene layers by chemical doping

International Nuclear Information System (INIS)

Khan, Muhammad Farooq; Iqbal, Muhammad Zahir; Iqbal, Muhammad Waqas; Eom, Jonghwa

2014-01-01

Although the electronic properties of graphene layers can be modulated by various doping techniques, most of doping methods cost degradation of structural uniqueness or electrical mobility. It is matter of huge concern to develop a technique to improve the electrical properties of graphene while sustaining its superior properties. Here, we report the modification of electrical properties of single- bi- and trilayer graphene by chemical reaction with potassium nitrate (KNO 3 ) solution. Raman spectroscopy and electrical transport measurements showed the n-doping effect of graphene by KNO 3 . The effect was most dominant in single layer graphene, and the mobility of single layer graphene was improved by the factor of more than 3. The chemical doping by using KNO 3 provides a facile approach to improve the electrical properties of graphene layers sustaining their unique characteristics. (paper)

Influence of UV light and heat on the ferroelectric properties of lithium niobate crystals

Energy Technology Data Exchange (ETDEWEB)

Steigerwald, Hendrik

2011-08-15

One of the most important non-linear-optical materials is lithium niobate, due to its ease of fabrication, robustness, transparency in the visible-to-infrared and excellent nonlinear properties. In this thesis the issue of tailoring ferroelectric domain structures in lithium niobate crystals is approached from two sides: interaction of defect structures inside the crystal with growing ferroelectric domains is investigated and also actual domain patterning on all crystal faces by different methods is performed. Special emphasis is given to the Mg-doped material. The fundamental understanding and the methods of domain patterning developed in this thesis are then used to obtain tailored domain structures that meet the requirements of their intended application in non-linear optics. (orig.)

Studies on the growth aspects, structural, thermal, dielectric and third order nonlinear optical properties of solution grown 4-methylpyridinium p-nitrophenolate single crystal

Science.gov (United States)

Devi, S. Reena; Kalaiyarasi, S.; Zahid, I. MD.; Kumar, R. Mohan

2016-11-01

An ionic organic optical crystal of 4-methylpyridinium p-nitrophenolate was grown from methanol by slow evaporation method at ambient temperature. Powder and single crystal X-ray diffraction studies revealed the crystal system and its crystalline perfection. The rocking curve recorded from HRXRD study confirmed the crystal quality. FTIR spectral analysis confirmed the functional groups present in the title compound. UV-visible spectral study revealed the optical window and band gap of grown crystal. The thermal, electrical and surface laser damage threshold properties of harvested crystal were examined by using TGA/DTA, LCR/Impedance Analyzer and Nd:YAG laser system respectively. The third order nonlinear optical property of grown crystal was elucidated by Z-scan technique.

Crystal chemical analysis of formation of solid solutions on the basis of compounds with garnet structure

International Nuclear Information System (INIS)

Kuz'micheva, G.M.; Kozlikin, S.N.

1989-01-01

Crystal chemical formulas permitting to evaluate the character of changes in interatomic distances during isomorphous substitution and, hence, the probability of formation of internal solid solutions and successive isomorphous substitution, are presented. The possibility of formation of introduction solid solutions is considered, using as an example Sc, Y oxides, rare earths with garnet structure

Chemical properties of mendelevium

International Nuclear Information System (INIS)

Hulet, E.K.

1980-11-01

Even with the most intense ion beams and the largest available quantities of target isotope, about 10 6 atoms at a time is all the Md that can be produced for chemical studies. This lack of sufficient sample size coupled with the very short lifetimes of the few atoms produced has severely restricted the gathering and the broadness of our knowledge concerning the properties of Md and the heavier elements. To illustrate, the literature contains a mere eleven references to the chemical studies of Md, and none of these deal with bulk properties associated with the element bound in solid phases. Some of these findings are: Md was found to be more volatile than other actinide metals which lead to the belief that it is divalent in the metallic state; separation of Md from the other actinides can be accomplished either by reduction of Md 3+ to the divalent state or by chromatographic separations with Md remaining in the tripositive state; extraction of Md 2+ with bis(2-ethylhexyl)phosphoric acid is much poorer than the extraction of the neighboring tripositive actinides; attempts to oxidize Md 3+ with sodium bismuthate failed to show any evidence for Md 4+ ; reduction potential of Md 3+ was found to be close to -0.1 volt; Md 3+ can be reduced to Md(Hg) by sodium amalgams and by electrolysis; the electrochemical behavior of Md is very similar to that of Fm and can be summarized in the equation, Md 2+ + 2e - = Md(Hg) and E 0 = -1.50 V.; and Md cannot be reduced to a monovalent ion with Sm 2+

Estimation for Retention Factor of Isoflavones in Physico-Chemical Properties

International Nuclear Information System (INIS)

Lee, Seung Ki; Row, Kyung Ho

2003-01-01

The estimation of retention factors by correlation equations with physico-chmical properties maybe helpful in chromatographic work. The physico-chemical properties were water solubility (S), hydrophobicity (P), total energy (Et), connectivity index 1 (1χ), hydrophilic-lipophlic balance (x) and hydrophilic surface area (h) of isoflavones. The retention factors were experimentally measured by RP-HPLC. Especially, the empirical regulations of water solubility and hydrophobicity were expressed in a linear form. The equation between retention factors and various physico-chemical properties of isoflavones was suggested as k = a0 + a 1 log S + a2 log P Q + a3 (E t ) + a4 ( 1 χ) + a5 (x) + a6 (h), and the correlation coefficients estimated were relatively higher than 0.95. The empirical equations might be successfully used for a prediction of the various chromatographic characteristics of substances, with a similar chemical structure

The special features of the crystal structure and properties of oxides with mixed conductivity based on lanthanum gallate

Science.gov (United States)

Politova, E. D.; Ivanov, S. A.; Kaleva, G. M.; Mosunov, A. V.; Rusakov, V. S.

2008-10-01

The paper presents a review of works on the synthesis, structural composition effects, phase transitions, and electrical conductivity properties of multicomponent solid solutions based on heterosubstituted lanthanum gallate (La,A)(Ga,M)O3 - y . High-temperature phase transitions and structural and charge ordering effects were studied. The presence of iron cations in different valence states was proved; the relative contents of these cations depended on the x parameter and nonstoichiometry parameter y of the base composition. For M = Fe, antiferromagnetic ordering was observed; its temperature interval was determined by the concentration of iron cations in the high-spin state. The total conductivity was found to increase as the concentration of transition metal cations grew because of an increase in the electronic conductivity component. The data on structural parameters and dc and ac conductivity substantiated the conclusion that the highest ionic conductivity and permeability to oxygen were characteristic of iron-containing oxides. The results obtained are evidence that crystal chemical factors play a determining role in the formation of the ion-conducting properties of anion-deficient perovskite-like oxides.

Frequency-Dependent Properties of Magnetic Nanoparticle Crystals

Energy Technology Data Exchange (ETDEWEB)

Majetich, Sara [Carnegie Mellon Univ., Pittsburgh, PA (United States)

2016-05-17

In the proposed research program we will investigate the time- and frequency-dependent behavior of ordered nanoparticle assemblies, or nanoparticle crystals. Magnetostatic interactions are long-range and anisotropic, and this leads to complex behavior in nanoparticle assemblies, particularly in the time- and frequency-dependent properties. We hypothesize that the high frequency performance of composite materials has been limited because of the range of relaxation times; if a composite is a dipolar ferromagnet at a particular frequency, it should have the advantages of a single phase material, but without significant eddy current power losses. Arrays of surfactant-coated monodomain magnetic nanoparticles can exhibit long-range magnetic order that is stable over time. The magnetic domain size and location of domain walls is governed not by structural grain boundaries but by the shape of the array, due to the local interaction field. Pores or gaps within an assembly pin domain walls and limit the domain size. Measurements of the magnetic order parameter as a function of temperature showed that domains can exist at high temoerature, and that there is a collective phase transition, just as in an exchange-coupled ferromagnet. Dipolar ferromagnets are not merely of fundamental interest; they provide an interesting alternative to exchange-based ferromagnets. Dipolar ferromagnets made with high moment metallic particles in an insulating matrix could have high permeability without large eddy current losses. Such nanocomposites could someday replace the ferrites now used in phase shifters, isolators, circulators, and filters in microwave communications and radar applications. We will investigate the time- and frequency-dependent behavior of nanoparticle crystals with different magnetic core sizes and different interparticle barrier resistances, and will measure the magnetic and electrical properties in the DC, low frequency (0.1 Hz - 1 kHz), moderate frequency (10 Hz - 500

Mechanical properties of melt-derived erbium oxide

International Nuclear Information System (INIS)

Neuman, A.D.; Blacic, M.J.; Platero, M.; Romero, R.S.; McClellan, K.J.; Petrovic, J.J.

1998-01-01

Erbium oxide (Er 2 O 3 ) is a rare earth oxide that is chemically and thermally stable and has a melting point of 2,430 C. There is relatively little information available regarding single crystal growth of erbia or the properties of erbia. In this study, erbia single crystals have been grown in a Xenon Optical Floating Zone Unit (XeOFZ) capable of melting materials at temperatures up to 3,000 C. Erbia was melt synthesized in the XeOFZ unit in a container less fashion, proving for little chance of contamination. Crystals were grown in compressed air and in reducing atmospheres. A recurring problem with melt synthesis of erbia is the appearance of flakes at the edges of the melt zone during growth; these flakes disrupt the growth process. The processing details and an initial survey of the physical properties of erbia single crystals is discussed

Synthesis, growth, structure, mechanical and optical properties of a new semi-organic 2-methyl imidazolium dihydrogen phosphate single crystal

Energy Technology Data Exchange (ETDEWEB)

Nagapandiselvi, P., E-mail: nagapandiselvip@ssn.edu.in [Department of Physics, SSN College of Engineering, Kalavakkam (India); Baby, C. [Sophisticated Analytical Instrument Facility, Indian Institute of Technology Madras, Chennai (India); Gopalakrishnan, R. [Crystal Research Lab, Department of Physics, Anna University, Chennai (India)

2016-09-15

Highlights: • 2MIDP crystals were grown by slow evaporation solution growth technique. • Single crystal XRD revealed self-assembled supramolecular framework. • Z scan technique is employed for third order nonlinear optical susceptibility. • Structure-property correlation is established. - Abstract: A new semi-organic compound, 2-methyl imidazolium dihydrogen phosphate (2MIDP), was prepared and good quality single crystals of 2MIDP were grown by slow evaporation solution growth technique. Crystal structure elucidated using Single crystal XRD showed that 2MIDP crystallizes in monoclinic system with P2{sub 1}/c space group. FT-IR, UV-Vis-NIR, Fluorescence and FT-NMR spectra confirm the molecular structure of 2MIDP. The UV-Vis-NIR spectra established the suitability of the compound for NLO applications. TG-DSC showed that 2MIDP is thermally stable up to 200 °C. Mechanical characteristics like hardness number (H{sub v}), stiffness constant (C{sub 11}), yield strength (σ{sub v}), fracture toughness (K{sub c}) and brittleness index (B{sub i}) were assessed using Vicker’s microhardness tester. Third order nonlinear optical properties determined from Z-scan measurement using femto and picosecond lasers showed two photon reverse saturable absorption. The enhancement of nonlinear optical properties in femto second laser, revealed the suitability of 2MIDP for optical limiting applications.

Crystal structure mediates mode of cell death in TiO{sub 2} nanotoxicity

Energy Technology Data Exchange (ETDEWEB)

Braydich-Stolle, Laura K.; Schaeublin, Nicole M.; Murdock, Richard C. [Wright-Patterson AFB, Applied Biotechnology Branch, Human Effectiveness Directorate, Air Force Research Laboratory (United States); Jiang, Jingkun; Biswas, Pratim [Washington University in St. Louis, Department of Energy, Environmental, and Chemical Engineering (United States); Schlager, John J.; Hussain, Saber M., E-mail: Saber.Hussain@wpafb.af.mi [Wright-Patterson AFB, Applied Biotechnology Branch, Human Effectiveness Directorate, Air Force Research Laboratory (United States)

2009-08-15

Certain properties that nanoparticles possess differentiate them from their bulk counterparts, and these characteristics must be evaluated prior to nanoparticle studies and include: size, shape, dispersion, physical and chemical properties, surface area, and surface chemistry. Early nanotoxicity studies evaluating TiO{sub 2} have yielded conflicting data which identify either size or crystal structure as the mediating property for nano-TiO{sub 2} toxicity. However, it is important to note that none of these studies examined size with the crystal structure composition controlled for or examined crystal structure while controlling the nanoparticle size. The goal of this study was to evaluate the role of size and crystal structure in TiO{sub 2} nanotoxicity while controlling for as many other nanoproperties as possible using the HEL-30 mouse keratinocyte cell line as a model for dermal exposure. In the size-dependent studies, all the nanoparticles are 100% anatase, and aggregate sizes were determined in order to take into account the effect of agglomeration on size-dependent toxicity. In addition, varying crystal structures were assessed while the size of the nanoparticles was controlled. We were able to identify that both size and crystal structure contribute to cytotoxicity and that the mechanism of cell death varies based on crystal structure. The 100% anatase TiO{sub 2} nanoparticles, regardless of size, induced cell necrosis, while the rutile TiO{sub 2} nanoparticles initiated apoptosis through formation of reactive oxygen species (ROS).

Stability of (Fe-Tm-B) amorphous alloys: relaxation and crystallization phenomena

International Nuclear Information System (INIS)

Zemcik, T.

1994-01-01

Fe-Tm-B base (TM = transition metal) amorphous alloys (metallic glasses) are thermodynamically metastable. This limits their use as otherwise favourable materials, e.g. magnetically soft, corrosion resistant and mechanically firm. By analogy of the mechanical strain-stress dependence, at a certain degree of thermal activation the amorphous structure reaches its limiting state where it changes its character and physical properties. Relaxation and early crystallization processes in amorphous alloys, starting already around 100 C, are reviewed involving subsequently stress relief, free volume shrinking, topological and chemical ordering, pre-crystallization phenomena up to partial (primary) crystallization. Two diametrically different examples are demonstrated from among the soft magnetic materials: relaxation and early crystallization processes in the Fe-Co-B metallic glasses and controlled crystallization of amorphous ribbons yielding rather modern nanocrystalline ''Finemet'' alloys where late relaxation and pre-crystallization phenomena overlap when forming extremely dispersive and fine-grained nanocrystals-in-amorphous-sauce structure. Moessbauer spectroscopy seems to be unique for magnetic and phase analysis of such complicated systems. (orig.)

Synthesis, characterization, crystal structure and quantum chemical investigations of three novel coumarin-benzenesulfonohydrazide derivatives

Science.gov (United States)

Chethan Prathap, K. N.; Lokanath, N. K.

2018-04-01

Coumarin derivatives are an important class of heterocyclic compounds due to their physical and biological properties. Coumarin derivatives have been identified with many significant electro-optical properties and biological activities. Three novel coumarin derivatives containing benzene sulfonohydrazide group were synthesized by condensation reaction. The synthesized compounds were characterized by various spectroscopic techniques (Mass, 1H/13C NMR and FTIR). Thermal and optical properties were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and UV-Vis spectroscopic studies. Finally their structures were confirmed by single crystal X-ray diffraction (XRD) studies. The three compounds exhibit diverse intermolecular interactions, as observed by the crystal packing and Hirshfeld surface analysis. Further, their structures were optimized by density functional theory (DFT) calculations using B3LYP hybrid functionals with 6-311G+(d,p) level basis set. The Mulliken charge, molecular electrostatic potential (MEP), frontier molecular orbitals (HOMO-LUMO) were investigated. The experimentally determined parameters were compared with those calculated theoretically and they complement each other with a very good correlation. The transitions among the molecular orbitals were investigated using time-dependent density functional theory (TD-DFT) and the electronic absorption spectra obtained showed very good agreement with the experimentally measured UV-Vis spectra. Furthermore, non-linear optical (NLO) properties were investigated by calculating polarizabilities and hyperpolarizabilities. All three compounds exhibit significantly high hyperpolarizabilities compared to the reference material urea, which makes them potential candidates for NLO applications.

Growth and scintillation properties of gadolinium and yttrium orthovanadate crystals

International Nuclear Information System (INIS)

Voloshina, O.V.; Baumer, V.N.; Bondar, V.G.; Kurtsev, D.A.; Gorbacheva, T.E.; Zenya, I.M.; Zhukov, A.V.; Sidletskiy, O.Ts.

2012-01-01

Aiming to explore the possibility of using the undoped rare-earth orthovanadates as scintillation materials, we developed the procedure for growth of gadolinium (GdVO 4 ) and yttrium (YVO 4 ) orthovanadate single crystals by Czochralski method, and determined the optimal conditions of their after-growth annealing. Optical, luminescent, and scintillation properties of YVO 4 and GdVO 4 were discussed versus known literature data. Scintillation characteristics of GdVO 4 were determined for the first time.

Symmetry Aspects of Dislocation-Effected Crystal Properties: Material Strength Levels and X-ray Topographic Imaging

Directory of Open Access Journals (Sweden)

Ronald W. Armstrong

2014-03-01

Full Text Available Several materials science type research topics are described in which advantageous use of crystal symmetry considerations has been helpful in ferreting the essential elements of dislocation behavior in determining material properties or for characterizing crystal/polycrystalline structural relationships; for example: (1 the mechanical strengthening produced by a symmetrical bicrystal grain boundary; (2 cleavage crack formation at the intersection within a crystal of symmetrical dislocation pile-ups; (3 symmetry aspects of anisotropic crystal indentation hardness measurements; (4 X-ray diffraction topography imaging of dislocation strains and subgrain boundary misorientations; and (5 point and space group aspects of twinning. Several applications are described in relation to the strengthening of grain boundaries in nanopolycrystals and of multiply-oriented crystal grains in polysilicon photovoltaic solar cell materials. A number of crystallographic aspects of the different topics are illustrated with a stereographic method of presentation.

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Growth and properties of oxygen doped Bi2Sr2CaCu2O8+δ single crystals

International Nuclear Information System (INIS)

Kapitulnik, A.; Mitzi, D.B.

1990-01-01

This paper reports results on oxygen doped single crystals in the Bi 2 Sr 2 CaCu 2 O 8+δ system grown by a directional solidification method. Annealing of as made crystals in increasing partial pressure of oxygen reversibly depresses the superconducting transition temperature from 90K (as made) to 77K (oxygen pressure annealed). Magnetic and photoemission properties of these crystals will be discussed

Crystal Structure and Ferroelectric Properties of ε-Ga2O3 Films Grown on (0001)-Sapphire.

Science.gov (United States)

Mezzadri, Francesco; Calestani, Gianluca; Boschi, Francesco; Delmonte, Davide; Bosi, Matteo; Fornari, Roberto

2016-11-21

The crystal structure and ferroelectric properties of ε-Ga 2 O 3 deposited by low-temperature MOCVD on (0001)-sapphire were investigated by single-crystal X-ray diffraction and the dynamic hysteresis measurement technique. A thorough investigation of this relatively unknown polymorph of Ga 2 O 3 showed that it is composed of layers of both octahedrally and tetrahedrally coordinated Ga 3+ sites, which appear to be occupied with a 66% probability. The refinement of the crystal structure in the noncentrosymmetric space group P6 3 mc pointed out the presence of uncompensated electrical dipoles suggesting ferroelectric properties, which were finally demonstrated by independent measurements of the ferroelectric hysteresis. A clear epitaxial relation is observed with respect to the c-oriented sapphire substrate, with the Ga 2 O 3 [10-10] direction being parallel to the Al 2 O 3 direction [11-20], yielding a lattice mismatch of about 4.1%.

Crystallographic Investigations into Properties of Acentric Hybrid Perovskite Single Crystals NH(CH3)3SnX3(X = Cl, Br)

KAUST Repository

Dang, Yangyang

2016-10-11

The hybrid perovskites with special optoelectronic properties have attracted more attention to the scientific and industrial applications. However, because of the toxicity and instability of lead complexes, there is interest in finding a nontoxic substitute for the lead in the halides perovskites and solving the ambiguous crystal structures and phase transition of NH(CH3)3SnX3 (X = Cl, Br). Here, we report the bulk crystal growths and different crystal morphologies of orthorhombic hybrid perovskites NH(CH3)3SnX3 (X = Cl, Br) in an ambient atmosphere by bottom-seeded solution growth (BSSG) method. More importantly, detailed structural determination and refinements, phase transition, band gap, band structure calculations, nonlinear optical (NLO) properties, XPS, thermal properties, and stability of NH(CH3)3SnX3 (X = Cl, Br) single crystals are demonstrated. NH(CH3)3SnCl3 single crystal undergoes reversible structural transformation from orthorhombic space group Cmc21 (no. 36) to monoclinic space group Cc (no. 9) and NH(CH3)3SnBr3 belongs to the orthorhombic space group Pna21 (no. 33) by DSC, single-crystal X-ray diffraction and temperature-dependent SHG measurements, which clarify the former results. These results should pave the way for further studies of these materials in optoelectronics.

Investigation on nonlinear optical and dielectric properties of L-arginine doped ZTC crystal to explore photonic device applications

Directory of Open Access Journals (Sweden)

Anis Mohd

2016-09-01

Full Text Available The present study is focused to explore the photonic device applications of L-arginine doped ZTC (LA-ZTC crystals using nonlinear optical (NLO and dielectric studies. The LA-ZTC crystals have been grown by slow evaporation solution technique. The chemical composition and surface of LA-ZTC crystal have been analyzed by means of energy dispersive spectroscopy (EDS and surface scanning electron microscopy (SEM techniques. The Vicker’s microhardness study has been carried out to determine the hardness, work hardening index, yield strength and elastic stiffness of LA-ZTC crystal. The enhanced SHG efficiency of LA-ZTC crystal has been ascertained using the Kurtz-Perry powder SHG test. The closed-and-open aperture Z-scan technique has been employed to confirm the third order nonlinear optical nature of LA-ZTC crystal. The Z-scan transmittance data has been utilized to calculate the superior cubic susceptibility, nonlinear refractive index, nonlinear absorption coefficient and figure of merit of LA-ZTC crystal. The behavior of dielectric constant and dielectric loss of LA-ZTC crystal at different temperatures has been investigated using the dielectric analysis.

Optical properties of tetrapod nanostructured zinc oxide by chemical ...

African Journals Online (AJOL)

... deposited onto indium tin oxide (ITO) coated glass substrate by thermal chemical vapor deposition (TCVD) technique. This work studies the effects of annealing temperature ranging from 100–500 ºC towards its physical and optical properties. FESEM images showed that the structural properties of tetrapod nanostructured ...

Effect of crystal structure on optical properties of sol–gel derived zirconia thin films

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiaodong, E-mail: xiaodong_wang@tongji.edu.cn [Pohl Institute of Solid State Physics, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Tongji University, Shanghai 200092 (China); Wu, Guangming; Zhou, Bin [Pohl Institute of Solid State Physics, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Tongji University, Shanghai 200092 (China); Shen, Jun, E-mail: shenjun67@tongji.edu.cn [Pohl Institute of Solid State Physics, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Tongji University, Shanghai 200092 (China)

2013-04-15

Highlights: ► ZrO{sub 2} films were deposited by sol–gel method. ► Crystal structures of the films were tuned by different thermal annealing methods. ► The refractive indices vary with the crystal structures of the films. ► Lattice-mismatch was found to reduce the refractive index of ZrO{sub 2} films. -- Abstract: The optical properties of sol–gel derived zirconia thin films and their relation to the crystal structure are studied in this paper. ZrO{sub 2} films were deposited on quartz glass and silicon wafer substrates by sol–gel method with conventional furnace annealing (CFA) and rapid thermal annealing (RTA). Crystal structures of the films were analyzed by X-ray diffraction (XRD) and Raman spectroscopy, while refractive indices of the films were determined from the reflectance and transmittance spectra. The refractive indices vary with the function of crystal structure and density of the films, which depends on annealing temperature and annealing technique. Lattice-mismatch between monoclinic phase and tetragonal phase was found to reduce the refractive index of ZrO{sub 2} films.

Growth, thermal and laser properties of Yb:YxLu1−xVO4 mixed crystal

International Nuclear Information System (INIS)

Zhong, Degao; Teng, Bing; Kong, Weijin; Li, Jianhong; Zhang, Shiming; Li, Yuyi; Cao, Lifeng; Yang, Liting; He, Linxiang; Huang, Wanxia

2015-01-01

New mixed crystal of Yb: Y 0.78 Lu 0.22 VO 4 with Yb ion concentration of 0.3 at% was grown by Czochralski method. Transmission synchrotron X-ray topography implies that this mixed crystal follows a rotational growth pattern. Crystal structure of this crystal was determined by X-ray diffraction. It showed that this crystal possesses a tetragonal zircon structure (ZrSiO 4 , space group I41/amd), as YVO 4 and LuVO 4 do. Thermal properties of this crystal were characterized by measuring its specific heat, thermal expansion coefficients and thermal conductivities. The specific heat was determined to be 0.500 J g −1 K −1 at 293 K. The average linear thermal expansion coefficients were calculated to be α 11 = 1.73 × 10 −6 K −1 and α 33 = 9.43 × 10 −6 K −1 , over the temperature range of 300–777 K. The thermal conductivities were calculated to be κ 11 = 5.47 W m −1 K −1 and κ 33 = 6.64 W m −1 K −1 at 303 K. Continuous-wave (cw) laser test on Yb: Y 0.78 Lu 0.22 VO 4 was conducted at room temperature in the wavelength range of 1035.7–1048.3 nm, and a 13.5% optical-to-optical efficiency was achieved. The good thermal properties of Yb:Y 0.78 Lu 0.22 VO 4 mixed crystal and its attractive cw laser performance make it very suitable for practical applications. - Highlights: • New Yb:Y 0.78 Lu 0.22 VO 4 mixed laser crystals were grown. • The thermal expansion, thermal diffusivity and specific heat were measured. • Cw laser operation was realized at room temperature in the range of 1035.7–1048.3 nm

Effect of rare-earth dopants on the growth and structural, optical, electrical and mechanical properties of L-arginine phosphate single crystals

International Nuclear Information System (INIS)

Arjunan, S.; Bhaskaran, A.; Kumar, R. Mohan; Mohan, R.; Jayavel, R.

2010-01-01

Research highlights: → Thorium, Lanthanum and Cerium rare-earth ions were doped with L-arginine phosphate material and the crystals were grown by slow evaporation technique. → The transparency of the rare-earth doped LAP crystals has enhanced compared to pure LAP. → The powder SHG measurements revealed that the SHG output of rare-earth doped LAP crystals increases considerably compared to that of LAP. → Vicker's hardness number of as-grown crystal of LAP is higher than that of rare-earth doped LAP crystals. - Abstract: Effect of Thorium, Lanthanum and Cerium rare-earth ions on the growth and properties of L-arginine phosphate single crystals has been reported. The incorporation of rare-earth dopants into the L-arginine phosphate crystals is confirmed by Inductively Coupled Plasma-Mass Spectroscopy analysis. The unit cell parameters for pure and rare-earth doped L-arginine phosphate crystals have been estimated by powder X-ray diffraction studies. UV-visible studies revealed the transmittance percentage and cut-off wavelengths of the grown crystals. Powder second harmonic generation measurement has been carried out for pure and doped L-arginine phosphate crystals. The dielectric behavior of the grown crystals was analyzed for different frequencies at room temperature. The mechanical properties have been determined for pure and the doped L-arginine phosphate crystals.

Mechanical properties of pure and doped InP single crystals under concentrated loading

International Nuclear Information System (INIS)

Boyarskaya, Yu.S.; Grabko, D.Z.; Medinskaya, M.I.; Palistrant, N.A.

1997-01-01

The mechanical properties of pure and doped (Fe, Zn, Sn) InP single crystals were investigated in the temperature interval from 293 to 600 K. It was shown that impurity hardening (the microhardness increase) was more pronounced at elevated temperatures than at 293 K. This is conditioned by braking of the moving dislocations with impurities which is more observed in the the high temperature region. The obvious anisotropy of the scratch hardness was revealed at room temperature for the (001) face of crystals under investigation. This anisotropy decreased sharply in increasing the temperature from 293 to 600 K

Studies on transport properties of copper doped tungsten diselenide single crystals

Science.gov (United States)

Deshpande, M. P.; Parmar, M. N.; Pandya, Nilesh N.; Chaki, Sunil; Bhatt, Sandip V.

2012-02-01

During recent years, transition metal dichalcogenides of groups IVB, VB and VIB have received considerable attention because of the great diversity in their transport properties. 2H-WSe 2 (Tungsten diselenide) is an interesting member of the transition metal dichalcogenide (TMDC's) family and known to be a semiconductor useful for photovoltaic and optoelectronic applications. The anisotropy usually observed in this diamagnetic semiconductor material is a result of the sandwich structure of Se-W-Se layers interacting with each other, loosely bonded by the weak Van der Waals forces. Recent efforts in studying the influence of the anisotropic electrical and optical properties of this layered-type transition metal dichalcogenides have been implemented by doping the samples with different alkali group elements. Unfortunately, little work is reported on doping of metals in WSe 2. Therefore, it is proposed in this work to carry out a systematic growth of single crystals of WSe 2 by doping it with copper in different proportions i.e. Cu xWSe 2 ( x=0, 0.5, 1.0) by direct vapour transport technique. Transport properties like low and high temperature resistivity measurements, high pressure resistivity, Seebeck coefficient measurements at low temperature and Hall Effect at room temperature were studied in detail on all these samples. These measurements show that tungsten diselenide single crystals are p-type whereas doped with copper makes it n-type in nature. The results obtained and their implications are discussed in this paper.

Metal-loaded pollucite-like aluminophosphates: dissymmetrisation of crystal structures and physical properties

Science.gov (United States)

Shvanskaya, L. V.; Yakubovich, O. V.; Koshelev, A. V.; Vasiliev, A. N.

2018-02-01

Two aluminophosphate analogues of the mineral pollucite with the general formula Cs2(M,Al)3P3O12 (where M = Cu or Mn) have been synthesized by high-temperature flux and structurally characterized using the single-crystal X-ray diffraction. Both samples crystallize in cubic I4132 space group, Z = 8, with a = 13.5911(5) and a = 13.8544(7) for Cu- and Mn-loaded phases, respectively. Their framework structures are based on the ANA-type topology and exhibit the partial ordering of the metal (M/Al) and phosphorus (P) cations over the tetrahedral sites. The regular changes in cell dimensions and volumes in the row Cs2(Cu,Al)3P3O12→Cs2(Mn,Al)3P3O12 obviously correspond to increasing radii of the transition metal. The crystal chemical analysis of both pollucite-like phases show correlations between the difference in the radii size of tetrahedral cations and the degree of distortion of flexible ANA-type framework due to decreasing of the intertetrahedral angles (T-O-T). Magnetic susceptibility measurements indicate that both compounds are paramagnets in the temperature range of 2-300 K.

PA6 and Kevlar fiber reinforced isotactic polypropylene: Structure, mechanical properties and crystallization and melting behavior

International Nuclear Information System (INIS)

Zhao, Songfang; Cheng, Lei; Guo, Yong; Zheng, Yuying; Li, Baoming

2012-01-01

Highlights: ► KF was modified with caprolactam using toluenediisocyanate (TDI) as bridge. ► Modified KF improves interfacial interaction of iPP/KF/PA6 composites. ► Fiber and nylon 6 inhibited the crystallization of PP continuous phase. -- Abstract: To improve the thermal and mechanical properties of isotactic polypropylene (iPP), iPP/Kevlar fiber (KF)/polyamide 6 (PA6) composites were prepared via the melt-extrusion method on twin-screw extruder. Kevlar fiber was modified with caprolactam using toluenediisocyanate (TDI) as bridge. The microstructure of modified KF was successfully characterized by Fourier transform infrared (FT-IR), X-ray photoelectron spectrometer (XPS) and scanning electron microscopy (SEM), the results showed that KF was bonded with caprolactam and became coarser. Then the modified KF was introduced into iPP, the composites have better mechanical and thermal properties, implying that modification of KF was helpful to improve the interfacial interaction of iPP/KF/PA6 composites. Besides, the crystallization curves indicated that crystallization behavior of PA6 in the composites was homogeneous and fractional. Furthermore, compatibilizer content played an important role in the mechanical and thermal properties of composites.

A materials informatics approach for crystal chemistry

Science.gov (United States)

Kong, Chang Sun

This thesis addresses one of the fundamental questions in materials crystal chemistry, namely why do atoms arrange themselves in the way they do? The ability to broadly design and predict new phases [i.e. crystal structures] can be partly met using concepts that employ phase homologies. Homologous series of compounds are those that seem chemically diverse but can be expressed in terms of a mathematical formula that is capable of producing each chemical member in that crystal structure. A well-established strategy to help discover new compounds -- or at least to try to develop chemical design strategies for discovery -- is to search, organize and classify homologous compounds from known data. These classification schemes are developed with the hope that they can provide sufficient insight to help us forecast with some certainty, specific new phases or compounds. Yet, while the classification schemes (over a dozen have been reported in the last 50 years) have proved to be instructive, mostly in hindsight, but they have had limited impact, if at all, on the a priori design of materials chemistry. The aim of this research project is to develop a totally new approach to the study of chemical complexity in materials science using the tools of information theory and data science, which link diverse and high dimensional data derived from physical modeling and experiments. A very large scale binary AB2 crystallographic database is used as a data platform to develop a new data mining/informatics protocol based on high dimensional recursive partitioning schemes coupled to information theoretic measures to: (1) Identify which type of structure prototype is preferred over another for a given chemistry of compound; (2) discover new classification schemes of structure/chemistry/property relationships that classical homologies do not detect and finally we; (3) Extract and organize the underlying design rules for the formation of a given structure by quantitatively assessing the

3D electron tomography of biological photonic crystals

Energy Technology Data Exchange (ETDEWEB)

Butz, Benjamin; Winter, Benjamin; Vieweg, Benito; Knoke, Isabel; Spallek, Stefanie; Spiecker, Erdmann [CENEM, Universitaet Erlangen-Nuernberg (Germany); Schroeder-Turk, Gerd; Mecke, Klaus [Theoretische Physik I, Universitaet Erlangen-Nuernberg (Germany)

2011-07-01

Photonic crystals, i.e. periodical nanostructures of materials with different dielectric constants, are highly interesting for applications in optics, optoelectronics, and sensing. By tailoring the geometrical parameters radically different and improved optical properties (e.g., optical band-gap structure, extreme refractive indices, or high anisotropy) can be achieved. Naturally occurring photonic crystals, like butterfly scales, exoskeletons of insects (chitin), or seashells (nacre), can serve as model systems for understanding the relationship between structure and optical properties. Butterfly scales are studied by TEM using a FEI Titan{sup 3} 80-300 instrument. An optimized FIB technique or ultramicrotome sectioning were used to prepare the sensitive specimens with desired thickness. Since the periodical structures have dimensions on the sub-{mu}m scale, HAADF-STEM tomography was employed for obtaining extended tilt series under conditions of atomic-number sensitive imaging. Since the solid crystal consists of chemically homogeneous chitin while the pores are unfilled, the distinct contrast in the images can easily be interpreted in terms of the local projected mass density allowing to reconstruct the chitin distribution within the optical unit cell of the scales with high 3D resolution.

Study of post annealing influence on structural, chemical and electrical properties of ZTO thin films

International Nuclear Information System (INIS)

Jain, Vipin Kumar; Kumar, Praveen; Kumar, Mahesh; Jain, Praveen; Bhandari, Deepika; Vijay, Y.K.

2011-01-01

Research highlights: → Structural, chemical and electrical properties of cost effective ZTO thin films with varying concentrations. → Effect of annealing of ZTO films. - Abstract: Zinc-Tin-Oxide (ZTO) thin films were deposited on glass substrate with varying concentrations (ZnO:SnO 2 ; 100:0, 90:10, 70:30 and 50:50 wt.%) at room temperature by flash evaporation technique. These deposited ZTO films were annealed at 450 deg. C in vacuum. These films were characterized to study the effect of annealing and addition of SnO 2 concentration on the structural, chemical and electrical properties. The XRD analysis indicates that crystallization of the ZTO films strongly depends on the concentration of SnO 2 and post annealing where annealed films showed polycrystalline nature. Atomic force microscopy (AFM) images manifest the surface morphology of these ZTO thin films. The XPS core level spectra of Zn(2p), O(1s) and Sn(3d) have been deconvoluted into their Gaussian component to evaluate the chemical changes, while valence band spectra reveal the electronic structures of these films. A small shift in Zn(2p) and Sn(3d) core level towards higher binding energy and O(1s) core level towards lower binding energy have been observed. The minimum electrical resistivity (ρ ∼ 3.69 x 10 -2 Ω-cm), maximum carrier concentration (n ∼ 3.26 x 10 19 cm -3 ) and Hall mobility (μ ∼ 5.2 cm 2 v -1 s -1 ) were obtained for as-prepared ZTO (50:50) film thereafter move towards lowest resistivity (ρ ∼ 1.12 x 10 -3 Ω-cm), highest carrier concentration (n ∼ 2.96 x 10 20 cm -3 ) and mobility (μ ∼ 18.8 cm 2 v -1 s -1 ) for annealed ZTO (50:50) thin film.

The polymorphic weddellite crystals in three species of Cephalocereus (Cactaceae).

Science.gov (United States)

Bárcenas-Argüello, María-Luisa; Gutiérrez-Castorena, Ma C-del-Carmen; Terrazas, Teresa

2015-10-01

Mineral inclusions in plant cells are genetically regulated, have an ecological function and are used as taxonomic characters. In Cactaceae, crystals in epidermal and cortical tissues have been reported; however, few studies have conducted chemical and morphological analyses on these crystals, and even fewer have reported non-mineral calcium to determine its systematic value. Cephalocereus apicicephalium, C. totolapensis and C. nizandensis are Cactaceae species endemic to the Isthmus of Tehuantepec, Mexico with abundant epidermal prismatic crystals. In the present study, we characterize the mineral cell inclusions, including their chemical composition and their morphology, for three species of Cephalocereus. Crystals of healthy branches of the three species were isolated and studied. The crystals were identified by X-ray diffraction (XRD), their morphology was described using a petrographic and scanning electron microscope (SEM), and their elemental composition was measured with Energy Dispersive X-ray (EDXAR). The three species synthesized weddellite with different degrees of hydration depending on the species. The optical properties of calcium oxalate crystals were different from the core, which was calcium carbonate. We observed a large diversity of predominantly spherical forms with SEM. EDXAR analysis detected different concentrations of Ca and significant amounts of elements, such as Si, Mg, Na, K, Cl, and Fe, which may be related to the edaphic environment of these cacti. The occurrence of weddellite is novel for the genus according to previous reports. The morphological diversity of the crystals may be related to their elemental composition and may be a source of phylogenetic characters. Copyright © 2015 Elsevier Ltd. All rights reserved.

EFFECT OF INTERFACIAL ADHESION ON CRYSTALLIZATION AND MECHANICAL PROPERTIES OF POLY (ETHYLENE TEREPHTHALATE)/GLASS BEAD COMPOSITES

Institute of Scientific and Technical Information of China (English)

OU Yuchun; YU Zhongzhen; ZHU Jin; LI Ge; ZHU Shanguang

1996-01-01

The interfacial adhesion between poly (ethylene terephthalate) (PET) and glass bead was investigated by scanning electron microscope and parallel-plate rheometer. Effect of interfacial adhesion on the crystallization and mechanical properties of PET/glass bead composites was also studied by differential scanning calorimeter and mechanical testers.The results obtained indicate that the glass bead has a heterogeneous nucleation effect on the PET crystallization. Although better interfacial adhesion is advantageous to the increase of the tensile strength of the composite, yet it is unfavorable to the crystallization of PET. It should be pointed out that the crystallization rate of filled PET is always higher than that of pure PET, regardless of the state of interfacial adhesion.

Effect of amino acid doping on the growth and ferroelectric properties of triglycine sulphate single crystals

International Nuclear Information System (INIS)

Raghavan, C.M.; Sankar, R.; Mohan Kumar, R.; Jayavel, R.

2008-01-01

Effect of amino acids (L-leucine and isoleucine) doping on the growth aspects and ferroelectric properties of triglycine sulphate crystals has been studied. Pure and doped crystals were grown from aqueous solution by low temperature solution growth technique. The cell parameter values were found to significantly vary for doped crystals. Fourier transform infrared analysis confirmed the presence of functional groups in the grown crystal. Morphology study reveals that amino acid doping induces faster growth rate along b-direction leading to a wide b-plane and hence suitable for pyroelectric detector applications. Ferroelectric domain structure has been studied by atomic force microscopy and hysteresis measurements reveal an increase of coercive field due to the formation of single domain pattern

Optical properties and radiation response of Ce{sup 3+}-doped GdScO{sub 3} crystals

Energy Technology Data Exchange (ETDEWEB)

Yamaji, Akihiro; Fujimoto, Yutaka; Futami, Yoshisuke; Yokota, Yuui; Kurosawa, Shunsuke [Institute of Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Kochurikhin, Vladimir [General Physics Institute, 38 Vavilov Str., 119991 Moscow (Russian Federation); Yanagida, Takayuki [New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Yoshikawa, Akira [Institute of Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

2012-12-15

10%-Ce doped GdScO{sub 3} perovskite type single crystal was grown by the Czochralski process. The Ce concentration in the crystal was measured. No impurity phases were observed by powder X-ray diffraction analysis. We evaluated the optical and radiation properties of the grown crystal. Ce:GdScO{sub 3} crystal showed photo- and radio-luminescence peaks due to Ce{sup 3+} of 5d-4f transition and colour centre. The photoluminescence decay time was sub-ns order. The relative light yield under 5.5 MeV alpha-ray excitation was calculated to be approximately 9% of BGO. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Crystal Growth and Scintillation Properties of Eu2+ doped Cs4CaI6 and Cs4SrI6

Science.gov (United States)

Stand, L.; Zhuravleva, M.; Chakoumakos, B.; Johnson, J.; Loyd, M.; Wu, Y.; Koschan, M.; Melcher, C. L.

2018-03-01

In this work we present the crystal growth and scintillation properties of two new ternarymetal halide scintillators activated with divalent europium, Cs4CaI6 and Cs4SrI6. Single crystals of each compound were grown in evacuated quartz ampoules via the vertical Bridgman technique using a two-zone transparent furnace. Single crystal X-ray diffraction experiments showed that both crystals have a trigonal (R-3c) structure, with a density of 3.99 g/cm3 and 4.03 g/cm3. The radioluminescence and photoluminescence measurements showed typical luminescence properties due to the 5d-4f radiative transitions in Eu2+. At this early stage of development Cs4SrI6:Eu and Cs4CaI6:Eu have shown very promising scintillation properties, with light yields and energy resolutions of 62,300 ph/MeV and 3.3%, and 51,800 photons/MeV and 3.6% at 662 keV, respectively.

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A framework for analysing relationships between chemical composition and crystal structure in metal oxides

International Nuclear Information System (INIS)

Thomas, N.W.

1991-01-01

A computer program has been written to characterize the coordination polyhedra of metal cations in terms of their volumes and polyhedral elements, i.e. corners, edges and faces. The sharing of these corners, edges and faces between polyhedra is also quantitatively monitored. In order to develop the methodology, attention is focused on ternary oxides containing the Al 3+ ion, whose structures were retrieved from the Inorganic Crystal Structure Database (ICSD). This also permits an objective assessment of the applicability of Pauling's rules. The influence of ionic valence on the structures of these compounds is examined, by calculating electrostatic bond strengths. Although Pauling's second rule is not supported in detail, the calculation of oxygen-ion valence reveals a basic structural requirement, that the average calculated oxygen-ion valence in any ionic oxide structure is equal to 2. The analysis is further developed to define a general method for the prediction of novel chemical compositions likely to adopt a given desired structure. The polyhedral volumes of this structure are calculated, and use is made of standard ionic radii for cations in sixfold coordination. The electroneutrality principle is invoked to take valence considerations into account. This method can be used to guide the development of new compositions of ceramic materials with certain desirable physical properties. (orig.)

Synthesis, Crystal Growth, Spectroscopic and Electrical Properties of 5-tert-Butyl-1,2,3-trinitrobenzene

Directory of Open Access Journals (Sweden)

S. Sahaya Jude Dhas

2013-01-01

Full Text Available 5-tert-Butyl-1,2,3-trinitrobenzene (TBTB was synthesized and characterized by NMR so as to confirm the structure. Single crystals were obtained from methanol by solvent evaporation technique at room temperature. Optically transparent single crystals with dimension up to 17×4×3 mm3 have been grown by submerged seed solution method within a period of 30 days. The modes of vibration of different molecular groups present in the title compound were identified by FTIR and FT-Raman spectral analyses, and it was found with the tabulation that both of the spectral vibrations are very close to each other confirming the existence of specific functional groups in the crystal. Optical behaviour of the crystal was analyzed by UV-Vis absorption studies, and the value of the optical band gap energy (Eg of the crystal has been determined using the optical absorption spectrum. The dielectric behaviour and AC conductivity of the grown crystals were also analyzed, and it is shown that both properties vary with respect to frequency and do not vary in accordance with temperature.

Chemical composition, physicochemical and functional properties of ...

African Journals Online (AJOL)

The results of chemical composition, physicochemical and functional properties for both lupin samples indicated that lupins can be used as a raw material for various food products manufacturing and provide consistency in food processing, analogous to other food legumes. Therefore, the research findings can be used by ...

Chemical properties and colors of fermenting materials in salmon fish sauce production

Directory of Open Access Journals (Sweden)

Mitsutoshi Nakano

2018-02-01

Full Text Available This data article reports the chemical properties (moisture, pH, salinity, and soluble solid content and colors of fermenting materials in salmon fish sauce products. The fish sauce was produced by mixing salt with differing proportions of raw salmon materials and fermenting for three months; the salmon materials comprised flesh, viscera, an inedible portion, and soft roe. Chemical properties and colors of the unrefined fish sauce (moromi, and the refined fish sauce, were analyzed at one, two, and three months following the start of fermentation. Data determined for all products are provided in table format. Keywords: Fish sauce, Chum salmon, Fermentation, Chemical properties, Color

Impact of physical and chemical parameters on the hydroxyapatite nanopowder synthesized by chemical precipitation method

Science.gov (United States)

Thu Trang Pham, Thi; Phuong Nguyen, Thu; Pham, Thi Nam; Phuong Vu, Thi; Tran, Dai Lam; Thai, Hoang; Thanh Dinh, Thi Mai

2013-09-01

In this paper, the synthesis of hydroxyapatite (HAp) nanopowder was studied by chemical precipitation method at different values of reaction temperature, settling time, Ca/P ratio, calcination temperature, (NH4)2HPO4 addition rate, initial concentration of Ca(NO3)2 and (NH4)2HPO4. Analysis results of properties, morphology, structure of HAp powder from infrared (IR) spectra, x-ray diffraction (XRD), energy dispersive x-ray (EDX) spectra and scanning electron microscopy (SEM) indicated that the synthesized HAp powder had cylinder crystal shape with size less than 100 nm, single-phase structure. The variation of the synthesis conditions did not affect the morphology but affected the size of HAp crystals.

Phenomenological crystal-field model of the magnetic and thermal properties of the Kondo-like system UCu2Si2

Science.gov (United States)

Troć, R.; Gajek, Z.; Pikul, A.; Misiorek, H.; Colineau, E.; Wastin, F.

2013-07-01

The transport properties described previously [Troć , Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.85.224434 85, 224434 (2012)] as well as the magnetic and thermal properties presented in this paper, observed for single-crystalline UCu2Si2, are discussed by assuming a dual (localized-itinerant) scenario. The electronic states of the localized 5f electrons in UCu2Si2 are constructed using the effective Hamiltonian known for ionic systems, allowing us to treat the Coulomb, spin-orbital, and crystal-field interactions on equal footing. The space of parameters has been restricted in the initial steps with the aid of the angular overlap model approximation. The final crystal-field parameters, obtained from the refined steps of calculations, are relatively large (in absolute values), which we attribute to the hybridization characteristic of the metallic systems on the verge of localization. The proposed crystal-field model reproduces correctly with satisfactory accuracy the magnetic and thermal properties of UCu2Si2 in agreement also with the transport properties reported previously. Considerable crystal-field splitting of the ground multiplet of 2760 K is responsible for a large anisotropy in the magnetic behavior, observed in the whole temperature range explored.

Crystal growth, spectroscopic and laser properties of Tm:LuAG crystal

Science.gov (United States)

Xu, X. D.; Wang, X. D.; Lin, Z. F.; Cheng, Y.; Li, D. Z.; Cheng, S. S.; Wu, F.; Zhao, Z. W.; Gao, C. Q.; Gao, M. W.; Xu, J.

2009-11-01

Tm:Lu3Al5O12 (Tm:LuAG) crystal was grown by the Czochralski method. The segregation coefficient was measured by Inductively Coupled Plasma Atomic Emission Spectrometer. The cell parameters were analyzed with X-ray powder diffraction experiments. The absorption and fluorescence spectra of Tm:LuAG crystal at room temperature were investigated. With a 20 W fiber-coupled diode laser as pump source, the continuous-wave (CW) laser action of Tm:LuAG crystal was demonstrated. The maximum output power at 2020 nm was obtained to be 3.04 W, and the slope efficiency was 25.3%.

Polarization and switching properties of holographic polymer-dispersed liquid-crystal gratings. I. Theoretical model

Science.gov (United States)

Sutherland, Richard L.

2002-12-01

Polarization properties and electro-optical switching behavior of holographic polymer-dispersed liquid-crystal (HPDLC) reflection and transmission gratings are studied. A theoretical model is developed that combines anisotropic coupled-wave theory with an elongated liquid-crystal-droplet switching model and includes the effects of a statistical orientational distribution of droplet-symmetry axes. Angle- and polarization-dependent switching behaviors of HPDLC gratings are elucidated, and the effects on dynamic range are described. A new type of electro-optical switching not seen in ordinary polymer-dispersed liquid crystals, to the best of the author's knowledge, is presented and given a physical interpretation. The model provides valuable insight to the physics of these gratings and can be applied to the design of HPDLC holographic optical elements.

Electrical and materials properties of ZrO2 gate dielectrics grown by atomic layer chemical vapor deposition

Science.gov (United States)

Perkins, Charles M.; Triplett, Baylor B.; McIntyre, Paul C.; Saraswat, Krishna C.; Haukka, Suvi; Tuominen, Marko

2001-04-01

Structural and electrical properties of gate stack structures containing ZrO2 dielectrics were investigated. The ZrO2 films were deposited by atomic layer chemical vapor deposition (ALCVD) after different substrate preparations. The structure, composition, and interfacial characteristics of these gate stacks were examined using cross-sectional transmission electron microscopy and x-ray photoelectron spectroscopy. The ZrO2 films were polycrystalline with either a cubic or tetragonal crystal structure. An amorphous interfacial layer with a moderate dielectric constant formed between the ZrO2 layer and the substrate during ALCVD growth on chemical oxide-terminated silicon. Gate stacks with a measured equivalent oxide thickness (EOT) of 1.3 nm showed leakage values of 10-5 A/cm2 at a bias of -1 V from flatband, which is significantly less than that seen with SiO2 dielectrics of similar EOT. A hysteresis of 8-10 mV was seen for ±2 V sweeps while a midgap interface state density (Dit) of ˜3×1011 states/cm eV was determined from comparisons of measured and ideal capacitance curves.

The plutonium: brief presentation of its nuclear, physical and chemical properties

International Nuclear Information System (INIS)

Madic, C.

1993-01-01

In this text we give a brief presentation of the nuclear properties (isotopes, isotopic composition of spent fuels, decay), of the physical properties (phase diagrams, alloys) and of the chemical properties (complexes, solvent extraction) of the plutonium

Properties of single crystal beta''-aluminas

International Nuclear Information System (INIS)

Bates, J.B.; Brown, G.M.; Kaneda, T.; Brundage, W.E.; Wang, J.C.; Engstrom, H.

1979-01-01

Large single crystals of sodium beta''-alumina were grown by slow evaporation of Na 2 O at 1690 0 C from a mixture of Na 2 CO 3 , MgO, and Al 2 O 3 . Polarized Raman measurements were made on the Na β'' single crystals and on single crystals of Li, K, Rb, and Ag β'' prepared by ion exchange of Na β''. The low frequency Raman spectra of Na, K, Rb, and Ag β'' contained four or more bands due to vibrations of the mobile cations. These results were analyzed by assuming the spectra to be due to the normal modes of a defect cluster consisting of a cation vacancy surrounded by three cations. From model calculations, the Raman band of Na β'' at 33 cm -1 is assigned to the attempt mode for diffusion of Na + ions. The structure of a Ag β'' single crystal was investigated by neutron diffraction, and 20% of the Ag + ion sites were found to be vacant

Photonic crystal fiber based chloride chemical sensors for corrosion monitoring

Science.gov (United States)

Wei, Heming; Tao, Chuanyi; Krishnaswamy, Sridhar

2016-04-01

Corrosion of steel is one of the most important durability issues in reinforced concrete (RC) structures because aggressive ions such as chloride ions permeate concrete and corrode steel, consequently accelerating the destruction of structures, especially in marine environments. There are many practical methods for corrosion monitoring in RC structures, mostly focusing on electrochemical-based sensors for monitoring the chloride ion which is thought as one of the most important factors resulting in steel corrosion. In this work, we report a fiber-optic chloride chemical sensor based on long period gratings inscribed in a photonic crystal fiber (PCF) with a chloride sensitive thin film. Numerical simulation is performed to determine the characteristics and resonance spectral response versus the refractive indices of the analyte solution flowing through into the holes in the PCF. The effective refractive index of the cladding mode of the LPGs changes with variations of the analyte solution concentration, resulting in a shift of the resonance wavelength, hence providing the sensor signal. This fiber-optic chemical sensor has a fast response, is easy to prepare and is not susceptible to electromagnetic environment, and can therefore be of use for structural health monitoring of RC structures subjected to such aggressive environments.

Variation in Pockels constants of silicate glass-ceramics prepared by perfect surface crystallization

Science.gov (United States)

Takano, Kazuya; Takahashi, Yoshihiro; Miyazaki, Takamichi; Terakado, Nobuaki; Fujiwara, Takumi

2018-01-01

We investigated the Pockels effect in polycrystalline materials consisting of highly oriented polar fresnoite-type Sr2TiSi2O8 fabricated using perfectly surface-crystallized glass-ceramics (PSC-GCs). The chemical composition of the precursor glass was shown to significantly affect the crystallized texture, e.g., the crystal orientation and appearance of amorphous nanoparasites in the domains, resulting in variations in the Pockels constants. Single crystals exhibiting spontaneous polarization possessed large structural anisotropy, leading to a strong dependence of the nonlinear-optical properties on the direction of polarized light. This study suggests that variations in the Pockels constants (r13 and r33) and tuning of the r13/r33 ratio can be realized in PSC-GC materials.

Heterogeneous nucleation of protein crystals on fluorinated layered silicate.

Directory of Open Access Journals (Sweden)

Keita Ino

Full Text Available Here, we describe an improved system for protein crystallization based on heterogeneous nucleation using fluorinated layered silicate. In addition, we also investigated the mechanism of nucleation on the silicate surface. Crystallization of lysozyme using silicates with different chemical compositions indicated that fluorosilicates promoted nucleation whereas the silicates without fluorine did not. The use of synthesized saponites for lysozyme crystallization confirmed that the substitution of hydroxyl groups contained in the lamellae structure for fluorine atoms is responsible for the nucleation-inducing property of the nucleant. Crystallization of twelve proteins with a wide range of pI values revealed that the nucleation promoting effect of the saponites tended to increase with increased substitution rate. Furthermore, the saponite with the highest fluorine content promoted nucleation in all the test proteins regardless of their overall net charge. Adsorption experiments of proteins on the saponites confirmed that the density of adsorbed molecules increased according to the substitution rate, thereby explaining the heterogeneous nucleation on the silicate surface.

Remarkable reduction of thermal conductivity in phosphorene phononic crystal

International Nuclear Information System (INIS)

Xu, Wen; Zhang, Gang

2016-01-01

Phosphorene has received much attention due to its interesting physical and chemical properties, and its potential applications such as thermoelectricity. In thermoelectric applications, low thermal conductivity is essential for achieving a high figure of merit. In this work, we propose to reduce the thermal conductivity of phosphorene by adopting the phononic crystal structure, phosphorene nanomesh. With equilibrium molecular dynamics simulations, we find that the thermal conductivity is remarkably reduced in the phononic crystal. Our analysis shows that the reduction is due to the depressed phonon group velocities induced by Brillouin zone folding, and the reduced phonon lifetimes in the phononic crystal. Interestingly, it is found that the anisotropy ratio of thermal conductivity could be tuned by the ‘non-square’ pores in the phononic crystal, as the phonon group velocities in the direction with larger projection of pores is more severely suppressed, leading to greater reduction of thermal conductivity in this direction. Our work provides deep insight into thermal transport in phononic crystals and proposes a new strategy to reduce the thermal conductivity of monolayer phosphorene. (paper)

Characterization of PbWO4 crystals for high-energy physics experiments

Science.gov (United States)

Kim, M. J.; Park, H.; Kim, H. J.

2016-09-01

High-energy physics (HEP) experiments have employed many new types of scintillators. Specifically, bismuth germanate, thallium-doped cesium iodide, and lead tungstate (PbWO4, PWO) have been used for the L3 experiment; CLEO II, Belle and BES-III; and CMS, respectively. PWO has particularly beneficial properties, such as high density, fast decay time, short radiation length and radiation hardness. In this study, we tested the PWO crystals at low temperatures to determine their applicability in future calorimeters. Various crystals from the Proton Antiproton Annihilations at Darmstadt (PANDA) experiment in Giessen, the Bogoroditsk Techno-Chemical Plant (BTCP) in Russia and by Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS) in China were investigated. We studied the scintillation properties of PWO crystals, such as their X-ray luminescence, relative light yields, absolute light yields, energy resolutions, decay times and longitudinal uniformities of their light yields. In addition, we measured the temperature dependences of the light yields and decay times by using a 137Cs γ-ray source. The emission spectra of the PWO crystals consisted of a broad band from 350 nm to 700 nm, and the peak emission wavelength in each spectrum was 420 nm. The emission spectra of the PWO crystals from SICCAS were slightly shifted to longer wavelengths compared with those of the crystals from the other institutions.

Transport properties of Lu.sub.2./sub.Fe.sub.17./sub. single crystals under extreme conditions

Czech Academy of Sciences Publication Activity Database

Skorokhod, Yuriy; Arnold, Zdeněk; Kamarád, Jiří; Andreev, Alexander V.

2004-01-01

Roč. 11, č. 3 (2004), s. 471-475 ISSN 1027-5495 R&D Projects: GA ČR(CZ) GA106/02/0943 Institutional research plan: CEZ:AV0Z1010914 Keywords : transport properties * magnetotransport properties * pressure effect * single crystals * intermetallic compounds Subject RIV: BM - Solid Matter Physics ; Magnetism

Synthesis, electronic transport and optical properties of Si:α-Fe2O3 single crystals

NARCIS (Netherlands)

Rettie, A.J.E.; Chemelewski, W.D.; Wygant, B.R.; Lindemuth, J.; Lin, J.F.; Eisenberg, D.; Brauer, C.S.; Johnson, T.J.; Beiswenger, T.N.; Ash, R.D.; Li, X.; Zhou, J.; Mullins, C.B.

2016-01-01

We report the synthesis of silicon-doped hematite (Si:alpha-Fe2O3) single crystals via chemical vapor transport, with Si incorporation on the order of 1019 cm(-3). The conductivity, Seebeck and Hall effect were measured in the basal plane between 200 and 400 K. Distinct differences in electron

Crystal structure and cation exchanging properties of a novel open framework phosphate of Ce (IV)

Energy Technology Data Exchange (ETDEWEB)

Bevara, Samatha; Achary, S. N., E-mail: sachary@barc.gov.in; Tyagi, A. K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Homi Bhabha National Insitute, Anushakti Nagar, Mumbai 400094 (India); Patwe, S. J. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Sinha, A. K. [Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Mishra, R. K.; Kumar, Amar; Kaushik, C. P. [Waste Management Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2016-05-23

Herein we report preparation, crystal structure and ion exchanging properties of a new phosphate of tetravalent cerium, K{sub 2}Ce(PO{sub 4}){sub 2}. A monoclinic structure having framework type arrangement of Ce(PO{sub 4}){sub 6} units formed by C2O{sub 8} square-antiprism and PO{sub 4} tetrahedra is assigned for K{sub C}e(PO{sub 4}){sub 2}. The K{sup +} ions are occupied in the channels formed by the Ce(PO{sub 4})6 and provide overall charge neutrality. The unique channel type arrangements of the K+ make them exchangeable with other cations. The ion exchanging properties of K2Ce(PO4)2 has been investigated by equilibrating with solution of 90Sr followed by radiometric analysis. In optimum conditions, significant exchange of K+ with Sr2+ with Kd ~ 8000 mL/g is observed. The details of crystal structure and ion exchange properties are explained and a plausible mechanism for ion exchange is presented.

Growth, structure, Hirshfeld surface and spectroscopic properties of 2-amino-4-hydroxy-6-methylpyrimidinium-2,3-pyrazinedicorboxylate single crystal

Science.gov (United States)

Faizan, Mohd; Alam, Mohammad Jane; Afroz, Ziya; Rodrigues, Vítor Hugo Nunes; Ahmad, Shabbir

2018-03-01

The present work is focused on the crystal structure, vibrational spectroscopy and DFT calculations of hydrogen bonded 2,3-pyrazinedicorboxylic acid and 2-amino-4-hydroxy-6-methylpyrimidine (PDCA-.AHMP+) crystal. The crystal structure has been determined using single crystal X-ray diffraction analysis which shows that the crystal belongs to monoclinic space group P21/n. The PDCA-.AHMP+ crystal has been characterized by FTIR, FT-Raman and FT-NMR spectroscopic techniques. The FTIR and FT-Raman spectra of the complex have unique spectroscopic feature as compared with those of the starting material to confirm salt formation. The theoretical vibrational studies have been performed to understand the modes of the vibrations of asymmetric unit of the complex by DFT methods. Hirschfeld surface and 2D fingerprint plots analyses were carried out to investigate the intermolecular interactions and its contribution in the building of PDCA-.AHMP+ crystal. The experimental and simulated 13C and 1H NMR studies have assisted in structural analysis of PDCA-.AHMP+ crystal. The electronic spectroscopic properties of the complex were explored by the experimental as well as theoretical electronic spectra simulated using TD-DFT/IEF-PCM method at B3LYP/6-311++G (d,p) level of theory. In addition, frontier molecular orbitals, molecular electrostatic potential map (MEP) and nonlinear optical (NLO) properties using DFT method have been also presented.

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Passivated graphene transistors fabricated on a millimeter-sized single-crystal graphene film prepared with chemical vapor deposition

International Nuclear Information System (INIS)

Lin, Meng-Yu; Lee, Si-Chen; Lin, Shih-Yen; Wang, Cheng-Hung; Chang, Shu-Wei

2015-01-01

In this work, we first investigate the effects of partial pressures and flow rates of precursors on the single-crystal graphene growth using chemical vapor depositions on copper foils. These factors are shown to be critical to the growth rate, seeding density and size of graphene single crystals. The prepared graphene films in millimeter sizes are then bubbling transferred to silicon-dioxide/silicon substrates for high-mobility graphene transistor fabrications. After high-temperature annealing and hexamethyldisilazane passivation, the water attachment is removed from the graphene channel. The elimination of uncontrolled doping and enhancement of carrier mobility accompanied by these procedures indicate that they are promising for fabrications of graphene transistors. (paper)

Effect of vegetation switch on soil chemical properties

Czech Academy of Sciences Publication Activity Database

Iwashima, N.; Masunaga, T.; Fujimaki, R.; Toyota, Ayu; Tayasu, I.; Hiura, T.; Kaneko, N.

2012-01-01

Roč. 58, č. 6 (2012), s. 783-792 ISSN 0038-0768 Institutional support: RVO:60077344 Keywords : earthworm * litter * nutrient cycling * soil chemical properties * vegetation switch Subject RIV: EH - Ecology, Behaviour Impact factor: 0.889, year: 2012

Effect of rare-earth dopants on the growth and structural, optical, electrical and mechanical properties of L-arginine phosphate single crystals

Energy Technology Data Exchange (ETDEWEB)

Arjunan, S., E-mail: arjunan_hce@yahoo.co.i [Department of Physics, Sri Ramachandra University, Porur, Chennai (India); Bhaskaran, A. [Department of Physics, Dr. Ambedkar Government College, Chennai (India); Kumar, R. Mohan; Mohan, R. [Department of Physics, Presidency College, Chennai (India); Jayavel, R. [Crystal Growth Centre, Anna University, Chennai (India)

2010-09-17

Research highlights: {yields} Thorium, Lanthanum and Cerium rare-earth ions were doped with L-arginine phosphate material and the crystals were grown by slow evaporation technique. {yields} The transparency of the rare-earth doped LAP crystals has enhanced compared to pure LAP. {yields} The powder SHG measurements revealed that the SHG output of rare-earth doped LAP crystals increases considerably compared to that of LAP. {yields} Vicker's hardness number of as-grown crystal of LAP is higher than that of rare-earth doped LAP crystals. - Abstract: Effect of Thorium, Lanthanum and Cerium rare-earth ions on the growth and properties of L-arginine phosphate single crystals has been reported. The incorporation of rare-earth dopants into the L-arginine phosphate crystals is confirmed by Inductively Coupled Plasma-Mass Spectroscopy analysis. The unit cell parameters for pure and rare-earth doped L-arginine phosphate crystals have been estimated by powder X-ray diffraction studies. UV-visible studies revealed the transmittance percentage and cut-off wavelengths of the grown crystals. Powder second harmonic generation measurement has been carried out for pure and doped L-arginine phosphate crystals. The dielectric behavior of the grown crystals was analyzed for different frequencies at room temperature. The mechanical properties have been determined for pure and the doped L-arginine phosphate crystals.

Effect of electromagnetic radiation on the physico-chemical properties of minerals; Efecto de la radiacion electromagnetica en las propiedades fisicoquimicas de los minerales

Energy Technology Data Exchange (ETDEWEB)

Lopez M, A.; Delgadillo G, J. A. [Universidad Autonoma de San Luis Potosi, Instituto de Metalurgia, Doctorado Institucional de Ingenieria y Ciencia de Materiales, Av. Sierra Leona 550, 78210 San Luis Potosi (Mexico); Vega C, H. R., E-mail: alopezm6@yahoo.com.mx [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

2014-08-15

The electromagnetic radiation effect represented by gamma rays was investigated through; chemical analysis, X-ray diffraction (XRD), scanning electron microscopy (Sem) and magnetization when applied at a dose of 0.5704 Gy (0.5704 J/ kg) at a feed relation of 18.40 ± 1.13 mGy/ h., in different minerals; in order to characterize the impact of the same from {sup 137}Cs in the physicochemical properties of these minerals. All the irradiated samples showed chemical stability at this stage undetectable other both in the XRD study and in the images analysis obtained by Sem; and at present almost the same chemical composition as the non-irradiated samples. So the same patterns of X-ray diffraction thereof, show a tendency to slightly lower the intensity of the most representative peaks of each mineral phase, which may be due to a decrease in crystallinity or preferential crystallographic orientation in crystals. In the micrographs analysis obtained by Sem on the irradiated samples, some holes (open pores) present in the particles were observed, mainly chalcopyrite and sphalerite lesser extent, seen this fact may be due to Compton Effect, in the radiation process. In relation to the magnetization property, a variation is obtained in the saturation magnetization (Ms) for the irradiated samples containing iron and more significantly in the chalcopyrite case. Therefore, with the radiation level used; slight changes occurring in the physical properties of minerals, whereas they remained stable chemically. These small changes may represent a signal that electromagnetic radiation applied at higher doses, is a viable option for improving the mineral processing. (author)

Chain alignment for improved properties - Optimization of PLA and PHB-V by crystallization and reinforcement

Science.gov (United States)

Moser, K.; Bergmann, B.; Diemert, J.; Elsner, P.

2014-05-01

In this paper two promising ways to improve the material characteristics of PLA and PHB-V are presented by showing their positive effects on mechanical, optical, and thermal properties. The optimization is achieved by increasing the crystallization from the melt of the polymer chains and the other by means of a reinforcement of the matrices by bio-based materials. In the case of crystallization specific nucleating agents and optimized process parameters promote optimized crystallization conditions and lead particularly in toughness to significant improvements. In addition to crystallization the introduction of cellulose-based reinforcing materials is also a good alternative to improve the ductility of a biopolymer matrix considerably. Due to their polar surface structure cellulose fibres are favouring a very good interaction to the also polar biopolymers. In addition, the polar surfaces of both materials results in very homogeneous dispersion within the compound.

Monitoring and Characterization of Crystal Nucleation and Growth during Batch Crystallization

NARCIS (Netherlands)

Kadam, S.S.

2012-01-01

Batch crystallization is commonly used in pharmaceutical, agrochemical, specialty and fine chemicals industry. The advantages of batch crystallization lie in its ease of operation and the relatively simple equipment that can be used. On the other hand a major disadvantage associated with it is the

Computer Aided Design of Ni-Based Single Crystal Superalloy for Industrial Gas Turbine Blades

Science.gov (United States)

Wei, Xianping; Gong, Xiufang; Yang, Gongxian; Wang, Haiwei; Li, Haisong; Chen, Xueda; Gao, Zhenhuan; Xu, Yongfeng; Yang, Ming

The influence of molybdenum, tungsten and cobalt on stress-rupture properties of single crystal superalloy PWA1483 has been investigated using the simulated calculation of JMatPro software which ha s been widely used to develop single crystal superalloy, and the effect of alloying element on the stability of strengthening phase has been revealed by using the Thermo-Calc software. Those properties calculation results showed that the increasing of alloy content could facilitate the precipitation of TCP phases and increase the lattice misfit between γ and γ' phase, and the effect of molybdenum, tantalum was the strongest and that of cobalt was the weakest. Then the chemical composition was optimized, and the selected compositions showed excellent microstructure stability and stress-rupture properties by the confirmation of d-electrons concept and software calculation.

Growth of Bulk Wide Bandgap Semiconductor Crystals and Their Potential Applications

Science.gov (United States)

Chen, Kuo-Tong; Shi, Detang; Morgan, S. H.; Collins, W. Eugene; Burger, Arnold

1997-01-01

Developments in bulk crystal growth research for electro-optical devices in the Center for Photonic Materials and Devices since its establishment have been reviewed. Purification processes and single crystal growth systems employing physical vapor transport and Bridgman methods were assembled and used to produce high purity and superior quality wide bandgap materials such as heavy metal halides and II-VI compound semiconductors. Comprehensive material characterization techniques have been employed to reveal the optical, electrical and thermodynamic properties of crystals, and the results were used to establish improved material processing procedures. Postgrowth treatments such as passivation, oxidation, chemical etching and metal contacting during the X-ray and gamma-ray device fabrication process have also been investigated and low noise threshold with improved energy resolution has been achieved.

Study of the effect of doping on the temperature stability of the optical properties of germanium single crystals

Energy Technology Data Exchange (ETDEWEB)

Podkopaev, O. I. [Joint-Stock Company “Germanium” (Russian Federation); Shimanskiy, A. F., E-mail: shimanaf@mail.ru [Siberian Federal University (Russian Federation); Kopytkova, S. A.; Filatov, R. A. [Joint-Stock Company “Germanium” (Russian Federation); Golubovskaya, N. O. [Siberian Federal University (Russian Federation)

2016-10-15

The effect of doping on the optical transmittance of germanium single crystals is studied by infrared Fourier spectroscopy. It is established that the introduction of silicon and tellurium additives into germanium doped with antimony provides a means for improving the temperature stability of the optical properties of the crystals.

Study of the effect of doping on the temperature stability of the optical properties of germanium single crystals

International Nuclear Information System (INIS)

Podkopaev, O. I.; Shimanskiy, A. F.; Kopytkova, S. A.; Filatov, R. A.; Golubovskaya, N. O.

2016-01-01

The effect of doping on the optical transmittance of germanium single crystals is studied by infrared Fourier spectroscopy. It is established that the introduction of silicon and tellurium additives into germanium doped with antimony provides a means for improving the temperature stability of the optical properties of the crystals.

Synthesis, crystal structures and luminescence properties of new multi-component co-crystals of isostructural Co(II) and Zn(II) complexes

Science.gov (United States)

Tella, Adedibu C.; Owalude, Samson O.; Omotoso, Mary F.; Olatunji, Sunday J.; Ogunlaja, Adeniyi S.; Alimi, Lukman O.; Popoola, Olugbenga K.; Bourne, Susan A.

2018-04-01

Two novel isostructural compounds containing multi-component co-crystals [M(C6H4NO2)2(H2O)2](C9H6O6)2 (M = Co (1), Zn (2), C6H4NO2 = Picolinic acid, C9H6O6 = Trimesic acid) have been synthesized. The compounds were characterized by elemental analysis, FT-IR, UV-Visible and 1H NMR spectroscopies as well as thermal and single crystal X-ray diffraction analyses. Single crystal X-ray diffraction analysis reveals that 1 and 2 are isostructural. Compound 1 crystallizes in triclinic space group (P-1, with a = 5.154 (10) Å, b = 11.125 (2) Å, c = 14.113 (3) Å, α = 91.01 (3)°, β = 100.54 (3)°, and γ = 102.71 (3)°). In a similar fashion, compound 2 crystallizes in triclinic space group (P-1, with a = 5.1735 (3) Å, b = 11.0930 (10) Å, c = 14.1554 (8) Å, α = 91.70 (3)°, β = 100.26 (3)°, γ = 102.90 (3)°). The metal (II) cation presents distorted MN2O4 octahedral geometry with H2O molecules coordinated to the metal in equatorial position while the picolinic acid molecules are axially coordinated through the pyridine N atom. The two trimesic acid molecules are not part of the first coordination sphere. Compounds 1 and 2 constitute an example of a class of coordination compound of multicomponent crystals having trimesic acid outside the coordination sphere where it is neither protonated or deprotonated. The two compounds were investigated for luminiscence properties.

Benchmark fragment-based (1)H, (13)C, (15)N and (17)O chemical shift predictions in molecular crystals.

Science.gov (United States)

Hartman, Joshua D; Kudla, Ryan A; Day, Graeme M; Mueller, Leonard J; Beran, Gregory J O

2016-08-21

The performance of fragment-based ab initio(1)H, (13)C, (15)N and (17)O chemical shift predictions is assessed against experimental NMR chemical shift data in four benchmark sets of molecular crystals. Employing a variety of commonly used density functionals (PBE0, B3LYP, TPSSh, OPBE, PBE, TPSS), we explore the relative performance of cluster, two-body fragment, and combined cluster/fragment models. The hybrid density functionals (PBE0, B3LYP and TPSSh) generally out-perform their generalized gradient approximation (GGA)-based counterparts. (1)H, (13)C, (15)N, and (17)O isotropic chemical shifts can be predicted with root-mean-square errors of 0.3, 1.5, 4.2, and 9.8 ppm, respectively, using a computationally inexpensive electrostatically embedded two-body PBE0 fragment model. Oxygen chemical shieldings prove particularly sensitive to local many-body effects, and using a combined cluster/fragment model instead of the simple two-body fragment model decreases the root-mean-square errors to 7.6 ppm. These fragment-based model errors compare favorably with GIPAW PBE ones of 0.4, 2.2, 5.4, and 7.2 ppm for the same (1)H, (13)C, (15)N, and (17)O test sets. Using these benchmark calculations, a set of recommended linear regression parameters for mapping between calculated chemical shieldings and observed chemical shifts are provided and their robustness assessed using statistical cross-validation. We demonstrate the utility of these approaches and the reported scaling parameters on applications to 9-tert-butyl anthracene, several histidine co-crystals, benzoic acid and the C-nitrosoarene SnCl2(CH3)2(NODMA)2.

Structural, optical and electrical properties of chemically deposited ...

Indian Academy of Sciences (India)

Structural, optical and electrical properties of chemically deposited nonstoichiometric copper ... One of these compounds, CuInSe2, with its optical absorption .... is clear from SEM images that the number of grains goes on increasing with the ...

Magnetocaloric properties of the hexagonal HoMnO{sub 3} single crystal revisited

Energy Technology Data Exchange (ETDEWEB)

Balli, M., E-mail: Mohamed.balli@Usherbrooke.ca [Regroupement québécois sur les matériaux de pointe, Département de physique, Université de Sherbrooke, QC, Canada J1K 2R1 (Canada); Roberge, B.; Vermette, J.; Jandl, S. [Regroupement québécois sur les matériaux de pointe, Département de physique, Université de Sherbrooke, QC, Canada J1K 2R1 (Canada); Fournier, P. [Regroupement québécois sur les matériaux de pointe, Département de physique, Université de Sherbrooke, QC, Canada J1K 2R1 (Canada); Canadian Institute for Advanced Research, Toronto, Ontario, Canada M5G 1Z8 (Canada); Gospodinov, M.M. [Institute of Solid State Physics, Bulgarian Academy of Science, Sofia 1184 (Bulgaria)

2015-12-01

Magnetic and magnetocaloric properties of the hexagonal HoMnO{sub 3} single crystal have been revisited. It was found that the magnetocaloric effect shown by HoMnO{sub 3} strongly depends on the crystal orientation in respect to the applied magnetic field. Consequently, a large thermal effect can be induced by spinning the single crystal HoMnO{sub 3} around the a (or b) axis in a constant magnetic field instead of the conventional magnetization–demagnetization process. Under 7 T, the maximum rotating entropy change was evaluated to be about 8 J/kg K. The associated adiabatic temperature change reaches a value of about 5 K. These values are comparable to those of the other oxides exhibiting a large rotating magnetocaloric effect. The presence of both conventional and rotating thermal effects makes the hexagonal HoMnO{sub 3} more interesting from a practical point of view.

Synthesis, growth, structural modeling and physio-chemical properties of a charge transfer molecule: Guanidinium tosylate

Science.gov (United States)

Era, Paavai; Jauhar, RO. MU.; Vinitha, G.; Murugakoothan, P.

2018-05-01

An organic nonlinear optical material, guanidinium tosylate was synthesized adopting slow evaporation method and the crystals were harvested from aqueous methanolic medium with dimensions 13 × 9 × 3 mm3. Constitution of crystalline material was confirmed by single crystal X-ray diffraction study. The title compound crystallizes in the monoclinic crystal system with space group P21/c. The UV-vis-NIR spectral study of the grown crystal exhibits high transparency of 80% in the entire visible region with lower cut-off wavelength at 282 nm. Optimized molecular geometry of the grown crystal was obtained using density functional theory (DFT) and the frontier energy gaps calculated from the DFT aids to understand the charge transfer taking place in the molecule. The dielectric properties were studied as a function of temperature and frequency to find the charge distribution within the crystal. The titular compound is thermally stable up to 230 °C assessed by thermogravimetric and differential thermal analysis. Anisotropy in the mechanical behavior was observed while measuring for individual planes. The laser induced surface damage threshold of the grown crystal was measured to be 0.344 GW/cm2 for 1064 nm Nd:YAG laser radiation. Z-scan technique confirms the third-order nonlinear optical property with the ascertained nonlinear refractive index (n2), nonlinear absorption coefficient (β) and third order nonlinear susceptibility (χ(3)). Optical limiting study divulges that the transmitted output power step-up linearly with the increase of the input power at lower power realms and saturates from the threshold 24.95 mW/cm2 and amplitude 0.23 mW/cm2.

Crystal Growth Technology

Science.gov (United States)

Scheel, Hans J.; Fukuda, Tsuguo

2004-06-01

This volume deals with the technologies of crystal fabrication, of crystal machining, and of epilayer production and is the first book on industrial and scientific aspects of crystal and layer production. The major industrial crystals are treated: Si, GaAs, GaP, InP, CdTe, sapphire, oxide and halide scintillator crystals, crystals for optical, piezoelectric and microwave applications and more. Contains 29 contributions from leading crystal technologists covering the following topics: General aspects of crystal growth technology Silicon Compound semiconductors Oxides and halides Crystal machining Epitaxy and layer deposition Scientific and technological problems of production and machining of industrial crystals are discussed by top experts, most of them from the major growth industries and crystal growth centers. In addition, it will be useful for the users of crystals, for teachers and graduate students in materials sciences, in electronic and other functional materials, chemical and metallurgical engineering, micro-and optoelectronics including nanotechnology, mechanical engineering and precision-machining, microtechnology, and in solid-state sciences.

Confined crystallization, crystalline phase deformation and their effects on the properties of crystalline polymers

Science.gov (United States)

Wang, Haopeng

With the recent advances in processing and catalyst technology, novel morphologies have been created in crystalline polymers and they are expected to substantially impact the properties. To reveal the structure-property relationships of some of these novel polymeric systems becomes the primary focus of this work. In the first part, using an innovative layer-multiplying coextrusion process to obtain assemblies with thousands of polymer nanolayers, dominating "in-plane" lamellar crystals were created when the confined poly(ethylene oxide) (PEO) layers were made progressively thinner. When the thickness was confined to 25 nanometers, the PEO crystallized as single, high-aspect-ratio lamellae that resembled single crystals. This crystallization habit imparted more than two orders of magnitude reduction in the gas permeability. The dramatic decrease in gas permeability was attributed to the reduced diffusion coefficient, because of the increase in gas diffusion path length through the in-plane lamellae. The temperature dependence of lamellar orientation and the crystallization kinetics in the confined nanolayers were also investigated. The novel olefinic block copolymer (OBC) studied in the second part consisted of long crystallizable sequences with low comonomer content alternating with rubbery amorphous blocks with high comonomer content. The crystallizable blocks formed lamellae that organized into space-filling spherulites even when the fraction of crystallizable block was so low that the crystallinity was only 7%. These unusual spherulites were highly elastic and recovered from strains as high as 300%. These "elastic spherulites" imparted higher strain recovery and temperature resistance than the conventional random copolymers that depend on isolated, fringed micellar-like crystals to provide the junctions for the elastomeric network. In the third part, positron annihilation lifetime spectroscopy (PALS) was used to obtain the temperature dependence of the free

Fast neutron irradiation and thermal properties of doped nonstoichiometric lithium potassium sulphate crystals

International Nuclear Information System (INIS)

Kassem, M.E.; Gomaa, N.G.; El-Khatib, A.M.

1990-01-01

The influence of point defects introduced by fast neutron irradiations with neutron fluences up to 1.08 x 10 10 n/cm 2 on the thermal properties of pure and doped Li 1.4 K 0.6 SO 4 single crystals are studied in the vicinity of high temperature phase transition at 705 K. The temperature dependence of specific heat is found to be shifted towards lower temperature with the increase of neutron fluence, and can be affected by the presence of Cu 2+ dopant. The change in the value of the specific heat can be attributed to the presence of internal strain generated inside the crystal. (author)

Microwave dielectric properties of nanostructured nickel ferrite

Indian Academy of Sciences (India)

Wintec

Abstract. Nickel ferrite is one of the important ferrites used in microwave devices. In the present work, we have synthesized nanoparticles of nickel ferrite using chemical precipitation technique. The crystal structure and grain size of the particles are studied using XRD. The microwave dielectric properties of nanostructured.

Chemical bonding and magnetic properties of gadolinium (Gd) substituted cobalt ferrite

International Nuclear Information System (INIS)

Puli, Venkata Sreenivas; Adireddy, Shiva; Ramana, C.V.

2015-01-01

Graphical abstract: Room temperature Raman spectra of CoFe 2−x Gd x O 4 (CFGO, x = 0.0–0.3) compounds as a function of wavenumber (cm −1 ). - Highlights: • Gd substituted ferrites were synthesized under controlled concentration. • Gd ion induced lattice dynamical changes are significant. • Enhanced magnetization is observed upon Gd-incorporation in cobalt ferrite. • A correlation between lattice dynamics and magnetic properties is established. - Abstract: Polycrystalline gadolinium (Gd) substituted cobalt ferrites (CoFe 2−x Gd x O 4 ; x = 0–0.3, referred to CFGO) ceramics have been synthesized by solid state reaction method. Chemical bonding, crystal structure and magnetic properties of CFGO compounds have been evaluated as a function of Gd-content. X-ray diffraction (XRD) and Raman spectroscopic analyses confirmed the formation of inverse spinel cubic structure. However, a secondary ortho-ferrite phase (GdFeO 3 ) nucleates for higher values of Gd-content. A considerable increase in the saturation magnetization has been observed upon the initial substitution of Gd (x = 0.1). The saturation magnetization drastically decreases at higher Gd content (x ⩾ 0.3). No contribution from ortho-ferrite GdFeO 3 phase is noted to the magnetic properties. The increase in the magnetic saturation magnetization is attributed to the higher magnetic moment of Gd 3+ (4f 7 ) residing in octahedral sites is higher when compared to that of Fe 3+ (3d 5 ) and as well due to the migration of Co 2+ (3d 7 ) ions from the octahedral to the tetrahedral sites with a magnetic moment aligned anti-parallel to those of rare earth (RE 3+ ) ions in the spinel lattice. Increase in coercivity with increase in Gd 3+ is content is attributed to magnetic anisotropy in the ceramics

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Imaging properties of a positron tomograph with 280 BGO crystals

International Nuclear Information System (INIS)

Derenzo, S.E.; Budinger, T.F.; Huesman, R.H.; Cahoon, J.L.; Vuletich, T.

1980-11-01

The basic imaging properties of the Donner 280-BGO-Crystal positron tomograph were measured and compared with the same system when it was equipped with 280 NaI(T1) crystals. The NaI(T1) crystals were 8 mm x 30 mm x 50 mm deep, sealed in 10 mm wide stainless steel cans. The BGO crystals are 9.5 mm x 32 mm x 32 mm deep and as they are not hygroscopic do not require sealed cans. With a shielding gap of 3 cm (section thickness 1.7 cm FWHM) the sensitivity of the BGO system is 55,000 events per sec for 1 μCi per cm 3 in a 20 cm cylinder of water, which is 2.3 times higher than the NaI(T1) system. For a 200 μCi/cm line source on the ring axis in a 20 cm diameter water cylinder, the BGO system records 86% of the scatter fraction and 66% of the accidental fraction of the NaI(T1) system. The lower light yield and poorer time resolution of BGO requires a wider coincidence timing window than NaI(T1). However, the ability to use full-energy pulse height selection with a 2.3-fold improvement in sensitivity results in an overall reduction in the fraction of accidental events recorded. The in-plane resolution of the BGO system is 9 to 10 mm FWHM within the central 30 cm diameter field, and the radial elongation at the edge of the field in the NaI(T1) system has been nearly eliminated

Structural, optical and electronic properties of K2Ba(NO3)4 crystal

Science.gov (United States)

Isaenko, L. I.; Korzhneva, K. E.; Goryainov, S. V.; Goloshumova, A. A.; Sheludyakova, L. A.; Bekenev, V. L.; Khyzhun, O. Y.

2018-02-01

Nitrate crystals reveal nonlinear optical properties and could be considered as converters of laser radiation in the short-wave region. The conditions for obtaining and basic properties of K2Ba(NO3)4 double nitrate crystals were investigated. Crystal growth was implemented by slow cooling in the temperature range of 72-49 °C and low rate evaporation. The structural analysis of K2Ba(NO3)4 formation on the basis of two mixed simple nitrate structures is discussed. The main groups of oscillations in K2Ba(NO3)4 crystal were revealed using Raman and IR spectroscopy, and the table of vibrations for this compound was compiled. The electronic structure of K2Ba(NO3)4 was elucidated in the present work from both experimental and theoretical viewpoints. In particular, X-ray photoelectron spectroscopy (XPS) was employed in the present work to measure binding energies of the atoms constituting the titled compound and its XPS valence-band spectrum for both pristine and Ar+ ion-bombarded surfaces. Further, total and partial densities of states of constituent atoms of K2Ba(NO3)4 have been calculated. The calculations reveal that the O 2p states dominate in the total valence-band region of K2Ba(NO3)4 except of its bottom, where K 3p and Ba 5p states are the principal contributors, while the bottom of the conduction band is composed mainly of the unoccupied O 2p states, with somewhat smaller contributions of the N 2p∗ states as well. With respect to the occupation of the valence band by the O 2p states, the present band-structure calculations are confirmed by comparison on a common energy scale of the XPS valence-band spectrum and the X-ray emission O Kα band for the K2Ba(NO3)4 crystal under study. Furthermore, the present calculations indicate that the K2Ba(NO3)4 compound is a direct-gap material.

Surface morphology and preferential orientation growth of TaC crystals formed by chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Xiong Xiang, E-mail: Xiong228@sina.co [State Key Lab for Powder Metallurgy, Central South University, Changsha 410083 (China); Chen Zhaoke; Huang Baiyun; Li Guodong [State Key Lab for Powder Metallurgy, Central South University, Changsha 410083 (China); Zheng Feng [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Xiao Peng; Zhang Hongbo [State Key Lab for Powder Metallurgy, Central South University, Changsha 410083 (China)

2009-04-02

TaC film was deposited on (002) graphite sheet by isothermal chemical vapor deposition using TaCl{sub 5}-Ar-C{sub 3}H{sub 6} mixtures, with deposition temperature 1200 {sup o}C and pressure about 200 Pa. The influence of deposition position (or deposition rate) on preferential orientation and surface morphology of TaC crystals were investigated by X-ray diffraction and scanning electron microscopy methods. The deposits are TaC plus trace of C. The crystals are large individual columns with pyramidal-shape at deposition rate of 32.4-37.3 {mu}m/h, complex columnar at 37.3-45.6 {mu}m/h, lenticular-like at 45.6-54.6 {mu}m/h and cauliflower-like at 54.6-77.3 {mu}m/h, with <001>, near <001>, <110> and no clear preferential orientation, respectively. These results agree in part with the preditions of the Pangarov's model of the relationship between deposition rate and preferential growth orientation. The growth mechanism of TaC crystals in <001>, near <001>, <111> and no clear preferential orientation can be fairly explained by the growth parameter {alpha} with Van der Drift's model, deterioration model and Meakin model. Furthermore, a nucleation and coalescence model is also proposed to explain the formation mechanism of <110> lenticular-like crystals.

Evaluation of physical and chemical properties and their interactions in fat, oil, and grease (FOG) deposits.

Science.gov (United States)

Gross, Martin A; Jensen, Jeanette L; Gracz, Hanna S; Dancer, Jens; Keener, Kevin M

2017-10-15

Fat, oil and grease (FOG) blockages in sewer systems are a substantial problem in the United States. It has been estimated that over 50% of sewer overflows are a result of FOG blockages. In this work, a thorough laboratory study was undertaken to examine key variables that contribute to FOG deposit formation under controlled conditions. Physical and chemical properties and their interactions were evaluated and conditions that generated deposits that mimicked field FOG deposits were identified. It was found that 96 of the of 128 reaction conditions tested in the laboratory formed FOG deposits with similar physical and chemical characteristics as field FOG deposits. It was also found that FOG deposits can be created through fatty acid crystallization and not just saponification. Furthermore FOG deposits were found to be more complex than previously documented and contain free fatty acids, fatty acid metal salts, triacylglycerol's, diacylglycerol's and, monoacylglycerol's. Lastly it was found that FOG deposits that only contained saturated fatty acids were on average 2.1 times higher yield strength than deposits that contained unsaturated fatty acids. Copyright © 2017 Elsevier Ltd. All rights reserved.

Near surface mechanical properties of optical single crystals and surface response to deterministic microgrinding

Science.gov (United States)

Randi, Joseph A., III

2005-12-01

This thesis makes use of microindentation, nanoindentation and nanoscratching methods to better understand the mechanical properties of single crystalline silicon, calcium fluoride, and magnesium fluoride. These properties are measured and are used to predict the material's response to material removal, specifically by grinding and polishing, which is a combination of elastic, plastic and fracture processes. The hardness anisotropy during Knoop microindentation, hardness from nanoindentation, and scratch morphology from nanoscratching are reported. This information is related to the surface microroughness from grinding. We show that mechanical property relationships that predict the surface roughness from lapping and deterministic microgrinding of optical glasses are applicable to single crystals. We show the range of hardness from some of the more common crystallographic faces. Magnesium fluoride, having a tetragonal structure, has 2-fold hardness anisotropy. Nanoindentation, as expected provides higher hardness than microindentation, but anisotropy is not observed. Nanoscratching provides the scratch profile during loading, after the load has been removed, and the coefficient of friction during the loading. Ductile and brittle mode scratching is present with brittle mode cracking being orientation specific. Subsurface damage (SSD) measurements are made using a novel process known as the MRF technique. Magnetorheological finishing is used to polish spots into the ground surface where SSD can be viewed. SSD is measured using an optical microscope and knowledge of the spot profile. This technique is calibrated with a previous technique and implemented to accurately measure SSD in single crystals. The data collected are compared to the surface microroughness of the ground surface, resulting in an upper bound relationship. The results indicate that SSD is always less than 1.4 times the peak-to-valley surface microroughness for single crystals regardless of the

Solid state synthesis, crystal growth and optical properties of urea and p-chloronitrobenzene solid solution

Energy Technology Data Exchange (ETDEWEB)

Rai, R.N., E-mail: rn_rai@yahoo.co.in [Department of Chemistry, Centre of Advanced Study, Banaras Hindu University, Varanasi 221005 (India); Kant, Shiva; Reddi, R.S.B. [Department of Chemistry, Centre of Advanced Study, Banaras Hindu University, Varanasi 221005 (India); Ganesamoorthy, S. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamilnadu (India); Gupta, P.K. [Laser Materials Development & Devices Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

2016-01-15

Urea is an attractive material for frequency conversion of high power lasers to UV (for wavelength down to 190 nm), but its usage is hindered due to its hygroscopic nature, though there is no alternative organic NLO crystal which could be transparent up to 190 nm. The hygroscopic character of urea has been modified by making the solid solution (UCNB) of urea (U) and p-chloronitrobenzene (CNB). The formation of the solid solution of CNB in U is explained on the basis of phase diagram, powder XRD, FTIR, elemental analysis and single crystal XRD studies. The solubility of U, CNB and UCNB in ethanol solution is evaluated at different temperatures. Transparent single crystals of UCNB are grown from its saturated solution in ethanol. Optical properties e.g., second harmonic generation (SHG), refractive index and the band gap for UCNB crystal were measured and their values were compared with the parent compounds. Besides modification in hygroscopic nature, UCNB has also shown the higher SHG signal and mechanical hardness in comparison to urea crystal. - Highlights: • The hygroscopic character of urea was modified by making the solid solution • Solid solution formation is support by elemental, powder- and single crystal XRD • Crystal of solid solution has higher SHG signal and mechanical stability. • Refractive index and band gap of solid solution crystal have determined.

Diamond nanostructured devices for chemical sensing applications

OpenAIRE

Ahmad, R. K.

2011-01-01

Research in the area of CVD single crystal diamond plates of which only recently has been made commercially available saw significant advancements during the last decade. In parallel to that, detonation nanodiamond (DND) particles also now widely made accessible for requisition are provoking a lot of scientific investigations. The remarkable properties of diamond including its extreme hardness, low coefficient of friction, chemical inertness, biocompatibility, high thermal c...

Growth and characterization of single-crystal CVD diamond for radiation detection applications

International Nuclear Information System (INIS)

Tranchant, N.

2008-01-01

This work aimed at the study of the synthesis of single crystal diamond using the Microwave enhanced Chemical Vapour Deposition technique (MPCVD). The work enabled the development and optimisation of the growth conditions, from the study of the crystalline quality, of the material purity, and of its electronic properties. The assessment of the transport properties was the most determinant: the use of the time of flight (TOF) technique has enabled the measurement of the carrier mobilities and of their kinetic properties as a function of the temperature. When coupled with collected charge efficiency measurements, the work led to remarkable carrier mobility values obtained in the synthesised crystals (3000 cm 2 .V-1.s -1 ). Prepared samples were mounted as detection devices and used successfully in real conditions for the monitoring of ultra-fast pulses, as well as for neutron fluency monitoring, and for medical dosimeters for radiotherapy applications. (author)

Relaxor properties of barium titanate crystals grown by Remeika method

Science.gov (United States)

Roth, Michel; Tiagunov, Jenia; Dul'kin, Evgeniy; Mojaev, Evgeny

2017-06-01

Barium titanate (BaTiO3, BT) crystals have been grown by the Remeika method using both the regular KF and mixed KF-NaF (0.6-0.4) solvents. Typical acute angle "butterfly wing" BT crystals have been obtained, and they were characterized using x-ray diffraction, scanning electron microscopy (including energy dispersive spectroscopy), conventional dielectric and acoustic emission methods. A typical wing has a triangular plate shape which is up to 0.5 mm thick with a 10-15 mm2 area. The plate has a (001) habit and an atomically smooth outer surface. Both K+ and F- solvent ions are incorporated as dopants into the crystal lattice during growth substituting for Ba2+ and O2- ions respectively. The dopants' distribution is found to be inhomogeneous, their content being almost an order of magnitude higher (up to 2 mol%) at out surface of the plate relatively to the bulk. A few μm thick surface layer is formed where a multidomain ferroelectric net is confined between two≤1 μm thick dopant-rich surfaces. The layer as a whole possess relaxor ferroelectric properties, which is apparent from the appearance of additional broad maxima, Tm, in the temperature dependence of the dielectric permittivity around the ferroelectric phase transition. Intense acoustic emission responses detected at temperatures corresponding to the Tm values allow to observe the Tm shift to lower temperatures at higher frequencies, or dispersion, typical for relaxor ferroelectrics. The outer surface of the BT wing can thus serve as a relaxor thin film for various electronic application, such as capacitors, or as a substrate for BT-based multiferroic structure. Crystals grown from KF-NaF fluxes contain sodium atoms as an additional impurity, but the crystal yield is much smaller, and while the ferroelectric transition peak is diffuse it does not show any sign of dispersion typical for relaxor behavior.

Properties of a barium fluoride-TMAE-multiwire proportional chamber detector using a large single crystal

International Nuclear Information System (INIS)

Woody, C.L.; Petridou, C.I.; Smith, G.C.

1985-01-01

The properties of a detector consisting of a large barium fluoride crystal and a multiwire proportional chamber operating at low pressure with TMAE have been studied. Measurements of the time resolution, pulse width, energy resolution, photoelectron yield and the effective energy threshold were carried out in a test beam using minimum ionizing particles. Although the detector is sensitive to signals originating from an adsorbed layer of TMAE from the crystal surface, no indication of such a signal was observed. 7 refs., 6 figs

Electrical properties and features of the crystallization behaviour and the phase morphology of polyethylene blends

International Nuclear Information System (INIS)

Kolesov, I.S.; Radusch, H.-J.; Kolesov, S.N.

1999-01-01

It was discovered that polyethylene blends show a typical concentration dependence of the specific electrical resistance and the electrical strength measured by the surge voltage method. The concentration dependencies show two local maxima at definite blend compositions (ω LDPE = 0,2 to 0,4 and 0,7 to 0,8). The results of investigation of the melt and crystallization behavior as well as of the supermolecular structure of these blends point out that the changes caused by mixing in topology and packaging density of the inter-phases between the phases and crystallites have an influence on the electrical properties of the polyethylene blends in correspondence to the composition. The changed structure-property relationships are caused essentially by a possible co-crystallization of the components and by the interactions at separate seeds formation. (orig.)

Growth and Properties of Cl- Incorporated ZnO Nanofilms Grown by Ultrasonic Spray-Assisted Chemical Vapor Deposition.

Science.gov (United States)

Chen, Tingfang; Wang, Aiji; Kong, Lingrui; Li, Yongliang; Wang, Yinshu

2016-04-01

Pure and Cl- incorporated ZnO nanofilms were grown by the ultrasonic spray-assisted chemical vapor deposition (CVD) method. The properties of the nanofilms were investigated. The effects of growth temperature and Cl- concentration on the crystal structure, morphology, and optical properties of the nanofilms were studied. Temperature plays an important role in the growth mode and morphology of the pure nanofilms. Preferential growth along the c-axis occurs only at modulating temperature. Lower temperature suppresses the preferential growth, and higher temperature suppresses the growth of the nanofilms. The morphologies of the nanofilms change from lamellar and spherical structures into hexagonal platelets, then into separated nanoparticles with an increase in the temperature. Incorporating Cl- results in the lattice contracting gradually along with c-axis. Grains composing the nanofilms refine, and the optical gap broadens with increasing of Cl- concentration in growth precursor. Incorporating Cl- could reduce oxygen vacancies and passivate the non-irradiated centers, thus enhancing the UV emission and suppressing the visible emission of ZnO nanofilms.

Property Model-Based Chemcal Substitution and Chemical Formulation Design

DEFF Research Database (Denmark)

Jhamb, Spardha Virendra; Liang, Xiaodong; Hukkerikar, Amol Shivajirao

Chemical-based products including structured product formulations and single molecule products have proven to be a boon to mankind and have been a significant part of our economies. Our life and the changes around us cannot be imagined without the presence or involvement of chemicals. But like...... with environmentally benign chemicals. Additionally, the decisions taken during chemical product design also have an impact on the process and product performance and are influenced by company strategy, availability of market and government policies [2]. Hence, undoubtedly there is a need to develop a systematic...... [3] will also be highlighted. A set of new group contribution-based models for a number of useful properties of amino acids will be presented. Through examples on substitution of chemicals from chemical-based products from various sectors namely cosmetics and personal care, pharmaceutical and food...

Anisotropic properties of single crystals of high Tc superconductors

International Nuclear Information System (INIS)

Tholence, J.L.; Saint-Paul, M.; Laborde, O.; Monceau, P.; Guillot, M.; Niel, H.; Levet, J.C.; Potel, M.; Padiou, J.; Gougeon, P.

1990-01-01

In this article the authors make a review of some of the anisotropic properties of high T c compounds, essentially RE Ba 2 Cu 3 O 7 , Bi-SR-Ca-Cu-O and Tl-Ca-Ba-Cu-O systems. In section 2 a short description of the crystal growth is reported. Section 3 deals with the anisotropic elastic properties measured by ultrasonic techniques. In section 4 the authors discuss the anisotropy in magnetization measurements and consequently on the critical currents. Section 5 concerns the magnetoresistance measurements, and the determination of the superconducting critical magnetic field H c2 . Finally in section 6, in conclusion of result described in sections 4 and 5, the authors discuss on the pinning force and on the controversial Lorentz force for explaining the broadening of the superconducting transition under magnetic field. The authors apologize for not having quoted all the works published on these different topics, which is in fact practically impossible

Thermodynamic and transport properties of gaseous tetrafluoromethane in chemical equilibrium

Science.gov (United States)

Hunt, J. L.; Boney, L. R.

1973-01-01

Equations and in computer code are presented for the thermodynamic and transport properties of gaseous, undissociated tetrafluoromethane (CF4) in chemical equilibrium. The computer code calculates the thermodynamic and transport properties of CF4 when given any two of five thermodynamic variables (entropy, temperature, volume, pressure, and enthalpy). Equilibrium thermodynamic and transport property data are tabulated and pressure-enthalpy diagrams are presented.

Ultrafast characterization of phase-change material crystallization properties in the melt-quenched amorphous phase.

Science.gov (United States)

Jeyasingh, Rakesh; Fong, Scott W; Lee, Jaeho; Li, Zijian; Chang, Kuo-Wei; Mantegazza, Davide; Asheghi, Mehdi; Goodson, Kenneth E; Wong, H-S Philip

2014-06-11

Phase change materials are widely considered for application in nonvolatile memories because of their ability to achieve phase transformation in the nanosecond time scale. However, the knowledge of fast crystallization dynamics in these materials is limited because of the lack of fast and accurate temperature control methods. In this work, we have developed an experimental methodology that enables ultrafast characterization of phase-change dynamics on a more technologically relevant melt-quenched amorphous phase using practical device structures. We have extracted the crystallization growth velocity (U) in a functional capped phase change memory (PCM) device over 8 orders of magnitude (10(-10) 10(8) K/s), which reveals the extreme fragility of Ge2Sb2Te5 in its supercooled liquid phase. Furthermore, these crystallization properties were studied as a function of device programming cycles, and the results show degradation in the cell retention properties due to elemental segregation. The above experiments are enabled by the use of an on-chip fast heater and thermometer called as microthermal stage (MTS) integrated with a vertical phase change memory (PCM) cell. The temperature at the PCM layer can be controlled up to 600 K using MTS and with a thermal time constant of 800 ns, leading to heating rates ∼10(8) K/s that are close to the typical device operating conditions during PCM programming. The MTS allows us to independently control the electrical and thermal aspects of phase transformation (inseparable in a conventional PCM cell) and extract the temperature dependence of key material properties in real PCM devices.

Creep Properties of NiAl-1Hf Single Crystals Re-Investigated

Science.gov (United States)

Whittenberger, J. Daniel; Locci, Ivan E.; Darolia, Ram; Bowman, Randy R.

2000-01-01

NiAl-1Hf single crystals have been shown to be quite strong at 1027 C, with strength levels approaching those of advanced Ni-based superalloys. Initial testing, however, indicated that the properties might not be reproducible. Study of the 1027 C creep behavior of four different NiAl-1Hf single-crystal ingots subjected to several different heat treatments indicated that strength lies in a narrow band. Thus, we concluded that the mechanical properties are reproducible. Recent investigations of the intermetallic NiAl have confirmed that minor alloying additions combined with single-crystal growth technology can produce elevated temperature strength levels approaching those of Ni-based superalloys. For example, General Electric alloy AFN 12 {Ni-48.5(at.%) Al-0.5Hf-1Ti-0.05Ga} has a creep rupture strength equivalent to Rene 80 combined with a approximately 30-percent lower density, a fourfold improvement in thermal conductivity, and the ability to form a self-protective alumina scale in aggressive environments. Although the compositions of strong NiAl single crystals are relatively simple, the microstructures are complex and vary with the heat treatment and with small ingot-toingot variations in the alloy chemistry. In addition, initial testing suggested a strong dependence between microstructure and creep strength. If these observations were true, the ability to utilize NiAl single-crystal rotating components in turbine machinery could be severely limited. To investigate the possible limitations in the creep response of high-strength NiAl single crystals, the NASA Glenn Research Center at Lewis Field initiated an in depth investigation of the effect of heat treatment on the microstructure and subsequent 1027 C creep behavior of [001]-oriented NiAl-1Hf with a nominal chemistry of Ni-47.5Al-1Hf-0.5Si. This alloy was selected since four ingots, grown over a number of years and possessing slightly different compositions, were available for study. Specimens taken from the

Liquid Crystals in Decorative and Visual Arts

Science.gov (United States)

Makow, David

The following sections are included: * INTRODUCTION * PIGMENT AND STRUCTURAL COLOURS AND THEIR RELEVANCE TO LIQUID CRYSTALS * LIQUID CRYSTAL MATERIALS AND TECHNIQUES FOR DECORATIVE AND VISUAL ARTS * Free cholesteric liquid crystals (FCLC's) * Encapsulated liquid crystals (ECLC's) * Nonsteroid Chiral nematics * Polymers with liquid crystalline properties (PLCs) * COLOUR PROPERTIES OF CHOLESTERIC LIQUID CRYSTALS (CLC's) * Molecular structure and the mechanism of colour production * Dependence of perceived colours on the angle of illumination and viewing * Dependence of perceived colours on temperature * Additive colour properties * Methods of doubling the peak reflectance of cholesteric liquid crystals * Colour gamut * Colours of superimposed and pigmented coatings * Colours in transmission * ACKNOWLEDGEMENTS * REFERENCES

Recent studies of nuclear and chemical properties of elements 103, 104 and 105

International Nuclear Information System (INIS)

Hoffman, D.C.

1990-08-01

Information obtained since 1983 on the nuclear and chemical properties of element 103, the last on the actinide series, and elements 104 and 105, at the beginning of the transactinide series, is reviewed. Their chemical properties are compared with their lanthanide and lighter group 4 and 5 homologs and evidence for possible relativistic effects is discussed. The current knowledge of the nuclear properties of these elements and how these affect of the study of chemical properties is discussed. Some of the challenges involved in the study of short-lived isotopes which can only be produced an ''atom-at-a-time'' at an appropriate accelerator and the prognosis for future studies of these and still heavier elements are considered. 40 refs., 4 figs

Investigation of the effects of swift heavy ion on the properties of yttrium calcium oxyborate (YCOB) NLO crystal

International Nuclear Information System (INIS)

Kalidasan, M.; Dhanasekaran, R.; Asokan, K.

2012-01-01

Heavy ion irradiation is a successful tool to create an effective refractive index change in a nonlinear optical (NLO) crystal surface in several micron thickness. It leads to the fabrication of non-leaky optical guiding structures. As irradiation can create the property changes with low ion fluence, it will be an alternative for the ion implantation. The present work is related to the creation of micrometer level surface modification in the YCa_4O(BO_3)_3 NLO crystal by the irradiation of 120 MeV Au"9"+ swift heavy ion and studying the changes in property of the material. The irradiation was carried out in the Materials Science beam line of the pelletron accelerator at Inter University Accelerator Centre, New Delhi. YCOB crystals were grown by high temperature flux technique in our laboratory. YCOB belongs to borate family of crystals which are superior to other NLO crystals due to their structural and optical features. Borate crystal can produce UV and deep UV laser through harmonic generation with good optical conversion efficiency. YCOB crystal attracted because of its high laser damage threshold, long nonlinear conversion length and large aperture scaling capability to be employed in high power laser applications. The Stopping and Range of Ions in Matter (SRIM) simulation has been carried out to study the variation of electronic (S_e) and nuclear (S_n) energy losses with penetration depth and energy of gold ions in YCOB crystal. Refractive index change was observed in the YCOB crystal due to the irradiation of 120 MeV Au"9"+ ion. The UV-Visible studies show optical band gap shift and confirms the refractive index change created in the YCOB crystal. The morphology of the irradiated crystal was analysed with scanning electron microscopy. The inhomogeneous broadening of emission curve of the YCOB crystal takes place due to ion irradiation which is analyzed in detail. From the fluorescence decay curves of pristine and irradiated crystals the excited state

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Electronic structure and pair potential energy analysis of 4-n-methoxy-4′-cyanobiphenyl: A nematic liquid crystal

Energy Technology Data Exchange (ETDEWEB)

Sharma, Dipendra, E-mail: d-11sharma@rediffmail.com; Tiwari, S. N., E-mail: sntiwari123@rediffmail.com [Department of Physics, DDU Gorakhpur University, Gorakhpur (India); Dwivedi, M. K., E-mail: dwivedi-ji@gmail.com [Department of Physics, Banaras Hindu University, Varanasi (India)

2016-05-06

Electronic structure properties of 4-n-methoxy-4′-cyanobiphenyl, a pure nematic liquid crystal have been examined using an ab‒initio, HF/6‒31G(d,p) technique with GAMESS program. Conformational and charge distribution analysis have been carried out. MEP, HOMO and LUMO surfaces have been scanned. Ionization potential, electron affinity, electronegativity, global hardness and softness of the liquid crystal molecule have been calculated. Further, stacking, side by side and end to end interactions between a molecular pair have been evaluated. Results have been used to elucidate the physico-chemical and liquid crystalline properties of the system.

Crystal growth, optical properties, and laser operation of Yb3+-doped NYW single crystal

Science.gov (United States)

Cheng, Y.; Xu, X. D.; Yang, X. B.; Xin, Z.; Cao, D. H.; Xu, J.

2009-11-01

Laser crystal Yb3+-doped NaY(WO4)2 (Yb:NYW) with excellent quality has been grown by Czochralski technique. The rocking curves from (400) plane of as-grown Yb:NYW crystal was measured and the full-width value at half-maximum was 19.92″. The effective segregation coefficients were measured by the X-ray fluorescence method. The polarized absorption spectra and the fluorescence spectra of Yb:NYW crystal were measured at room temperature. The fluorescence decay lifetime of Yb3+ ion in NYW crystal has been investigated. The spectroscopic parameters of Yb:NYW crystal are calculated and compared with those of Yb:YAG crystal. A continuous wave output power of 3.06 W at 1031 nm was obtained with a slope efficiency of 42% by use of diode pumping.

Effect of a Polymercaptan Material on the Electro-Optical Properties of Polymer-Dispersed Liquid Crystal Films

OpenAIRE

Yujian Sun; Cuihong Zhang; Le Zhou; Hua Fang; Jianhua Huang; Haipeng Ma; Yi Zhang; Jie Yang; Lan-Ying Zhang; Ping Song; Yanzi Gao; Jiumei Xiao; Fasheng Li; Kexuan Li

2016-01-01

Polymer-dispersed liquid crystal (PDLC) films were prepared by the ultraviolet-light-induced polymerization of photopolymerizable monomers in nematic liquid crystal/chiral dopant/thiol-acrylate reaction monomer composites. The effects of the chiral dopant and crosslinking agents on the electro-optical properties of the PDLC films were systematically investigate. While added the chiral dopant S811 into the PDLC films, the initial off-state transmittance of the films was decreased. It was found...

Solution-printed organic semiconductor blends exhibiting transport properties on par with single crystals

KAUST Repository

Niazi, Muhammad Rizwan; Li, Ruipeng; Li, Erqiang; Kirmani, Ahmad R.; Abdelsamie, Maged; Wang, Qingxiao; Pan, Wenyang; Payne, Marcia M.; Anthony, John E.; Smilgies, Detlef-M.; Thoroddsen, Sigurdur T; Giannelis, Emmanuel P.; Amassian, Aram

2015-01-01

Solution-printed organic semiconductors have emerged in recent years as promising contenders for roll-to-roll manufacturing of electronic and optoelectronic circuits. The stringent performance requirements for organic thin-film transistors (OTFTs) in terms of carrier mobility, switching speed, turn-on voltage and uniformity over large areas require performance currently achieved by organic single-crystal devices, but these suffer from scale-up challenges. Here we present a new method based on blade coating of a blend of conjugated small molecules and amorphous insulating polymers to produce OTFTs with consistently excellent performance characteristics (carrier mobility as high as 6.7 cm2 V−1 s−1, low threshold voltages of<1 V and low subthreshold swings <0.5 V dec−1). Our findings demonstrate that careful control over phase separation and crystallization can yield solution-printed polycrystalline organic semiconductor films with transport properties and other figures of merit on par with their single-crystal counterparts.

Solution-printed organic semiconductor blends exhibiting transport properties on par with single crystals

KAUST Repository

Niazi, Muhammad Rizwan

2015-11-23

Solution-printed organic semiconductors have emerged in recent years as promising contenders for roll-to-roll manufacturing of electronic and optoelectronic circuits. The stringent performance requirements for organic thin-film transistors (OTFTs) in terms of carrier mobility, switching speed, turn-on voltage and uniformity over large areas require performance currently achieved by organic single-crystal devices, but these suffer from scale-up challenges. Here we present a new method based on blade coating of a blend of conjugated small molecules and amorphous insulating polymers to produce OTFTs with consistently excellent performance characteristics (carrier mobility as high as 6.7 cm2 V−1 s−1, low threshold voltages of<1 V and low subthreshold swings <0.5 V dec−1). Our findings demonstrate that careful control over phase separation and crystallization can yield solution-printed polycrystalline organic semiconductor films with transport properties and other figures of merit on par with their single-crystal counterparts.

Crystallization of pyroxene phases and physico-chemical properties of glass-ceramics based on Li{sub 2}O–Cr{sub 2}O{sub 3}–SiO{sub 2} eutectic glass system

Energy Technology Data Exchange (ETDEWEB)

Salman, S.M.; Salama, S.N.; Abo-Mosallam, H.A., E-mail: abomosallam@yahoo.com.au

2015-01-15

The crystallization characteristics, crystalline phase assemblages and solid solution phases developed due to thermally crystallized glasses based on the Li{sub 2}SiO{sub 3}–Li{sub 2}Si{sub 2}O{sub 5}–LiCrSi{sub 2}O{sub 6} (1028 ± 3 °C) eutectic glass system by replacing some trivalent oxides instead of Cr{sub 2}O{sub 3} were investigated. The microhardness and chemical durability of the glass-ceramics were also determined. Lithium meta and disilicate (Li{sub 2}SiO{sub 3} and Li{sub 2}Si{sub 2}O{sub 5}), lithium gallium silicate (LiGaSiO{sub 4}), and varieties of pyroxene phases, including Cr-pyroxene phase, i.e. lithium-kosmochlor (LiCrSi{sub 2}O{sub 6}), lithium aluminum silicate (LiAlSi{sub 2}O{sub 6}), lithium indium silicate (LiInSi{sub 2}O{sub 6}) and pyroxene solid solution of Li-aegerine type [Li (Fe{sub 0.5}, Cr{sub 0.5}) Si{sub 2}O{sub 6}] were the main crystalline phases formed in the crystallized glasses. There is no evidence for the formation of solid solution or liquid immiscibility gaps between LiAlSi{sub 2}O{sub 6} or LiInSi{sub 2}O{sub 6} phases and LiCrSi{sub 2}O{sub 6} phase. However, LiCrSi{sub 2}O{sub 6} and LiFeSi{sub 2}O{sub 6} components were accommodated in the pyroxene structure under favorable conditions of crystallization to form monomineralic pyroxene solid solution phase of the probably formula [Li (Fe{sub 0.5}, Cr{sub 0.5}) Si{sub 2}O{sub 6}]. The type and compatibility of the crystallized phases are discussed in relation to the compositional variation of the glasses and heat-treatment applied. The microhardness values of the crystalline materials ranged between 5282 and 6419 MPa while, the results showed that the chemical stability of the glass-ceramics was better in alkaline than in acidic media. - Highlights: • Glass ceramics based on Li{sub 2}O–Cr{sub 2}O{sub 3}–SiO{sub 2} eutectic (1028 ± 3 °C) glass were prepared. • LiCrSi{sub 2}O{sub 6} and LiFeSi{sub 2}O{sub 6} phases form monomineralic pyroxene solid

Exploration of crystal simulation potential by fluconazole isomorphism and its application in improvement of pharmaceutical properties

Science.gov (United States)

Thakur, Amitha; Kumar, Dinesh; Thipparaboina, Rajesh; Shastri, Nalini R.

2014-11-01

Control of crystal morphology during crystallization is a paramount challenge in pharmaceutical processing. Hence, there is need to introduce computational methods for morphology prediction to manage production cost of drugs and improve related pharmaceutical and biopharmaceutical properties. Layer docking approach with molecular dynamics opens a new avenue for crystal habit prediction in presence of solvent. In the present study, attempts were made to correlate predicted and experimental crystal habits of fluconazole considering solvent interactions using layer docking approach. Simulated results from layer docking approach with methanol as solvent gave two dominant facets (0 1 1) and (1 0 1) with a surface area 22.43% and 19.82% respectively, which were in agreement with the experimental results. Experimentally grown modified crystal habit of fluconazole in methanol showed enhanced dissolution rate (phabit change and absence of any polymorphs, hydrates or solvates. Flow and compressibility of fluconazole recrystallized in methanol was significantly improved when compared to plain drug. This study demonstrates a methodical approach using computational tools for prediction and modification of crystal habit, to enhance dissolution of poorly soluble drugs, for future pharmaceutical applications.

Surface properties of hydrogenated nanodiamonds: a chemical investigation.

Science.gov (United States)

Girard, H A; Petit, T; Perruchas, S; Gacoin, T; Gesset, C; Arnault, J C; Bergonzo, P

2011-06-28

Hydrogen terminations (C-H) confer to diamond layers specific surface properties such as a negative electron affinity and a superficial conductive layer, opening the way to specific functionalization routes. For example, efficient covalent bonding of diazonium salts or of alkene moieties can be performed on hydrogenated diamond thin films, owing to electronic exchanges at the interface. Here, we report on the chemical reactivity of fully hydrogenated High Pressure High Temperature (HPHT) nanodiamonds (H-NDs) towards such grafting, with respect to the reactivity of as-received NDs. Chemical characterizations such as FTIR, XPS analysis and Zeta potential measurements reveal a clear selectivity of such couplings on H-NDs, suggesting that C-H related surface properties remain dominant even on particles at the nanoscale. These results on hydrogenated NDs open up the route to a broad range of new functionalizations for innovative NDs applications development. This journal is © the Owner Societies 2011

13C NMR Chemical Shifts of the Triclinic and Monoclinic Crystal forms of Valinomycin

International Nuclear Information System (INIS)

Kameda, Tsunenori; McGeorge, Gary; Orendt, Anita M.; Grant, David M.

2004-01-01

Two different crystalline polymorphs of valinomycin, the triclinic and monoclinic forms, have been studied by high resolution, solid state 13 C CP-MAS NMR spectroscopy. Although the two polymorphs of the crystal are remarkably similar, there are distinct differences in the isotropic chemical shifts between the two spectra. For the triclinic form, the carbon chemical shift tensor components for the alpha carbons adjacent to oxygen in the lactic acid and hydroxyisovaleric acid residues and the ester carbonyls of the valine residue were obtained using the FIREMAT experiment. From the measured components, it was found that the behavior of the isotropic chemical shift, δ iso , for valine residue ester carbonyl carbons is predominately influenced by the intermediate component, δ 22 . Additionally it was found that the smallest shift component, δ 33 , for the L-lactic acid (L-Lac) and D-α-hydroxyisovaleric acid (D-Hyi) C α -O carbon was significantly displaced depending upon the nature of individual amino acid residues, and it is the δ 33 component that governs the behavior of δ iso in these alpha carbons

Crystal habit modification of nickel-ferrite: development and results of initial laboratory testing

International Nuclear Information System (INIS)

Anderson, C.E.; Varrin, R.D.; Marks, C.; Barkatt, A.; Kim, K.; Fruzzetti, K.P.

2010-01-01

This paper documents the results of a laboratory test program conducted to assess the feasibility of using a new type of additive in the primary coolant of pressurized water reactors (PWRs) or to boiling water reactor (BWR) coolant. These additives, known as crystal habit modifiers (CHMs), could potentially be used to control the crystal habits, or shapes, that comprise primary deposits and crud. Similar additives are used throughout the chemical process industry to produce products with desirable crystalline structure, morphology, density, particle size, or surface area. Based on the successes of CHM technologies in other industries, CHMs may have the potential to alleviate problems associated with deposits in nuclear plants including axial offset anomaly (AOA). By controlling the habit of deposit materials, it may be possible to retard deposit formation, produce deposits with desirable properties (e.g., high friability, low or high porosity), or promote a preferred chemical composition or deposit structure that is more amenable to removal. Desirable properties that could be selected for include enhanced boiling efficiency, reduced surface affinity for boron, and resistance to consolidation. The results of this project demonstrate that crystal habit modification of nickel ferrite, a typical primary side deposit species, can be achieved by the addition of both inorganic and organic chemical species (CHMs). The most significant habit modification of nickel ferrite was observed with the addition of metal species (e.g., Zn, Cr) due to their incorporation into the crystal lattice of the oxide. Lesser degrees of modification were achieved with organic additives such as acetate. Specific CHM candidates that may have a beneficial effect on PWR operation are identified in this paper. In addition, this paper summarizes the refinement of several methods for synthesizing nickel ferrites under hydrothermal conditions that may benefit those interested in studying crud and

Crystal habit modification of nickel-ferrite: development and results of initial laboratory testing

Energy Technology Data Exchange (ETDEWEB)

Anderson, C.E.; Varrin, R.D.; Marks, C. [Dominion Engineering, Inc., Reston, Virginia (United States); Barkatt, A. [The Catholic Univ. of America, Dept. of Chemistry, Washington, District of Columbia (United States); Kim, K.; Fruzzetti, K.P. [Electric Power Research Inst., Palo Alto, California (United States)

2010-07-01

This paper documents the results of a laboratory test program conducted to assess the feasibility of using a new type of additive in the primary coolant of pressurized water reactors (PWRs) or to boiling water reactor (BWR) coolant. These additives, known as crystal habit modifiers (CHMs), could potentially be used to control the crystal habits, or shapes, that comprise primary deposits and crud. Similar additives are used throughout the chemical process industry to produce products with desirable crystalline structure, morphology, density, particle size, or surface area. Based on the successes of CHM technologies in other industries, CHMs may have the potential to alleviate problems associated with deposits in nuclear plants including axial offset anomaly (AOA). By controlling the habit of deposit materials, it may be possible to retard deposit formation, produce deposits with desirable properties (e.g., high friability, low or high porosity), or promote a preferred chemical composition or deposit structure that is more amenable to removal. Desirable properties that could be selected for include enhanced boiling efficiency, reduced surface affinity for boron, and resistance to consolidation. The results of this project demonstrate that crystal habit modification of nickel ferrite, a typical primary side deposit species, can be achieved by the addition of both inorganic and organic chemical species (CHMs). The most significant habit modification of nickel ferrite was observed with the addition of metal species (e.g., Zn, Cr) due to their incorporation into the crystal lattice of the oxide. Lesser degrees of modification were achieved with organic additives such as acetate. Specific CHM candidates that may have a beneficial effect on PWR operation are identified in this paper. In addition, this paper summarizes the refinement of several methods for synthesizing nickel ferrites under hydrothermal conditions that may benefit those interested in studying crud and

Properties and crystal structure of methylenetetrahydrofolate reductase from Thermus thermophilus HB8.

Directory of Open Access Journals (Sweden)

Sayaka Igari

Full Text Available Methylenetetrahydrofolate reductase (MTHFR is one of the enzymes involved in homocysteine metabolism. Despite considerable genetic and clinical attention, the reaction mechanism and regulation of this enzyme are not fully understood because of difficult production and poor stability. While recombinant enzymes from thermophilic organisms are often stable and easy to prepare, properties of thermostable MTHFRs have not yet been reported.MTHFR from Thermus thermophilus HB8, a homologue of Escherichia coli MetF, has been expressed in E. coli and purified. The purified MTHFR was chiefly obtained as a heterodimer of apo- and holo-subunits, that is, one flavin adenine dinucleotide (FAD prosthetic group bound per dimer. The crystal structure of the holo-subunit was quite similar to the β(8α(8 barrel of E. coli MTHFR, while that of the apo-subunit was a previously unobserved closed form. In addition, the intersubunit interface of the dimer in the crystals was different from any of the subunit interfaces of the tetramer of E. coli MTHFR. Free FAD could be incorporated into the apo-subunit of the purified Thermus enzyme after purification, forming a homodimer of holo-subunits. Comparison of the crystal structures of the heterodimer and the homodimer revealed different intersubunit interfaces, indicating a large conformational change upon FAD binding. Most of the biochemical properties of the heterodimer and the homodimer were the same, except that the homodimer showed ≈50% activity per FAD-bound subunit in folate-dependent reactions.The different intersubunit interfaces and rearrangement of subunits of Thermus MTHFR may be related to human enzyme properties, such as the allosteric regulation by S-adenosylmethionine and the enhanced instability of the Ala222Val mutant upon loss of FAD. Whereas E. coli MTHFR was the only structural model for human MTHFR to date, our findings suggest that Thermus MTHFR will be another useful model for this important enzyme.

Growth of congruently melting Ca0.59Sr0.41F2 crystals and study of their properties

Science.gov (United States)

Karimov, D. N.; Komar'kova, O. N.; Sorokin, N. I.; Bezhanov, V. A.; Chernov, S. P.; Popov, P. A.; Sobolev, B. P.

2010-05-01

Homogeneous crystals of Ca0.59Sr0.41F2 alloy (sp. gr., Fm bar 3 m, a = 0.56057 nm), corresponding to the point of minimum in the melting curve in the CaF2-SrF2 phase diagram, have been grown by the vertical Bridgman method. The optical, mechanical, electrical, and thermophysical properties of Ca0.59Sr0.41F2 and MF2 crystals ( M = Ca, Sr) have been studied and comparatively analyzed. Ca0.59Sr0.41F2 crystals are transparent in the range of 0.133-11.5 μm, have refractive index n D = 1.436, microhardness H μ = 2.63 ± 0.10 GPa, ion conductivity σ = 5 × 10-5 S/cm at 825 K, and thermal conductivity k = 4.0 W m-1 K-1 at 300 K. It is shown that the optical properties of Ca0.59Sr0.41F2 crystals are intermediate between those of CaF2 and SrF2, whereas their mechanical and electrical characteristics are better than the latter compounds.

High-quality bulk hybrid perovskite single crystals within minutes by inverse temperature crystallization

KAUST Repository

Saidaminov, Makhsud I.

2015-07-06

Single crystals of methylammonium lead trihalide perovskites (MAPbX3; MA=CH3NH3+, X=Br− or I−) have shown remarkably low trap density and charge transport properties; however, growth of such high-quality semiconductors is a time-consuming process. Here we present a rapid crystal growth process to obtain MAPbX3 single crystals, an order of magnitude faster than previous reports. The process is based on our observation of the substantial decrease of MAPbX3 solubility, in certain solvents, at elevated temperatures. The crystals can be both size- and shape-controlled by manipulating the different crystallization parameters. Despite the rapidity of the method, the grown crystals exhibit transport properties and trap densities comparable to the highest quality MAPbX3 reported to date. The phenomenon of inverse or retrograde solubility and its correlated inverse temperature crystallization strategy present a major step forward for advancing the field on perovskite crystallization.

A facile strategy to design zeolite L crystals with tunable morphology and surface architecture.

Science.gov (United States)

Lupulescu, Alexandra I; Kumar, Manjesh; Rimer, Jeffrey D

2013-05-01

Tailoring the anisotropic growth rates of materials to achieve desired structural outcomes is a pervasive challenge in synthetic crystallization. Here we discuss a method to selectively control the growth of zeolite crystals, which are used extensively in a wide range of industrial applications. This facile method cooperatively tunes crystal properties, such as morphology and surface architecture, through the use of inexpensive, commercially available chemicals with specificity for binding to crystallographic surfaces and mediating anisotropic growth. We examined over 30 molecules as potential zeolite growth modifiers (ZGMs) of zeolite L (LTL type) crystallization. ZGM efficacy was quantified through a combination of macroscopic (bulk) and microscopic (surface) investigations that identified modifiers capable of dramatically altering the cylindrical morphology of LTL crystals. We demonstrate an ability to tailor properties critical to zeolite performance, such as external porous surface area, crystal shape, and pore length, which can enhance sorbate accessibility to LTL pores, tune the supramolecular organization of guest-host composites, and minimize the diffusion path length, respectively. We report that a synergistic combination of ZGMs and the judicious adjustment of synthesis parameters produce LTL crystals with unique surface features, and a range of length-to-diameter aspect ratios spanning 3 orders of magnitude. A systematic examination of different ZGM structures and molecular compositions (i.e., hydrophobicity and binding moieties) reveal interesting physicochemical properties governing their efficacy and specificity. Results of this study suggest this versatile strategy may prove applicable for a host of framework types to produce unrivaled materials that have eluded more conventional techniques.

Crystal growth, spectral properties, and laser demonstration of laser crystal Nd:LYSO

Science.gov (United States)

Li, D. Z.; Xu, X. D.; Zhou, D. H.; Zhuang, S. D.; Wang, Z. P.; Xia, C. T.; Wu, F.; Xu, J.

2010-11-01

A Nd:LYSO crystal has been grown by the Czochralski technique. The cell parameters were analyzed with X-ray diffraction (XRD). The Judd-Ofelt intense parameters Ω2,4,6 were obtained to be 2.65, 5.75, and 7.37×10-20 cm2, respectively. The absorption and emission cross sections and the branching ratios were calculated. The large absorption cross section (6.14×10-20 cm2) and broad absorption band (5 nm) around 811 nm indicate that this crystal can be pumped efficiently by laser diodes. The broad emission band from the 4F3/2 multiplet shows that the crystal is a promising medium for ultrashort pulse lasers. Pumped by a laser diode, the maximum 814 mW continuous-wave laser output has been obtained with a slope efficiency of 28.9%. All the results show that this crystal is a promising laser material.

Crystal growth, spectral properties, and laser demonstration of laser crystal Nd:LYSO

International Nuclear Information System (INIS)

Li, D Z; Xu, X D; Zhou, D H; Xia, C T; Wu, F; Zhuang, S D; Wang, Z P; Xu, J

2010-01-01

A Nd:LYSO crystal has been grown by the Czochralski technique. The cell parameters were analyzed with X-ray diffraction (XRD). The Judd-Ofelt intense parameters Ω 2,4,6 were obtained to be 2.65, 5.75, and 7.37×10 -20 cm 2 , respectively. The absorption and emission cross sections and the branching ratios were calculated. The large absorption cross section (6.14×10 -20 cm 2 ) and broad absorption band (5 nm) around 811 nm indicate that this crystal can be pumped efficiently by laser diodes. The broad emission band from the 4 F 3/2 multiplet shows that the crystal is a promising medium for ultrashort pulse lasers. Pumped by a laser diode, the maximum 814 mW continuous-wave laser output has been obtained with a slope efficiency of 28.9%. All the results show that this crystal is a promising laser material

Physico-chemical properties of Nigerian pumpkin ( Curcurbita pepo ...

African Journals Online (AJOL)

Physico-chemical properties of Nigerian pumpkin (Curcurbita pepo) seed oil. NC Ihediohanma, CN Ubbaonu, ENT Akobundu, EOI Banigo. Abstract. No Abstract. Nigerian Food Journal Vol. 24(1) 2006: 123-126. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT.

Analysis on the anisotropic electromechanical properties of lead magnoniobate titanate single crystal for ring type ultrasonic motors

Directory of Open Access Journals (Sweden)

Xiang Shi

2016-11-01

Full Text Available This work discussed the optimized cut of single crystal lead magnoniobate titanate (PMNT for use of ring type travelling wave ultrasonic motors (USMs, according to anisotropic analysis on electromechanical properties. The selection criterion of crystal orientation relies on the circular uniformity of the induced travelling wave amplitude on the stator surface. By calculating the equivalent elastic coefficient c11 and lateral piezoelectric constant d31, the optimal crystal orientations were proposed for PMNT single crystals poled along different directions. For single crystal poled along c directions, the optimal orientation lies along [001]c with d31=-1335pC/N and k31=0.87. The crystallographic orientation [025]c is the optimized orientation for single crystals poled along c direction with d31=199pC/N and k31=0.55. The optimal orientation of 1R configuration is [332¯]c with a large enhancement of d31 = 1201 and k31=0.92.

Kinetic Control of Aqueous Hydrolysis: Modulating Structure/Property Relationships in Inorganic Crystals

Science.gov (United States)

Neilson, James R.

2011-12-01

A grand challenge in materials science and chemistry revolves around the preparation of materials with desired properties by controlling structure on multiple length scales. Biology approaches this challenge by evolving tactics to transform soluble precursors into materials and composites with macro-scale and atomic precision. Studies of biomineralization in siliceous sponges led to the discovery of slow, catalytic hydrolysis of molecular precursors in the biogenesis of silica skeletal elements with well defined micro- and nano-scale architectures. However, the role of aqueous hydrolysis in the limit of kinetic control is not well understood; this allows us to form a central hypothesis: that the kinetics of hydrolysis modulate the structures of materials and their properties. As a model system, the diffusion of a simple hydrolytic catalyst (such as ammonia) across an air-water interface into a metal salt solution reproduces some aspects of the chemistry found in biomineralization, namely kinetic and vectorial control. Variation of the catalyst concentration modulates the hydrolysis rate, and thus alters the resulting structure of the inorganic crystals. Using aqueous solutions of cobalt(II) chloride, each product (cobalt hydroxide chloride) forms with a unique composition, despite being prepared from identical mother liquors. Synchrotron X-ray total scattering methods are needed to locate the atomic positions in the material, which are not aptly described by a traditional crystallographic unit cell due to structural disorder. Detailed definition of the structure confirms that the hydrolysis conditions systematically modulate the arrangement of atoms in the lattice. This tightly coupled control of crystal formation and knowledge of local and average structures of these materials provides insight into the unusual magnetic properties of these cobalt hydroxides. The compounds studied show significant and open magnetization loops with little variation with composition

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History of EPI Suite™ and future perspectives on chemical property estimation in US Toxic Substances Control Act new chemical risk assessments.

Science.gov (United States)

Card, Marcella L; Gomez-Alvarez, Vicente; Lee, Wen-Hsiung; Lynch, David G; Orentas, Nerija S; Lee, Mari Titcombe; Wong, Edmund M; Boethling, Robert S

2017-03-22

Chemical property estimation is a key component in many industrial, academic, and regulatory activities, including in the risk assessment associated with the approximately 1000 new chemical pre-manufacture notices the United States Environmental Protection Agency (US EPA) receives annually. The US EPA evaluates fate, exposure and toxicity under the 1976 Toxic Substances Control Act (amended by the 2016 Frank R. Lautenberg Chemical Safety for the 21 st Century Act), which does not require test data with new chemical applications. Though the submission of data is not required, the US EPA has, over the past 40 years, occasionally received chemical-specific data with pre-manufacture notices. The US EPA has been actively using this and publicly available data to develop and refine predictive computerized models, most of which are housed in EPI Suite™, to estimate chemical properties used in the risk assessment of new chemicals. The US EPA develops and uses models based on (quantitative) structure-activity relationships ([Q]SARs) to estimate critical parameters. As in any evolving field, (Q)SARs have experienced successes, suffered failures, and responded to emerging trends. Correlations of a chemical structure with its properties or biological activity were first demonstrated in the late 19 th century and today have been encapsulated in a myriad of quantitative and qualitative SARs. The development and proliferation of the personal computer in the late 20 th century gave rise to a quickly increasing number of property estimation models, and continually improved computing power and connectivity among researchers via the internet are enabling the development of increasingly complex models.

Luminescence properties of KCl:Ag{sup -} crystals excited near the fundamental absorption edge

Energy Technology Data Exchange (ETDEWEB)

Kawai, Taketoshi, E-mail: buri@p.s.osakafu-u.ac.jp [Department of Physical Science, Graduate School of Science, Osaka Prefecture University, Gakuen-cho 1-1, Naka-ku, Sakai, Osaka 599-8531 (Japan); Hirai, Takeshi [Department of Physical Science, Faculty of Science and Engineering, Ritsumeikan University, Noji Higashi 1-1-1, Kusatsu, Shiga 525-8577 (Japan)

2012-02-15

Luminescence properties of KCl single crystals doped with Ag{sup -} centers have been investigated under various excitation energies around the fundamental absorption edge at low temperatures. Under the excitation at 6.89 eV, which is lower than the intrinsic exciton energy by 0.87 eV, the A Prime luminescence band due to the intraionic transition in the Ag{sup -} ion is dominantly observed at 2.91 eV. On the other hand, the excitation at 6.66 eV induces a broad luminescence band at 2.60 eV in addition to the A Prime luminescence band. From the comparison with the localized excitons in KCl:I crystals, the 2.60 eV luminescence band is attributed to the two-center type localized exciton related with the Ag{sup -} ion. The adiabatic potential energy surfaces of the excited states in the Ag{sup -} center and the localized exciton in KCl:Ag{sup -} are discussed. - Highlights: Black-Right-Pointing-Pointer We study the luminescence properties of KCl single crystals doped with Ag{sup -} ions. Black-Right-Pointing-Pointer The excitation around the absorption edge induces a broad luminescence at 2.60 eV. Black-Right-Pointing-Pointer The 2.60 eV luminescence is attributed to the exciton localized at the Ag{sup -} ion. Black-Right-Pointing-Pointer The localized exciton has the two-center type configuration of the relaxed exciton.

Crystallization behavior and mechanical properties of nano-CaCO3/β-nucleated ethylene-propylene random copolymer composites

Directory of Open Access Journals (Sweden)

W. H. Ruan

2012-09-01

Full Text Available To provide ethylene-propylene random copolymer (PPR with balanced mechanical properties, β-nucleating agent and CaCO3 nanoparticles are incorporated into PPR matrix by melt blending. It is found that crystallization rate and relative content of β-crystal increase with the addition of β-nucleating agent together with nanoparticles. Size of PPR spherulite is greatly reduced, and a specific morphology appears, in which α-crystal lamella is grown upon the β-nucleus. The results suggest that both β-nucleating agent and nano-CaCO3 have heterogeneous nucleation and synergistic effects on β-nucleation of PPR. Mechanical characterization shows that mechanical properties of PPR can be tuned by incorporation of β-nucleating agent and nano-CaCO3 particles. Under suitable compositions, low temperature impact strength and high temperature creep resistance of PPR, the bottlenecks of application of such material, can be simultaneously improved without sacrificing the Youngs’modulus and tensile strength.

Synthesis, growth, and structural, optical, mechanical, electrical properties of a new inorganic nonlinear optical crystal: Sodium manganese tetrachloride (SMTC

Directory of Open Access Journals (Sweden)

M. Packiya raj

2017-01-01

Full Text Available A new inorganic nonlinear optical single crystal of sodium manganese tetrachloride (SMTC has been successfully grown from aqueous solution using the slow evaporation technique at room temperature. The crystals obtained using the aforementioned method were characterized using different techniques. The crystalline nature of the as-grown crystal of SMTC was analyzed using powder X-ray diffraction. Single-crystal X-ray diffraction revealed that the crystal belongs to an orthorhombic system with non-centrosymmetric space group Pbam. The optical transmission study of the SMTC crystal revealed high transmittance in the entire UV–vis region, and the lower cut-off wavelength was determined to be 240 nm. The mechanical strength of the as-grown crystal was estimated using the Vickers microhardness test. The second harmonic generation (SHG efficiency of the crystal was measured using Kurtz's powder technique, which indicated that the crystal has a nonlinear optical (NLO efficiency that is 1.32 times greater than that of KDP. The dielectric constant and dielectric loss of the compound were measured at different temperatures with varying frequencies. The photoconductivity study confirmed that the title compound possesses a negative photoconducting nature. The growth mechanism and surface features of the as-grown crystals were investigated using chemical etching analysis.

Compositional Tuning, Crystal Growth, and Magnetic Properties of Iron Phosphate Oxide

Science.gov (United States)

Tarne, Michael

Iron phosphate oxide, Fe3PO4O 3, is a crystalline solid featuring magnetic Fe3+ ions on a complex lattice composed of closely-spaced triangles. Previous work from our research group on this compound has proposed a helical magnetic structure below T = 163 K attributed to J1 - J2 competing interactions between nearest-neighbor and next-nearest-neighbor iron atoms. This was based on neutron powder diffraction featuring unique broad, flat-topped magnetic reflections due to needle-like magnetic domains. In order to confirm the magnetic structure and origins of frustration, this thesis will expand upon the research focused on this compound. The first chapter focuses on single crystal growth of Fe3PO 4O3. While neutron powder diffraction provides insight to the magnetic structure, powder and domain averaging obfuscate a conclusive structure for Fe3PO4O3 and single crystal neutron scattering is necessary. Due to the incongruency of melting, single crystal growth has proven challenging. A number of techniques including flux growth, slow cooling, and optical floating zone growth were attempted and success has been achieved via heterogenous chemical vapor transport from FePO 4 using ZrCl4 as a transport agent. These crystals are of sufficient size for single crystal measurements on modern neutron diffractometers. Dilution of the magnetic sublattice in frustrated magnets can also provide insight into the nature of competing spin interactions. Dilution of the Fe 3+ lattice in Fe3PO4O3 is accomplished by substituting non-magnetic Ga3+ to form the solid solution series Fe3-xGaxPO4O3 with x = 0, 0.012, 0.06, 0.25, 0.5, 1.0, 1.5. The magnetic susceptibility and neutron powder diffraction data of these compounds are presented. A dramatic decrease of the both the helical pitch length and the domain size is observed with increasing x; for x > 0.5, the compounds lack long range magnetic order. The phases that do exhibit magnetic order show a decrease in helical pitch with increasing x

Size dependences of crystal structure and magnetic properties of DyMnO{sub 3} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Tajiri, T., E-mail: tajiri@fukuoka-u.ac.jp [Faculty of Science, Fukuoka University, Fukuoka 814-0180 (Japan); Terashita, N.; Hamamoto, K.; Deguchi, H.; Mito, M. [Faculty of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550 (Japan); Morimoto, Y.; Konishi, K. [Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577 (Japan); Kohno, A. [Faculty of Science, Fukuoka University, Fukuoka 814-0180 (Japan)

2013-11-15

We synthesized DyMnO{sub 3} nanoparticles with particle sizes of about 7.5–15.3 nm in the pores of mesoporous silica and investigated their crystal structure and magnetic properties. As the particle size decreased, the lattice constants of the DyMnO{sub 3} nanoparticles deviated from those of the bulk crystal, and the Jahn–Teller distortion in the nanoparticle systems decreased. In addition, the estimated lattice strain increased with decreasing particle size. The DyMnO{sub 3} nanoparticles showed superparamagnetic behavior. The blocking temperature and the coercive field increased with decreasing particle size, and this behavior was contrary to the usual magnetic size effects. It is deduced that these unique size dependences of the magnetic properties for the DyMnO{sub 3} nanoparticles were derived from the changes in lattice constants and lattice strain. The anisotropic lattice deformation in the crystal structure of the nanoparticles induces an enhancement of the magnetic anisotropy, which results in the increase in blocking temperature and coercive field with decreasing particle size. - Highlights: • We successfully synthesized DyMnO{sub 3} nanoparticles with particle size of 7.5–15.3 nm. • Lattice strain increases with decreasing particle size. • Lattice constants exhibit anisotropic change with decreasing particle size. • Distortion of crystal structure leads to enhancement of magnetic anisotropy constant. • Blocking temperature and coercive field increases with decreasing particle size.

Crystallization Mechanism and Phase Transition Properties of W-doped VO2 Synthesized by Hydrothermal Method

Directory of Open Access Journals (Sweden)

LI Yao

2017-11-01

Full Text Available VO2 sol was firstly prepared using vanadyl sulfate as a vanadium source by precipitation-peptization method. Then tungsten(W doping vanadium dioxide(W-VO2 was prepared by hydrothermal crystallization of prepared sol with the presence of ammonium metatungstate. The morphologies, crystal structure of the as-prepared samples and phase transition properties were studied by X-ray diffraction(XRD, field emission scanning electron microscope(FESEMand differential scanning calorimetry(DSC analysis. The results indicate that rod-like W-VO2(B crystal with length of 1-2μm and radius of 100-200nm is firstly formed during hydrothermal treatment for 4-48h at 280℃, then the rod-like crystal dissolves gradually and sheet-like or snowflake-like crystal is formed with the phase transition from W-VO2(B to W-VO2(M and eventually, the W-VO2(M crystals can further grow up while the W-VO2(B gradually dissolves; the phase transition temperature of VO2 decreases with the increase in W doping content, and the phase transition temperature of W-VO2(M reduces to about 28℃ when the nominal dopant concentration is 6.0%(atom fraction.The "nucleation-growth-transformation-ripening" mechanism is proposed as the formation mechanism based on the hydrothermal crystallization and morphological evolution process of W-VO2(M.

Annealing effect on structural and optical properties of chemical bath deposited MnS thin film

Energy Technology Data Exchange (ETDEWEB)

Ulutas, Cemal, E-mail: cemalulutas@hakkari.edu.tr [Faculty of Education, Hakkari Universty, 30000, Hakkari (Turkey); Gumus, Cebrail [Faculty of Science and Letters, Cukurova University, 01330, Adana (Turkey)

2016-03-25

MnS thin film was prepared by the chemical bath deposition (CBD) method on commercial microscope glass substrate deposited at 30 °C. The as-deposited film was given thermal annealing treatment in air atmosphere at various temperatures (150, 300 and 450 °C) for 1 h. The MnS thin film was characterized by using X-ray diffraction (XRD), UV-vis spectrophotometer and Hall effect measurement system. The effect of annealing temperature on the structural, electrical and optical properties such as optical constants of refractive index (n) and energy band gap (E{sub g}) of the film was determined. XRD measurements reveal that the film is crystallized in the wurtzite phase and changed to tetragonal Mn{sub 3}O{sub 4} phase after being annealed at 300 °C. The energy band gap of film decreased from 3.69 eV to 3.21 eV based on the annealing temperature.

Effect of a Polymercaptan Material on the Electro-Optical Properties of Polymer-Dispersed Liquid Crystal Films

Directory of Open Access Journals (Sweden)

Yujian Sun

2016-12-01

Full Text Available Polymer-dispersed liquid crystal (PDLC films were prepared by the ultraviolet-light-induced polymerization of photopolymerizable monomers in nematic liquid crystal/chiral dopant/thiol-acrylate reaction monomer composites. The effects of the chiral dopant and crosslinking agents on the electro-optical properties of the PDLC films were systematically investigate. While added the chiral dopant S811 into the PDLC films, the initial off-state transmittance of the films was decreased. It was found that the weight ratio among acrylate monomers, thiol monomer PETMP and the polymercaptan Capcure 3-800 showed great influence on the properties of the fabricated PDLC films because of the existence of competition between thiol-acrylate reaction and acrylate monomer polymerization reaction. While adding polymercaptans curing agent Capcure 3-800 with appropriate concentration into the PDLC system, lower driven voltage and higher contrast ratio were achieved. This made the polymer network and electro-optical properties of the PDLC films easily tunable by the introduction of the thiol monomers.

Effect of a Polymercaptan Material on the Electro-Optical Properties of Polymer-Dispersed Liquid Crystal Films.

Science.gov (United States)

Sun, Yujian; Zhang, Cuihong; Zhou, Le; Fang, Hua; Huang, Jianhua; Ma, Haipeng; Zhang, Yi; Yang, Jie; Zhang, Lan-Ying; Song, Ping; Gao, Yanzi; Xiao, Jiumei; Li, Fasheng; Li, Kexuan

2016-12-30

Polymer-dispersed liquid crystal (PDLC) films were prepared by the ultraviolet-light-induced polymerization of photopolymerizable monomers in nematic liquid crystal/chiral dopant/thiol-acrylate reaction monomer composites. The effects of the chiral dopant and crosslinking agents on the electro-optical properties of the PDLC films were systematically investigate. While added the chiral dopant S811 into the PDLC films, the initial off-state transmittance of the films was decreased. It was found that the weight ratio among acrylate monomers, thiol monomer PETMP and the polymercaptan Capcure 3-800 showed great influence on the properties of the fabricated PDLC films because of the existence of competition between thiol-acrylate reaction and acrylate monomer polymerization reaction. While adding polymercaptans curing agent Capcure 3-800 with appropriate concentration into the PDLC system, lower driven voltage and higher contrast ratio were achieved. This made the polymer network and electro-optical properties of the PDLC films easily tunable by the introduction of the thiol monomers.

Engineering electrical properties of graphene: chemical approaches

International Nuclear Information System (INIS)

Kim, Yong-Jin; Kim, Yuna; Hong, Byung Hee; Novoselov, Konstantin

2015-01-01

To ensure the high performance of graphene-based devices, it is necessary to engineer the electrical properties of graphene with enhanced conductivity, controlled work function, opened or closed bandgaps, etc. This can be performed by various non-covalent chemical approaches, including molecular adsorption, substrate-induced doping, polymerization on graphene, deposition of metallic thin films or nanoparticles, etc. In addition, covalent approaches such as the substitution of carbon atoms with boron or nitrogen and the functionalization with hydrogen or fluorine are useful to tune the bandgaps more efficiently, with better uniformity and stability. In this review, representative examples of chemically engineered graphene and its device applications will be reviewed, and remaining challenges will be discussed. (topical review)

Single-Crystalline cooperite (PtS): Crystal-Chemical characterization, ESR spectroscopy, and {sup 195}Pt NMR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Rozhdestvina, V. I., E-mail: veronika@ascnet.ru; Ivanov, A. V.; Zaremba, M. A. [Far East Division, Russian Academy of Sciences, Institute of Geology and Nature Management (Russian Federation); Antsutkin, O. N.; Forsling, W. [Lulea University of Technology (Sweden)

2008-05-15

Single-crystalline cooperite (PtS) with a nearly stoichiometric composition was characterized in detail by X-ray diffraction, electron-probe X-ray microanalysis, and high-resolution scanning electron microscopy. For the first time it was demonstrated that {sup 195}Pt static and MAS NMR spectroscopy can be used for studying natural platinum minerals. The {sup 195}Pt chemical-shift tensor of cooperite was found to be consistent with the axial symmetry and is characterized by the following principal values: {delta}{sub xx} = -5920 ppm, {delta}{sub yy} = -3734 ppm, {delta}{sub zz} = +4023 ppm, and {delta}{sub iso} = -1850 ppm. According to the ESR data, the samples of cooperite contain copper(II), which is adsorbed on the surface during the layer-by-layer crystal growth and is not involved in the crystal lattice.

Method for Non-Invasive Determination of Chemical Properties of Aqueous Solutions

Science.gov (United States)

Todd, Paul W. (Inventor); Jones, Alan (Inventor); Thomas, Nathan A. (Inventor)

2016-01-01

A method for non-invasively determining a chemical property of an aqueous solution is provided. The method provides the steps of providing a colored solute having a light absorbance spectrum and transmitting light through the colored solute at two different wavelengths. The method further provides the steps of measuring light absorbance of the colored solute at the two different transmitted light wavelengths, and comparing the light absorbance of the colored solute at the two different wavelengths to determine a chemical property of an aqueous solution.

XV International conference on chemical thermodynamics in Russia. RCCT-2005. Summary of reports. Volume I

International Nuclear Information System (INIS)

2005-01-01

Proceedings of the XV International conference on chemical thermodynamics are performed. The release covers wide frame on physical chemistry and chemical thermodynamics, and present-day conception on properties as individual substances, so their mixtures on phase and chemical equilibriums, surface effects in different systems is demonstrated. Solutions and melts, complex fluid systems (polymer solutions, liquid crystals, micellar solutions), new materials are part of concerned problems. Theoretical and experimental methods of chemical thermodynamics, automated experimental databases are among discussed problems [ru

Synthesis, growth, structural, optical, thermal, electrical and mechanical properties of hydrogen bonded organic salt crystal: Triethylammonium-3, 5-dinitrosalicylate

Science.gov (United States)

Rajkumar, Madhu; Chandramohan, Angannan

2017-04-01

Triethylammonium-3, 5-dinitrosalicylate, an organic salt was synthesized and single crystals grown by slow solvent evaporation solution growth technique using methanol as a solvent. The presence of various functional groups and mode of vibrations has been confirmed by FT-IR spectroscopic technique. The UV-vis-NIR Spectrum was recorded in the range 200-1200 nm to find optical transmittance window and lower cut off wavelength of the title crystal. The formation of the salt and the molecular structure was confirmed by NMR spectroscopic technique. Crystal system, crystalline nature, cell parameters and hydrogen bonding interactions of the grown crystal were determined by single crystal x-ray diffraction analysis. The thermal characteristics of grown crystal were analyzed by thermo gravimetric and differential thermal analyses. Dielectric studies were carried out to study the distribution of charges within the crystal. The mechanical properties of the title crystal were studied by Vicker's microhardness technique.

Optical properties of tungsten disulfide single crystals doped with gold

International Nuclear Information System (INIS)

Dumcenco, D.O.; Hsu, H.P.; Huang, Y.S.; Liang, C.H.; Tiong, K.K.; Du, C.H.

2008-01-01

Single crystals of WS 2 doped with gold have been grown by the chemical vapour transport method using iodine as a transporting agent. X-ray diffraction (XRD) pattern analysis revealed presence of mixed three-layer rhombohedral (3R) and two-layer hexagonal (2H) polytypes for the doped crystals while the undoped one shows only 2H form. Hall measurements indicate that the samples are p-type in nature. The doping effects of the materials are characterized by surface photovoltage (SPV), photoconductivity (PC) and piezoreflectance (PzR) measurements. Room temperature SPV and PC spectra reveal a feature located at ∼60 meV below the A exciton and has been tentatively assigned to be an impurity level caused by Au dopant. Excitonic transition energies of the A, B, d and C excitons detected in PzR spectra show red shift due to the presence of a small amount of Au and the broadening parameters of the excitonic transition features increase due to impurity scattering. The values of the parameters that describe the electron (exciton)-phonon interaction of excitonic transitions of A-B are about two times larger than that of d-C excitonic pairs. The possible assignments of the different origins of A-B and d-C excitonic pairs have been discussed

Principles of crystallization, and methods of single crystal growth

International Nuclear Information System (INIS)

Chacra, T.

2010-01-01

Most of single crystals (monocrystals), have distinguished optical, electrical, or magnetic properties, which make from single crystals, key elements in most of technical modern devices, as they may be used as lenses, Prisms, or grating sin optical devises, or Filters in X-Ray and spectrographic devices, or conductors and semiconductors in electronic, and computer industries. Furthermore, Single crystals are used in transducer devices. Moreover, they are indispensable elements in Laser and Maser emission technology.Crystal Growth Technology (CGT), has started, and developed in the international Universities and scientific institutions, aiming at some of single crystals, which may have significant properties and industrial applications, that can attract the attention of international crystal growth centers, to adopt the industrial production and marketing of such crystals. Unfortunately, Arab universities generally, and Syrian universities specifically, do not give even the minimum interest, to this field of Science.The purpose of this work is to attract the attention of Crystallographers, Physicists and Chemists in the Arab universities and research centers to the importance of crystal growth, and to work on, in the first stage to establish simple, uncomplicated laboratories for the growth of single crystal. Such laboratories can be supplied with equipment, which are partly available or can be manufactured in the local market. Many references (Articles, Papers, Diagrams, etc..) has been studied, to conclude the most important theoretical principles of Phase transitions,especially of crystallization. The conclusions of this study, are summarized in three Principles; Thermodynamic-, Morphologic-, and Kinetic-Principles. The study is completed by a brief description of the main single crystal growth methods with sketches, of equipment used in each method, which can be considered as primary designs for the equipment, of a new crystal growth laboratory. (author)

Data on the chemical properties of commercial fish sauce products.

Science.gov (United States)

Nakano, Mitsutoshi; Sagane, Yoshimasa; Koizumi, Ryosuke; Nakazawa, Yozo; Yamazaki, Masao; Watanabe, Toshihiro; Takano, Katsumi; Sato, Hiroaki

2017-12-01

This data article reports on the chemical properties of commercial fish sauce products associated with the fish sauce taste and flavor. All products were analyzed in triplicate. Dried solid content was analyzed by moisture analyzer. Fish sauce salinity was determined by a salt meter. pH was measured using a pH meter. The acidity was determined using a titration assay. Amino nitrogen and total nitrogen were evaluated using a titration assay and Combustion-type nitrogen analyzer, respectively. The analyzed products originated from Japan, Thailand, Vietnam, China, the Philippines, and Italy. Data on the chemical properties of the products are provided in table format in the current article.

Development and measurement of luminescence properties of Ce-doped Cs2LiGdBr6 crystals irradiated with X-ray, γ-ray and proton beam

Science.gov (United States)

Jang, Jonghun; Kim, H. J.; Rooh, Gul; Kim, Sunghwan

2017-12-01

The effect of higher Ce-concentration on the luminescence and scintillation properties of Cs2LiGdBr6 single crystals are studied. We used the Bridgman method for the growth of Ce-doped Cs2LiGdBr6 single crystals. Luminescence properties of the grown crystals are measured by X-ray and proton excitations. We measured the pulse height and fluorescence decay time spectra of Cs2LiGdBr6:Ce3+ with a bi-alkali photo multiplier tube (PMT) under γ-ray excitation from 137Cs source. Improvements in the scintillation properties are observed with the increase of Ce-concentration in the lattice. Detailed procedure of the crystal growth is also discussed.

Structural, mechanical, electrical and optical properties of a new lithium boro phthalate NLO crystal synthesized by a slow evaporation method

Science.gov (United States)

Mohanraj, K.; Balasubramanian, D.; Jhansi, N.

2017-11-01

A new non-linear optical (NLO) single crystal of lithium boro phthalate (LiBP) was grown by slow solvent evaporation technique. The powder sample was subjected to powder X-ray diffraction (PXRD) to find its crystalline nature and the crystal structure of the grown crystal was determined using single crystal X-ray (SXRD) diffraction analysis. The Fourier Transform Infrared (FTIR) spectrum was recorded for grown crystal to identify the various functional groups present in the compound. The mechanical property of the LiBP single crystal was studied using Vickers microhardness tester. The dielectric constant and dielectric loss measurements were carried out for the grown crystal at various temperatures. The grown crystal was subjected to UV-Visible Spectral Studies to analyze the linear optical behavior of the grown crystal. The Kurtz-Perry Powder technique was employed to measure the Second Harmonic Generation efficiency of the grown crystal.

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