Structure of Biocompatible Coatings Produced from Hydroxyapatite Nanoparticles by Detonation Spraying.

PubMed

Nosenko, Valentyna; Strutynska, Nataliia; Vorona, Igor; Zatovsky, Igor; Dzhagan, Volodymyr; Lemishko, Sergiy; Epple, Matthias; Prymak, Oleg; Baran, Nikolai; Ishchenko, Stanislav; Slobodyanik, Nikolai; Prylutskyy, Yuriy; Klyui, Nickolai; Temchenko, Volodymyr

2015-12-01

Detonation-produced hydroxyapatite coatings were studied by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Raman spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy. The source material for detonation spraying was a B-type carbonated hydroxyapatite powder. The coatings consisted of tetracalcium phosphate and apatite. The ratio depended slightly on the degree of crystallinity of the initial powder and processing parameters of the coating preparation. The tetracalcium phosphate phase was homogeneous; the apatite phase contained defects localized on the sixfold axis and consisted of hydroxyapatite and oxyapatite. Technological factors contributing to the transformation of hydroxyapatite powder structure during coating formation by detonation spraying are discussed.

Analysis of a nanocrystalline polymer dispersion of ebselen using solid-state NMR, Raman microscopy, and powder X-ray diffraction.

PubMed

Vogt, Frederick G; Williams, Glenn R

2012-07-01

Nanocrystalline drug-polymer dispersions are of significant interest in pharmaceutical delivery. The purpose of this work is to demonstrate the applicability of methods based on two-dimensional (2D) and multinuclear solid-state NMR (SSNMR) to a novel nanocrystalline pharmaceutical dispersion of ebselen with polyvinylpyrrolidone-vinyl acetate (PVP-VA), after initial characterization with other techniques. A nanocrystalline dispersion of ebselen with PVP-VA was prepared and characterized by powder X-ray diffraction (PXRD), confocal Raman microscopy and mapping, and differential scanning calorimetry (DSC), and then subjected to detailed 1D and 2D SSNMR analysis involving ¹H, ¹³C, and ⁷⁷Se isotopes and ¹H spin diffusion. PXRD was used to show that dispersion contains nanocrystalline ebselen in the 35-60 nm size range. Confocal Raman microscopy and spectral mapping were able to detect regions where short-range interactions may occur between ebselen and PVP-VA. Spin diffusion effects were analyzed using 2D SSNMR experiments and are able to directly detect interactions between ebselen and the surrounding PVP-VA. The methods used here, particularly the 2D SSNMR methods based on spin diffusion, provided detailed structural information about a nanocrystalline polymer dispersion of ebselen, and should be useful in other studies of these types of materials.

Rietveld analysis of the cubic crystal structure of Na-stabilized zirconia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fagherazzi, G.; Canton, P.; Benedetti, A.

Using x-ray Rietveld analysis the fcc (fluorite-type) structure of a Na-containing nanocrystalline zirconia powder (9.5 nm estimated of crystallite size) obtained by precipitation and subsequent calcination has been confirmed. The result shows that using conventional x-ray diffraction techniques the cubic crystallographic form of ZrO{sub 2} from the tetragonal one in nanosized powders. These conclusions are supported by the findings of independent Raman scattering experiments. {copyright} {ital 1997 Materials Research Society.}

Structural and mechanical properties of CVD deposited titanium aluminium nitride (TiAlN) thin films

NASA Astrophysics Data System (ADS)

Das, Soham; Guha, Spandan; Ghadai, Ranjan; Kumar, Dhruva; Swain, Bibhu P.

2017-06-01

Titanium aluminium nitride (TiAlN) thin films were deposited by chemical vapour deposition using TiO2 powder, Al powder and N2 gas. The morphology and mechanical properties of the films were characterized by scanning electron microscopy and nanoindentation technique, respectively. The structural properties were characterized by Raman spectroscopy and X-ray diffraction. The XRD result shows TiAlN films are of NaCl-type metal nitride structure. Micro-Raman peaks of the TiAlN thin film were observed within 450 and 642 cm-1 for acoustic and optic range, respectively. A maximum hardness and Young modulus up to 22 and 272.15 GPa, respectively, were observed in the TiAlN film deposited at 1200 °C.

Preparation of thermally stable nanocrystalline hydroxyapatite by hydrothermal method.

PubMed

Prakash Parthiban, S; Elayaraja, K; Girija, E K; Yokogawa, Y; Kesavamoorthy, R; Palanichamy, M; Asokan, K; Narayana Kalkura, S

2009-12-01

Thermally stable hydroxyapatite (HAp) was synthesized by hydrothermal method in the presence of malic acid. X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), differential thermal analysis (DTA), thermogravimetric analysis (TGA) was done on the synthesized powders. These analyses confirmed the sample to be free from impurities and other phases of calcium phosphates, and were of rhombus morphology along with nanosized particles. IR and Raman analyses indicated the adsorption of malic acid on HAp. Thermal stability of the synthesized HAp was confirmed by DTA and TGA. The synthesized powders were thermally stable upto 1,400 degrees C and showed no phase change. The proposed method might be useful for producing thermally stable HAp which is a necessity for high temperature coating applications.

[The study of ultra-fine diamond powder used in magnetic head polishing slurry].

PubMed

Jin, Hong-Yun; Hou, Shu-En; Pan, Yong; Xiao, Hong-Yan

2008-05-01

In the present paper, atomic absorption spectrometry(AAS), inductively-coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and laser Raman spectroscopy (RM) were employed to study the commercial ultra-fine diamond powders prepared by the static pressure-catalyst method and used in magnetic head polishing slurry. The results of AAS and ICP-MS indicated that there were silicon oxide, Fe, Ni, Al and some other metal elements in the ultra-fine powders. XRD patterns showed the peaks of SiO2 at 2theta = 35.6 degrees, 39.4 degrees and 59.7 degrees and diamond sharp peaks in agreement with the results above. Diamond sharp peaks implied perfect crystal and high-hardness beneficial to high-efficiency in polishing. The broader Raman band of graphite at 1 592 cm(-1) observed by Raman analysis proved graphite existing in the diamond powders. In the TEM images, the size of ultra-fine powders was estimated between 0.1 and 0.5 microm distributed in a wide scope, however, sharp edges of the powder particles was useful to polish. The ultra-fine diamond powders have many advantages, for example, high-hardness, well abrasion performance, high-polishing efficiency and being useful in magnetic head polishing slurry. But, the impurities influence the polishing efficiency, shortening its service life and the wide distribution reduces the polishing precision. Consequently, before use the powders must be purified and classified. The purity demands is 99.9% and trace silicon oxide under 0.01% should be reached. The classification demands that the particle distribution should be in a narrower scope, with the mean size of 100 nm and the percentage of particles lager than 200 nm not over 2%.

In Situ Investigation of a Self-Accelerated Cocrystal Formation by Grinding Pyrazinamide with Oxalic Acid.

PubMed

Kulla, Hannes; Greiser, Sebastian; Benemann, Sigrid; Rademann, Klaus; Emmerling, Franziska

2016-07-14

A new cocrystal of pyrazinamide with oxalic acid was prepared mechanochemically and characterized by PXRD, Raman spectroscopy, solid-state NMR spectroscopy, DTA-TG, and SEM. Based on powder X-ray diffraction data the structure was solved. The formation pathway of the reaction was studied in situ using combined synchrotron PXRD and Raman spectroscopy. Using oxalic acid dihydrate the initially neat grinding turned into a rapid self-accelerated liquid-assisted grinding process by the release of crystallization water. Under these conditions, the cocrystal was formed directly within two minutes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deus, R.C.; Cortés, J.A., E-mail: leandrosrr89@gmail.com; Ramirez, M.A.

Highlights: • CeO{sub 2} nanoparticles were obtained by microwave-hydrothermal method. • Rietveld refinement reveals a cubic structure. • KOH mineralizer agent exhibit weak agglomeration at low temperature and shorter time. - Abstract: The structural and photoluminescent properties at room temperature of CeO{sub 2} and La-doped CeO{sub 2} particles were undertaken. The obtained particles were synthesized by a microwave-assisted hydrothermal method (MAH) under different lanthanum contents. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman), Ultra-violet spectroscopy (UV–vis) and photoluminescence (PL) measurements were carried out. XRD revealed that the powders are free of secondary phases and crystallize in themore » cubic structure. Raman data show that increasing La doping content increase oxygen vacancies due to lattice expansion. The UV/vis absorption spectroscopy suggested the presence of intermediate energy levels in the band gap of structurally ordered powders. Lanthanum addition creates oxygen vacancies and shifts the photoluminescence in the low energy range leading to intense PL emission.« less

Kinetic studies of methane-ethane mixed gas hydrates by neutron diffraction and Raman spectroscopy.

PubMed

Murshed, M Mangir; Kuhs, Werner F

2009-04-16

In situ formations of CH(4)-C(2)H(6) mixed gas hydrates were made using high flux neutron diffraction at 270 K and 5 MPa. For this purpose, a feed gas composition of CH(4) and C(2)H(6) (95 mol% CH(4)) was employed. The rates of transformation of spherical grains of deuterated ice Ih into hydrates were measured by time-resolved neutron powder diffraction on D20 at ILL, Grenoble. Phase fractions of the crystalline constituents were obtained from Rietveld refinements. A concomitant formation of structure type I (sI) and structure type II (sII) hydrates were observed soon after the gas pressure was applied. The initial fast formation of sII hydrate reached its maximum volume and started declining very slowly. The formation of sI hydrate followed a sigmoid growth kinetics that slowed down due to diffusion limitation. This observation has been interpreted in terms of a kinetically favored nucleation of the sII hydrate along with a slow transformation into sI. Both powder diffraction and Raman spectroscopic results suggest that a C(2)H(6)-rich sII hydrate was formed at the early part of the clathration, which slowly decreased to approximately 3% after a reaction of 158 days as confirmed by synchrotron XRD. The final persistence of a small portion of sII hydrate points to a miscibility gap between CH(4)-rich sI and C(2)H(6)-rich sII hydrates.

Nano-Crystalline Thermally Evaporated Bi2Se3 Thin Films Synthesized from Mechanically Milled Powder

NASA Astrophysics Data System (ADS)

Amara, A.; Abdennouri, N.; Drici, A.; Abdelkader, D.; Bououdina, M.; Chaffar Akkari, F.; Khemiri, N.; Kanzari, M.; Bernède, J. C.

2017-08-01

Bi2Se3 powder has been successfully synthesized via mechanical ball milling of bismuth and selenium as starting materials. X-ray diffraction characterization revealed the formation of the rhombohedral and orthorhombic phases of Bi2Se3 material belonging to systems with space groups R\\bar{3}m and Pbnm, respectively. The advantageous last finding is confirmed by the Rietveld refinement of the x-ray diffraction data. Furthermore, the analysis of the x-ray data of thermally deposited thin films revealed that both orthorhombic and rhombohedral phases are coexisting in the layer. The morphology of the ball milled powder was studied by scanning electron microscopy. The phase formation of the material is confirmed by Raman spectroscopy. M-H (Magnetization versus Magnetic field) curve indicates that Bi2Se3 powder has a ferromagnetic behavior. Additionally, absorbance and transmittance measurements were carried out on the obtained thermally evaporated thin films and yielded a band gap of 1.33 eV supporting the potential application of the heterogeneous rhombohedral/orthorhombic Bi2Se3 material in photovoltaics.

Improved electrochemical properties of a coin cell using LiMn 1.5Ni 0.5O 4 as cathode in the 5 V range

NASA Astrophysics Data System (ADS)

Singhal, Rahul; Das, Suprem R.; Oviedo, Osbert; Tomar, Maharaj S.; Katiyar, Ram S.

Phase pure LiMn 1.5Ni 0.5O 4 powders were synthesized by a chemical synthesis route and were subsequently characterized as cathode materials in a Li-ion coin cell comprising a Li anode and lithium hexafluorophosphate (LiPF 6), dissolved in dimethyl carbonate (DMC) + ethylene carbonate (EC) [1:1, v/v ratio] as electrolyte. The spinel structure and phase purity of the powders were characterized using X-ray diffraction and micro-Raman spectroscopy. The presence of both oxidation and reduction peaks in the cyclic voltammogram revealed Li + extraction and insertion from the spinel structure. The charge-discharge characteristics of the coin cell were performed in the 3.0-4.8 V range. An initial discharge capacity of ∼140 mAh g -1 was obtained with 94% initial discharge capacity retention after 50 repeated cycles. The microstructures and compositions of the cathode before and after electrochemistry were investigated using scanning electron microscopy and energy-dispersive analysis by X-ray analysis, respectively. Using X-ray diffraction, Raman spectroscopy and electrochemical analysis, we correlated the structural stability and the electrochemical performance of this cathode.

Structural and microstructural description of the glacial state in triphenyl phosphite from powder synchrotron X-ray diffraction data and Raman scattering investigations

NASA Astrophysics Data System (ADS)

Derollez, P.; Hernandez, O.; Hédoux, A.; Guinet, Y.; Masson, O.; Lefebvre, J.; Descamps, M.

2004-06-01

The structure and microstructure (refinement of the isotropic size and microstrain parameters) of the glacial state in triphenyl phosphite (TPP, P(OC 6H 5) 3) transformed at 222K have been determined from powder synchrotron X-ray diffraction data through a Rietveld and a Le Bail refinement, respectively. It is shown that the glacial state is composed of crystallites of the stable crystal phase coexisting with non-transformed supercooled liquid, the apparent size of the crystallites—depending on the aging temperature at which the glacial state is isothermally formed, [Phys. Rev. B 60 (1999) 9390]—being equal to 329.2(2) Å at 222K. The molecular conformation is slightly less mirror-symmetric than the one in the crystal state, and correlatively only one of the two unusual weak intermolecular C-H⋯O hydrogen bonds already observed in the latter state is encountered in the glacial one. Additional Raman scattering investigations confirm the previous result and reveal in addition that no hydrogen bonding interaction is observed neither in the glass nor in the liquid states.

Diamond-silicon carbide composite

DOEpatents

Qian, Jiang; Zhao, Yusheng

2006-06-13

Fully dense, diamond-silicon carbide composites are prepared from ball-milled microcrystalline diamond/amorphous silicon powder mixture. The ball-milled powder is sintered (P=5–8 GPa, T=1400K–2300K) to form composites having high fracture toughness. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPa.dot.m^1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness. X-ray diffraction patterns and Raman spectra indicate that amorphous silicon is partially transformed into nanocrystalline silicon at 5 GPa/873K, and nanocrystalline silicon carbide forms at higher temperatures.

Diamond-Silicon Carbide Composite And Method For Preparation Thereof

DOEpatents

Qian, Jiang; Zhao, Yusheng

2005-09-06

Fully dense, diamond-silicon carbide composites are prepared from ball-milled microcrystalline diamond/amorphous silicon powder mixture. The ball-milled powder is sintered (P=5-8 GPa, T=1400K-2300K) to form composites having high fracture toughness. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPa.multidot.m.sup.1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness. X-ray diffraction patterns and Raman spectra indicate that amorphous silicon is partially transformed into nanocrystalline silicon at 5 GPa/873K, and nanocrystalline silicon carbide forms at higher temperatures.

Effect of particle size and laser power on the Raman spectra of CuAlO2 delafossite nanoparticles

NASA Astrophysics Data System (ADS)

Yassin, O. A.; Alamri, S. N.; Joraid, A. A.

2013-06-01

A transparent conductive oxide CuAlO2 delafossite is studied using x-ray powder diffraction (XRD) and micro-Raman spectroscopy measurements as a function of the particle size and laser power from 2 to 20 mW. The XRD results indicate that the lattice parameters and the cell volume expand as the particle size reduces. Large red shifts (˜60 cm-1) and line broadening (˜50 cm-1) are observed as the particle size becomes of the order of 13 nm. These huge values can only be justified if collective effects on the Raman spectra created by the lattice expansion, confinement of phonons and enhanced phonon-phonon interactions are included in the interpretations of the Raman spectra of the CuAlO2 nanoparticles.

High temperature phase stability in Li{sub 0.12}Na{sub 0.88}NbO{sub 3}: A combined powder X-ray and neutron diffraction study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishra, S. K.; Krishna, P. S. R.; Shinde, A. B.

2015-09-07

The phase stabilities of ecofriendly piezoelectric material of lithium doped sodium niobate for composition Li{sub 0.12}Na{sub 0.88}NbO{sub 3} (LNN12) have been investigated by a combination of powder X-ray and neutron diffraction techniques in the temperature range of 300–1100 K. We observed interesting changes with appearance or disappearance of the super-lattice reflections in the powder diffraction patterns. Unambiguous experimental evidence is shown for coexistence of paraelectric and ferroelectric orthorhombic phases in the temperature range of 525 K to 675 K. We identified the correct crystal structure of LNN12 with temperature and correlated it with observed anomaly in the physical properties. Identification of crystal structuremore » also helps in the mode assignments in Raman and infrared spectroscopies. We argued that application of chemical pressure as a result of Li substitution in NaNbO{sub 3} matrix favors the freezing of zone centre phonons in contrast to the freezing of zone boundary phonons in pure NaNbO{sub 3} with the variation of temperature.« less

FT-IR, FT-Raman spectra and DFT calculations of melaminium perchlorate monohydrate

NASA Astrophysics Data System (ADS)

Kanagathara, N.; Marchewka, M. K.; Drozd, M.; Renganathan, N. G.; Gunasekaran, S.; Anbalagan, G.

2013-08-01

Melaminium perchlorate monohydrate (MPM), an organic material has been synthesized by slow solvent evaporation method at room temperature. Powder X-ray diffraction analysis confirms that MPM crystal belongs to triclinic system with space group P-1. FTIR and FT Raman spectra are recorded at room temperature. Functional group assignment has been made for the melaminium cations and perchlorate anions. Vibrational spectra have also been discussed on the basis of quantum chemical density functional theory (DFT) calculations using Firefly (PC GAMESS) version 7.1 G. Vibrational frequencies are calculated and scaled values are compared with experimental values. The assignment of the bands has been made on the basis of the calculated PED. The Mulliken charges, HOMO-LUMO orbital energies are analyzed directly from Firefly program log files and graphically illustrated. HOMO-LUMO energy gap and other related molecular properties are also calculated. The theoretically constructed FT-IR and FT-Raman spectra of MPM coincide with the experimental one. The chemical structure of the compound has been established by 1H and 13C NMR spectra. No detectable signal was observed during powder test for second harmonic generation.

The effect of ultrasonic irradiation on the crystallinity of nano-hydroxyapatite produced via the wet chemical method.

PubMed

Barbosa, Michelle C; Messmer, Nigel R; Brazil, Tayra R; Marciano, Fernanda R; Lobo, Anderson O

2013-07-01

Nanohydroxyapatite (nHAp) powders were produced via aqueous precipitation by adopting four different experimental conditions, assisted or non-assisted by ultrasound irradiation (UI). The nHAp powders were characterized by X-ray diffraction, energy-dispersive X-ray fluorescence, Raman and attenuated total reflection Fourier transform infrared spectroscopies, which showed typical surface chemical compositions of nHAp. Analysis found strong connections between UI and the crystallization process, crystal growth properties, as well as correlations between calcination and substitution reactions. Copyright © 2013 Elsevier B.V. All rights reserved.

X-ray diffraction, Raman, and photoacoustic studies of ZnTe nanocrystals

NASA Astrophysics Data System (ADS)

Ersching, K.; Campos, C. E. M.; de Lima, J. C.; Grandi, T. A.; Souza, S. M.; da Silva, D. L.; Pizani, P. S.

2009-06-01

Nanocrystalline ZnTe was prepared by mechanical alloying. X-ray diffraction (XRD), energy dispersive spectroscopy, Raman spectroscopy, and photoacoustic absorption spectroscopy techniques were used to study the structural, chemical, optical, and thermal properties of the as-milled powder. An annealing of the mechanical alloyed sample at 590 °C for 6 h was done to investigate the optical properties in a defect-free sample (close to bulk form). The main crystalline phase formed was the zinc-blende ZnTe, but residual trigonal tellurium and hexagonal ZnO phases were also observed for both as-milled and annealed samples. The structural parameters, phase fractions, average crystallite sizes, and microstrains of all crystalline phases were obtained from Rietveld analyses of the X-ray patterns. Raman results corroborate the XRD results, showing the longitudinal optical phonons of ZnTe (even at third order) and those modes of trigonal Te. Nonradiative surface recombination and thermal bending heat transfer mechanisms were proposed from photoacoustic analysis. An increase in effective thermal diffusivity coefficient was observed after annealing and the carrier diffusion coefficient, the surface recombination velocity, and the recombination time parameters remained the same.

Structural properties of barium stannate

NASA Astrophysics Data System (ADS)

Phelan, D.; Han, F.; Lopez-Bezanilla, A.; Krogstad, M. J.; Gim, Y.; Rong, Y.; Zhang, Junjie; Parshall, D.; Zheng, H.; Cooper, S. L.; Feygenson, M.; Yang, Wenge; Chen, Yu-Sheng

2018-06-01

BaSnO3 has attracted attention as a transparent conducting oxide with high room temperature carrier mobility. We report a series of measurements that were carried out to assess the structure of BaSnO3 over a variety of length scales. Measurements included single crystal neutron and x-ray diffraction, Rietveld and pair distribution analysis of neutron powder diffraction, Raman scattering, and high-pressure x-ray diffraction. Results from the various diffraction probes indicate that both the long-range and local structures are consistent with the cubic symmetry. The diffraction data under pressure was consistent with a robustly cubic phase up to 48.9 GPa, which is supported by density functional calculations. Additionally, transverse phonon velocities were determined from measured dispersion of the transverse acoustic phonon branches, the results of which are in good agreement with previous theoretical estimates and ultrasound measurements.

Spectroscopy investigation of nanostructured nickel–zinc ferrite obtained by mechanochemical synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lazarević, Zorica Ž., E-mail: lzorica@yahoo.com; Milutinović, Aleksandra N.; Jovalekić, Čedomir D.

2015-03-15

Highlights: • Nano powder of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} prepared by a soft mechanochemicaly after 10 h milling. • Phase formation controlled by XRD, Raman and IR spectroscopy. • Spectroscopy measurements indicate that the prepared samples have spinel structure. • The average particles size are found to be around 20 nm. • The degree of inversion is δ = 0.36 for NZF obtained from hydroxides for 10 h. - Abstract: Nano crystalline samples of nickel–zinc ferrite, Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} were prepared by mechanochemical route in a planetary ball mill starting from two mixtures of the appropriate quantitiesmore » of the powders: case (1) oxide powders: NiO, ZnO and α-Fe{sub 2}O{sub 3} in one case, and in the second case (2) hydroxide powders: Ni(OH){sub 2}, Zn(OH){sub 2} and Fe(OH){sub 3}. In order to monitor the progress of chemical reaction and confirm phase formation, powder samples obtained after 5 h and 10 h of milling were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman, IR and Mössbauer spectroscopy. It is shown that the soft mechanochemical method, i.e. mechanochemical activation of hydroxides, produces high quality single phase Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} samples in much more efficient way. From the IR spectroscopy of single phase samples it is obvious that energy of modes depends on the ratio of cations. The deconvolution of Raman spectra allows to separate contributions of different cations to a particular type of vibration and to estimate the degree of inversion.« less

Synthesis, DFT calculations of structure, vibrational and thermal decomposition studies of the metal complex Pb[Mn(C3H2O4)2(H2O)2].

PubMed

Gil, Diego M; Carbonio, Raúl E; Gómez, María Inés

2015-04-15

The metallo-organic complex Pb[Mn(C3H2O4)2(H2O)2] was synthesized and characterized by IR and Raman spectroscopy and powder X-ray diffraction methods. The cell parameters for the complex were determined from powder X-ray diffraction using the autoindexing program TREOR, and refined by the Le Bail method with the Fullprof program. A hexagonal unit cell was determined with a=b=13.8366(7)Å, c=9.1454(1)Å, γ=120°. The DFT calculated geometry of the complex anion [Mn(C3H2O4)2(H2O)2](2-) is very close to the experimental data reported for similar systems. The IR and Raman spectra and the thermal analysis of the complex indicate that only one type of water molecules is present in the structure. The thermal decomposition of Pb[Mn(C3H2O4)2(H2O)2] at 700 °C in air produces PbO and Pb2MnO4 as final products. The crystal structure of the mixed oxide is very similar to that reported for Pb3O4. Copyright © 2015 Elsevier B.V. All rights reserved.

Kinetics of methane-ethane gas replacement in clathrate-hydrates studied by time-resolved neutron diffraction and Raman spectroscopy.

PubMed

Murshed, M Mangir; Schmidt, Burkhard C; Kuhs, Werner F

2010-01-14

The kinetics of CH(4)-C(2)H(6) replacement in gas hydrates has been studied by in situ neutron diffraction and Raman spectroscopy. Deuterated ethane structure type I (C(2)H(6) sI) hydrates were transformed in a closed volume into methane-ethane mixed structure type II (CH(4)-C(2)H(6) sII) hydrates at 5 MPa and various temperatures in the vicinity of 0 degrees C while followed by time-resolved neutron powder diffraction on D20 at ILL, Grenoble. The role of available surface area of the sI starting material on the formation kinetics of sII hydrates was studied. Ex situ Raman spectroscopic investigations were carried out to crosscheck the gas composition and the distribution of the gas species over the cages as a function of structure type and compared to the in situ neutron results. Raman micromapping on single hydrate grains showed compositional and structural gradients between the surface and core of the transformed hydrates. Moreover, the observed methane-ethane ratio is very far from the one expected for a formation from a constantly equilibrated gas phase. The results also prove that gas replacement in CH(4)-C(2)H(6) hydrates is a regrowth process involving the nucleation of new crystallites commencing at the surface of the parent C(2)H(6) sI hydrate with a progressively shrinking core of unreacted material. The time-resolved neutron diffraction results clearly indicate an increasing diffusion limitation of the exchange process. This diffusion limitation leads to a progressive slowing down of the exchange reaction and is likely to be responsible for the incomplete exchange of the gases.

Electrical properties of CZTS pellets made from microwave-processed powder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghediya, Prashant R., E-mail: prashantghediya@yahoo.co.in; Chaudhuri, Tapas K.

2015-06-24

Electrical properties of the kesterite copper zinc tin sulphide (CZTS) pellets in the temperature range from 300 K to 500 K are reported. The pellets are p-type with thermoelectric power (TEP) of + 175 µV/K. Electrical conductivity (σ) increases with the temperatures and is found to be due to thermionic emission (TE) over grain boundary (GB) barriers with activation energy of 170 meV. CZTS pellets are made from micropowders synthesized by microwave irradiation of precursor solution. Formation of kesterite CZTS is confirmed by X-ray diffraction (XRD) and Raman spectroscopy. Scanning Electron Microscope (SEM) shows that powder is micron sized spherical particles.

Structural Properties of Barium Stannate.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phelan, D.; Han, F.; Lopez-Bezanilla, A.

2018-06-01

BaSnO3 has attracted attention as a transparent conducting oxide with high room temperature carrier mobility. We report a series of measurements that were carried out to assess the structure of BaSnO3 over a variety of length scales. Measurements included single crystal neutron and x-ray diffraction, Rietveld and pair distribution analysis of neutron powder diffraction, Raman scattering, and high-pressure x-ray diffraction. Results from the various diffraction probes indicate that both the long-range and local structures are consistent with the cubic symmetry. The diffraction data under pressure was consistent with a robustly cubic phase up to 48.9 GPa, which is supported bymore » density functional calculations. Additionally, transverse phonon velocities were determined from measured dispersion of the transverse acoustic phonon branches, the results of which are in good agreement with previous theoretical estimates and ultrasound measurements.« less

FT-IR, FT-Raman spectra and DFT calculations of melaminium perchlorate monohydrate.

PubMed

Kanagathara, N; Marchewka, M K; Drozd, M; Renganathan, N G; Gunasekaran, S; Anbalagan, G

2013-08-01

Melaminium perchlorate monohydrate (MPM), an organic material has been synthesized by slow solvent evaporation method at room temperature. Powder X-ray diffraction analysis confirms that MPM crystal belongs to triclinic system with space group P-1. FTIR and FT Raman spectra are recorded at room temperature. Functional group assignment has been made for the melaminium cations and perchlorate anions. Vibrational spectra have also been discussed on the basis of quantum chemical density functional theory (DFT) calculations using Firefly (PC GAMESS) version 7.1 G. Vibrational frequencies are calculated and scaled values are compared with experimental values. The assignment of the bands has been made on the basis of the calculated PED. The Mulliken charges, HOMO-LUMO orbital energies are analyzed directly from Firefly program log files and graphically illustrated. HOMO-LUMO energy gap and other related molecular properties are also calculated. The theoretically constructed FT-IR and FT-Raman spectra of MPM coincide with the experimental one. The chemical structure of the compound has been established by (1)H and (13)C NMR spectra. No detectable signal was observed during powder test for second harmonic generation. Copyright © 2013 Elsevier B.V. All rights reserved.

Sodium Hydroxide Activated Nanoporous Carbons Based on Lapsi Seed Stone.

PubMed

Joshi, Sahira; Shrestha, Lok Kumar; Kamachi, Yuichiro; Yamauchi, Yusuke; Pradhananga, Mandira Adhikari; Pokhrel, Bhadra Prasad; Ariga, Katsuhiko; Pradhananga, Raja Ram

2015-02-01

Nanoporous activated carbons (ACs) were prepared from Lapsi (Choerospondias axillaris) seed powder by chemical activation with sodium hydroxide (NaOH) at different NaOH impregnation ratios. The prepared ACs were characterized by Fourier transform-infrared (FTIR) spectroscopy, Raman scattering, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Semi-quantitative information on the surface properties was obtained by estimating iodine number. FTIR spectra showed the presence of oxygenated functional groups such as hydroxyl, carbonyl, and carboxyl in the prepared ACs. Raman scattering showed clear D and G bands in the spectra. The intensity ratio of G and D band peak intensity was ca. 1.39 at lowest NaOH and Lapsi seed powder ratio 0.25:1 showing high graphitic degree. This ratio decreased with increase in the NaOH impregnation ratio and reached minimum ca. 0.94 (comparable with commercial AC) at NaOH and Lapsi seed powder ratio 1:1 demonstrating that higher NaOH impregnation reduces the graphitic structure of the carbon. XRD patterns showed two broad peaks at diffraction angles of approximately 25 and 43 degrees indicating the amorphous structure. Surface properties of the ACs (BET surface area, pore volume, and pore size distributions) were evaluated by nitrogen adsorption-desorption isotherm. Our ACs showed strong methylene blue adsorption property (maximum methylene blue is ca. 200 mg/g). Judging from the iodine number and methylene blue values, structure, and surface areas, it can be concluded that NaOH impregnation ratio is one of the key parameters to tune the surface properties of Lapsi seed stone-based activated carbons.

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCormac, Kathleen; Byrd, Ian; Brannen, Rodney

We prepared highly porous Si/TiO 2 composite nanofibres using a unique sulphur-templating method combined with electrospinning. The structure, morphology, surface area, phase and composition of these nanofibres were characterized using Raman spectroscopy, scanning electron microscopy, powder X-ray diffraction, surface area analyser and thermogravimetric analyser. The specific surface area of Si/TiO 2 porous NFs is as large as 387m 2g -1, whose silicon capacity can be maintained above 1580mAhg -1 in 180 cycles.

Thermal annealing of natural, radiation-damaged pyrochlore

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zietlow, Peter; Beirau, Tobias; Mihailova, Boriana

Abstract Radiation damage in minerals is caused by the α-decay of incorporated radionuclides, such as U and Th and their decay products. The effect of thermal annealing (400–1000 K) on radiation-damaged pyrochlores has been investigated by Raman scattering, X-ray powder diffraction (XRD), and combined differential scanning calorimetry/thermogravimetry (DSC/TG). The analysis of three natural radiation-damaged pyrochlore samples from Miass/Russia [6.4 wt% Th, 23.1·10

Hydrogen bonds in crystalline D-alanine: diffraction and spectroscopic evidence for differences between enantiomers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belo, Ezequiel A.; Pereira, Jose E. M.; Freire, Paulo T. C.

Enantiomeric amino acids have specific physiological functions in complex biological systems. Systematic studies focusing on the solid-state properties of D-amino acids are, however, still limited. To shed light on this field, structural and spectroscopic studies of D-alanine using neutron powder diffraction, polarized Raman scattering and ab initio calculations of harmonic vibrational frequencies were carried out. Clear changes in the number of vibrational modes are observed as a function of temperature, which can be directly connected to variations of the N—D bond lengths. These results reveal dissimilarities in the structural properties of D-alanine compared with L-alanine.

Hydrogen bonds in crystalline D-alanine: diffraction and spectroscopic evidence for differences between enantiomers

DOE PAGES

Belo, Ezequiel A.; Pereira, Jose E. M.; Freire, Paulo T. C.; ...

2018-01-01

Enantiomeric amino acids have specific physiological functions in complex biological systems. Systematic studies focusing on the solid-state properties of D-amino acids are, however, still limited. To shed light on this field, structural and spectroscopic studies of D-alanine using neutron powder diffraction, polarized Raman scattering and ab initio calculations of harmonic vibrational frequencies were carried out. Clear changes in the number of vibrational modes are observed as a function of temperature, which can be directly connected to variations of the N—D bond lengths. These results reveal dissimilarities in the structural properties of D-alanine compared with L-alanine.

Low temperature synthesis and characterization of carbonated hydroxyapatite nanocrystals

NASA Astrophysics Data System (ADS)

Anwar, Aneela; Asghar, Muhammad Nadeem; Kanwal, Qudsia; Kazmi, Mohsin; Sadiqa, Ayesha

2016-08-01

Carbonate substituted hydroxyapatite (CHA) nanorods were synthesized via coprecipitation method from aqueous solution of calcium nitrate tetrahydrate and diammonium hydrogen phosphate (with urea as carbonate ion source) in the presence of ammonium hydroxide solution at 70 °C at the conditions of pH 11. The obtained powders were physically characterized using transmission electron microscopy (TEM), X-ray powder diffraction analysis (XRD), and FTIR and Raman spectroscopy. The particle size was evaluated by Dynamic light scattering (DLS). The chemical structural analysis of as prepared sample was performed using X-ray photoelectron spectroscopy (XPS). After ageing for 12 h, and heat treatment at 1000 °C for 1 h, the product was obtained as highly crystalline nanorods of CHA.

Synthesis and electrochemical property of few-layer molybdenum disulfide nanosheets

NASA Astrophysics Data System (ADS)

Fu, Yanjue; Wang, Chunrui; Wang, Linlin; Peng, Xia; Wu, Binhe; Sun, Xingqu; Chen, Xiaoshuang

2016-12-01

Large-scale few-layer MoS2 nanosheets have been fabricated via a simple hydrothermal route using molybdenum powder as precursors. The as-prepared MoS2 samples were characterized by X-ray powder diffraction (XRD) analysis, transmission electron microscopy (TEM), and Raman and photoluminescence (PL) spectral analyses at room temperature. The results confirm that the as-prepared MoS2 displays a sheet-like morphology with a thickness of few (bi- to tri-) layers. Electrochemical measurements showed that the as-prepared few-layer MoS2 exhibited the highest reversible capacity of 1127 mAh g-1 and a stable reversible capacity of 1057 mAh g-1 after 30 cycles.

Synthesis of ZnSnO{sub 3} nanostructure by sol gel method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Para, Touseef Ahmad; Reshi, Hilal Ahmad; Shelke, Vilas, E-mail: drshelke@gmail.com

2016-05-23

Zinc Stannate (ZST) with composition ZnSnO{sub 3} is known for high electron mobility, optical, piezoelectric and charge storage properties. ZST crystalizes in different lattice structures, which allows a wide range of tunablity. We demonstrate successful synthesis of ZnSnO{sub 3} nanomaterial by sol-gel method. ZnSnO{sub 3} nanomaterials were calcined and sintered at different temperatures. Powder X-ray diffraction confirmed the single phase of the nanomaterial with rhombohedral R-3 space group. The Rietveld refinement of diffraction pattern yielded lattice parameter values a=5.26Å, c=14.09Å. Raman spectroscopy revealed higher activity towards higher wavenumbers. Raman shift around 530cm{sup −1} was found to be highly structure dependent,more » most probably due to anharmonic atomic vibrations in ZnO{sub 6}/SnO{sub 6} octahedra around center of mass. Sharp Peak around 650cm{sup −1} is characteristic of ZnSnO{sub 3} molecule.« less

Symposium U: Thermoelectric Power Generation. Held in Boston, Massachusetts on November 26-29, 2007

DTIC Science & Technology

2008-04-01

including X - ray /electron diffraction, TGA analysis, Raman / Fourier Transform Infrared Spectroscopy, electron microscopy, Rutherford back-scattering and...Energy dispersive X - ray analysis were performed on the treated sample. The results revealed that a surface layer (from 10 nm to up to micron in...nanoparticles into a matrix of bulk Bi2Te 3 material via a hot pressing process. These nanocomposites have been examined by SEM and X - ray powder

Raman spectroscopic study of hydrogen ordered ice XIII and of its reversible phase transition to disordered ice V.

PubMed

Salzmann, Christoph G; Hallbrucker, Andreas; Finney, John L; Mayer, Erwin

2006-07-14

Raman spectra of recovered ordered H(2)O (D(2)O) ice XIII doped with 0.01 M HCl (DCl) recorded in vacuo at 80 K are reported in the range 3600-200 cm(-1). The bands are assigned to the various types of modes on the basis of isotope ratios. On thermal cycling between 80 and 120 K, the reversible phase transition to disordered ice V is observed. The remarkable effect of HCl (DCl) on orientational ordering in ice V and its phase transition to ordered ice XIII, first reported in a powder neutron diffraction study of DCl doped D(2)O ice V (C. G. Salzmann, P. G. Radaelli, A. Hallbrucker, E. Mayer, J. L. Finney, Science, 2006, 311, 1758), is demonstrated by Raman spectroscopy and discussed. The dopants KOH and HF have only a minor effect on hydrogen ordering in ice V, as shown by the Raman spectra.

Preparation of graphite intercalation compounds containing oligo and polyethers

NASA Astrophysics Data System (ADS)

Zhang, Hanyang; Lerner, Michael M.

2016-02-01

Layered host-polymer nanocomposites comprising polymeric guests between inorganic sheets have been prepared with many inorganic hosts, but there is limited evidence for the incorporation of polymeric guests into graphite. Here we report for the first time the preparation, and structural and compositional characterization of graphite intercalation compounds (GICs) containing polyether bilayers. The new GICs are obtained by either (1) reductive intercalation of graphite with an alkali metal in the presence of an oligo or polyether and an electrocatalyst, or (2) co-intercalate exchange of an amine for an oligo or polyether in a donor-type GIC. Structural characterization of products using powder X-ray diffraction, Raman spectroscopy, and thermal analyses supports the formation of well-ordered, first-stage GICs containing alkali metal cations and oligo or polyether bilayers between reduced graphene sheets.Layered host-polymer nanocomposites comprising polymeric guests between inorganic sheets have been prepared with many inorganic hosts, but there is limited evidence for the incorporation of polymeric guests into graphite. Here we report for the first time the preparation, and structural and compositional characterization of graphite intercalation compounds (GICs) containing polyether bilayers. The new GICs are obtained by either (1) reductive intercalation of graphite with an alkali metal in the presence of an oligo or polyether and an electrocatalyst, or (2) co-intercalate exchange of an amine for an oligo or polyether in a donor-type GIC. Structural characterization of products using powder X-ray diffraction, Raman spectroscopy, and thermal analyses supports the formation of well-ordered, first-stage GICs containing alkali metal cations and oligo or polyether bilayers between reduced graphene sheets. Electronic supplementary information (ESI) available: Domain size, additional Raman spectra info, compositional calculation, and packing fractions. See DOI: 10.1039/c5nr08226a

A multi-analytical approach for the characterization of powders from the Pompeii archaeological site.

PubMed

Canevali, Carmen; Gentile, Paolo; Orlandi, Marco; Modugno, Francesca; Lucejko, Jeannette Jacqueline; Colombini, Maria Perla; Brambilla, Laura; Goidanich, Sara; Riedo, Chiara; Chiantore, Oscar; Baraldi, Pietro; Baraldi, Cecilia; Gamberini, Maria Cristina

2011-10-01

Nine black powders found in Pompeii houses in three different types of bronze vessels (cylindrical theca atramentaria, unguentaries, and aryballoi) were characterized in order to assess a correspondence between the composition and the type of vessel and, possibly, to verify if these powders were inks or not. For the compositional characterization, a multi-analytical approach was adopted, which involved the use of scanning electron microscopy-energy dispersive X-ray, Fourier-transformed infrared spectroscopy, Raman, X-ray diffraction, electron paramagnetic resonance spectroscopy, thermogravimetric analysis, gas chromatography coupled with mass spectrometry (GC/MS), and pyrolysis GC/MS. Powders contained in cylindrical theca atramentaria form a homogeneous group, and their organic and inorganic compositions suggest that they were writing inks, while powders contained in unguentaries and aryballoi could have had several different uses, including writing inks and cosmetics. Furthermore, the composition profile of the powders found in cylindrical cases shows that, at 79 AD: , in Pompeii, carbon-based inks were still used for writing, and iron gall inks had not been introduced yet.

Study of structural and magnetic characterization of polycrystalline Y0.5Ho0.5CrO3

NASA Astrophysics Data System (ADS)

Mall, Ashish Kumar; Garg, Ashish; Gupta, Rajeev

2018-05-01

A polycrystalline ceramic sample of Y0.5Ho0.5CrO3 was studied using powder X-ray diffraction, Raman spectroscopic and dc magnetometry measurement to understand the structural and magnetic properties. The Rietveld refinement of X-ray data suggests sample crystallized in Pnma orthorhombic structure without formation of any secondary phases confirming their phase-pure nature. However, Raman study shows a prominent effect of Ho doping in low wavenumber Raman active phonon modes. Further, M-T measurement shows magnetic phase transition (TN) at 141 K and a negative value of Curie-Weiss temperature suggesting an antiferromagnetic system. Subsequent, the appearance of the clear opening in the M-H loop below TN is an evidence of the appearance of a weak ferromagnetic component in the low- temperature regime while the magnetization increases linearly in the high magnetic field regime suggest antiferromagnetic component.

In situ synthesis of semiconducting single-walled carbon nanotubes by modified arc discharging method

NASA Astrophysics Data System (ADS)

Zhao, Tingkai; Ji, Xianglin; Jin, Wenbo; Yang, Wenbo; Zhao, Xing; Dang, Alei; Li, Hao; Li, Tiehu

2017-02-01

Semiconducting single-walled carbon nanotubes (s-SWCNTs) were in situ synthesized by a temperature-controlled arc discharging furnace with DC electric field using Co-Ni alloy powder as catalyst in helium gas. The microstructures of s-SWCNTs were characterized using high-resolution transmission electron microscopy, electron diffraction, and Raman spectrometry apparatus. The experimental results indicated that the best voltage value in DC electric field is 54 V, and the environmental temperature of the reaction chamber is 600 °C. The mean diameter of s-SWCNTs was estimated about 1.3 nm. The chiral vector ( n, m) of s-SWCNTs was calculated to be (10, 10) type according to the electron diffraction patterns.

Improving the dissolution and bioavailability of 6-mercaptopurine via co-crystallization with isonicotinamide.

PubMed

Wang, Jian-Rong; Yu, Xueping; Zhou, Chun; Lin, Yunfei; Chen, Chen; Pan, Guoyu; Mei, Xuefeng

2015-03-01

6-Mercaptopurine (6-MP) is a clinically important antitumor drug. The commercially available form was provided as monohydrate and belongs to BCS class II category. Co-crystallization screening by reaction crystallization method (RCM) and monitored by powder X-ray diffraction led to the discovery of a new co-crystal formed between 6-MP and isonicotinamide (co-crystal 1). Co-crystal 1 was thoroughly characterized by X-ray diffraction, FT-IR and Raman spectroscopy, and thermal analysis. Noticeably, the in vitro and in vivo studies revealed that co-crystal 1 possesses improved dissolution rate and superior bioavailability on animal model. Copyright © 2015 Elsevier Ltd. All rights reserved.

One step synthesis of porous graphene by laser ablation: A new and facile approach

NASA Astrophysics Data System (ADS)

Kazemizadeh, Fatemeh; Malekfar, Rasoul

2018-02-01

Porous graphene (PG) was obtained using one step laser process. Synthesis was carried out by laser ablation of nickel-graphite target under ultra-high flow of argon gas. The field emission scanning electron microscopy (FE-SEM) results showed the formation of a porous structure and the transmission electron microscopy (TEM) revealed that the porosity of PGs increase under intense laser irradiation. Structural characterization study using Raman spectroscopy, X-ray powder diffraction (XRD) and selected area electron diffraction (SAED) technique showed that the obtained PGs display high crystalline structure in the form of few layer rhombohedral graphitic arrangement that can be interpreted as the phase prior to the formation of other carbon nanostructures.

High-pressure Raman study on the superconducting pyrochlore oxide Cd2Re2O7

NASA Astrophysics Data System (ADS)

Matsubayashi, Yasuhito; Hasegawa, Takumi; Ogita, Norio; Yamaura, Jun-ichi; Hiroi, Zenji

2018-05-01

The superconducting pyrochlore oxide Cd2Re2O7 (Tc = 1 K), which is now considered as a candidate of the spin-orbit-coupled metal, shows an inversion-symmetry-breaking structural transition at Ts1 = 200 K . Ts1 decreases with increasing pressure and disappears at around Pc = 4.2 GPa , where at least four high-pressure phases with tiny structural distortions are suggested by means of powder X-ray diffraction [Yamaura PRB 2017]. We have carried out Raman scattering experiments to investigate changes in the crystal symmetry under high pressures up to 4.8 GPa. A structural transition at 1.9-3.0 GPa and the recovery of inversion symmetry above Pc are observed at 12 K.

Investigations of Ba{sub x}Sr{sub 1−x}TiO{sub 3} ceramics and powders prepared by direct current arc discharge technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Shuangbin; Wang, Xiaohan; University of Chinese Academy of Sciences, Beijing 100049

2014-09-01

Ba{sub x}Sr{sub 1−x}TiO{sub 3} ceramics with x ranging from 0 to 1 were prepared by direct current arc discharge technique and studied by means of x-ray diffraction (XRD) and Raman spectroscopy. The cubic-tetragonal ferroelectric phase transition in Ba{sub x}Sr{sub 1−x}TiO{sub 3} ceramics was found to occur at x ≈ 0.75. XRD investigation of as-grown BaTiO{sub 3} ceramics revealed co-existence of tetragonal and hexagonal modifications with a small amount of impurity phase BaTi{sub 4}O{sub 9}. No evidences of hexagonal phase were observed in Raman spectra of as-grown BaTiO{sub 3} ceramics, while Raman peaks related to hexagonal phase were clearly observed in the spectrummore » of fine-grain powders prepared from the same ceramics. A core-shell model for BaTiO{sub 3} ceramics prepared by direct current arc discharge technique is proposed. Absence of the hexagonal phase in any Ba{sub x}Sr{sub 1−x}TiO{sub 3} solid solution with x < 1 is discussed in the frame of specific atomic arrangement.« less

Synthesis of samarium doped gadolinium oxide nanorods, its spectroscopic and physical properties

NASA Astrophysics Data System (ADS)

Boopathi, G.; Gokul Raj, S.; Ramesh Kumar, G.; Mohan, R.; Mohan, S.

2018-06-01

One-dimensional samarium doped gadolinium oxide [Sm:Gd2O3] nanorods have been synthesized successfully through co-precipitation technique in aqueous solution. The as-synthesized and calcined products were characterized by using powder X-ray diffraction pattern, Fourier transform Raman spectroscopy, thermogravimetric/differential thermal analysis, scanning electron microscopy with energy-dispersive X-ray analysis, transmission electron microscopy, Fourier transform infrared spectroscopy, Ultraviolet-Visible spectrometry, photoluminescence spectrophotometer and X-ray photoelectron spectroscopy techniques. The obtained results are discussed in detailed manner.

DEVELOPMENT OF LiCo0.90Mg0.05Al0.05O2 THIN FILMS BY PULSED LASER DEPOSITION TECHNIQUE

NASA Astrophysics Data System (ADS)

Vasanthi, R.; Ruthmangani, I.; Manoravi, P.; Joseph, M.; Kesavamoorthy, R.; Sundar, C.; Selladurai, S.

LiCo0.90Mg0.05Al0.05O2 bulk powders are synthesized using combustion process and made into a thin film by depositing on silicon wafer using a pulsed laser ablation technique. A comparative study by SEM (Scanning Electron Microscope) XRD (X-ray diffraction), Infrared spectroscopy and Raman Spectroscopy is performed on both bulk and PLD thin films.

Screening of adulterants in powdered foods and ingredients using line-scan Raman chemical imaging.

USDA-ARS?s Scientific Manuscript database

A newly developed line-scan Raman imaging system using a 785 nm line laser was used to authenticate powdered foods and ingredients. The system was used to collect hyperspectral Raman images in the range of 102–2865 wavenumber from three representative food powders mixed with selected adulterants eac...

Immobilized TiO2 nanoparticles produced by flame spray for photocatalytic water remediation

NASA Astrophysics Data System (ADS)

Bettini, Luca Giacomo; Diamanti, Maria Vittoria; Sansotera, Maurizio; Pedeferri, Maria Pia; Navarrini, Walter; Milani, Paolo

2016-08-01

Anatase/rutile mixed-phase titanium dioxide (TiO2) photocatalysts in the form of nanostructured powders with different primary particle size, specific surface area, and rutile content were produced from the gas-phase by flame spray pyrolysis (FSP) starting from an organic solution containing titanium (IV) isopropoxide as Ti precursor. Flame spray-produced TiO2 powders were characterized by means of X-ray diffraction, Raman spectroscopy, and BET measurements. As-prepared powders were mainly composed of anatase crystallites with size ranging from 7 to 15 nm according to the synthesis conditions. TiO2 powders were embedded in a multilayered fluoropolymeric matrix to immobilize the nanoparticles into freestanding photocatalytic membranes. The photocatalytic activity of the TiO2-embedded membranes toward the abatement of hydrosoluble organic pollutants was evaluated employing the photodegradation of rhodamine B in aqueous solution as test reaction. The photoabatement rate of best performing membranes significantly overcomes that of membranes produced by the same method and incorporating commercial P25-TiO2.

Formation of Fluorohydroxyapatite with Silver Diamine Fluoride

PubMed Central

Mei, M.L.; Nudelman, F.; Marzec, B.; Walker, J.M.; Lo, E.C.M.; Walls, A.W.; Chu, C.H.

2017-01-01

Silver diamine fluoride (SDF) is found to promote remineralization and harden the carious lesion. Hydroxyapatite crystallization is a crucial process in remineralization; however, the role of SDF in crystal formation is unknown. We designed an in vitro experiment with calcium phosphate with different SDF concentrations (0.38, 1.52, 2.66, 3.80 mg/mL) to investigate the effect of this additive on the nucleation and growth of apatite crystals. Two control groups were also prepared—calcium phosphate (CaCl2·2H2O + K2HPO4 in buffer solution) and SDF (Ag[NH3]2F in buffer solution). After incubation at 37 oC for 24 h, the shape and organization of the crystals were examined by bright-field transmission electron microscopy and electron diffraction. Unit cell parameters of the obtained crystals were determined with powder X-ray diffraction. The vibrational and rotational modes of phosphate groups were analyzed with Raman microscopy. The transmission electron microscopy and selected-area electron diffraction confirmed that all solids precipitated within the SDF groups were crystalline and that there was a positive correlation between the increased percentage of crystal size and the concentration of SDF. The powder X-ray diffraction patterns indicated that fluorohydroxyapatite and silver chloride were formed in all the SDF groups. Compared with calcium phosphate control, a contraction of the unit cell in the a-direction but not the c-direction in SDF groups was revealed, which suggested that small localized fluoride anions substituted the hydroxyl anions in hydroxyapatite crystals. This was further evidenced by the Raman spectra, which displayed up-field shift of the phosphate band in all the SDF groups and confirmed that the chemical environment of the phosphate functionalities indeed changed. The results suggested that SDF reacted with calcium and phosphate ions and produced fluorohydroxyapatite. This preferential precipitation of fluorohydroxyapatite with reduced solubility could be one of the main factors for arrest of caries lesions treated with SDF. PMID:28521107

Crystal Chemistry of Pyroaurite from the Kovdor Pluton, Kola Peninsula, Russia, and the Långban Fe-Mn deposit, Värmland, Sweden

NASA Astrophysics Data System (ADS)

Zhitova, E. S.; Ivanyuk, G. Yu.; Krivovichev, S. V.; Yakovenchuk, V. N.; Pakhomovsky, Ya. A.; Mikhailova, Yu. A.

2017-12-01

Pyroaurite [Mg6Fe2 3+ (OH)16][(CO3)(H2O)] from the Kovdor Pluton on the Kola Peninsula, Russia, and the Långban deposit in Filipstad, Värmland, Sweden were studied with single crystal and powder X-ray diffraction, an electron microprobe, and Raman spectroscopy. Both samples are rhombohedral, space group R3̅ m, a = 3.126(3), c = 23.52(2) Å (Kovdor), and a = 3.1007(9), c = 23.34(1) (Långban). The powder XRD revealed only the 3 R polytype. The ratio of di- and trivalent cations M 2+: M 3+ was determined as 3.1-3.2 (Kovdor) and 3.0 (Långban). The Raman spectroscopy of the Kovdor sample verified hydroxyl groups and/or water molecules in the mineral (absorption bands in the region of 3600-3500 cm-1) and carbonate groups (absorption bands in the region of 1346-1058 cm-1). Based on the data obtained, the studied samples should be identified as pyroaurite-3 R (hydrotalcite group).

Spectroscopic investigation on the efficient organic nonlinear crystals of pure and diethanolamine added DAST.

PubMed

Karthikeyan, C; Haja Hameed, A S; Sagaya Agnes Nisha, J; Ravi, G

2013-11-01

4-N,N'-dimethylamino-N-methyl-4-stilbazolium toyslate (DAST) and diethanolamine (DEA) added DAST crystals are grown by slow cooling method. The corresponding powder samples are examined by characterization studies such as XRD, FT-IR, FT-Raman, UV-Vis-NIR and photoluminescence studies. From the powder X-ray diffraction, their lattice parameter values are found out. Since the vibrational spectra of the molecules are considerably contributed to their linear and nonlinear optical effects, Infrared and Raman spectroscopic studies are carried out for the samples. The UV-Vis-NIR absorption spectra of the samples are used to find the nature of transitions occurred in the samples. Using the density functional theory, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) analyses are done in order to explain the transition and density of states (DOS). The first order hyperpolarizability is calculated by HF and B3LYP/6-311 G(d,p) basis sets for the DAST molecule. From the photoluminescence (PL) spectral studies, the strong excitation emissions are observed. Copyright © 2013 Elsevier B.V. All rights reserved.

Evaluation of Turmeric Powder Adulterated with Metanil Yellow Using FT-Raman and FT-IR Spectroscopy

PubMed Central

Dhakal, Sagar; Chao, Kuanglin; Schmidt, Walter; Qin, Jianwei; Kim, Moon; Chan, Diane

2016-01-01

Turmeric powder (Curcuma longa L.) is valued both for its medicinal properties and for its popular culinary use, such as being a component in curry powder. Due to its high demand in international trade, turmeric powder has been subject to economically driven, hazardous chemical adulteration. This study utilized Fourier Transform-Raman (FT-Raman) and Fourier Transform-Infra Red (FT-IR) spectroscopy as separate but complementary methods for detecting metanil yellow adulteration of turmeric powder. Sample mixtures of turmeric powder and metanil yellow were prepared at concentrations of 30%, 25%, 20%, 15%, 10%, 5%, 1%, and 0.01% (w/w). FT-Raman and FT-IR spectra were acquired for these mixture samples as well as for pure samples of turmeric powder and metanil yellow. Spectral analysis showed that the FT-IR method in this study could detect the metanil yellow at the 5% concentration, while the FT-Raman method appeared to be more sensitive and could detect the metanil yellow at the 1% concentration. Relationships between metanil yellow spectral peak intensities and metanil yellow concentration were established using representative peaks at FT-Raman 1406 cm−1 and FT-IR 1140 cm−1 with correlation coefficients of 0.93 and 0.95, respectively. PMID:28231130

The synthesis and the spectroscopic, thermal, and structural properties of the M2[(fumarate)Ni(CN)4]·2(1,4-Dioxane) clathrate (M = Co, Ni, Cd and Hg)

NASA Astrophysics Data System (ADS)

Kartal, Zeki; Yavuz, Abdülkerim

2018-03-01

In this study, the clathrates of fumarate-tetracyanonickel-dioxane, given by the formula M2[(fumarate)Ni(CN)4]·2(1,4-Dioxane) (M = Co, Ni, Cd and Hg), have been obtained for the first time through chemical methods. These clathrates have been characterized by elemental, thermal, FT-IR, and FT-Raman spectroscopies. The parameters of structures of clathrates have been determined by X-ray powder diffraction. The thermal behaviors of these clathrates have been also investigated by thermo-gravimetric analysis (TGA), differential thermal analysis (DTA), and derivative thermal gravimetric analysis (DTG) in the range of 20-900 °C. X-ray powder diffraction data have been recorded at ambient temperature in the 2θ range 5-50°. The FT-IR and FT-Raman spectra of clathrates have been recorded in the region of 4000-400 cm-1 and 4000-100 cm-1, respectively. The results of the spectral and thermal analyses of the newly synthesized clathrates of fumarate-tetracyanonickel-dioxane suggest that these clathrates are new examples of the Hofmann-type dioxane clathrates. In our study, the Hofmann-type dioxane clathrates, which are formed by bounding electrons of oxygen-donor atoms of fumarate ion ligand molecule to transition metal atoms, consist of the corrugated |M-Ni(CN)4|∞ polymeric layers, which are held in parallel through the chain of (-M-fumarate-M-).

Growth and characterization of ammonium nickel-cobalt sulfate Tutton's salt for UV light applications

NASA Astrophysics Data System (ADS)

Ghosh, Santunu; Oliveira, Michelle; Pacheco, Tiago S.; Perpétuo, Genivaldo J.; Franco, Carlos J.

2018-04-01

We have obtained a set of sample crystals of the family of Tutton's salt comprise in the isomorphic series with general chemical formula (NH4)2NixCo(1-x) (SO4)2·6H2O, by employing growth from solutions by slow evaporation technique. The samples crystals were characterized by ICP-AES, X-ray powder diffraction analysis, thermogravimetric analysis, UV-Vis-NIR, Raman and FTIR spectroscopy. This type of material has been studied because of its physical and chemical properties not yet understood and they have potential technological applications. Chemical analysis of the samples by ICP-AES method allowed us to investigate the efficiency of the method of growth used. Thermogravimetric analysis provides the information about the thermal stability of the obtained crystals for high temperature applications, and powder X-ray diffraction analysis at ambient and high temperature reveals the structural quality and structural change of the samples respectively. We have used Raman spectroscopy in the range 100-4000 cm-1 and FTIR spectroscopy in the range 400-4000 cm-1 to understand the internal vibrational mode of the octahedral complexes [Ni(H2O)6]2+ and [Co(H2O)6]2+, SO42- and NH4+ tetrahedra. The transmittance of our mixed ammonium nickel cobalt sulfate hexahydrate (ACNSH) crystals is 75% in the UV region, which indicates that they are ideal to use in UV light filters and UV sensors.

Structural, electrical and dielectric properties of spinel nickel ferrite prepared by soft mechanochemical synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lazarević, Zorica Ž., E-mail: lzorica@yahoo.com; Jovalekić, Čedomir; Sekulić, Dalibor L.

2013-10-15

Graphical abstract: - Highlights: • Sintered NiFe{sub 2}O{sub 4} was prepared by a soft mechanochemical route from mixture powders. • XRD and Raman measurements indicate that the prepared samples have spinel structure. • The activation energy ΔE are 0.653 and 0.452 eV for NiFe{sub 2}O{sub 4} samples. • Ferrite from Ni(OH){sub 2}/Fe{sub 2}O{sub 3} has lower DC conductivity than from Ni(OH){sub 2}/Fe(OH){sub 3} powders. • The values of dielectric constant of samples NiFe{sub 2}O{sub 4} are 70 and 200, respectively. - Abstract: Nickel ferrite, NiFe{sub 2}O{sub 4} was prepared by a soft mechanochemical route from a mixture of (1) Ni(OH){submore » 2} and α-Fe{sub 2}O{sub 3} and (2) Ni(OH){sub 2} and Fe(OH){sub 3} powders in a planetary ball mill for 25 h. The powder samples were sintered at 1100 °C for 2 h and were characterized by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). Impedance spectroscopy techniques were used to study the effect of grain and grain boundary on the electrical properties of the prepared samples. A difference in dielectric constant (ε) and dielectric loss tangent (tan δ) of NiFe{sub 2}O{sub 4} samples obtained by the same methods but starting from different initial components was observed.« less

Crystal structure, Raman scattering and magnetic properties of CuCr2-xZrxSe4 and CuCr2-xSnxSe4 selenospinels

NASA Astrophysics Data System (ADS)

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.

Crystal growth, electronic structure and optical properties of Sr2Mg(BO3)2

NASA Astrophysics Data System (ADS)

Lv, Xianshun; Wei, Lei; Wang, Xuping; Xu, Jianhua; Yu, Huajian; Hu, Yanyan; Zhang, Huadi; Zhang, Cong; Wang, Jiyang; Li, Qinggang

2018-02-01

Single crystals of Sr2Mg(BO3)2 (SMBO) were grown by Kyropoulos method. X-ray powder diffraction (XRD) analysis, transmission spectrum, thermal properties, band structure, density of states and charge distribution as well as Raman spectra of SMBO were described. The as-grown SMBO crystals show wide transparency range with UV cut-off below 180 nm. A direct band gap of 4.66 eV was obtained from the calculated electronic structure results. The calculated band structure and density of states results indicated the top valence band is determined by O 2p states whereas the low conduction band mainly consists of Sr 5s states. Twelve Raman peaks were observed in the experimental spectrum, fewer than the number predicted by the site group analysis. Raman peaks of SMBO were assigned combining first-principle calculation and site group analysis results. The strongest peak at 917 cm-1 in the experimental spectrum is assigned to symmetric stretching mode A1‧(ν1) of free BO3 units. SMBO is a potential Raman crystal which can be used in deep UV laser frequency conversion.

Pressure-induced amorphization of La{sub 1/3}TaO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noked, O., E-mail: noked@bgu.ac.il; Physics Department, Ben-Gurion University, Beer Sheva 84105; Melchior, A.

2013-06-15

La{sub 1/3}TaO{sub 3}, an A-site cation deficient perovskite, has been studied under pressure by synchrotron X-ray powder diffraction and Raman spectroscopy. It undergoes irreversible pressure induced amorphization at P=18.5 GPa. An almost linear unit cell volume decrease vs. pressure is observed from ambient pressure up to the phase transition. The Raman spectroscopy also shows amorphization at the same pressure, with positive shifts of all modes as a function of pressure. The pressure dependence of the E{sub g} and A{sub 1g} Raman modes arising from the octahedral oxygen network is discussed. - Graphical abstract: La{sub 1/3}Tao{sub 3} exhibits linear pressure–volume relationmore » until irreversible pressure induced amorphization at 18.5 Gpa. - Highlights: • La{sub 1/3}TaO{sub 3} has been studied under pressure by synchrotron XRD and Raman spectroscopy. • La{sub 1/3}TaO{sub 3} undergoes irreversible pressure induced amorphization around 18.5 GPa. • The transition is manifested in both XRD and Raman measurements. • A linear P–V relation is observed from ambient pressure up to the phase transition.« less

FT-Raman and chemometric tools for rapid determination of quality parameters in milk powder: Classification of samples for the presence of lactose and fraud detection by addition of maltodextrin.

PubMed

Rodrigues Júnior, Paulo Henrique; de Sá Oliveira, Kamila; de Almeida, Carlos Eduardo Rocha; De Oliveira, Luiz Fernando Cappa; Stephani, Rodrigo; Pinto, Michele da Silva; de Carvalho, Antônio Fernandes; Perrone, Ítalo Tuler

2016-04-01

FT-Raman spectroscopy has been explored as a quick screening method to evaluate the presence of lactose and identify milk powder samples adulterated with maltodextrin (2.5-50% w/w). Raman measurements can easily differentiate samples of milk powder, without the need for sample preparation, while traditional quality control methods, including high performance liquid chromatography, are cumbersome and slow. FT-Raman spectra were obtained from samples of whole lactose and low-lactose milk powder, both without and with addition of maltodextrin. Differences were observed between the spectra involved in identifying samples with low lactose content, as well as adulterated samples. Exploratory data analysis using Raman spectroscopy and multivariate analysis was also developed to classify samples with PCA and PLS-DA. The PLS-DA models obtained allowed to correctly classify all samples. These results demonstrate the utility of FT-Raman spectroscopy in combination with chemometrics to infer about the quality of milk powder. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis, characterization and electrical properties of a lead sodium vanadate apatite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakroun-Ouadhour, E.; Ternane, R.; Hassen-Chehimi, D. Ben

2008-08-04

The lacunary lead sodium vanadate apatite Pb{sub 8}Na{sub 2}(VO{sub 4}){sub 6} was synthesized by the solid-state reaction method. The compound was characterized by X-ray powder diffraction, infrared (IR) absorption spectroscopy and Raman scattering spectroscopy. By comparing the effect of vanadate and phosphate ions on electrical properties, it was concluded that Pb{sub 8}Na{sub 2}(VO{sub 4}){sub 6} apatite is better conductor than Pb{sub 8}Na{sub 2}(PO{sub 4}){sub 6} apatite.

Preparation of porous Si and TiO 2 nanofibres using a sulphur-templating method for lithium storage

DOE PAGES

McCormac, Kathleen; Byrd, Ian; Brannen, Rodney; ...

2015-02-03

We prepared highly porous Si/TiO 2 composite nanofibres using a unique sulphur-templating method combined with electrospinning. The structure, morphology, surface area, phase and composition of these nanofibres were characterized using Raman spectroscopy, scanning electron microscopy, powder X-ray diffraction, surface area analyser and thermogravimetric analyser. The specific surface area of Si/TiO 2 porous NFs is as large as 387m 2g -1, whose silicon capacity can be maintained above 1580mAhg -1 in 180 cycles.

Structural and spectroscopic investigations on deuteron glasses belonging to the potassium dihydrogen phosphate family

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choudhury, Rajul Ranjan, E-mail: rajul@barc.gov.in; Chitra, R.; Abraham, Geogy J.

2015-06-24

X-ray powder diffraction and Raman measurements were performed on the mixed crystals of deuterated potassium dihydrogen phosphate (DKDP) and deuterated ammonium dihydrogen phosphate (DADP) grown at our lab. These crystals are known to behave like deuteron glasses due to frustration between ferroelectric and antiferroelectric ordering. Both spectral as well as structural studies indicate that crystals belonging to the glassy regions of the crystal composition have stronger O-D-O hydrogen bonds as compared to those belong to the ferroelectric or antiferroelectric regions of the crystal composition.

Structural analysis and ferroelectric properties of Fe doped BaTiO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishra, Ashutosh, E-mail: a.mansuri14@gmail.com, E-mail: amishra1960@yahoo.co.in; Mansuri, Amantulla, E-mail: a.mansuri14@gmail.com, E-mail: amishra1960@yahoo.co.in; Dwivedi, J. P.

2016-05-23

The polycrystalline samples of Fe doped BaTiO{sub 3} (BTO) with compositional formula BaTi{sub 1-x}Fe{sub x}O{sub 3} (x = 0, 0.03, 0.04 and 0.05) were prepared by solid-state reaction route. The influence of the Fe content on the structural, vibrational and electric properties of BaTiO{sub 3} was investigated using X-ray powder diffraction (XRD), Raman spectroscopy and Polarization techniques. XRD analysis indicates the formation of single-phase tetragonal structure for all the prepared samples. Tetragonal cubic structure with space group P4mm of all samples is further approved by Rietveld refinement. Room temperature Raman spectra of pure BaTiO{sub 3} show four active modes ofmore » vibration whose intensity decreases with increasing Fe doping. Small shift in Raman modes and increment in the line width has been observed with the doping ions. The hysteresis loop is very well performed with regular sharp characteristic of ferroelectric materials.« less

Growth of single crystals, thermal dependency of lattice parameters and Raman scattering in the Nd 2- xCe xCuO 4- δ system

NASA Astrophysics Data System (ADS)

Sadowski, W.; Hagemann, H.; François, M.; Bill, H.; Peter, M.; Walker, E.; Yvon, K.

1990-09-01

We report on the growth of Nd 2- xCe xCuO 4- δ single crystals (0< x<0.2) from Cu 2O flux. Free separated crystals with maximum size of 5x8x0.15 nm 3 have been obtained. Magnetic AC susceptibility measurements show a sharp superconducting transition at temperatures up to 23 K. The temperature dependence of the lattice parameters has been measured by means of X-ray powder diffraction between 10 K ( a=3.9413(3) Å, c=12.0290(18) Å) and 290 K ( a=3.9482(3) Å, c=12.0590(18) Å). Room temperature Raman spectra reveal a new band at 320 cm -1 which is not observed in Nd 2CuO 4. Raman spectra of crystals with Tc ranging from 7 to 22 K show a systematic intensity change of the broad band at 590 cm -1.

Detection of azo dyes in curry powder using a 1064-nm dispersive hyperspectral Raman imaging system

USDA-ARS?s Scientific Manuscript database

Curry powder is extensively used in Southeast Asian dishes. It has been subject to adulteration by azo dyes. This study used a newly developed 1064 nm dispersive hyperspectral Raman imaging system for detection of metanil yellow and Sudan-I contamination in curry powder. Curry powder was mixed with ...

Nonlinear optical imaging for sensitive detection of crystals in bulk amorphous powders.

PubMed

Kestur, Umesh S; Wanapun, Duangporn; Toth, Scott J; Wegiel, Lindsay A; Simpson, Garth J; Taylor, Lynne S

2012-11-01

The primary aim of this study was to evaluate the utility of second-order nonlinear imaging of chiral crystals (SONICC) to quantify crystallinity in drug-polymer blends, including solid dispersions. Second harmonic generation (SHG) can potentially exhibit scaling with crystallinity between linear and quadratic depending on the nature of the source, and thus, it is important to determine the response of pharmaceutical powders. Physical mixtures containing different proportions of crystalline naproxen and hydroxyl propyl methyl cellulose acetate succinate (HPMCAS) were prepared by blending and a dispersion was produced by solvent evaporation. A custom-built SONICC instrument was used to characterize the SHG intensity as a function of the crystalline drug fraction in the various samples. Powder X-ray diffraction (PXRD) and Raman spectroscopy were used as complementary methods known to exhibit linear scaling. SONICC was able to detect crystalline drug even in the presence of 99.9 wt % HPMCAS in the binary mixtures. The calibration curve revealed a linear dynamic range with a R(2) value of 0.99 spanning the range from 0.1 to 100 wt % naproxen with a root mean square error of prediction of 2.7%. Using the calibration curve, the errors in the validation samples were in the range of 5%-10%. Analysis of a 75 wt % HPMCAS-naproxen solid dispersion with SONICC revealed the presence of crystallites at an earlier time point than could be detected with PXRD and Raman spectroscopy. In addition, results from the crystallization kinetics experiment using SONICC were in good agreement with Raman spectroscopy and PXRD. In conclusion, SONICC has been found to be a sensitive technique for detecting low levels (0.1% or lower) of crystallinity, even in the presence of large quantities of a polymer. Copyright © 2012 Wiley-Liss, Inc.

The Back Scattering Micro-Raman Spectroscopy of Different Crystalline Phases of TiO2 Nanoparticles Produced by Sol-Gel Technique

NASA Astrophysics Data System (ADS)

Malekfar, R.; Mihanyar, S.; Mozaffari, M.

2007-09-01

TiO2 is known to be one of the best photocatalysts among the semiconductors. In order to improve its photocatalytic features, it is necessary to be able to control factors such as the mean particle size, nanocrystalline system, grain shapes and diffraction. Nanocrystalline TiO2 sample powders were produced using H2O2 and Ti(OBu)4 as precursor materials and their above features were then characterized by using XRD, Raman spectroscopy and SEM. The grain size was calculated using the Debye Scherrer formula for anatase phase, 15 nm, which is in agreement with the value obtained by SEM imaging. Ti(OBu)4 was added dropwise to a very ice-cold solution of H2O2 under intensive stirring. This immediately yielded a red solution which was shortly followed by a strong exothermic reaction due to the unstable nature of the reaction at this stage. This process also involved rigorous giving off of H2O2, O2, and butyl alcohol. A yellow transparent peroxo-polytitanic (PPT) acid gel was thus prepared. This gel was then heated at 150 °C for 5 hours and was transformed into amorphous TiO2. The produced yellow powder was heated at 250 °C, 350 °C and 450 °C for one hour with a ramping up speed of 5 °C/min heating rate. It was later calcined at 550 °C, 750 °C and 950 °C for 30 minutes. By investigating the Raman spectra typically shown in figure 1 and also XRD patterns, it was confirmed that the anatase phase nanocrystalline powder, which is well known for its application as photocatalysts, was produced at the first three lower treatment temperatures mentioned above.

Detecting adulterants in milk powder using high-throughput Raman chemical imaging

USDA-ARS?s Scientific Manuscript database

This study used a line-scan high-throughput Raman imaging system to authenticate milk powder. A 5 W 785 nm line laser (240 mm long and 1 mm wide) was used as a Raman excitation source. The system was used to acquire hyperspectral Raman images in a wavenumber range of 103–2881 cm-1 from the skim milk...

Probing Pharmaceutical Mixtures during Milling: The Potency of Low-Frequency Raman Spectroscopy in Identifying Disorder.

PubMed

Walker, Greg; Römann, Philipp; Poller, Bettina; Löbmann, Korbinian; Grohganz, Holger; Rooney, Jeremy S; Huff, Gregory S; Smith, Geoffrey P S; Rades, Thomas; Gordon, Keith C; Strachan, Clare J; Fraser-Miller, Sara J

2017-12-04

This study uses a multimodal analytical approach to evaluate the rates of (co)amorphization of milled drug and excipient and the effectiveness of different analytical methods in detecting these changes. Indomethacin and tryptophan were the model substances, and the analytical methods included low-frequency Raman spectroscopy (785 nm excitation and capable of measuring both low- (10 to 250 cm -1 ) and midfrequency (450 to 1800 cm -1 ) regimes, and a 830 nm system (5 to 250 cm -1 )), conventional (200-3000 cm -1 ) Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRPD). The kinetics of amorphization were found to be faster for the mixture, and indeed, for indomethacin, only partial amorphization occurred (after 360 min of milling). Each technique was capable of identifying the transformations, but some, such as low-frequency Raman spectroscopy and XRPD, provided less ambiguous signatures than the midvibrational frequency techniques (conventional Raman and FTIR). The low-frequency Raman spectra showed intense phonon mode bands for the crystalline and cocrystalline samples that could be used as a sensitive probe of order. Multivariate analysis has been used to further interpret the spectral changes. Overall, this study demonstrates the potential of low-frequency Raman spectroscopy, which has several practical advantages over XRPD, for probing (dis-)order during pharmaceutical processing, showcasing its potential for future development, and implementation as an in-line process monitoring method.

Optimizing laser crater enhanced Raman scattering spectroscopy

NASA Astrophysics Data System (ADS)

Lednev, V. N.; Sdvizhenskii, P. A.; Grishin, M. Ya.; Fedorov, A. N.; Khokhlova, O. V.; Oshurko, V. B.; Pershin, S. M.

2018-05-01

The laser crater enhanced Raman scattering (LCERS) spectroscopy technique has been systematically studied for chosen sampling strategy and influence of powder material properties on spectra intensity enhancement. The same nanosecond pulsed solid state Nd:YAG laser (532 nm, 10 ns, 0.1-1.5 mJ/pulse) was used for laser crater production and Raman scattering experiments for L-aspartic acid powder. Increased sampling area inside crater cavity is the key factor for Raman signal improvement for the LCERS technique, thus Raman signal enhancement was studied as a function of numerous experimental parameters including lens-to-sample distance, wavelength (532 and 1064 nm) and laser pulse energy utilized for crater production. Combining laser pulses of 1064 and 532 nm wavelengths for crater ablation was shown to be an effective way for additional LCERS signal improvement. Powder material properties (particle size distribution, powder compactness) were demonstrated to affect LCERS measurements with better results achieved for smaller particles and lower compactness.

Anisotropic lattice thermal expansion of PbFeBO 4: A study by X-ray and neutron diffraction, Raman spectroscopy and DFT calculations

DOE PAGES

Murshed, M. Mangir; Mendive, Cecilia B.; Curti, Mariano; ...

2014-11-01

We present the lattice thermal expansion of mullite-type PbFeBO 4 in this study. The thermal expansion coefficients of the metric parameters were obtained from composite data collected from temperature-dependent neutron and X-ray powder diffraction between 10 K and 700 K. The volume thermal expansion was modeled using extended Grüneisen first-order approximation to the zero-pressure equation of state. The additive frame of the model includes harmonic, quasi-harmonic and intrinsic anharmonic potentials to describe the change of the internal energy as a function of temperature. Moreover, the unit-cell volume at zero-pressure and 0 K was optimized during the DFT simulations. Harmonic frequenciesmore » of the optical Raman modes at the Γ-point of the Brillouin zone at 0 K were also calculated by DFT, which help to assign and crosscheck the experimental frequencies. The low-temperature Raman spectra showed significant anomaly in the antiferromagnetic regions, leading to softening or hardening of some phonons. Selected modes were analyzed using a modified Klemens model. The shift of the frequencies and the broadening of the line-widths helped to understand the anharmonic vibrational behaviors of the PbO4, FeO6 and BO3 polyhedra as a function of temperature.« less

High-pressure X-ray diffraction, Raman, and computational studies of MgCl2 up to 1 Mbar: Extensive pressure stability of the β-MgCl2 layered structure.

PubMed

Stavrou, Elissaios; Yao, Yansun; Zaug, Joseph M; Bastea, Sorin; Kalkan, Bora; Konôpková, Zuzana; Kunz, Martin

2016-08-12

Magnesium chloride (MgCl2) with the rhombohedral layered CdCl2-type structure (α-MgCl2) has been studied experimentally using synchrotron angle-dispersive powder x-ray diffraction and Raman spectroscopy using a diamond-anvil cell up to 100 GPa at room temperature and theoretically using first-principles density functional calculations. The results reveal a pressure-induced second-order structural phase transition to a hexagonal layered CdI2-type structure (β-MgCl2) at 0.7 GPa: the stacking sequence of the Cl anions are altered resulting in a reduction of the c-axis length. Theoretical calculations confirm this phase transition sequence and the calculated transition pressure is in excellent agreement with the experiment. Lattice dynamics calculations also reproduce the experimental Raman spectra measured for the ambient and high-pressure phase. According to our experimental results MgCl2 remains in a 2D layered phase up to 100 GPa and further, the 6-fold coordination of Mg cations is retained. Theoretical calculations of relative enthalpy suggest that this extensive pressure stability is due to a low enthalpy of the layered structure ruling out kinetic barrier effects. This observation is unusual, as it contradicts with the general structural behavior of highly compressed AB2 compounds.

High-pressure X-ray diffraction, Raman, and computational studies of MgCl 2 up to 1 Mbar: Extensive pressure stability of the β-MgCl 2 layered structure

DOE PAGES

Stavrou, Elissaios; Yao, Yansun; Zaug, Joseph M.; ...

2016-08-12

We studied magnesium chloride (MgCl 2) with the rhombohedral layered CdCl 2-type structure (α-MgCl 2), experimentally, using synchrotron angle-dispersive powder x-ray diffraction and Raman spectroscopy using a diamond-anvil cell up to 100 GPa at room temperature and theoretically using first-principles density functional calculations. Our results reveal a pressure-induced second-order structural phase transition to a hexagonal layered CdI 2-type structure (β-MgCl 2) at 0.7 GPa: the stacking sequence of the Cl anions are altered resulting in a reduction of the c-axis length. Theoretical calculations confirm this phase transition sequence and the calculated transition pressure is in excellent agreement with the experiment.more » Lattice dynamics calculations also reproduce the experimental Raman spectra measured for the ambient and high-pressure phase. According to our experimental results MgCl 2 remains in a 2D layered phase up to 100 GPa and further, the 6-fold coordination of Mg cations is retained. Theoretical calculations of relative enthalpy suggest that this extensive pressure stability is due to a low enthalpy of the layered structure ruling out kinetic barrier effects. Our observation is unusual, as it contradicts with the general structural behavior of highly compressed AB 2 compounds.« less

Hydrogen storage in double clathrates with tert-butylamine.

PubMed

Prasad, Pinnelli S R; Sugahara, Takeshi; Sum, Amadeu K; Sloan, E Dendy; Koh, Carolyn A

2009-06-18

The first proof-of-concept of the formation of a double tert-butylamine (t-BuNH(2)) + hydrogen (H(2)) clathrate hydrate has been demonstrated. Binary clathrate hydrates with different molar concentrations of the large guest t-BuNH(2) (0.98-9.31 mol %) were synthesized at 13.8 MPa and 250 K, and characterized by powder X-ray diffraction and Raman microscopy. A structural transformation from sVI to sII of t-BuNH(2) hydrate was clearly observed under hydrogen pressures. Raman spectroscopic data suggested that the hydrogen molecules occupied the small cages and had similar occupancy to hydrogen in the double tetrahydrofuran (THF) + H(2) clathrate hydrate. The hydrogen storage capacity in this system was approximately 0.7 H(2) wt % at the molar concentration of t-BuNH(2) close to the sII stoichiometry.

Mechanical and tribological property of single layer graphene oxide reinforced titanium matrix composite coating

NASA Astrophysics Data System (ADS)

Hu, Zengrong; Li, Yue; Fan, Xueliang; Chen, Feng; Xu, Jiale

2018-04-01

Single layer grapheme oxide Nano sheets and Nano titanium powder were dispersed in deionized water by ultrasonic dispersion. Then the mixed solution was pre-coating on AISI4140 substrate. Using laser sintering process to fabricated grapheme oxide and Ti composite coating. Microstructures and composition of the composite coating was studied by Scanning Electron Microscopy (SEM), x-ray diffract meter (XRD) and Raman spectroscopy. Raman spectrum, XRD pattern and SEM results proved that grapheme oxide sheets were dispersed in the composite coating. The composite coating had much higher average Vickers hardness values than that of pure Ti coating. The tribological performance of the composite coatings became better while the suitable GO content was selected. For the 2.5wt. % GO content coating, the friction coefficient was reduced to near 0.1.

Morphological and phase evolution of TiO 2 nanocrystals prepared from peroxotitanate complex aqueous solution: Influence of acetic acid

NASA Astrophysics Data System (ADS)

Chang, Jeong Ah; Vithal, Muga; Baek, In Chan; Seok, Sang Il

2009-04-01

Nanosized anatase and rutile TiO 2 having different shape, phase and size have been prepared from aqueous solutions of peroxo titanium complex starting from titanium(IV) isopropoxide (TTIP), acetic acid and hydrogen peroxide (H 2O 2) in water/isopropanol media by a facile sol-gel process. The TiO 2 nanocrystals are characterized by powder X-ray diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, TEM, high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) techniques. The influence of pH and the sequence of addition of reaction contents on the phase and morphology of TiO 2 are studied. The reasons for the observation of only anatase and/or mixture of anatase and rutile are given.

Chemical bonding in TiSb(2) and VSb(2): a quantum chemical and experimental study.

PubMed

Armbrüster, Marc; Schnelle, Walter; Schwarz, Ulrich; Grin, Yuri

2007-08-06

The chemical bonding in the isostructural intermetallic compounds TiSb2 and VSb2, crystallizing in the CuAl2 type, was investigated by means of quantum chemical calculations, particularly the electron localization function (ELF), as well as by Raman spectroscopy, Hall effect and conductivity measurements on oriented single crystals, and high-pressure X-ray powder diffraction. The homogeneity ranges of the compounds were determined by powder X-ray diffraction, WDXS, and DSC measurements. TiSb2 exhibits no significant homogeneity range, while VSb2 shows a small homogeneity range of approximately 0.3 at. %. According to the ELF calculations, the Sb atoms form dumbbells via a two-center two-electron bond, while the T atoms (T = Ti, V) build up chains along the crystallographic c-axis. Both building units are connected by covalent T-Sb-T three-center bonds, thus forming a three-dimensional network. The strength of the bonds involving Sb was determined by fitting a force constant model to the vibrational mode frequencies observed by polarized Raman measurements on oriented single crystals. The resulting bond order of the Sb2 dumbbells is 1, while the strength of the three-center bonds resembles a bond order of 1.5. The weak pressure dependence of the c/a ratio confirms the slightly different bonding picture in TiSb2 compared to that in CuAl2. Electrical transport measurements show the presence of free charge carriers, as well as a metal-like temperature dependence of the electrical resistivity.

Ternary and coupled binary zinc tin oxide nanopowders: Synthesis, characterization, and potential application in photocatalytic processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivetić, T.B., E-mail: tamara.ivetic@df.uns.ac.rs; Finčur, N.L.; Đačanin, Lj. R.

2015-02-15

Highlights: • Mechanochemically synthesized nanocrystalline zinc tin oxide (ZTO) powders. • Photocatalytic degradation of alprazolam in the presence of ZTO water suspensions. • Coupled binary ZTO exhibits enhanced photocatalytic activity compared to ternary ZTO. - Abstract: In this paper, ternary and coupled binary zinc tin oxide nanocrystalline powders were prepared via simple solid-state mechanochemical method. X-ray diffraction, scanning electron microscopy, Raman and reflectance spectroscopy were used to study the structure and optical properties of the obtained powder samples. The thermal behavior of zinc tin oxide system was examined through simultaneous thermogravimetric-differential scanning calorimetric analysis. The efficiencies of ternary (Zn{sub 2}SnO{submore » 4} and ZnSnO{sub 3}) and coupled binary (ZnO/SnO{sub 2}) zinc tin oxide water suspensions in the photocatalytic degradation of alprazolam, short-acting anxiolytic of the benzodiazepine class of psychoactive drugs, under UV irradiation were determined and compared with the efficiency of pure ZnO and SnO{sub 2}.« less

Development of a Raman chemical imaging detection method for authenticating skim milk powder

USDA-ARS?s Scientific Manuscript database

This research demonstrated that Raman chemical imaging coupled with a simple image classification algorithm can be used to detect multiple chemical adulterants in skim milk powder. Ammonium sulfate, dicyandiamide, melamine, and urea were mixed into the milk powder as chemical adulterants in the conc...

Study on Raman spectral imaging method for simultaneous estimation of ingredients concentration in food powder

USDA-ARS?s Scientific Manuscript database

This study investigated the potential of point scan Raman spectral imaging method for estimation of different ingredients and chemical contaminant concentration in food powder. Food powder sample was prepared by mixing sugar, vanillin, melamine and non-dairy cream at 5 different concentrations in a ...

Development of a Raman chemical image detection algorithm for authenticating dry milk

USDA-ARS?s Scientific Manuscript database

This research developed a Raman chemical imaging method for detecting multiple adulterants in skim milk powder. Ammonium sulfate, dicyandiamide, melamine, and urea were mixed into the milk powder as chemical adulterants in the concentration range of 0.1–5.0%. A Raman imaging system using a 785-nm la...

Crucibleless crystal growth and Radioluminescence study of calcium tungstate single crystal fiber

NASA Astrophysics Data System (ADS)

Silva, M. S.; Jesus, L. M.; Barbosa, L. B.; Ardila, D. R.; Andreeta, J. P.; Silva, R. S.

2014-11-01

In this article, single phase and high optical quality scheelite calcium tungstate single crystal fibers were grown by using the crucibleless laser heated pedestal growth technique. The as-synthesized calcium tungstate powders used for shaping seed and feed rods were investigated by X-ray diffraction technique. As-grown crystals were studied by Raman spectroscopy and Radioluminescence measurements. The results indicate that in both two cases, calcined powder and single crystal fiber, only the expected scheelite CaWO4 phase was observed. It was verified large homogeneity in the crystal composition, without the presence of secondary phases. The Radioluminescence spectra of the as-grown single crystal fibers are in agreement with that present in Literature for bulk single crystals, presented a single emission band centered at 420 nm when irradiated with β-rays.

Identification and evaluation of composition in food powder using point-scan Raman spectral imaging

USDA-ARS?s Scientific Manuscript database

This study used Raman spectral imaging coupled with self-modeling mixture analysis (SMA) for identification of three components mixed into a complex food powder mixture. Vanillin, melamine, and sugar were mixed together at 10 different concentration levels (spanning 1% to 10%, w/w) into powdered non...

Raman spectral imaging for quantitative contaminant evaluation in skim milk powder

USDA-ARS?s Scientific Manuscript database

This study uses a point-scan Raman spectral imaging system for quantitative detection of melamine in milk powder. A sample depth of 2 mm and corresponding laser intensity of 200 mW were selected after evaluating the penetration of a 785 nm laser through milk powder. Horizontal and vertical spatial r...

Raman spectral imaging technique on detection of melamine in skim milk powder

USDA-ARS?s Scientific Manuscript database

A point-scan Raman spectral imaging system was used for quantitative detection of melamine in milk powder. A sample depth of 2 mm and corresponding laser intensity of 200 mW were selected after evaluating the penetration of a 785 nm laser through milk powder. Horizontal and vertical spatial resoluti...

Structure and stability of hydrous minerals at high pressure

NASA Technical Reports Server (NTRS)

Duffy, T. S.; Fei, Y.; Meade, C.; Hemley, R. J.; Mao, H. K.

1994-01-01

The presence of even small amounts of hydrogen in the Earth's deep interior may have profound effects on mantle melting, rheology, and electrical conductivity. The recent discovery of a large class of high-pressure H-bearing silicates further underscores the potentially important role for hydrous minerals in the Earth's mantle. Hydrogen may also be a significant component of the Earth's core, as has been recently documented by studies of iron hydride at high pressure. In this study, we explore the role of H in crystal structures at high pressure through detailed Raman spectroscopic and x ray diffraction studies of hydrous minerals compressed in diamond anvil cells. Brucite, Mg(OH)2, has a simple structure and serves as an analogue for the more complex hydrous silicates. Over the past five years, this material has been studied at high pressure using shock-compression, powder x ray diffraction, infrared spectroscopy, Raman spectroscopy, and neutron diffraction. In addition, we have recently carried out single-crystal synchrotron x-ray diffraction on Mg(OH)2 and Raman spectroscopy on Mg(OD)2 at elevated pressure. From all these studies, an interesting picture of the crystal chemical behavior of this material at high pressure is beginning to emerge. Some of the primary conclusions are as follows: First, hydrogen bonding is enhanced by the application of pressure. Second, layered minerals which are elastically anisotropic at low pressure may not be so at high pressure. Furthermore, the brucite data place constraints on the effect of hydrogen on seismic velocities and density at very high pressure. Third, the stability of hydrous minerals may be enhanced at high P by subtle structural rearrangements that are difficult to detect using traditional probes and require detailed spectroscopic analyses. Finally, brucite appears to be unique in that it undergoes pressure-induced disordering that is confined solely to the H-containing layers of the structure.

Optimizing laser crater enhanced Raman spectroscopy.

PubMed

Lednev, V N; Sdvizhenskii, P A; Grishin, M Ya; Filichkina, V A; Shchegolikhin, A N; Pershin, S M

2018-03-20

Raman signal enhancement by laser crater production was systematically studied for 785 nm continuous wave laser pumping. Laser craters were produced in L-aspartic acid powder by a nanosecond pulsed solid state neodymium-doped yttrium aluminum garnet laser (532 nm, 8 ns, 1 mJ/pulse), while Raman spectra were then acquired by using a commercial spectrometer with 785 nm laser beam pumping. The Raman signal enhancement effect was studied in terms of the number of ablating pulses used, the lens-to-sample distance, and the crater-center-laser-spot offset. The influence of the experiment parameters on Raman signal enhancement was studied for different powder materials. Maximum Raman signal enhancement reached 11 fold for loose powders but decreased twice for pressed tablets. Raman signal enhancement was demonstrated for several diverse powder materials like gypsum or ammonium nitrate with better results achieved for the samples tending to give narrow and deep craters upon the laser ablation stage. Alternative ways of cavity production (steel needle tapping and hole drilling) were compared with the laser cratering technique in terms of Raman signal enhancement. Drilling was found to give the poorest enhancement of the Raman signal, while both laser ablation and steel needle tapping provided comparable results. Here, we have demonstrated for the first time, to the best of our knowledge, that a Raman signal can be enhanced 10 fold with the aid of simple cavity production by steel needle tapping in rough highly reflective materials. Though laser crater enhancement Raman spectroscopy requires an additional pulsed laser, this technique is more appropriate for automatization compared to the needle tapping approach.

Morphology and structural development of reduced anatase-TiO{sub 2} by pure Ti powder upon annealing and nitridation: Synthesis of TiO{sub x} and TiO{sub x}N{sub y} powders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolokang, A.S., E-mail: Sylvester.Bolokang@transnet.net; DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria 0001; Transnet Engineering, Product Development, Private Bag X 528, Kilnerpark 0127

2015-02-15

It is well known that nitriding of titanium is suitable for surface coating of biomaterials and in other applications such as anti-reflective coating, while oxygen-rich titanium oxynitride has been applied in thin film resistors and photocatalysis. Thus in this work anatase was reduced with pure titanium powder during annealing in argon. This was done to avoid any metallic contamination and unwanted residual metal doping. As a result, interesting and different types of particle morphology were synthesized when the pre-milled elemental anatase and titanium powders were mixed. The formation of metastable face centred cubic and monoclinic titanium monoxide was detected bymore » the X-ray diffraction technique. The phases were confirmed by energy dispersive X-ray spectroscopy analysis. Raman analysis revealed weak intensity peaks for samples annealed in argon as compared to those annealed under nitrogen. - Graphical abstract: Display Omitted - Highlights: • Reaction of TiO{sub 2} and Ti induced metastable FCC and monoclinic TiO{sub x}. • Compositions of mixed powder were prepared from the unmilled and pre-milled powders. • Nitridation of TiO{sub x} yielded TiO{sub x}N{sub y} phase. • Mixed morphology was observed on all three powder samples.« less

Line-scan macro-scale Raman chemical imaging for authentication of powdered foods and ingredients

USDA-ARS?s Scientific Manuscript database

Adulteration and fraud for powdered foods and ingredients are rising food safety risks that threaten consumers’ health. In this study, a newly developed line-scan macro-scale Raman imaging system using a 5 W 785 nm line laser as excitation source was used to authenticate the food powders. The system...

Structural transformations of sVI tert-butylamine hydrates to sII binary hydrates with methane.

PubMed

Prasad, Pinnelli S R; Sugahara, Takeshi; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A

2009-10-22

Binary clathrate hydrates with methane (CH(4), 4.36 A) and tert-butylamine (t-BuNH(2), 6.72 A) as guest molecules were synthesized at different molar concentrations of t-BuNH(2) (1.00-9.31 mol %) with methane at 7.0 MPa and 250 K, and were characterized by powder X-ray diffraction (PXRD) and Raman microscopy. A structural transformation from sVI to sII of t-BuNH(2) hydrate was clearly observed on pressurizing with methane. The PXRD showed sII signatures and the remnant sVI signatures were insignificant, implying the metastable nature of sVI binary hydrates. Raman spectroscopic data on these binary hydrates suggest that the methane molecules occupy the small cages and vacant large cages. The methane storage capacity in this system was nearly doubled to approximately 6.86 wt % for 5.56 mol % > t-BuNH(2) > 1.0 mol %.

A 1:1 pharmaceutical cocrystal of myricetin in combination with uncommon piracetam conformer: X-ray single crystal analysis and mechanochemical synthesis

NASA Astrophysics Data System (ADS)

Sowa, Michał; Ślepokura, Katarzyna; Matczak-Jon, Ewa

2014-01-01

Combination of two Active Pharmaceutical Ingredients, myricetin and piracetam, yields a 1:1 cocrystal characterized by X-ray single-crystal and powder diffraction, Raman spectroscopy, 1H NMR, thermal analysis (DSC and TG-DTA) methods. Constituents of the cocrystalline phase were also investigated in terms of Hirshfeld surfaces. Compounds in their neutral forms cocrystallize in the Pna21 space group of orthorhombic system. Notably, piracetam adopts an uncommon conformation, not encountered in its cocrystals previously described. In the crystal lattice, a three-dimensional hydrogen-bonded network is observed, including formation of a 2D molecular scaffolding motif. A scale-up procedure is readily available with use of solvent-drop grinding method, in which application of a variety of common solvents leads to formation of the cocrystal, as confirmed by XRPD and Raman spectroscopy.

Raman and X-Ray Investigation of High-Temperature Methane in the Diamond Anvil Cell

NASA Astrophysics Data System (ADS)

Spaulding, D.; Weck, G.; Loubeyre, P.; Mezouar, M.

2016-12-01

The chemistry and equations of state of simple molecular systems are of extreme importance to planetary astrophysics and for accurate characterization of reaction products and pathways at high pressures and temperatures. Simple molecules such as H2O, CO2 and CH4 are model systems for understanding the effects of pressure on chemical bonding. Here we present recent work to conduct fine-scale studies of the vibrational, chemical and structural properties of CH4 at pressures and temperatures up to 12 GPa and 1000K, with particular attention to behavior in the vicinity of the melting curve. We present results from resistive and laser-heating experiments, coupled with Raman spectroscopy. In addition, high P/T synchrotron powder x-ray diffraction provides tight constraints on melting and solid structure. Our results favor a somewhat higher melting curve and lower dissociative stability limit for the CH4 molecule than other recent work.

Pressure-induced polymerization of P(CN) 3

DOE PAGES

Gou, Huiyang; Yonke, Brendan L.; Epshteyn, Albert; ...

2015-05-21

Motivated to explore the formation of novel extended carbon-nitrogen solids via well-defined molecular precursor pathways, we studied the chemical reactivity of highly pure phosphorous tricyanide, P(CN) 3, under conditions of high pressure at room temperature. Raman and infrared (IR) spectroscopic measurements reveal a series of phase transformations below 10 GPa, and several low-frequency vibrational modes are reported for the first time. Synchrotron powder Xray diffraction (PXRD) measurements taken during compression show that molecular P(CN) 3 is highly compressible with a bulk modulus of 10.0±0.3 GPa and polymerizes into an amorphous solid above ~10.0 GPa. Raman and infrared (IR) spectra, togethermore » with first-principles molecular-dynamics simulations, show that the amorphization transition is associated with polymerization of the cyanide groups into CN bonds with predominantly sp 2 character, similar to known carbon nitrides, resulting in a novel PCN polymeric phase, which is recoverable to ambient pressure.« less

Preparation and characterization of CdS/Si coaxial nanowires

NASA Astrophysics Data System (ADS)

Fu, X. L.; Li, L. H.; Tang, W. H.

2006-04-01

CdS/Si coaxial nanowires were fabricated via a simple one-step thermal evaporation of CdS powder in mass scale. Their crystallinities, general morphologies and detailed microstructures were characterized by using X-ray diffraction, scanning electron microscope, transmission electron microscope and Raman spectra. The CdS core crystallizes in a hexagonal wurtzite structure with lattice constants of a=0.4140 nm and c=0.6719 nm, and the Si shell is amorphous. Five Raman peaks from the CdS core were observed. They are 1LO at 305 cm -1, 2LO at 601 cm -1, A 1-TO at 212 cm -1, E 1-TO at 234 cm -1, and E 2 at 252 cm -1. Photoluminescence measurements show that the nanowires have two emission bands around 510 and 590 nm, which originate from the intrinsic transitions of CdS cores and the amorphous Si shells, respectively.

Synthesis of zirconia (ZrO2) nanowires via chemical vapor deposition

NASA Astrophysics Data System (ADS)

Baek, M. K.; Park, S. J.; Choi, D. J.

2017-02-01

Monoclinic zirconia nanowires were synthesized by chemical vapor deposition using ZrCl4 powder as a starting material at 1200 °C and 760 Torr. Graphite was employed as a substrate, and an Au thin film was pre-deposited on the graphite as a catalyst. The zirconia nanostructure morphology was observed through scanning electron microscopy and transmission electron microscopy. Based on X-ray diffraction, selected area electron diffraction, and Raman spectroscopy data, the resulting crystal structure was found to be single crystalline monoclinic zirconia. The homogeneous distributions of Zr, O and Au were studied by scanning transmission electron microscopy with energy dispersive X-ray spectroscopy mapping, and there was no metal droplet at the nanowire tips despite the use of an Au metal catalyst. This result is apart from that of conventional metal catalyzed nanowires.

Molecular structure of hybrid imino-chalcone in the solid state: X-ray diffraction, spectroscopy study and third-order nonlinear optical properties

NASA Astrophysics Data System (ADS)

Custodio, J. M. F.; Santos, F. G.; Vaz, W. F.; Cunha, C. E. P.; Silveira, R. G.; Anjos, M. M.; Campos, C. E. M.; Oliveira, G. R.; Martins, F. T.; da Silva, C. C.; Valverde, C.; Baseia, B.; Napolitano, H. B.

2018-04-01

A comprehensive structural study of the compound (2E)-1-((E)-4-(4-methoxybenzylideneamino)phenyl)-3-(4-methoxyphenyl)prop-2-en-1-one was carried out in this work. Single crystal X-ray diffraction (SCXRD), X-ray powder diffraction (XRPD), NMR, Raman and Infrared spectroscopies, and DFT calculations were performed for characterization of this iminochalcone hybrid. Intermolecular interactions were described by Hirshfeld surface analysis derived from crystal structure. Reactivity and intramolecular charge transfer were investigated using the frontier molecular orbitals and molecular electrostatic potential. In addition, we have calculated the Nonlinear Optical Properties at the CAM-B3LYP/6-311+g(d) level of theory in the presence of different solvents (gas-phase, acetone, chloroform, dichloromethane, dimethyl sulfoxide, ethanol, methanol, and water), being found meaningful NLO parameters for our compound. At last, there is a good agreement between calculated and experimental IR spectrum, allowing the assignment of some of normal vibrational modes of the iminochalcone hybrid.

Growth, structural, thermal, linear and nonlinear optical and laser damage threshold studies of picolinium tartrate monohydrate single crystals.

PubMed

Peramaiyan, G; Pandi, P; Sornamurthy, B M; Bhagavannarayana, G; Mohan Kumar, R

2012-09-01

Picolinium tartrate monohydrate (PTM), a novel organic nonlinear optical material was synthesized and bulk crystals were grown from aqueous solution by slow cooling technique. The cell parameters of the grown crystal were found by single and powder X-ray diffraction analyses. The crystalline perfection of the grown crystals has been analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements. The presence of functional groups in the grown crystal was identified by FTIR and FT-Raman spectral analyses. UV-Vis spectral studies reveal PTM crystals are transparent in the wavelength region of 295-1100 nm. The thermal characteristics of PTM were analyzed by TGA/DTA studies. The dielectric and mechanical behaviours of PTM crystals were investigated. Dislocation density was estimated to be 2.89 × 10(3) cm(-2) on the flat-surface of PTM crystals from the etching studies. The laser induced surface damage threshold for the grown crystal was measured using Nd:YAG laser. Its second harmonic generation relative efficiency was measured by Kurtz and Perry powder technique and was observed to be comparable with KDP crystal. Copyright © 2012 Elsevier B.V. All rights reserved.

X-ray powder diffraction, spectroscopic study, dielectric properties and thermal analysis of new doped compound TiGa0.67Te2.33O8

NASA Astrophysics Data System (ADS)

Smaoui, S.; Ben Aribia, W.; Kabadou, A.; Abdelmouleh, M.

2017-04-01

A novel mixed valence tellurium oxide, TiGa0.67Te2.33O8, was synthesized and its crystal structure determined using the X-ray powder diffraction technique. The obtained oxide was found to crystallize in a cubic unit-cell, Ia 3 bar space group, with the lattice parameter a = 10.9557(1) Å. Rietveld refinement of the structure led to ultimate confidence factors Rp = 7.63 and Rwp = 6.71. This structure was based on slabs containing groups of (Te/Ga)O4 joined by the metal cations Ti4+. The structure analysis showed a cation ordering of Te4+ and Te6+ yielding a TiGa2/3Te7/3O8 formula. The IR and RAMAN spectra confirmed the presence of the TiO6 and (Te/Ga)O4 groups. The dielectric anomalies observed at 500 K were attributed to the mixed valence structure, arising from the mixed-valence Te6+/Te4+. We detected only one peak in thermal behavior by the DTA/TG analysis; which implied a melting reaction.

Surface enhanced Raman spectral studies of 2-bromo-1,4-naphthoquinone.

PubMed

Geetha, K; Umadevi, M; Sathe, G V; Vanelle, P; Terme, T; Khoumeri, O

2015-03-05

Silver nanoparticles have been synthesized by a simple and inexpensive solution combustion method with urea as fuel. The structural and morphology of the silver nanoparticles were investigated through X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersion Spectra (EDS) techniques. Structural and morphological results confirmed the nanocrystalline nature of the silver nanoparticles. Density Functional Theory (DFT) calculations were also performed to study the ground and excited state behavior of 2-bromo-1,4-naphthoquinone (2-BrNQ) and 2-BrNQ on silver nanoparticles. Surface-Enhanced Raman Scattering (SERS) spectra of 2-BrNQ adsorbed on silver nanoparticles were investigated. The CO, CH in-plane bending and CBr stretching modes were enhanced in SERS spectrum with respect to normal Raman spectrum. The spectral analysis reveals that the 2-BrNQ adsorbed 'stand-on' orientation on the silver surface. Density Functional Theory (DFT) calculations are also performed to study the vibrational features of 2-BrNQ molecule and 2-BrNQ molecule on silver surface. Copyright © 2014 Elsevier B.V. All rights reserved.

Coexistence of metallic and insulating channels in compressed YbB6

NASA Astrophysics Data System (ADS)

Ying, Jianjun; Tang, Lingyun; Chen, Fei; Chen, Xianhui; Struzhkin, Viktor V.

2018-03-01

It remains controversial whether compressed YbB6 material is a topological insulator or a Kondo topological insulator. We performed high-pressure transport, x-ray diffraction (XRD), x-ray absorption spectroscopy, and Raman-scattering measurements on YbB6 samples in search for its topological Kondo phase. Both high-pressure powder XRD and Raman measurements show no trace of structural phase transitions in YbB6 up to 50 GPa. The nonmagnetic Yb2 + gradually change to magnetic Yb3 + above 18 GPa concomitantly with the increase in resistivity. However, the transition to the insulating state occurs only around 30 GPa, accompanied by the increase in the shear stress, and anomalies in the pressure dependence of the Raman T2 g mode and in the B atomic position. The resistivity at high pressures can be described by a model taking into account coexisting insulating and metallic channels with the activation energy for the insulating channel about 30 meV. We argue that YbB6 may become a topological Kondo insulator at high pressures above 35 GPa.

Synthesis, spectroscopic, thermal and structural properties of [M(3-aminopyridine)2Ni(μ-CN)2(CN)2]n (M(II) = Co and Cu) heteropolynuclear cyano-bridged complexes

NASA Astrophysics Data System (ADS)

Kartal, Zeki

2016-01-01

Two novel cyano-bridged heteropolynuclear complexes, [Co(3-aminopyridine)2Ni(μ-CN)2(CN)2]n and [Cu(3-aminopyridine)2Ni(μ-CN)2(CN)2]n have been synthesized and characterized by elemental, thermal, FT-IR and FT-Raman spectroscopies. The structures of complexes have been determined by X-ray powder diffraction. The FT-IR and FT-Raman spectra of complexes have been recorded in the region of 3500-400 cm-1 and 3500-100 cm-1, respectively. General information was acquired about structural properties of these complexes from FT-IR and FT-Raman spectra by considering changes at characteristic peaks of the cyano group and 3AP. The splitting of the ν(Ctbnd N) stretching bands in the FT-IR spectra for complexes indicates the presence of terminal and bridging cyanides. The thermal behaviors of these complexes have been also investigated in the range of 25-950 °C using TG and DTG methods. Magnetic susceptibility measurements were made at room temperature using Gouy-balance.

Nanotwinning and structural phase transition in CdS quantum dots

NASA Astrophysics Data System (ADS)

Kumar, Pragati; Saxena, Nupur; Chandra, Ramesh; Gupta, Vinay; Agarwal, Avinash; Kanjilal, Dinakar

2012-10-01

Nanotwin structures are observed in high-resolution transmission electron microscopy studies of cubic phase CdS quantum dots in powder form by chemical co-precipitation method. The deposition of thin films of nanocrystalline CdS is carried out on silicon, glass, and TEM grids keeping the substrates at room temperature (RT) and 200°C by pulsed laser ablation. These films are then subjected to thermal annealing at different temperatures. Glancing angle X-ray diffraction results confirm structural phase transitions after thermal annealing of films deposited at RT and 200°C. The variation of average particle size and ratio of intensities in Raman peaks I 2LO/ I 1LO with annealing temperature are studied. It is found that electron-phonon interaction is a function of temperature and particle size and is independent of the structure. Besides Raman modes LO, 2LO and 3LO of CdS at approximately 302, 603, and 903 cm-1 respectively, two extra Raman modes at approximately 390 and 690 cm-1 are studied for the first time. The green and orange emissions observed in photoluminescence are correlated with phase transition.

Nanotwinning and structural phase transition in CdS quantum dots.

PubMed

Kumar, Pragati; Saxena, Nupur; Chandra, Ramesh; Gupta, Vinay; Agarwal, Avinash; Kanjilal, Dinakar

2012-10-23

Nanotwin structures are observed in high-resolution transmission electron microscopy studies of cubic phase CdS quantum dots in powder form by chemical co-precipitation method. The deposition of thin films of nanocrystalline CdS is carried out on silicon, glass, and TEM grids keeping the substrates at room temperature (RT) and 200°C by pulsed laser ablation. These films are then subjected to thermal annealing at different temperatures. Glancing angle X-ray diffraction results confirm structural phase transitions after thermal annealing of films deposited at RT and 200°C. The variation of average particle size and ratio of intensities in Raman peaks I2LO/I1LO with annealing temperature are studied. It is found that electron-phonon interaction is a function of temperature and particle size and is independent of the structure. Besides Raman modes LO, 2LO and 3LO of CdS at approximately 302, 603, and 903 cm-1 respectively, two extra Raman modes at approximately 390 and 690 cm-1 are studied for the first time. The green and orange emissions observed in photoluminescence are correlated with phase transition.

Detection and quantification of adulterants in milk powder using high-throughput Raman chemical imaging technique

USDA-ARS?s Scientific Manuscript database

Milk is a vulnerable target for economically motivated adulteration. In this study, a line-scan high-throughput Raman imaging system was used to authenticate milk powder. A 5 W 785 nm line laser (240 mm long and 1 mm wide) was used as a Raman excitation source. The system was used to acquire hypersp...

The spectroscopic detection of exogenous material in fingerprints after development with powders and recovery with adhesive lifters.

PubMed

West, Matthew J; Went, Michael J

2008-01-15

The application of powders to fingerprints has long been established as an effective and reliable method for developing latent fingerprints. The powders adhere to the ridge pattern of the fingerprint only, thus allowing the image to be visualised. Fingerprints developed in situ at a crime scene routinely undergo lifting with specialist tapes to facilitate subsequent laboratory analysis. As with all recovered evidence these samples would be stored in evidence bags to allow secure transit from the scene to the laboratory and also to preserve the chain of evidence. In this paper, the application of Raman spectroscopy for the analysis of exogenous material in latent fingerprints is reported for contaminated fingerprints that had been treated with powders and also subsequently lifted with adhesive tapes. A selection of over the counter (OTC) analgesics were used as samples for the analysis and contaminated fingerprints were deposited on clean glass slides. The application of aluminium or iron based powders to contaminated fingerprints did not interfere with the Raman spectra obtained for the contaminants. In most cases background fluorescence attributed to the sebaceous content of the latent fingerprint was reduced by the application of the powder thus reducing spectral interference. Contaminated fingerprints developed with powders and then lifted with lifting tapes were also examined. The combination of these two techniques did not interfere with the successful analysis of exogenous contaminants by Raman spectroscopy. The lifting process was repeated using hinge lifters. As the hinge lifters exhibited strong Raman bands the spectroscopic analysis was more complex and an increase in the number of exposures to the detector allowed for improved clarification. Raman spectra of developed and lifted fingerprints recorded through evidence bags were obtained and it was found that the detection process was not compromised in any way. Although the application of powders did not interfere with the detection process the time taken to locate the contaminant was increased due to the physical presence of more material within the fingerprint. The presence of interfering Raman bands from lifting tapes is another potential complication. This, however, could be removed by spectral subtraction or by the choice of lifting tapes that have only weak Raman bands.

Impact of the long chain omega-acylceramides on the stratum corneum lipid nanostructure. Part 1: Thermotropic phase behaviour of CER[EOS] and CER[EOP] studied using X-ray powder diffraction and FT-Raman spectroscopy.

PubMed

Kessner, Doreen; Brezesinski, Gerald; Funari, Sergio S; Dobner, Bodo; Neubert, Reinhard H H

2010-01-01

The stratum corneum (SC), the outermost layer of the mammalian skin, is the main skin barrier. Ceramides (CERs) as the major constituent of the SC lipid matrix are of particular interest. At the moment, 11 classes of CERs are identified, but the effect of each single ceramide species is still not known. Therefore in this article, the thermotropic behaviour of the long chain omega-acylceramides CER[EOS] and CER[EOP] was studied using X-ray powder diffraction and FT-Raman spectroscopy. It was found that the omega-acylceramides CER[EOS] and CER[EOP] do not show a pronounced polymorphism which is observed for shorter chain ceramides as a significant feature. The phase behaviour of both ceramides is strongly influenced by the extremely long acyl-chain residue. The latter has a much stronger influence compared with the structure of the polar head group, which is discussed as extremely important for the appearance of a rich polymorphism. Despite the strong influence of the long chain, the additional OH-group of the phyto-sphingosine type CER[EOP] influences the lamellar repeat distance and the chain packing. The less polar sphingosine type CER[EOS] is stronger influenced by the long acyl-chain residue. Hydration is necessary for the formation of an extended hydrogen-bonding network between the polar head groups leading to the appearance of a long-periodicity phase (LPP). In contrast, the more polar CER[EOP] forms the LPP with densely packed alkyl chains already in the dry state.

Fast surface crystallization of amorphous griseofulvin below T g.

PubMed

Zhu, Lei; Jona, Janan; Nagapudi, Karthik; Wu, Tian

2010-08-01

To study crystal growth rates of amorphous griseofulvin (GSF) below its glass transition temperature (T (g)) and the effect of surface crystallization on the overall crystallization kinetics of amorphous GSF. Amorphous GSF was generated by melt quenching. Surface and bulk crystal growth rates were determined using polarized light microscope. X-ray powder diffraction (XRPD) and Raman microscopy were used to identify the polymorph of the crystals. Crystallization kinetics of amorphous GSF powder stored at 40 degrees C (T (g)-48 degrees C) and room temperature (T (g)-66 degrees C) was monitored using XRPD. Crystal growth at the surface of amorphous GSF is 10- to 100-fold faster than that in the bulk. The surface crystal growth can be suppressed by an ultrathin gold coating. Below T (g), the crystallization of amorphous GSF powder was biphasic with a rapid initial crystallization stage dominated by the surface crystallization and a slow or suspended late stage controlled by the bulk crystallization. GSF exhibits the fastest surface crystallization kinetics among the known amorphous pharmaceutical solids. Well below T (g), surface crystallization dominated the overall crystallization kinetics of amorphous GSF powder. Thus, surface crystallization should be distinguished from bulk crystallization in studying, modeling and controlling the crystallization of amorphous solids.

Detection of metanil yellow contamination in turmeric using FT-Raman and FT-IR spectroscopy

NASA Astrophysics Data System (ADS)

Dhakal, Sagar; Chao, Kuanglin; Qin, Jianwei; Kim, Moon; Schmidt, Walter; Chan, Dian

2016-05-01

Turmeric is well known for its medicinal value and is often used in Asian cuisine. Economically motivated contamination of turmeric by chemicals such as metanil yellow has been repeatedly reported. Although traditional technologies can detect such contaminants in food, high operational costs and operational complexities have limited their use to the laboratory. This study used Fourier Transform Raman Spectroscopy (FT-Raman) and Fourier Transform - Infrared Spectroscopy (FT-IR) to identify metanil yellow contamination in turmeric powder. Mixtures of metanil yellow in turmeric were prepared at concentrations of 30%, 25%, 20%, 15%, 10%, 5%, 1% and 0.01% (w/w). The FT-Raman and FT-IR spectral signal of pure turmeric powder, pure metanil yellow powder and the 8 sample mixtures were obtained and analyzed independently to identify metanil yellow contamination in turmeric. The results show that FT-Raman spectroscopy and FT-IR spectroscopy can detect metanil yellow mixed with turmeric at concentrations as low as 1% and 5%, respectively, and may be useful for non-destructive detection of adulterated turmeric powder.

Synthesis of Multimetal-Graphene Composite by Mechanical Milling

NASA Astrophysics Data System (ADS)

Saiphaneendra, Bachu; Srivastava, Avi Krishna; Srivastava, Chandan

2016-10-01

Multimetal-graphene composites were synthesized using the ball milling technique. To prepare the composite, graphite powder was mixed with Fe, Cr, Co, Cu and Mg powders. This mixture was then mechanically milled for 35 h in toluene medium. After milling, the multimetal-graphite mixture was mixed with sodium lauryl sulfate and sonicated for 2 h. Sonication led to the exfoliation of graphene sheets. Formation of graphene was confirmed from x-ray diffraction and Raman spectroscopy. Transmission electron microscopy-based analysis revealed the formation of multimetal deposits over the graphene surface. Compositional analysis of the multimetal deposits revealed fairly uniform distribution of all the five component metal atoms over the graphene sheet. The average composition of the multimetal deposit was determined to be 11.4 ± 4 at.% Mg, 33.8 ± 19 at.% Cr, 21.8 ± 16 at.% Fe, 9.4 ± 5.7 at.% Co and 23.6 ± 12 at.% Cu.

Nonequilibrium Diamond Growth during the High-Temperature High-Pressure Synthesis of a Composite Material Made of a Mixture of Cobalt and Fullerene Powders

NASA Astrophysics Data System (ADS)

Bulienkov, N. A.; Zheligovskaya, E. A.; Chernogorova, O. P.; Drozdova, E. I.; Ushakova, I. N.; Ekimov, E. A.

2018-01-01

A composite material (CM) reinforced by diamond particles is fabricated from a mixture of cobalt and 10 wt % C60 powders at a pressure of 8 GPa and a temperature of 1200-1300°C, which is close to the melting temperature of the metastable Co-C eutectic. The results of X-ray diffraction, Raman spectroscopy, and electron-probe microanalysis demonstrate that the CM consists of diamond and the Co3C carbide. Diamond crystals are shown to grow as plates parallel to a {100} plane according to the mechanism of nonequilibrium normal growth during liquid-phase CM synthesis. The diamond particles have a hardness of 82 GPa at an elastic recovery of 95%. The structure of the synthesized cobalt-based CM with diamond inclusions ensures its ultrahigh wear resistance and antifriction properties.

Water-mediated solid-state transformation of a polymorphic drug during aqueous-based drug-layer coating of pellets.

PubMed

Lust, Andres; Lakio, Satu; Vintsevits, Julia; Kozlova, Jekaterina; Veski, Peep; Heinämäki, Jyrki; Kogermann, Karin

2013-11-01

During aqueous drug-layer coating, drug substance(s) are exposed to water and elevated temperatures which can lead to water-mediated process induced transformations (PITs). The effects of aqueous drug-layer coating of pellets (Cellets(®)) on the anhydrous piroxicam, PRX, were investigated in the miniaturized coating equipment and with free films. Hydroxypropyl methylcellulose (HPMC) was used as a carrier coating polymer. Free films were prepared by using an in-house small-scale rotating plate system equipped with an atomization air nozzle. Raman spectroscopy, X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were used to characterize the solid-state properties and surface morphology of the pellets and free films. The results showed that anhydrous PRX form I (AH) and monohydrate (MH) were stable during drug-layer coating, but amorphous PRX in solid dispersion (SD) crystallized as MH already after 10 min of coating. Furthermore, the increase in a dissolution rate was achieved from the drug-layer coated inert pellets compared to powder forms. In conclusion, water-mediated solid-state PITs of amorphous PRX is evident during aqueous-based drug-layer coating of pellets, and solid-state change can be verified using Raman spectroscopy. Copyright © 2013 Elsevier B.V. All rights reserved.

Enhanced luminescence in Mg{sup 2+} codoped CaTiO{sub 3}:Eu{sup 3+} phosphor prepared by solid state reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vandana, C. Sai; Rudramadevi, B. Hemalatha

2016-05-23

CaTiO{sub 3} phosphors doped with Eu{sup 3+} and codoped with Mg{sup 2+} were prepared by Solid State Reaction method. The powders were characterized by X-ray diffraction, SEM with EDS, Raman scattering, and photoluminescence spectroscopy. The Crystalline phase and vibrational modes of the phosphors were studied using XRD pattern and Raman Spectrum respectively. The morphological studies of the phosphor samples were carried out using SEM analysis. From PL spectra we have observed two prominent red emission peaks around at 595 nm ({sup 5}D{sub 0}→{sup 7}F{sub 1}), 619 nm ({sup 5}D{sub 0}→{sup 7}F{sub 2}) with the excitation of 399 nm for Eu{supmore » 3+} doped CaTiO{sub 3} powders. The PL intensity of CaTiO{sub 3}:Eu{sup 3+} phosphor is enhanced significantly on codoping with Mg{sup 2+}. The observed enhanced emissions are due to energy transfer from Mg{sup 2+} to Eu{sup 3+}, which is due to radiative recombination. Eu{sup 3+} doped phosphors are well known to be promising materials for electroluminescent devices, optical amplifiers, and lasers.« less

UV-visible light photocatalytic properties of NaYF4:(Gd, Si)/TiO2 composites

NASA Astrophysics Data System (ADS)

Mavengere, Shielah; Kim, Jung-Sik

2018-06-01

In this study, a new novel composite photocatalyst of NaYF4:(Gd, Si)/TiO2 phosphor has been synthesized by two step method of solution combustion and sol-gel. The photocatalyst powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV-vis spectroscopy and photoluminescence (PL) spectroscopy. Raman spectroscopy confirmed the anatase TiO2 phase which remarkably increased with existence of yttrium silicate compounds between 800 cm-1 and 900 cm-1. Double-addition of Gd3+-Si4+ ions in NaYF4 host introduced sub-energy band levels with intense absorption in the ultraviolet (UV) light region. Photocatalytic activity was examined by exposing methylene blue (MB) solutions mixed with photocatalyst powders to 254 nm UV-C fluorescent lamp and 200 W visible lights. The UV and visible photocatalytic reactivity of the NaYF4:(Gd, 1% Si)/TiO2 phosphor composites showed enhanced MB degradation efficiency. The coating of NaYF4:(Gd, 1% Si) phosphor with TiO2 nanoparticles creates energy band bending at the phosphor/TiO2 interfaces. Thus, these composites exhibited enhanced absorption of UV/visible light and the separation of electron and hole pairs for efficient photocatalysis.

Raman effect, structural and dielectric properties of sol-gel synthesized polycrystalline GaFe{sub 1-x}Zr{sub x}O{sub 3} (0≤x≤0.15)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Rajeev, E-mail: rajeevgiitk@gmail.com; Mall, Ashish Kumar; Gupta, Rajeev

2016-05-23

Polycrystalline ceramic samples of Zirconium (Zr)-doped GaFeO{sub 3} (GaFe{sub 1-x}Zr{sub x}O{sub 3}) were studied using powder X-ray diffraction, complex impedance spectroscopy and Raman spectroscopic measurements to understand the effect of Zr doping on the structural and dielectric properties. The samples with varying Zr content were prepared by Sol-Gel method. X-ray data analysis confirmed the formation of single phase material without formation of any secondary phases and all are crystallized in Pc2{sub 1}n orthorhombic symmetry. Rietveld refinement of the X-ray data suggested an increase in the lattice constants due to size effect and decreases on x = 0.15 due to themore » effect of change in interplanner spacing. Impedance studies on the samples showed that the dielectric constant increases while loss tangent decrease as the Zr content increases. Raman scattering on GaFe{sub 1-x}Zr{sub x}O{sub 3} (x = 0, 0.05, 0.10, & 0.15) used to understand the composition dependence on phonon modes at room temperature. On Zr doping, Raman modes frequencies shifts to lower energies consistent with the X-ray data.« less

Nanostructure Diffraction Gratings for Integrated Spectroscopy and Sensing

NASA Technical Reports Server (NTRS)

Guo, Junpeng (Inventor)

2015-01-01

The present disclosure pertains to metal or dielectric nanostructures of the subwavelength scale within the grating lines of optical diffraction gratings. The nanostructures have surface plasmon resonances or non-plasmon optical resonances. A linear photodetector array is used to capture the resonance spectra from one of the diffraction orders. The combined nanostructure super-grating and photodetector array eliminates the use of external optical spectrometers for measuring surface plasmon or optical resonance frequency shift caused by the presence of chemical and biological agents. The nanostructure super-gratings can be used for building integrated surface enhanced Raman scattering (SERS) spectrometers. The nanostructures within the diffraction grating lines enhance Raman scattering signal light while the diffraction grating pattern of the nanostructures diffracts Raman scattering light to different directions of propagation according to their wavelengths. Therefore, the nanostructure super-gratings allows for the use of a photodetector array to capture the surface enhanced Raman scattering spectra.

Nanostructure Diffraction Gratings for Integrated Spectroscopy and Sensing

NASA Technical Reports Server (NTRS)

Guo, Junpeng (Inventor)

2016-01-01

The present disclosure pertains to metal or dielectric nanostructures of the subwavelength scale within the grating lines of optical diffraction gratings. The nanostructures have surface plasmon resonances or non-plasmon optical resonances. A linear photodetector array is used to capture the resonance spectra from one of the diffraction orders. The combined nanostructure super-grating and photodetector array eliminates the use of external optical spectrometers for measuring surface plasmon or optical resonance frequency shift caused by the presence of chemical and biological agents. The nanostructure super-gratings can be used for building integrated surface enhanced Raman scattering (SERS) spectrometers. The nanostructures within the diffraction grating lines enhance Raman scattering signal light while the diffraction grating pattern of the nanostructures diffracts Raman scattering light to different directions of propagation according to their wavelengths. Therefore, the nanostructure super-gratings allows for the use of a photodetector array to capture the surface enhanced Raman scattering spectra.

Flux growth of high-quality CoFe 2O 4 single crystals and their characterization

NASA Astrophysics Data System (ADS)

Wang, W. H.; Ren, X.

2006-04-01

We report the growth of high-quality CoFe 2O 4 single crystals using a borax flux method. The crystals were characterized by powder X-ray diffraction, electron probe microanalysis and Raman spectroscopy. We found the crystals are flux-free and highly homogeneous in composition. X-ray rocking curves of the CoFe 2O 4 single crystals showed a full-width at half-maximum of 0.15°. The saturation magnetization of the CoFe 2O 4 single crystals was measured to be 90 emu/g or equivalently 3.65 μ B/f.u. at 5 K.

Synthesis of a Glibenclamide Cocrystal: Full Spectroscopic and Thermal Characterization.

PubMed

Silva Filho, Silvério Ferreira; Pereira, Andreia Cardoso; Sarraguça, Jorge M G; Sarraguça, Mafalda C; Lopes, João; Façanha Filho, Pedro de Freitas; Dos Santos, Adenilson Oliveira; da Silva Ribeiro, Paulo Roberto

2018-06-01

A cocrystal of glibenclamide, an antidiabetic drug classified as type II compound according to the Biopharmaceutics Classification System, has been synthesized using tromethamine as coformer in 1:1 molar ratio, by slow solvent evaporation cocrystalization. The cocrystal obtained was characterized by X-ray powder diffraction, differential scanning calorimetry, Raman, mid infrared, and near-infrared spectroscopy. The results consistently show the formation of a cocrystal between active pharmaceutical ingredients and conformer with the synthons corresponding to hydrogen bonding between hydrogen in amines of tromethamine and carbonyl and sulfonyl groups in glibenclamide. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Microwave-Hydrothermal Synthesis of SnO2-CNTs Hybrid Nanocomposites with Visible Light Photocatalytic Activity.

PubMed

Wu, Shuisheng; Dai, Weili

2017-03-03

SnO2 nanoparticles coated on carbon nanotubes (CNTs) were prepared via a simple microwave-hydrothermal route. The as-obtained SnO2-CNTs composites were characterized using X-ray powder diffraction, Raman spectroscopy, and transmission electron microscopy. The photocatalytic activity of as-prepared SnO2-CNTs for degradation of Rhodamine B under visible light irradiation was investigated. The results show that SnO2-CNTs nanocomposites have a higher photocatalytic activity than pure SnO2 due to the rapid transferring of electrons and the effective separation of holes and electrons on SnO2-CNTs.

Microwave-Hydrothermal Synthesis of SnO2-CNTs Hybrid Nanocomposites with Visible Light Photocatalytic Activity

PubMed Central

Wu, Shuisheng; Dai, Weili

2017-01-01

SnO2 nanoparticles coated on carbon nanotubes (CNTs) were prepared via a simple microwave-hydrothermal route. The as-obtained SnO2-CNTs composites were characterized using X-ray powder diffraction, Raman spectroscopy, and transmission electron microscopy. The photocatalytic activity of as-prepared SnO2-CNTs for degradation of Rhodamine B under visible light irradiation was investigated. The results show that SnO2-CNTs nanocomposites have a higher photocatalytic activity than pure SnO2 due to the rapid transferring of electrons and the effective separation of holes and electrons on SnO2-CNTs. PMID:28336888

Crystal structure, spectrum character and explosive property of a new cocrystal CL-20/DNT

NASA Astrophysics Data System (ADS)

Liu, Ke; Zhang, Gao; Luan, Jieyu; Chen, Zhiqun; Su, Pengfei; Shu, Yuanjie

2016-04-01

A new cocrystal explosive of 2,4,6,8,10,12-hexanitrohexaazaiso-wurtzitane(CL-20) and 2,5-dinitrotoluene(DNT) in a molar ratio of 1:2 has been prepared by slow solvent evaporation method. Crystal structure of the cocrystal characterized by single crystal X-ray diffraction (SXRD) reveals that the cocrystal is formed by intermolecular hydrogen bond interactions and belongs to the triclinic system with P-1 group. Moreover, the obivious differences of powder X-ray diffraction (PXRD) patterns, infrared spectroscopy and Raman spectroscopy confirm that the intermolecular interactions have great influence for the crystal structure and formation of cocrystal. The cocrystal exhibits a lower impact height of 44 cm, suggesting a substantial reduction of sensitivity in comparison with CL-20. And thermal test results showed cocrystal obtains a lower melting point than DNT, which means huge advantages in blasting engineering.

High throughput screening of ligand binding to macromolecules using high resolution powder diffraction

DOEpatents

Von Dreele, Robert B.; D'Amico, Kevin

2006-10-31

A process is provided for the high throughput screening of binding of ligands to macromolecules using high resolution powder diffraction data including producing a first sample slurry of a selected polycrystalline macromolecule material and a solvent, producing a second sample slurry of a selected polycrystalline macromolecule material, one or more ligands and the solvent, obtaining a high resolution powder diffraction pattern on each of said first sample slurry and the second sample slurry, and, comparing the high resolution powder diffraction pattern of the first sample slurry and the high resolution powder diffraction pattern of the second sample slurry whereby a difference in the high resolution powder diffraction patterns of the first sample slurry and the second sample slurry provides a positive indication for the formation of a complex between the selected polycrystalline macromolecule material and at least one of the one or more ligands.

Rietveld analysis using powder diffraction data with anomalous scattering effect obtained by focused beam flat sample method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, Masahiko, E-mail: masahiko@spring8.or.jp; Katsuya, Yoshio, E-mail: katsuya@spring8.or.jp; Sakata, Osami, E-mail: SAKATA.Osami@nims.go.jp

2016-07-27

Focused-beam flat-sample method (FFM) is a new trial for synchrotron powder diffraction method, which is a combination of beam focusing optics, flat shape powder sample and area detectors. The method has advantages for X-ray diffraction experiments applying anomalous scattering effect (anomalous diffraction), because of 1. Absorption correction without approximation, 2. High intensity X-rays of focused incident beams and high signal noise ratio of diffracted X-rays 3. Rapid data collection with area detectors. We applied the FFM to anomalous diffraction experiments and collected synchrotron X-ray powder diffraction data of CoFe{sub 2}O{sub 4} (inverse spinel structure) using X-rays near Fe K absorptionmore » edge, which can distinguish Co and Fe by anomalous scattering effect. We conducted Rietveld analyses with the obtained powder diffraction data and successfully determined the distribution of Co and Fe ions in CoFe{sub 2}O{sub 4} crystal structure.« less

Amorphization of Ta2O5 under swift heavy ion irradiation

NASA Astrophysics Data System (ADS)

Cusick, Alex B.; Lang, Maik; Zhang, Fuxiang; Sun, Kai; Li, Weixing; Kluth, Patrick; Trautmann, Christina; Ewing, Rodney C.

2017-09-01

Crystalline Ta2O5 powder is shown to amorphize under 2.2 GeV 197Au ion irradiation. Synchrotron X-ray diffraction (XRD), Raman spectroscopy, small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM) were used to characterize the structural transition from crystalline to fully-amorphous. Based on Rietveld refinement of XRD data, the initial structure is orthorhombic (P2mm) with a very large unit cell (a = 6.20, b = 40.29, c = 3.89 Å; V = 971.7 Å3), ideally containing 22 Ta and 55 O atoms. At a fluence of approximately 3 × 1011 ions/cm2, a diffuse amorphous background becomes evident, increasing in intensity relative to diffraction maxima until full amorphization is achieved at approximately 3 × 1012 ions/cm2. An anisotropic distortion of the orthorhombic structure occurred during the amorphization process, with an approximately constant unit cell volume. The amorphous phase fraction as a function of fluence was determined, yielding a trend that is consistent with a direct-impact model for amorphization. SAXS and TEM data indicate that ion tracks exhibit a core-shell morphology. Raman data show that the amorphous phase is comprised of TaO6 and TaO5 coordination-polyhedra in contrast to the TaO6 and TaO7 units that exist in crystalline Ta2O5. Analysis of Raman data shows that oxygen-deficiency increases with fluence, indicating a loss of oxygen that leads to an estimated final stoichiometry of Ta2O4.2 at a fluence of 1 × 1013 ions/cm2.

Micro-nano zinc oxide film fabricated by biomimetic mineralization: Designed architectures for SERS substrates

NASA Astrophysics Data System (ADS)

Lu, Fei; Guo, Yue; Wang, Yunxin; Song, Wei; Zhao, Bing

2018-05-01

In this study, we have investigated the effect of the surface morphologies of the zinc oxide (ZnO) substrates on surface enhanced Raman spectroscopy (SERS). During synthetic process, the self-assembly monolayers (SAMs) with different terminal groups are used as templates to induce the nucleation and growth of Zn(NO3)2·6H2O crystals, then different morphologies micro-nano ZnO powders are obtained by annealing Zn(NO3)2·6H2O crystals at 450 °C. The products obtained at different conditions are characterized by means of X-ray diffraction (XRD) patterns, scanning electron microscopy (SEM) and Raman spectra. The as-prepared ZnO micro-sized particles have been used the efficient Surface enhanced Raman scattering (SERS) substrates, and the SERS signals of 4-mercaptopyridine (Mpy) probe molecules are much influenced by the morphologies of the ZnO structures. Results indicated that the more (0001) facets appear in the of ZnO morphology, the greater degree of charge-transfer (PCT) for the SERS enhancement on the surface of semiconductors is achieved. The chemical interaction between ZnO structures and Mpy molecules plays a very important role in the SERS enhancement.

Nanotwinning and structural phase transition in CdS quantum dots

PubMed Central

2012-01-01

Nanotwin structures are observed in high-resolution transmission electron microscopy studies of cubic phase CdS quantum dots in powder form by chemical co-precipitation method. The deposition of thin films of nanocrystalline CdS is carried out on silicon, glass, and TEM grids keeping the substrates at room temperature (RT) and 200°C by pulsed laser ablation. These films are then subjected to thermal annealing at different temperatures. Glancing angle X-ray diffraction results confirm structural phase transitions after thermal annealing of films deposited at RT and 200°C. The variation of average particle size and ratio of intensities in Raman peaks I2LO/I1LO with annealing temperature are studied. It is found that electron-phonon interaction is a function of temperature and particle size and is independent of the structure. Besides Raman modes LO, 2LO and 3LO of CdS at approximately 302, 603, and 903 cm−1 respectively, two extra Raman modes at approximately 390 and 690 cm−1 are studied for the first time. The green and orange emissions observed in photoluminescence are correlated with phase transition. PMID:23092351

Spectroscopic, structural and drug docking studies of carbocysteine

NASA Astrophysics Data System (ADS)

Manivannan, M.; Rajeshwaran, K.; Govindhan, R.; Karthikeyan, B.

2017-09-01

Carbocysteine or carbocisteine having the empirical formula C5H9NO4S,is one of the most therapeutically prescribed expectorant, sold under the brand name viz., Mucodyne (UK and India), Rhinathiol and Mucolite. In pediatric respiratory pathology, it can relieve the symptoms of obstructive pulmonary disease (COPD) and bronchiectasis. On the consideration of its extensive pharmaceutical usage and medicinal value, we have investigated its chemical structure and composition by employing various spectral techniques like 1H, 13C NMR, FT-IR,Raman, UV-Visible spectroscopy and powder X-ray diffraction method. Density Functional Theoretical (DFT) studies on its electronic structure is also carried out. Drug docking studies were carried out to ascertain the nature of molecular interaction with the biological protein system. Furthermore theoretical Raman spectrum of this molecule has been computed and compared with the experimental Raman spectrum. The forbidden energy gap between its frontier molecular orbitals, viz., HOMO-LUMO is calculated and correlated with its observed λmax value. Atomic orbitals which are mainly contributes to the frontier molecular orbitals were identified. Molecular electrostatic potential diagram has been mapped to explain its chemical activity. Based on the results, a suitable mechanism of its protein binding mode and drug action has been discussed.

Synthesis and high (pressure, temperature) stability of ZnTiO3 polymorphs studied by Raman spectroscopy

NASA Astrophysics Data System (ADS)

Bernert, T.; Ruiz-Fuertes, J.; Bayarjargal, L.; Winkler, B.

2015-05-01

The phase-purity of ilmenite-type ZnTiO3 prepared by the ceramic method was investigated in dependence of the conditions during ball milling. The previously proposed addition of 2 ml ethanol to the starting materials led to a significant contamination of the product phase after a subsequent sintering process at 1073 K. However, by omitting ethanol this synthesis route led to a phase-pure sample of ZnTiO3 as confirmed by X-ray powder diffraction and Raman spectroscopy. High-temperature high-pressure experiments gave an ilmenite-type to perovskite-type phase boundary with a slope of dT/dP∼-135 K GPa-1 crossing ambient temperature conditions at ∼ 24 GPa in good agreement with previous calculations. Room-temperature high-pressure Raman spectroscopy experiments have shown the stability of the ilmenite-type phase up to a pressure of at least 38.5 GPa, the highest pressure applied in this study, indicating the presence of a kinetic barrier in this phase transition. The synthesis of ferroelectric LiNbO3-type ZnTiO3 was confirmed by second harmonic generation.

Spectral analysis of allogeneic hydroxyapatite powders

NASA Astrophysics Data System (ADS)

Timchenko, P. E.; Timchenko, E. V.; Pisareva, E. V.; Vlasov, M. Yu; Red'kin, N. A.; Frolov, O. O.

2017-01-01

In this paper we discuss the application of Raman spectroscopy to the in vitro analysis of the hydroxyapatite powder samples produced from different types of animal bone tissue during demineralization process at various acid concentrations and exposure durations. The derivation of the Raman spectrum of hydroxyapatite is attempted by the analysis of the pure powders of its known constituents. Were experimentally found spectral features of hydroxyapatite, based on analysis of the line amplitude at wave numbers 950-965 cm-1 ((PO4)3- (ν1) vibration) and 1065-1075 cm-1 ((CO3)2-(ν1) B-type replacement). Control of physicochemical properties of hydroxyapatite was carried out by Raman spectroscopy. Research results are compared with an infrared Fourier spectroscopy.

Optical properties of hydroxyapatite obtained by mechanical alloying

NASA Astrophysics Data System (ADS)

Silva, C. C.; Thomazini, D.; Pinheiro, A. G.; Lanciotti, F.; Sasaki, J. M.; Góes, J. C.; Sombra, A. S. B.

2002-09-01

Calcium phosphate based bioceramics, mainly in the form of hydroxyapatite (HA), have been in use in medicine and dentistry for the last 20 years. Applications include coatings of orthopaedic and dental implants, alveolar ridge augmentation, maxillofacial surgery, otolaryngology, and scaffolds for bone growth and as powders in total hip and knee surgery. These materials exhibit several problems of handling and fabrication, which can be overcome by mixing with a suitable binder. In this paper, mechanical alloying has been used successfully to produce nanocrystalline powders of HA using five different experimental procedures. The milled HA were studied by X-ray powder diffraction, infrared and Raman scattering spectroscopy. For four different procedures, HA was obtained after a couple of hours of milling (on an average, 20 h of milling depending on the reaction procedure). The XRD patterns indicate that the grain size is within the range of 29-103 nm. This milling process, used to produce HA, presents the advantage that melting is not necessary and the powder obtained is nanocrystalline with extraordinary mechanical properties. The material can be compacted and transformed in solid ceramic samples. The high efficiency of the process opens a way to produce commercial amount of nanocrystalline HA. Due to the nanocrystalline character of this powder, their mechanical properties have changed and for this reason a pressure of 1 GPa is enough to shape the sample into any geometry.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarkar, S.; Mondal, A.; Dey, K.

Highlights: • Reduced graphene oxides (RGO) are prepared by two chemical routes. • Defects in RGO are characterized by Raman, FTIR and XPS studies. • Defects tailor colossal dielectricity in RGO. - Abstract: Reduced graphene oxide (RGO) is prepared in two different chemical routes where reduction of graphene oxide is performed by hydrazine hydrate and through high pressure in hydrothermal reactor. Samples are characterized by X-ray powdered diffraction (XRD), thermo gravimetric analysis (TGA), field emission scanning electron microscopy (FESEM) and tunneling electron microscopy (TEM). Types of defects are probed by Raman, FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). UV–vis absorptionmore » reveals different optical band gaps of the two RGOs. Conductivity mechanism is studied through I–V measurements displaying different characteristic features which are addressed due to the presence of defects appeared in different synthesis. Significantly high value (∼10{sup 4}) of dielectric permittivity at 10 MHz is attractive for technological application which could be tuned by the defects present in RGO.« less

Mineralogy of mine waste at the Vermont Asbestos Group mine, Belvidere Mountain, Vermont

USGS Publications Warehouse

Levitan, D.M.; Hammarstrom, J.M.; Gunter, M.E.; Seal, R.R.; Chou, I.-Ming; Piatak, N.M.

2009-01-01

Samples from the surfaces of waste piles at the Vermont Asbestos Group mine in northern Vermont were studied to determine their mineralogy, particularly the presence and morphology of amphiboles. Analyses included powder X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and Raman spectroscopy. Minerals identified by XRD were serpentine-group minerals, magnetite, chlorite, quartz, olivine, pyroxene, and brucite; locally, mica and carbonates were also present. Raman spectroscopy distinguished antigorite and chrysotile, which could not be differentiated using XRD. Long-count, short-range XRD scans of the (110) amphibole peak showed trace amounts of amphibole in most samples. Examination of amphiboles in tailings by optical microscopy, SEM, and EPMA revealed non-fibrous amphiboles compositionally classified as edenite, magnesiohornblende, magnesiokatophorite, and pargasite. No fibrous amphibole was found in the tailings, although fibrous tremolite was identified in a sample of host rock. Knowledge of the mineralogy at the site may lead to better understanding of potential implications for human health and aid in designing a remediation plan.

A multi-analytical approach for the characterization of wall painting materials on contemporary buildings

NASA Astrophysics Data System (ADS)

Magrini, Donata; Bracci, Susanna; Cantisani, Emma; Conti, Claudia; Rava, Antonio; Sansonetti, Antonio; Shank, Will; Colombini, MariaPerla

2017-02-01

Samples from Keith Haring's wall painting of the Necker Children Hospital in Paris were studied by a multi-analytical protocol. X-ray fluorescence (XRF), powder X-ray diffraction (XRDP), Electron microscope (SEM-EDS), Infrared and Raman spectroscopy (μ-FT-IR and μ-Raman) measurements were performed in order to characterize the materials and to identify the art technique used to produce this contemporary work. Materials from the mural suffered from severe detachments of materials and several fragments were found on the ground beneath. Some of these fragments, which were representative of the whole palette and stratigraphic sequence, were collected and studied. The fragments were sufficiently large to enable non-invasive measurements to be performed in order to characterize the materials. A comparison of the data of the techniques applied revealed that Haring's palette was composed of organic pigments such as Naphtol red, phthalocyanine blue and green and Hansa yellow, in accordance with those used previously by the artist in other painted murals.

Rietveld refined structural and room temperature vibrational properties of BaTiO3 doped La0.67Ba0.33MnO3 composites

NASA Astrophysics Data System (ADS)

Dar, M. A.; Sheikh, M. W.; Malla, M. S.; Varshney, Dinesh

2016-05-01

The composites of (1-x) La0.67Ba0.33MnO3 (LBMO) + xBaTiO3 (BTO) (x = 0, 0.25 and 1.0) were synthesized by conventional solid-state reaction method. Rietveld refinement was employed to characterize the structural information of the prepared ceramics. The result of the Rietveld refinement of X-ray powder diffraction of La0.67Ba0.33MnO3 and BaTiO3 shows that these compounds crystallize in rhombohedral (R3c) and tetragonal (P4mm), respectively. The structural parameters and the reliability factors for the LBMO-BTO composite ceramics were successfully determined by the Rietveld refinement. At room temperature, Raman active phonon modes predicted by the group theory were observed only in BaTiO3 and composite sample. Pure LBMO does not show any Raman active Phonon mode at room temperature.

β-Na2TeO4: Phase Transition from an Orthorhombic to a Monoclinic Form. Reversible CO2 Capture.

PubMed

Galven, Cyrille; Pagnier, Thierry; Rosman, Noël; Le Berre, Françoise; Crosnier-Lopez, Marie-Pierre

2018-06-18

The present work concerns the tellurate Na 2 TeO 4 which has a 1D structure and could then present a CO 2 capture ability. It has been synthesized in a powder form via a solid-state reaction and structurally characterized by thermal X-ray diffraction experiments, Raman spectroscopy, and differential scanning calorimetry. The room temperature structure corresponds to the β-Na 2 TeO 4 orthorhombic form, and we show that it undergoes a reversible structural transition near 420 °C toward a monoclinic system. Ab initio computations were also performed on the room temperature structure, the Raman vibration modes calculated, and a normal mode attribution proposed. In agreement with our expectations, this sodium oxide is able to trap CO 2 by a two-step mechanism: Na + /H + exchange and carbonation of the released sodium as NaHCO 3 . This capture is reversible since CO 2 can be released upon heating by recombination of the mother phase.

Physicochemical and antibacterial characterization of ionocity Ag/Cu powder nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nowak, A., E-mail: ana.maria.nowak@gmail.com; Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1A, 41-500 Chorzów; Szade, J.

Metal ion in bimetallic nanoparticles has shown vast potential in a variety of applications. In this paper we show the results of physical and chemical investigations of powder Ag/Cu nanoparticles obtained by chemical synthesis. Transmission electron microscopy (TEM) experiment indicated the presence of bimetallic nanoparticles in the agglomerated form. The average size of silver and copper nanoparticles is 17.1(4) nm (Ag) and 28.9(2) nm (Cu) basing on the X-ray diffraction (XRD) data. X-ray photoelectron (XPS) and Raman spectroscopies revealed the existence of metallic silver and copper as well as Cu{sub 2}O and CuO being a part of the nanoparticles. Moreover,more » UV–Vis spectroscopy showed surface alloy of Ag and Cu while Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) and Energy Dispersive X-ray Spectroscopy (EDX) showed heterogeneously distributed Ag structures placed on spherical Cu nanoparticles. The tests of antibacterial activity show promising killing/inhibiting growth behaviour for Gram positive and Gram negative bacteria. - Highlights: • Ag/Cu nanoparticles were obtained in the powder form. • The average size of nanoparticles is 17.1(4) nm (Ag) and 28.9(2) nm (Cu). • Ag/Cu powder nanoparticle shows promising antibacterial properties.« less

Magnetic, Mössbauer and optical spectroscopic properties of the AFe3O(PO4)3 (A = Ca, Sr, Pb) series of powder compounds

NASA Astrophysics Data System (ADS)

El Hafid, Hassan; Velázquez, Matias; El Jazouli, Abdelaziz; Wattiaux, Alain; Carlier, Dany; Decourt, Rodolphe; Couzi, Michel; Goldner, Philippe; Delmas, Claude

2014-10-01

AFe3O(PO4)3 (A = Ca, Sr and Pb) powder compounds were studied by means of X-ray diffraction (XRD), electron-probe microanalysis (EPMA) coupled with wavelength dispersion spectroscopy (WDS), Raman and diffuse reflectance spectroscopies, specific heat and magnetic properties measurements. Magnetization, magnetic susceptibility and specific heat measurements carried out on AFe3O(PO4)3 (A = Sr, Ca and Pb) powders firmly establish a series of three ferromagnetic (FM)-like second order phase transitions spanned over the 32-8 K temperature range. Room temperature Mössbauer spectroscopy and associated DFT calculations confirm the existence of three crystallographically non equivalent Fe3+ sites in the three compounds. Mössbauer spectra recorded as a function of temperature in the PbFe3O(PO4)3 compound also establishes the occurrence of two purely magnetic and reversible phase transitions at 32 and 10 K. Diffuse reflectance measurements reveal two broad absorption bands at 1047 and 837 nm, in both PbFe3O(PO4)3 and SrFe3O(PO4)3 powders, with peak cross sections ∼10-20 cm2 typical of spin-forbidden and forced electric dipole intraconfigurational transitions.

STRUCTURAL ANALYSIS OF THE COMBUSTION SYNTHESIZED Y3+ DOPED CERIA (Ce0.9Y0.1O1.95)

NASA Astrophysics Data System (ADS)

Jeyanthi, C. Esther; Siddheswaran, R.; Kumar, Pushpendra; Mangalaraja, R. V.; Siva Shankar, V.; Rajarajan, K.

2013-07-01

Y3+ doped CeO2 nanopowders (Ce0.9Y0.1O1.95, abbreviated as YDC) were synthesized by citrate-nitrate-auto combustion process using cerium nitrate hexahydrate, yttrium nitrate hexahydrate and citric acid. The as-synthesized powders were calcined at 700°C and converted into dense bodies followed by sintering at 1200°C. The microstructure of the synthesized powders and sintered bodies were examined by scanning electron microscopy (SEM). The surface morphology of the nanoparticles and clusters were also analysed by transmission electron microscopy (TEM). The particles size of the YDC was found to be in the range from 10 to 30 nm, which is in good agreement with the crystallite size calculated from X-ray peak broadening method. Also, the X-ray diffraction confirmed that the Ce0.9Y0.1O1.95 crystallizes as the cubic fluorite structure of pure ceria. The optical absorption by functional molecules, impurities and oxygen vacancies were analysed by FTIR and Raman spectroscopic studies. From the FTIR spectrum, the absorption peak found at 530 cm-1 is attributed to the vibrations of metal-oxygen bonds. The characteristic Raman peak was found to be 468 cm-1, and the minute absorption of oxygen vacancies were observed in the region 500-640 cm-1.

Experiments indicating a second hydrogen ordered phase of ice VI

PubMed Central

Gasser, Tobias M.; Thoeny, Alexander V.; Plaga, Lucie J.; Köster, Karsten W.; Etter, Martin; Böhmer, Roland

2018-01-01

In the last twelve years five new ice phases were experimentally prepared. Two of them are empty clathrate hydrates and three of them represent hydrogen ordered counterparts of previously known disordered ice phases. Here, we report on hydrogen ordering in ice VI samples produced by cooling at pressures up to 2.00 GPa. Based on results from calorimetry, dielectric relaxation spectroscopy, Raman spectroscopy, and powder X-ray diffraction the existence of a second hydrogen ordered polymorph related to ice VI is suggested. Powder X-ray data show the oxygen network to be the one of ice VI. For the 1.80 GPa sample the activation energy from dielectric spectroscopy is 45 kJ mol–1, which is much larger than for the known hydrogen ordered proxy of ice VI, ice XV. Raman spectroscopy indicates the 1.80 GPa sample to be more ordered than ice XV. It is further distinct from ice XV in that it experiences hydrogen disordering above ≈103 K which is 26 K below the ice XV to ice VI disordering transition. Consequently, below 103 K it is thermodynamically more stable than ice XV, adding a stability region to the phase diagram of water. For the time being we suggest to call this new phase ice β-XV and to relabel it ice XVIII once its crystal structure is known. PMID:29780552

Experiments indicating a second hydrogen ordered phase of ice VI.

PubMed

Gasser, Tobias M; Thoeny, Alexander V; Plaga, Lucie J; Köster, Karsten W; Etter, Martin; Böhmer, Roland; Loerting, Thomas

2018-05-14

In the last twelve years five new ice phases were experimentally prepared. Two of them are empty clathrate hydrates and three of them represent hydrogen ordered counterparts of previously known disordered ice phases. Here, we report on hydrogen ordering in ice VI samples produced by cooling at pressures up to 2.00 GPa. Based on results from calorimetry, dielectric relaxation spectroscopy, Raman spectroscopy, and powder X-ray diffraction the existence of a second hydrogen ordered polymorph related to ice VI is suggested. Powder X-ray data show the oxygen network to be the one of ice VI. For the 1.80 GPa sample the activation energy from dielectric spectroscopy is 45 kJ mol -1 , which is much larger than for the known hydrogen ordered proxy of ice VI, ice XV. Raman spectroscopy indicates the 1.80 GPa sample to be more ordered than ice XV. It is further distinct from ice XV in that it experiences hydrogen disordering above ≈103 K which is 26 K below the ice XV to ice VI disordering transition. Consequently, below 103 K it is thermodynamically more stable than ice XV, adding a stability region to the phase diagram of water. For the time being we suggest to call this new phase ice β-XV and to relabel it ice XVIII once its crystal structure is known.

The spectroscopic detection of drugs of abuse in fingerprints after development with powders and recovery with adhesive lifters

NASA Astrophysics Data System (ADS)

West, Matthew J.; Went, Michael J.

2009-01-01

The application of powders to fingerprints has long been established as an effective and reliable method for developing latent fingerprints. Fingerprints developed in situ at a crime scene routinely undergo lifting with specialist tapes and are then stored in evidence bags to allow secure transit and also to preserve the chain of evidence. In a previous study we have shown that exogenous material within a fingerprint can be detected using Raman spectroscopy following development with powders and lifting with adhesive tapes. Other reports have detailed the use of Raman spectroscopy to the detection of drugs of abuse in latent fingerprints including cyanoacrylate-fumed fingerprints. This study involves the application of Raman spectroscopy for the analysis of drugs of abuse in latent fingerprints for fingerprints that had been treated with powders and also subsequently lifted with adhesive tapes. Samples of seized ecstasy, cocaine, ketamine and amphetamine were supplied by East Sussex Police and by the TICTAC unit at St. Georges Hospital Tooting. Contaminated fingerprints were deposited on clean glass slides. The application of aluminium or iron based powders to contaminated fingerprints did not interfere with the Raman spectra obtained for the contaminants. Contaminated fingerprints developed with powders and then lifted with lifting tapes were also examined. The combination of these two techniques did not interfere with the successful analysis. The lifting process was repeated using hinge lifters. As the hinge lifters exhibited strong Raman bands the spectroscopic analysis was more complex and an increase in the number of exposures to the detector allowed for improved clarification. Spectral subtraction was performed to remove peaks due to the hinge lifters using OMNIC software. Raman spectra of developed and lifted fingerprints recorded through evidence bags were obtained and it was found that the detection process was not compromised. Although the application of powders did not interfere with the detection process the time taken to locate the contaminant was increased due to the physical presence of more material within the fingerprint.

The spectroscopic detection of drugs of abuse in fingerprints after development with powders and recovery with adhesive lifters.

PubMed

West, Matthew J; Went, Michael J

2009-01-01

The application of powders to fingerprints has long been established as an effective and reliable method for developing latent fingerprints. Fingerprints developed in situ at a crime scene routinely undergo lifting with specialist tapes and are then stored in evidence bags to allow secure transit and also to preserve the chain of evidence. In a previous study we have shown that exogenous material within a fingerprint can be detected using Raman spectroscopy following development with powders and lifting with adhesive tapes. Other reports have detailed the use of Raman spectroscopy to the detection of drugs of abuse in latent fingerprints including cyanoacrylate-fumed fingerprints. This study involves the application of Raman spectroscopy for the analysis of drugs of abuse in latent fingerprints for fingerprints that had been treated with powders and also subsequently lifted with adhesive tapes. Samples of seized ecstasy, cocaine, ketamine and amphetamine were supplied by East Sussex Police and by the TICTAC unit at St. Georges Hospital Tooting. Contaminated fingerprints were deposited on clean glass slides. The application of aluminium or iron based powders to contaminated fingerprints did not interfere with the Raman spectra obtained for the contaminants. Contaminated fingerprints developed with powders and then lifted with lifting tapes were also examined. The combination of these two techniques did not interfere with the successful analysis. The lifting process was repeated using hinge lifters. As the hinge lifters exhibited strong Raman bands the spectroscopic analysis was more complex and an increase in the number of exposures to the detector allowed for improved clarification. Spectral subtraction was performed to remove peaks due to the hinge lifters using OMNIC software. Raman spectra of developed and lifted fingerprints recorded through evidence bags were obtained and it was found that the detection process was not compromised. Although the application of powders did not interfere with the detection process the time taken to locate the contaminant was increased due to the physical presence of more material within the fingerprint.

Solid-state studies and antioxidant properties of the γ-cyclodextrin·fisetin inclusion compound.

PubMed

Pais, Joana M; Barroca, Maria João; Marques, Maria Paula M; Almeida Paz, Filipe A; Braga, Susana S

2017-01-01

Fisetin is a natural antioxidant with a wide range of nutraceutical properties, including antidiabetic, neuroprotecting, and suppression or prevention of tumors. The present work describes the preparation of a water-soluble, solid inclusion compound of fisetin with gamma-cyclodextrin (γ-CD), a cyclic oligosaccharide approved for human consumption. A detailed physicochemical analysis of the product is carried out using elemental analysis, powder X-ray diffraction (PXRD), Raman, infrared and 13 C{ 1 H} CP-MAS NMR spectroscopies, and thermal analysis (TGA) to verify fisetin inclusion and to present a hypothetical structural arrangement for the host-guest units. The antioxidant activity of the γ-CD·fisetin inclusion compound is evaluated by the DPPH assay.

Nanoparticles of wurtzite aluminum nitride from the nut shells

NASA Astrophysics Data System (ADS)

Qadri, S. B.; Gorzkowski, E. P.; Rath, B. B.; Feng, C. R.; Amarasinghe, R.

2016-11-01

Nanoparticles of aluminum nitride were produced from a thermal treatment of a mixture of aluminum oxide (Al2O3) and shells of almond, cashew, coconuts, pistachio, and walnuts in a nitrogen atmosphere at temperatures in excess of 1450 °C. By selecting the appropriate ratios of each nut powder to Al2O3, it is shown that stoichiometric aluminum nitride can be produced by carbo-thermal reduction in nitrogen atmosphere. Using x-ray diffraction analysis, Raman scattering and Fourier Transform Infrared spectroscopy, it is demonstrated that aluminum nitride consists of pure wurtzite phase. Transmission electron microscopy showed the formation of nanoparticles and in some cases nanotubes of AlN.

Synthesis and Characterization of YVO4-Based Phosphor Doped with Eu3+ Ions for Display Devices

NASA Astrophysics Data System (ADS)

Thakur, Shashi; Gathania, Arvind K.

2015-10-01

YVO4:Eu nanophosphor has been synthesized by the sol-gel method. Samples were characterized by x-ray diffraction (XRD), energy-dispersive x-ray spectroscopy, Fourier-transform infrared spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, photoluminescence, and Raman spectroscopy. The XRD profile confirms the tetragonal phase of the Eu3+-doped YVO4 nanophosphor. The efficiency of the prepared phosphor was analyzed by means of its emission spectral profile. We also observed rich red emission from the prepared phosphor on excitation by an ultraviolet source. The calculated Commission International de l'Éclairage coordinates reveal excellent color purity efficiency. Such luminescent powder is useful as red phosphor in display device applications.

Periodic Density Functional Theory Study of the Structure, Raman Spectrum, and Mechanical Properties of Schoepite Mineral.

PubMed

Colmenero, Francisco; Cobos, Joaquín; Timón, Vicente

2018-04-16

The structure and Raman spectrum of schoepite mineral, [(UO 2 ) 8 O 2 (OH) 12 ]·12H 2 O, was studied by means of theoretical calculations. The computations were carried out by using density functional theory with plane waves and pseudopotentials. A norm-conserving pseudopotential specific for the U atom developed in a previous work was employed. Because it was not possible to locate H atoms directly from X-ray diffraction (XRD) data by structure refinement in previous experimental studies, all of the positions of the H atoms in the full unit cell were determined theoretically. The structural results, including the lattice parameters, bond lengths, bond angles, and powder XRD pattern, were found to be in good agreement with their experimental counterparts. However, the calculations performed using the unit cell designed by Ostanin and Zeller in 2007, involving half of the atoms of the full unit cell, led to significant errors in the computed powder XRD pattern. Furthermore, Ostanin and Zeller's unit cell contains hydronium ions, H 3 O + , which are incompatible with the experimental information. Therefore, while the use of this schoepite model may be a very useful approximation requiring a much smaller amount of computational effort, the full unit cell should be used to study this mineral accurately. The Raman spectrum was also computed by means of density functional perturbation theory and compared with the experimental spectrum. The results were also in agreement with the experimental data. A normal-mode analysis of the theoretical spectra was performed to assign the main bands of the Raman spectrum. This assignment significantly improved the current empirical assignment of the bands of the Raman spectrum of schoepite mineral. In addition, the equation of state and elastic properties of this mineral were determined. The crystal structure of schoepite was found to be stable mechanically and dynamically. Schoepite can be described as a brittle material exhibiting small anisotropy and large compressibility in the direction perpendicular to the layers, which characterize its structure. The calculated bulk modulus, B, was ∼35 GPa.

A fast-reliable methodology to estimate the concentration of rutile or anatase phases of TiO2

NASA Astrophysics Data System (ADS)

Zanatta, A. R.

2017-07-01

Titanium-dioxide (TiO2) is a low-cost, chemically inert material that became the basis of many modern applications ranging from, for example, cosmetics to photovoltaics. TiO2 exists in three different crystal phases - Rutile, Anatase and, less commonly, Brookite - and, in most of the cases, the presence or relative amount of these phases are essential to decide the TiO2 final application and its related efficiency. Traditionally, X-ray diffraction has been chosen to study TiO2 and provides both the phases identification and the Rutile-to-Anatase ratio. Similar information can be achieved from Raman scattering spectroscopy that, additionally, is versatile and involves rather simple instrumentation. Motivated by these aspects this work took into account various TiO2 Rutile+Anatase powder mixtures and their corresponding Raman spectra. Essentially, the method described here was based upon the fact that the Rutile and Anatase crystal phases have distinctive phonon features, and therefore, the composition of the TiO2 mixtures can be readily assessed from their Raman spectra. The experimental results clearly demonstrate the suitability of Raman spectroscopy in estimating the concentration of Rutile or Anatase in TiO2 and is expected to influence the study of TiO2-related thin films, interfaces, systems with reduced dimensions, and devices like photocatalytic and solar cells.

Increasing hydrogen storage capacity using tetrahydrofuran.

PubMed

Sugahara, Takeshi; Haag, Joanna C; Prasad, Pinnelli S R; Warntjes, Ashleigh A; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A

2009-10-21

Hydrogen hydrates with tetrahydrofuran (THF) as a promoter molecule are investigated to probe critical unresolved observations regarding cage occupancy and storage capacity. We adopted a new preparation method, mixing solid powdered THF with ice and pressurizing with hydrogen at 70 MPa and 255 +/- 2 K (these formation conditions are insufficient to form pure hydrogen hydrates). All results from Raman microprobe spectroscopy, powder X-ray diffraction, and gas volumetric analysis show a strong dependence of hydrogen storage capacity on THF composition. Contrary to numerous recent reports that claim it is impossible to store H(2) in large cages with promoters, this work shows that, below a THF mole fraction of 0.01, H(2) molecules can occupy the large cages of the THF+H(2) structure II hydrate. As a result, by manipulating the promoter THF content, the hydrogen storage capacity was increased to approximately 3.4 wt % in the THF+H(2) hydrate system. This study shows the tuning effect may be used and developed for future science and practical applications.

Anatase/rutile bi-phasic titanium dioxide nanoparticles for photocatalytic applications enhanced by nitrogen doping and platinum nano-islands.

PubMed

Bear, Joseph C; Gomez, Virginia; Kefallinos, Nikolaos S; McGettrick, James D; Barron, Andrew R; Dunnill, Charles W

2015-12-15

Titanium dioxide (TiO2) bi-phasic powders with individual particles containing an anatase and rutile hetero-junction have been prepared using a sequential layer sol-gel deposition technique to soluble substrates. Sequential thin films of rutile and subsequently anatase TiO2 were deposited onto sodium chloride substrates yielding extremely fragile composite layered discs that fractured into "Janus-like" like powders on substrate dissolution. Nitrogen doped and platinum sputtered analogues were also prepared, and analysed for photocatalytic potential using the photodegradation of Rhodamine B, a model organic pollutant under UV and visible light irradiation. The materials were characterised using X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy and scanning electron microscopy. This paper sheds light on the relationship between anatase and rutile materials when in direct contact and demonstrates a robust method for the synthesis of bi-phasic nanoparticles, ostensibly of any two materials, for photocatalytic reactions or otherwise. Copyright © 2015 Elsevier Inc. All rights reserved.

Sulvanite (Cu 3VS 4) nanocrystals for printable thin film photovoltaics

DOE PAGES

Chen, Ching -Chin; Stone, Kevin H.; Lai, Cheng -Yu; ...

2017-09-21

Copper Vanadium Sulfide (Cu 3VS 4), also known as sulvanite, has recently emerged as a suitable absorber material for thin film photovoltaics. The synthesis of Cu 3VS 4 nanocrystals via a rapid solvothermal route is reported for the first time. The phase purity of the Cu 3VS 4 nanocrystals has been confirmed by X-ray powder diffraction (XRD) and Raman spectroscopy, while the nanoparticle size, of about 10 nm, was evaluated by transmission electron microscopy (TEM). Successful ligand exchange with sulfide, an inorganic ligand, demonstrated that the nanoparticles are amenable to surface modifications, key element in solution processing. Further annealing ofmore » as-synthesized nanocrystals under a sulfur/argon atmosphere at 600 °C, rendered highly crystalline Cu 3VS 4 powders exhibiting an impurity that could be potentially mitigated by annealing temperature optimization. Furthermore, Cu 3VS 4, formed solely from Earth-abundant elements, could provide an inexpensive, reliable approach to fabricating solution processed thin film photovoltaic absorbers.« less

MoS2 thin films prepared by sulfurization

NASA Astrophysics Data System (ADS)

Sojková, M.; Chromik, Å.; Rosová, A.; Dobročka, E.; Hutár, P.; Machajdík, D.; Kobzev, A. P.; Hulman, M.

2017-08-01

Sulfurization of a Mo layer is one of the most used methods for preparation of thin MoS2 films. In the method, a sulfur powder and Mo covered substrate are placed in different positions within a furnace, and heated separately. This requires a furnace having at least two zones. Here, we present a simplified version of the method where a one-zone tube furnace was used. A molybdenum film on a substrate and a sulfur powder were placed in the center of the furnace and heated at temperatures above 800°C. Mo films transform into MoS2 in vapors of sulphur at high temperatures. As-prepared films were characterized by number of techniques including X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman, Rutherford backscattering (RBS) and X-ray photoelectron spectroscopy (XPS). It appears that one-zone sulfurization, with just one annealing temperature used, is a suitable method for fabrication of MoS2 thin films. This method is fast, cheap and easy to scale up.

Boron-doped diamond synthesized at high-pressure and high-temperature with metal catalyst

NASA Astrophysics Data System (ADS)

Shakhov, Fedor M.; Abyzov, Andrey M.; Kidalov, Sergey V.; Krasilin, Andrei A.; Lähderanta, Erkki; Lebedev, Vasiliy T.; Shamshur, Dmitriy V.; Takai, Kazuyuki

2017-04-01

The boron-doped diamond (BDD) powder consisting of 40-100 μm particles was synthesized at 5 GPa and 1500-1600 °C from a mixture of 50 wt% graphite and 50 wt% Ni-Mn catalyst with an addition of 1 wt% or 5 wt% boron powder. The size of crystal domains of doped and non-doped diamond was evaluated as a coherent scattering region by X-ray diffraction (XRD) and using small-angle neutron scattering (SANS), being ≥180 nm (XRD) and 100 nm (SANS). Magnetic impurities of NiMnx originating from the catalyst in the synthesis, which prevent superconductivity, were detected by magnetization measurements at 2-300 K. X-ray photoelectron spectroscopy, the temperature dependence of the resistivity, XRD, and Raman spectroscopy reveal that the concentration of electrically active boron is as high as (2±1)×1020 cm-3 (0.1 at%). To the best of our knowledge, this is the highest boron content for BDD synthesized in high-pressure high-temperature process with metal catalysts.

The synthesis of ternary acetylides with tellurium: Li 2 TeC 2 and Na 2 TeC 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Németh, Károly; Unni, Aditya K.; Kalnmals, Christopher

The synthesis of ternary acetylides Li 2TeC 2 and Na 2TeC 2 is presented as the first example of ternary acetylides with metalloid elements instead of transition metals. The synthesis was carried out by the direct reaction of the corresponding bialkali acetylides with tellurium powder in liquid ammonia. Alternatively, the synthesis of Na 2TeC 2 was also carried out by the direct reaction of tellurium powder and two equivalents of NaC 2H in liquid ammonia leading to Na 2TeC 2 and acetylene gas through an equilibrium containing the assumed NaTeC 2H molecules besides the reactants and the products. The resultingmore » disordered crystalline materials were characterized by X-ray diffraction and Raman spectroscopy. Implications of these new syntheses on the synthesis of other ternary acetylides with metalloid elements and transition metals are also discussed.« less

Sulvanite (Cu 3VS 4) nanocrystals for printable thin film photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Ching -Chin; Stone, Kevin H.; Lai, Cheng -Yu

Copper Vanadium Sulfide (Cu 3VS 4), also known as sulvanite, has recently emerged as a suitable absorber material for thin film photovoltaics. The synthesis of Cu 3VS 4 nanocrystals via a rapid solvothermal route is reported for the first time. The phase purity of the Cu 3VS 4 nanocrystals has been confirmed by X-ray powder diffraction (XRD) and Raman spectroscopy, while the nanoparticle size, of about 10 nm, was evaluated by transmission electron microscopy (TEM). Successful ligand exchange with sulfide, an inorganic ligand, demonstrated that the nanoparticles are amenable to surface modifications, key element in solution processing. Further annealing ofmore » as-synthesized nanocrystals under a sulfur/argon atmosphere at 600 °C, rendered highly crystalline Cu 3VS 4 powders exhibiting an impurity that could be potentially mitigated by annealing temperature optimization. Furthermore, Cu 3VS 4, formed solely from Earth-abundant elements, could provide an inexpensive, reliable approach to fabricating solution processed thin film photovoltaic absorbers.« less

The Powder Diffraction File: Past, Present, and Future

PubMed Central

Smith, Deane K.; Jenkins, Ron

1996-01-01

The Powder Diffraction file has been the primary reference for Powder Diffraction Data for more than half a century. The file is a collection of about 65 000 reduced powder patterns stored as sets of d/I data along with the appropriate crystallographic, physical and experimental information. This paper reviews the development and growth of the PDF and discusses the role of the ICDD in the maintenance and dissemination of the file. PMID:27805163

Determination of cellulose crystallinity from powder diffraction diagrams: Powder Diffraction Diagrams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lindner, Benjamin; Petridis, Loukas; Langan, Paul

2014-10-01

Commonly one-dimensional (1D) (spherically averaged) powder diffraction diagrams are used to determine the degree of cellulose crystallinity in biomass samples. Here, it is shown using molecular modeling how disorder in cellulose fibrils can lead to considerable uncertainty in conclusions drawn concerning crystallinity based on 1D powder diffraction data alone. For example, cellulose microfibrils that contain both crystalline and noncrystalline segments can lead to powder diffraction diagrams lacking identifiable peaks, while microfibrils without any crystalline segments can lead to such peaks. Moreover, this leads to false positives, that is, assigning disordered cellulose as crystalline, and false negatives, that is, categorizing fibrilsmore » with crystalline segments as amorphous. Finally, the reliable determination of the fraction of crystallinity in any given biomass sample will require a more sophisticated approach combining detailed experiment and simulation.« less

Calibration and testing of a Raman hyperspectral imaging system to reveal powdered food adulteration

PubMed Central

Lohumi, Santosh; Lee, Hoonsoo; Kim, Moon S.; Qin, Jianwei; Kandpal, Lalit Mohan; Bae, Hyungjin; Rahman, Anisur

2018-01-01

The potential adulteration of foodstuffs has led to increasing concern regarding food safety and security, in particular for powdered food products where cheap ground materials or hazardous chemicals can be added to increase the quantity of powder or to obtain the desired aesthetic quality. Due to the resulting potential health threat to consumers, the development of a fast, label-free, and non-invasive technique for the detection of adulteration over a wide range of food products is necessary. We therefore report the development of a rapid Raman hyperspectral imaging technique for the detection of food adulteration and for authenticity analysis. The Raman hyperspectral imaging system comprises of a custom designed laser illumination system, sensing module, and a software interface. Laser illumination system generates a 785 nm laser line of high power, and the Gaussian like intensity distribution of laser beam is shaped by incorporating an engineered diffuser. The sensing module utilize Rayleigh filters, imaging spectrometer, and detector for collection of the Raman scattering signals along the laser line. A custom-built software to acquire Raman hyperspectral images which also facilitate the real time visualization of Raman chemical images of scanned samples. The developed system was employed for the simultaneous detection of Sudan dye and Congo red dye adulteration in paprika powder, and benzoyl peroxide and alloxan monohydrate adulteration in wheat flour at six different concentrations (w/w) from 0.05 to 1%. The collected Raman imaging data of the adulterated samples were analyzed to visualize and detect the adulterant concentrations by generating a binary image for each individual adulterant material. The results obtained based on the Raman chemical images of adulterants showed a strong correlation (R>0.98) between added and pixel based calculated concentration of adulterant materials. This developed Raman imaging system thus, can be considered as a powerful analytical technique for the quality and authenticity analysis of food products. PMID:29708973

Calibration and testing of a Raman hyperspectral imaging system to reveal powdered food adulteration.

PubMed

Lohumi, Santosh; Lee, Hoonsoo; Kim, Moon S; Qin, Jianwei; Kandpal, Lalit Mohan; Bae, Hyungjin; Rahman, Anisur; Cho, Byoung-Kwan

2018-01-01

The potential adulteration of foodstuffs has led to increasing concern regarding food safety and security, in particular for powdered food products where cheap ground materials or hazardous chemicals can be added to increase the quantity of powder or to obtain the desired aesthetic quality. Due to the resulting potential health threat to consumers, the development of a fast, label-free, and non-invasive technique for the detection of adulteration over a wide range of food products is necessary. We therefore report the development of a rapid Raman hyperspectral imaging technique for the detection of food adulteration and for authenticity analysis. The Raman hyperspectral imaging system comprises of a custom designed laser illumination system, sensing module, and a software interface. Laser illumination system generates a 785 nm laser line of high power, and the Gaussian like intensity distribution of laser beam is shaped by incorporating an engineered diffuser. The sensing module utilize Rayleigh filters, imaging spectrometer, and detector for collection of the Raman scattering signals along the laser line. A custom-built software to acquire Raman hyperspectral images which also facilitate the real time visualization of Raman chemical images of scanned samples. The developed system was employed for the simultaneous detection of Sudan dye and Congo red dye adulteration in paprika powder, and benzoyl peroxide and alloxan monohydrate adulteration in wheat flour at six different concentrations (w/w) from 0.05 to 1%. The collected Raman imaging data of the adulterated samples were analyzed to visualize and detect the adulterant concentrations by generating a binary image for each individual adulterant material. The results obtained based on the Raman chemical images of adulterants showed a strong correlation (R>0.98) between added and pixel based calculated concentration of adulterant materials. This developed Raman imaging system thus, can be considered as a powerful analytical technique for the quality and authenticity analysis of food products.

Optical Characterization of Lead Monoxide Films Grown by Laser-Assisted Deposition

NASA Astrophysics Data System (ADS)

Baleva, M.; Tuncheva, V.

1994-05-01

The Raman spectra of PbO films, grown by laser-assisted deposition (LAD) at different substrate temperatures are investigated. The spectra of the films, deposited on amorphous, single crystal quartz and polycrystal PbTe substrates, are compared with the Raman spectra of tetragonal and orthorhombic powder samples. The phonon frequencies determined in our experiment with powder samples coincide fairly well with those obtained by Adams and Stevens, J. Chem. Soc., Dalton Trans., 1096 (1977). Thus the Raman spectra of the powder samples presented in this paper can be considered as unambiguous characteristics of the two different PbO crystal phases. It was concluded that the Raman scattering may serve as a tool for identification of PbO films and their crystal modifications. On the basis of this investigation it was concluded that the film structure changes from orthorhombic to tetragonal with increased substrate temperature, and that the nature of the substrate influences the crystal structure of the films. On the basis of the Raman spectra of the β-PbO films with prevailing (001) orientation of crystallization, an assignment of the modes is proposed.

In situ monitoring of powder blending by non-invasive Raman spectrometry with wide area illumination.

PubMed

Allan, Pamela; Bellamy, Luke J; Nordon, Alison; Littlejohn, David; Andrews, John; Dallin, Paul

2013-03-25

A 785nm diode laser and probe with a 6mm spot size were used to obtain spectra of stationary powders and powders mixing at 50rpm in a high shear convective blender. Two methods of assessing the effect of particle characteristics on the Raman sampling depth for microcrystalline cellulose (Avicel), aspirin or sodium nitrate were compared: (i) the information depth, based on the diminishing Raman signal of TiO(2) in a reference plate as the depth of powder prior to the plate was increased, and (ii) the depth at which a sample became infinitely thick, based on the depth of powder at which the Raman signal of the compound became constant. The particle size, shape, density and/or light absorption capability of the compounds were shown to affect the "information" and "infinitely thick" depths of individual compounds. However, when different sized fractions of aspirin were added to Avicel as the main component, the depth values of aspirin were the same and matched that of the Avicel: 1.7mm for the "information" depth and 3.5mm for the "infinitely thick" depth. This latter value was considered to be the minimum Raman sampling depth when monitoring the addition of aspirin to Avicel in the blender. Mixing profiles for aspirin were obtained non-invasively through the glass wall of the vessel and could be used to assess how the aspirin blended into the main component, identify the end point of the mixing process (which varied with the particle size of the aspirin), and determine the concentration of aspirin in real time. The Raman procedure was compared to two other non-invasive monitoring techniques, near infrared (NIR) spectrometry and broadband acoustic emission spectrometry. The features of the mixing profiles generated by the three techniques were similar for addition of aspirin to Avicel. Although Raman was less sensitive than NIR spectrometry, Raman allowed compound specific mixing profiles to be generated by studying the mixing behaviour of an aspirin-aspartame-Avicel mixture. Copyright © 2013 Elsevier B.V. All rights reserved.

Studies on Optical and Electrical Properties of Hafnium Oxide Nanoparticles

NASA Astrophysics Data System (ADS)

Jayaraman, Venkatachalam; Sagadevan, Suresh; Sudhakar, Rajesh

2017-07-01

In this paper, the synthesis and physico-chemical properties of hafnium oxide nanoparticles (HfO2 NPs) are analyzed and reported. The synthesis was carried out by the precipitation route by using hafnium tetrachloride (HfCl4) as precursor material with potassium hydroxide (KOH) dissolved in Millipore water. In the precipitation technique, the chemical reaction is comparatively simple, low-cost and non-toxic compared to other synthetic methods. The synthesized HfO2 NPs were characterized by using powder x-ray diffraction (PXRD), ultraviolet-visible (UV-Vis) spectroscopy, Raman analysis, and high-resolution transmission electron microscopy (HRTEM). The monoclinic structure of the HfO2 NPs was resolved utilizing x-ray diffraction (XRD). The optical properties were studied from the UV-Vis absorption spectrum. The optical band gap of the HfO2NPs was observed to be 5.1 eV. The Raman spectrum shows the presence of HfO2 NPs. The HRTEM image showed that the HfO2 NPs were of spherical shape with an average particle size of around 28 nm. The energy-dispersive x-ray spectroscopy (EDS) spectrum obviously demonstrated the presence of HfO2 NPs. Analysis and studies on the dielectric properties of the HfO2 NPs such as the dielectric constant, the dielectric loss, and alternating current (AC) conductivity were carried out at varying frequencies and temperatures.

Experimental and first-principles calculation study of the pressure-induced transitions to a metastable phase in GaP O4 and in the solid solution AlP O4-GaP O4

NASA Astrophysics Data System (ADS)

Angot, E.; Huang, B.; Levelut, C.; Le Parc, R.; Hermet, P.; Pereira, A. S.; Aquilanti, G.; Frapper, G.; Cambon, O.; Haines, J.

2017-08-01

α -Quartz-type gallium phosphate and representative compositions in the AlP O4-GaP O4 solid solution were studied by x-ray powder diffraction and absorption spectroscopy, Raman scattering, and by first-principles calculations up to pressures of close to 30 GPa. A phase transition to a metastable orthorhombic high-pressure phase along with some of the stable orthorhombic C m c m CrV O4 -type material is found to occur beginning at 9 GPa at 320 ∘C in GaP O4 . In the case of the AlP O4-GaP O4 solid solution at room temperature, only the metastable orthorhombic phase was obtained above 10 GPa. The possible crystal structures of the high-pressure forms of GaP O4 were predicted from first-principles calculations and the evolutionary algorithm USPEX. A predicted orthorhombic structure with a P m n 21 space group with the gallium in sixfold and phosphorus in fourfold coordination was found to be in the best agreement with the combined experimental data from x-ray diffraction and absorption and Raman spectroscopy. This method is found to very powerful to better understand competition between different phase transition pathways at high pressure.

Coordination trends in alkali metal crown ether uranyl halide complexes: the series [A(crown)]2[UO(2)X(4)] where A=Li, Na, K and X=Cl, Br.

PubMed

Danis, J A; Lin, M R; Scott, B L; Eichhorn, B W; Runde, W H

2001-07-02

UO(2)(C(2)H(3)O(2))(2).2H(2)O reacts with AX or A(C(2)H(3)O(2) or ClO(4)) (where A = Li, Na, K; X = Cl, Br) and crown ethers in HCl or HBr aqueous solutions to give the sandwich-type compounds [K(18-crown-6)](2)[UO(2)Cl(4)] (1), [K(18-crown-6)](2)[UO(2)Br(4)] (2), [Na(15-crown-5)](2)[UO(2)Cl(4)] (3), [Na(15-crown-5)](2)[UO(2)Br(4)] (4), [Li(12-crown-4)](2)[UO(2)Cl(4)] (5), and [Li(12-crown-4)](2)[UO(2)Br(4)] (6). The compounds have been characterized by single-crystal X-ray diffraction, powder diffraction, elemental analysis, IR, and Raman spectroscopy. The [UO(2)X(4)](2-) ions coordinate to two [A(crown)](+) cations through the four halides only (2), through two halides only (3), through the two uranyl oxygens and two halides (3, 4), or through the two uranyl oxygen atoms only (5, 6). Raman spectra reveal nu(U-O) values that correlate with expected trends. The structural trends are discussed within the context of classical principles of hard-soft acid-base theory.

Temperature dependent Raman spectroscopy of melamine and structural analogs in milk powder

USDA-ARS?s Scientific Manuscript database

Hyperspectral Raman imaging has the potential for rapid screening of solid-phase samples for potential adulterants. We found that the Raman spectra of melamine analogs changed dramatically and uniquely as a function of elevated temperature. Raman spectra were acquired for urea, biuret, cyanuric acid...

Asymmetric diffraction by atomic gratings with optical PT symmetry in the Raman-Nath regime

NASA Astrophysics Data System (ADS)

Shui, Tao; Yang, Wen-Xing; Liu, Shaopeng; Li, Ling; Zhu, Zhonghu

2018-03-01

We propose and analyze an efficient scheme for the lopsided Raman-Nath diffraction of one-dimensional (1 D ) and two-dimensional (2 D ) atomic gratings with periodic parity-time (PT )-symmetric refractive index. The atomic grating is constructed by the cold-atomic vapor with two isotopes of rubidium, which is driven by weak probe field and space-dependent control field. Using experimentally achievable parameters, we identify the conditions under which PT -symmetric refractive index allows us to observe the lopsided Raman-Nath diffraction phenomenon and improve the diffraction efficiencies beyond what is achievable in a conventional atomic grating. The nontrivial atomic grating is a superposition of an amplitude grating and a phase grating. It is found that the lopsided Raman-Nath diffraction at the exceptional point (EP) of PT -symmetric grating originates from constructive and destructive interferences between the amplitude and phase gratings. Furthermore, we show that the PT -phase transition from unbroken to broken PT -symmetric regimes can modify the asymmetric distribution of the diffraction spectrum and that the diffraction efficiencies in the non-negative diffraction orders can be significantly enhanced when the atomic grating is pushed into a broken PT -symmetric phase. In addition, we also analyze the influence of the grating thickness on the diffraction spectrum. Our scheme may provide the possibility to design a gain-beam splitter with tunable splitting ratio and other optical components in integrated optics.

A Spatially Offset Raman Spectroscopy Method for Non-Destructive Detection of Gelatin-Encapsulated Powders

PubMed Central

Chao, Kuanglin; Dhakal, Sagar; Qin, Jianwei; Peng, Yankun; Schmidt, Walter F.; Kim, Moon S.; Chan, Diane E.

2017-01-01

Non-destructive subsurface detection of encapsulated, coated, or seal-packaged foods and pharmaceuticals can help prevent distribution and consumption of counterfeit or hazardous products. This study used a Spatially Offset Raman Spectroscopy (SORS) method to detect and identify urea, ibuprofen, and acetaminophen powders contained within one or more (up to eight) layers of gelatin capsules to demonstrate subsurface chemical detection and identification. A 785-nm point-scan Raman spectroscopy system was used to acquire spatially offset Raman spectra for an offset range of 0 to 10 mm from the surfaces of 24 encapsulated samples, using a step size of 0.1 mm to obtain 101 spectral measurements per sample. As the offset distance was increased, the spectral contribution from the subsurface powder gradually outweighed that of the surface capsule layers, allowing for detection of the encapsulated powders. Containing mixed contributions from the powder and capsule, the SORS spectra for each sample were resolved into pure component spectra using self-modeling mixture analysis (SMA) and the corresponding components were identified using spectral information divergence values. As demonstrated here for detecting chemicals contained inside thick capsule layers, this SORS measurement technique coupled with SMA has the potential to be a reliable non-destructive method for subsurface inspection and authentication of foods, health supplements, and pharmaceutical products that are prepared or packaged with semi-transparent materials. PMID:28335453

Pressure-Induced Polymerization of LiN(CN) 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keefer, Derek W.; Gou, Huiyang; Purdy, Andrew P.

The high-pressure behavior of lithium dicyanamide (LiN(CN) 2) was studied with in situ Raman and infrared (IR) spectroscopies, and synchrotron angle-dispersive powder X-ray diffraction (PXRD) in a diamond anvil cell (DAC) to 22 GPa. The fundamental vibrational modes associated with molecular units were assigned using a combination of experimental data and density functional perturbation theory. Some low-frequency modes were observed for the first time. On the basis of spectroscopic and diffraction data, we suggest a polymorphic phase transformation at ~8 GPa, wherein dicyanamide ions remain as discrete molecular species. Above ca. 18 GPa, dicyanamide units polymerize, forming a largely disorderedmore » network, and the extent of polymerization may be increased by annealing at elevated temperature. The polymerized product consists of tricyanomelaminate-like groups containing sp 2-hybidized carbon–nitrogen bonds and exhibits a visible absorption edge near 540 nm. The product is recoverable to ambient conditions but is not stable in air/moisture.« less

Ultrasonic irradiation-assisted synthesis of Bi2S3 nanoparticles in aqueous ionic liquid at ambient condition.

PubMed

de la Parra-Arciniega, Salomé M; Garcia-Gomez, Nora A; Garza-Tovar, Lorena L; García-Gutiérrez, Domingo I; Sánchez, Eduardo M

2017-05-01

In this work, an easy, fast and environmentally friendly method to obtain Bi 2 S 3 nanostructures with sphere-like morphology is introduced. The promising material was successfully synthesized by a sonochemical route in 20% 1-ethyl-3-methylimidazolium ethyl sulfate [EMIM][EtSO 4 ] ionic liquid solution (IL). Morphological studies by electron microscopy (SEM and TEM) show that the use of IL in the synthesis of Bi 2 S 3 favors the formation of nanocrystals non-agglomerated. Micro Raman and energy dispersive X-ray spectroscopy (EDXS) were used to determine the composition and purity of the synthesized material. X-ray powder diffraction (XRD) and selective area electron diffraction (SAED) revealed that ultrasonic radiation accelerated the crystallization of Bi 2 S 3 into orthorhombic bismuthinite structure. The band gap calculated from the diffuse reflectance spectra (DRS) was found to be 1.5eV. Copyright © 2016 Elsevier B.V. All rights reserved.

Pb 2MnTeO 6 Double Perovskite: An Antipolar Anti-ferromagnet

DOE PAGES

Retuerto, Maria; Skiadopoulou, Stella; Li, Man-Rong; ...

2016-04-08

Pb 2MnTeO 6, a new double perovskite, has been synthesized. Its crystal structure was determined by synchrotron X-ray and powder neutron diffraction.Pb 2MnTeO 6 is monoclinic (I2/m) at room temperature with a regular arrangement of all the cations in their polyhedra. However, when the temperature is lowered to ~120 K it undergoes a phase transition from I2/m to C2/c structure. This transition is accompanied by a displacement of the Pb atoms from the center of their polyhedra due to the 6s 2 lone-pair electrons, together with a surprising off-centering of Mn 2+ (d 5) magnetic cations. This strong first-order phasemore » transition is also evidenced by specific heat, dielectric, Raman, and infrared spectroscopy measurements. The magnetic characterizations indicate an anti-ferromagnetic (AFM) order below T N ≈ 20 K; analysis of powder neutron diffraction data confirms the magnetic structure with propagation vector k = (0 1 0) and collinear AFM spins. The observed jump in dielectric permittivity near ~150 K implies possible anti-ferroelectric behavior; however, the absence of switching suggests that Pb 2MnTeO 6 can only be antipolar. First-principle calculations confirmed that the crystal and magnetic structures determined are locally stable and that anti-ferroelectric switching is unlikely to be observed in Pb 2MnTeO 6.« less

Solid state vibrational spectroscopy of anhydrous lithium hexafluorophosphate (LiPF6)

NASA Astrophysics Data System (ADS)

Kock, L. D.; Lekgoathi, M. D. S.; Crouse, P. L.; Vilakazi, B. M.

2012-10-01

Raman and infrared studies of solid anhydrous lithium hexafluorophosphate (LiPF6) have been carried out. The studies were complemented by X-ray powder diffraction (XRD) and Thermogravimetric (TG) analysis techniques. The results indicate that when solid LiPF6 is studied in a strictly anhydrous environment, more consistent thermal stability data can be obtained. TG analysis, using a scan rate of 10 °C min-1, indicate the onset of thermal decomposition of the anhydrous LiPF6 occurring at about 134.84 °C while the partially hydrolysed compound starts at 114.46 °C. The Raman spectra of anhydrous MPF6 (M = Li+, Na+ and K+) are best interpreted in terms of a cubic space group Fm3m(Ohs), (ZB = 1), giving rise to 21 vibrational modes (A1g(R)+Eg(R)+T1g+T2g(R)+3T1u(1R)+T2u) and as such, LiPF6 may be considered isostructural with NaPF6 and KPF6. Crystal symmetry distortions in the anhydrous LiPF6 give rise additional bands in the Raman spectrum due to T1u infrared active modes and the ν1 (A1g) Raman band appears in the infrared spectrum in violation of the mutual exclusion selection rule for centro-symmetric sites. When these observations are considered, the Raman spectrum of LiPF6 is similar to those of NaPF6 and KPF6, with observations of the expected shifts due to cation size and/or electronegativity effects.

Radiation-Induced Changes in Quartz, A Mineral Analog of Nuclear Power Plant Concrete Aggregates.

PubMed

Silva, Chinthaka M; Rosseel, Thomas M; Kirkegaard, Marie C

2018-03-19

Quartz single-crystal samples consisting of α-quartz crystal structure were neutron irradiated to fluences of 5 × 10 18 , 4 × 10 19 , and 2 × 10 20 n/cm 2 (E > 0.1 MeV) at two temperatures (52 and 95 °C). The changes in the α-quartz phase as a function of these two conditions (temperature and fluence) were studied using X-ray powder diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM), and the results acquired using these complementary techniques are presented in a single place for the first time. XRD studies showed that the lattice parameters of α-quartz increased with increasing neutron flux. The lattice growth was larger for the samples that were neutron irradiated at 52 °C than at 95 °C. Moreover, an amorphous content was determined in the quartz samples neutron irradiated at 4 × 10 19 n/cm 2 , with the greater amount being in the 52 °C irradiated sample. Complete amorphization of quartz was observed at a fluence of 2 × 10 20 n/cm 2 (E > 0.1 MeV) using XRD and confirmed by TEM characterization and Raman spectroscopic studies. The cause for α-quartz lattice expansion and sample amorphization was also explored using XRD and Raman spectroscopic studies.

Vibrational spectroscopic study, charge transfer interaction and nonlinear optical properties of L-asparaginium picrate: a density functional theoretical approach.

PubMed

Elleuch, Nabil; Amamou, Walid; Ben Ahmed, Ali; Abid, Younes; Feki, Habib

2014-07-15

Single crystals of L-asparaginium picrate (LASP) were grown by slow evaporation technique at room temperature and were the subject of an X-ray powder diffraction study to confirm the crystalline nature of the synthesized compound. FT-IR and Raman spectra were recorded and analyzed with the aid of the density functional theory (DFT) calculations in order to make a suitable assignment of the observed bands. The optimum molecular geometry, normal mode wavenumbers, infrared and Raman intensities and the first hyperpolarizability were investigated with the help of B3LYP method using 6-31G(d) basis set. The theoretical FT-IR and Raman spectra of LASP were simulated and compared with the experimental data. A good agreement was shown and a reliable vibrational assignment was made. Natural bond orbital (NBO) analysis was carried out to demonstrate the various inter and intramolecular interactions that are responsible for the stabilization of the title compound leading to high NLO activity. A study on the electronic properties was performed by time-dependent DFT (TD-DFT) approach. The lowering in the HOMO and LUMO energy gap explains the eventual charge transfer interactions that take place within the molecules. Copyright © 2014 Elsevier B.V. All rights reserved.

Optical and vibrational properties of PbSe nanoparticles synthesized in clinoptilolite

NASA Astrophysics Data System (ADS)

Flores-Valenzuela, J.; Cortez-Valadez, M.; Ramírez-Bon, R.; Arizpe-Chavez, H.; Román-Zamorano, J. F.; Flores-Acosta, M.

2015-08-01

In this work, the optical and vibrational properties of composites based on PbSe semiconductor immersed in a zeolite matrix are reported. The natural zeolite, (clinoptilolite) was used as the host material of PbSe nanoparticles. The method for obtaining these particles is also reported here, which is based on ion exchange processes inside the natural zeolite in alkaline aqueous solution that contains the precursor ions Pb2+ and Se2-. The process of synthesis was conducted temperature, volume, concentration and reaction time of the precursors. The samples were studied by powder X-ray diffraction, TEM (transmission electron microscopy), diffuse reflectance and Raman spectroscopy. The experimental results demonstrate that with this method, the particles with nanometric PbSe sizes were synthesized in the zeolite matrix. Vibrational Raman bands at low wave numbers were detected in these particles by the presence of a shoulder located at 135 cm-1 and a band at around 149 cm-1. The vibrational calculations for small clusters of PbSe at LSDA (Local Spin Density Approximation) level combined with the basis set LANDL2DZ (Los Alamos National Laboratory 2 double ζ), were considered through DFT (Density Functionl Theory). The "breathing" Raman modes located at 119-152 cm-1 were detected for this level of theory.

Occurrence and structural characterization of gas hydrates associated with a cold vent field, offshore Vancouver Island

NASA Astrophysics Data System (ADS)

Lu, Hailong; Moudrakovski, Igor; Riedel, Michael; Spence, George; Dutrisac, Regent; Ripmeester, John; Wright, Fred; Dallimore, Scott

2005-10-01

Gas hydrate samples recovered from a cold vent field offshore Vancouver Island were studied in detail both by macroscopic observations and instrumental methods (powder X-ray diffraction method (PXRD), nuclear magnetic resonance (NMR), and Raman spectroscopy). It was found that gas hydrates were massive from 2.64 to 2.94 m below seafloor (mbsf), elongated, nodular and tabular from 4.60 to 4.81 mbsf, and vein-like from 5.48 to 5.68 mbsf, showing a trend of decreasing hydrate content with increasing depth. All samples were determined to be structure I hydrate from PXRD, NMR, and Raman spectroscopies. The hydration numbers were estimated to be 6.1 ± 0.2 on average as determined from the methane distribution over the cage sites from NMR and Raman analytical results. Estimates of conversion levels indicated that ˜78% of the water in the massive samples was hydrate, down to a low value of ˜0.4% for the pore hydrate samples. The results are compared with measurements on synthetic hydrates and samples recovered from below the permafrost on the Mallik site. Differences in methane content and lattice parameters for synthetic and natural samples are relatively minor. Additional work is needed to address the presence of minor gas components and the heterogeneity of natural hydrate samples.

JCPDS-ICDD Research Associateship (Cooperative Program with NBS/NIST)

PubMed Central

Wong-Ng, W.; McMurdie, H. F.; Hubbard, C. R.; Mighell, A. D.

2001-01-01

The Research Associateship program of the Joint Committee on Powder Diffraction-International Centre for Diffraction Data (JCPDS-ICDD, now known as the ICDD) at NBS/NIST was a long standing (over 35 years) successful industry-government cooperation. The main mission of the Associateship was to publish high quality x-ray reference patterns to be included in the Powder Diffraction File (PDF). The PDF is a continuing compilation of patterns gathered from many sources, compiled and published by the ICDD. As a result of this collaboration, more than 1500 high quality powder diffraction patterns, which have had a significant impact on the scientific community, were reported. In addition, various research collaborations with NBS/NIST also led to the development of several standard reference materials (SRMs) for instrument calibration and quantitative analyses, and computer software for data collection, calibration, reduction, for the editorial process of powder pattern publication, analysis of powder data, and for quantitative analyses. This article summarizes information concerning the JCPDS-ICDD organization, the Powder Diffraction File (PDF), history and accomplishments of the JCPDS-ICDD Research Associateship. PMID:27500061

Synthesis, crystal structure and spectroscopy properties of Na 3AZr(PO 4) 3 ( A=Mg, Ni) and Li 2.6Na 0.4NiZr(PO 4) 3 phosphates

NASA Astrophysics Data System (ADS)

Chakir, M.; El Jazouli, A.; de Waal, D.

2006-06-01

Na 3AZr(PO 4) 3 ( A=Mg, Ni) phosphates were prepared at 750 °C by coprecipitation route. Their crystal structures have been refined at room temperature from X-ray powder diffraction data using Rietveld method. Li 2.6Na 0.4NiZr(PO 4) 3 was synthesized through ion exchange from the sodium analog. These materials belong to the Nasicon-type structure. Raman spectra of Na 3AZr(PO 4) 3 ( A=Mg, Ni) phosphates present broad peaks in favor of the statistical distribution in the sites around PO 4 tetrahedra. Diffuse reflectance spectra indicate the presence of octahedrally coordinated Ni 2+ ions.

Structural and optical studies of Mg doped nanoparticles of chromium oxide (Cr2O3) synthesized by co-precipitation method

NASA Astrophysics Data System (ADS)

Singh, Jarnail; Verma, Vikram; Kumar, Ravi

2018-04-01

We present here the synthesization, structural and optical studies of Mg doped nanoparticles of Chromium oxide (Cr2O3) prepared using co-precipitation method. These samples were characterized using powder X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Raman spectroscopy and UV-Vis spectroscopy techniques. We have demonstrated that there is negligible change in optical band gap with the Mg doping. The prepared Cr2O3 nanoparticles are spherical in shape, but they are transformed into platelets when doped with Mg. The XRD studies reveal that the Mg doping in Cr2O3 doesn't affect the structure of Chromium oxide (Cr2O3).

Formation of Nanodimensional 3C-SiC Structures from Rice Husks

NASA Astrophysics Data System (ADS)

Gorzkowski, E. P.; Qadri, S. B.; Rath, B. B.; Goswami, R.; Caldwell, J. D.

2013-05-01

We have demonstrated that large quantities of β-SiC nanostructures can be obtained from rice husk agricultural waste by using controlled conditions in a thermogravimetric setup. This simple and inexpensive method of producing these structures on a large scale is critical for applications in nanoelectronics, nanosensors, and biotechnology. The temperature and atmosphere are two critical elements in forming either α-cristobalite (SiO2) or β-SiC. Using different characterization methods (x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy), we have shown that pyrolysis of rice husks in argon atmosphere at 1375°C results in simultaneous formation of carbon nanotubes, β-SiC nanowires/nanorods, and β-SiC powder.

Studies of doped LaMnO3 samples prepared by citrate combustion process

NASA Astrophysics Data System (ADS)

Dimri, M. Chandra; Khanduri, H.; Mere, A.; Stern, R.

2018-04-01

La0.95A0.05MnO3 (where A=Na, Sr, Er, Dy and Ce) powder samples were synthesized by chemical solution route and the magnetic and structural properties are reported in this paper. The pervoskite structure was confirmed from X-ray diffraction patterns and Raman spectra at room temperature in all of these doped samples. Curie transition temperatures in doped LaMnO3 bulk samples were around 250K, which are much higher than the ideal value (˜140 K) in undoped samples. The increase in the magnetic transition temperatures can be related to non-stoichiometry and cation vacancies created due to higher valence substitutions for the univalent La1+ ions.

High-pressure polymorphism of the electrochemically active organic molecule tetrahydroxy-p-benzoquinone

DOE PAGES

Ciezak-Jenkins, Jennifer A.

2016-04-22

We have studied the structural and chemical response of tetrahydroxy-p-benzoquinone to isothermal compression to near 20 GPa using powder x-ray diffraction and vibrational spectroscopy. Compression beyond 11.5 GPa resulted in the appearance of several new peaks in the x-ray patterns, changes in the peak distribution and intensities, as well as the disappearance of features observed at lower pressures, which when coupled with concomitant changes in the infrared spectrum are indicative of a phase transition. Further analysis of the infrared spectra suggest this phase transition results in an increase in the anharmonicity of the system. Finally, Raman spectroscopic experiments indicate themore » high-pressure phase to be highly photosensitive and easily polymerized.« less

Plasma induced grafting carboxymethyl cellulose on multiwalled carbon nanotubes for the removal of UO(2)(2+) from aqueous solution.

PubMed

Shao, Dadong; Jiang, Zhongqing; Wang, Xiangke; Li, Jiaxing; Meng, Yuedong

2009-01-29

Carboxymethyl cellulose (CMC) is grafted on multiwalled carbon nanotubes (MWCNT) by using plasma techniques. The CMC grafted MWCNT (MWCNT-g-CMC) is characterized by using Fourier transform infrared spectra (FT-IR), Raman spectra, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA)-differential thermal analysis (DTA), scanning electron microscopy (SEM), and N(2)-BET methods in detail. The application of MWCNT-g-CMC in the removal of UO(2)(2+) from aqueous solution is investigated. MWCNT-g-CMC has much higher sorption ability in the removal of UO(2)(2+) than raw MWCNT. The MWCNT-g-CMC is a suitable material in the preconcentration and solidification of heavy metal ions from large volume of aqueous solutions.

Total-scattering pair-distribution function of organic material from powder electron diffraction data.

PubMed

Gorelik, Tatiana E; Schmidt, Martin U; Kolb, Ute; Billinge, Simon J L

2015-04-01

This paper shows that pair-distribution function (PDF) analyses can be carried out on organic and organometallic compounds from powder electron diffraction data. Different experimental setups are demonstrated, including selected area electron diffraction and nanodiffraction in transmission electron microscopy or nanodiffraction in scanning transmission electron microscopy modes. The methods were demonstrated on organometallic complexes (chlorinated and unchlorinated copper phthalocyanine) and on purely organic compounds (quinacridone). The PDF curves from powder electron diffraction data, called ePDF, are in good agreement with PDF curves determined from X-ray powder data demonstrating that the problems of obtaining kinematical scattering data and avoiding beam damage of the sample are possible to resolve.

Crystal Structure of 17α-Dihydroequilin, C18H22O2, from Synchrotron Powder Diffraction Data and Density Functional Theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaduk, James; Gindhart, Amy; Blanton, Thomas

The crystal structure of 17α-dihydroequilin has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. 17α-dihydroequilin crystallizes in space group P212121 (#19) with a = 6.76849(1) Å, b = 8.96849(1) Å, c = 23.39031(5) Å, V = 1419.915(3) Å3, and Z = 4. Both hydroxyl groups form hydrogen bonds to each other, resulting in zig-zag chains along the b-axis. The powder diffraction pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ as the entry 00-066-1608.

Structure of magnesium selenate enneahydrate, MgSeO4·9H2O, from 5 to 250 K using neutron time-of-flight Laue diffraction.

PubMed

Fortes, A Dominic; Alfè, Dario; Hernández, Eduardo R; Gutmann, Matthias J

2015-06-01

The complete structure of MgSeO4·9H2O has been refined from neutron single-crystal diffraction data obtained at 5, 100, 175 and 250 K. It is monoclinic, space group P2₁/c, Z = 4, with unit-cell parameters a = 7.222 (2), b = 10.484 (3), c = 17.327 (4) Å, β = 109.57 (2)°, and V = 1236.1 (6) Å(3) [ρ(calc) = 1770 (1) kg m(-3)] at 5 K. The structure consists of isolated [Mg(H2O)6](2+) octahedra, [SeO4](2-) tetrahedra and three interstitial lattice water molecules, all on sites of symmetry 1. The positions of the H atoms agree well with those inferred on the basis of geometrical considerations in the prior X-ray powder diffraction structure determination: no evidence of orientational disorder of the water molecules is apparent in the temperature range studied. Six of the nine water molecules are hydrogen bonded to one another to form a unique centrosymmetric dodecamer, (H2O)12. Raman spectra have been acquired in the range 170-4000 cm(-1) at 259 and 78 K; ab initio calculations, using density functional theory, have been carried out in order to aid in the analysis of the Raman spectrum as well as providing additional insights into the geometry and thermodynamics of the hydrogen bonds. Complementary information concerning the thermal expansion, crystal morphology and the solubility are also presented.

Effect of Cr3+ concentration on structural and optical properties of TiO2:Cr3+ anatase and rutile phases

NASA Astrophysics Data System (ADS)

Loan, Trinh Thi; Bang, Ngac An; Huong, Vu Hoang; Long, Nguyen Ngoc

2017-07-01

TiO2 powders doped with different amounts of Cr3+ions (from 0 to 10 mol%) have been prepared by hydrothermal technique. TiO2:Cr3+ powders were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, diffuse reflection, absorption, photoluminescence and photoluminescence excitation spectra. The results showed that the Cr3+ dopant concentrations did not affect on the lattice constants of TiO2 crystal, but affected on shift and broadening of the Raman modes for both anatase and rutile phases. The band gap of both the anatase and rutile TiO2 host lattice was strongly decreased with increasing Cr3+ dopant concentration. The photoluminescence spectra of TiO2:Cr3+ anatase phase exhibited a weak narrow peak (the so-called R-line) at 698 nm, meanwhile those of TiO2:Cr3+ rutile phase consisted of a very intense narrow zero-phonon R-line at 695 nm assigned to the 2E(2G) → 4A2(4F) transition of Cr3+ ions in strong octahedral field and its phonon-sidebands. In particular, in the PL spectrum of TiO2:Cr3+ rutile phase is also observed an abroad emission band centered at 813 nm assigned to the 4T2(4F) → 4A2(4F) transition of ions Cr3+ in weak octahedral field.

Enhancement of Electrical Conductivity of LiFePO4 by Controlled Solution Combustion Synthesis

NASA Astrophysics Data System (ADS)

Rajoba, S. J.; Jadhav, L. D.; Patil, P. S.; Tyagi, D. K.; Varma, S.; Wani, B. N.

2017-03-01

LiFePO4 has been synthesized by a solution combustion method at different oxidant-to-fuel ratios. At stoichiometric oxidant-to-fuel ratio (1:2), Fe2O3 formed in addition to LiFePO4 during combustion. Hence, reducing atmosphere was generated by increasing the ratio from stoichiometric to 1:4 and 1:8, named as 1-LFP, 2-LFP, and 4-LFP, respectively. Furthermore, as-prepared powders were calcined in inert atmosphere to avoid oxidation of LiFePO4 to Fe2O3 and Li3PO4, as confirmed by x-ray diffraction (XRD) and thermogravimetric and differential thermal analyses. The calcined powders were characterized by XRD analysis, Raman spectroscopy, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. X-ray photoelectron spectroscopy ascertained oxidation state of +2 and +5 for Fe and P, respectively. With increasing oxidant-to-fuel ratio, the binding energies of 2 p 3/2 and 2 p 1/2 levels of Fe shifted downwards and showed increased splitting. According to Raman spectroscopy results, the residual carbon is amorphous with sp 2 C-C bond. The conductivity of 1-LFP, 2-LFP, and 4-LFP measured at 313 K was 0.15 × 10-6 S/cm, 8.46 × 10-6 S/cm, and 1.21 × 10-3 S/cm, respectively. The enhanced conductivity of 4-LFP is due to presence of residual carbon and Fe2P.

Characteristics of zircon suitable for REE extraction

NASA Astrophysics Data System (ADS)

Watanabe, Y.; Hoshino, M.

2011-12-01

Zircons (ZrSiO4) from Naegi and Ohro granitic pegmatites, Japan and from Saigon alkaline basalt, Vietnam, were mineralogically characterized by inductively couples plasma mass spectrometry (ICP-MS), electron-microprobe analysis (EMPA), X-ray powder diffraction, micro-Raman spectroscopy and leaching experiment. The powder XRD and Raman spectra analyses show that the degree of crystallinity decreases from Saigon, to Ohro and Naegi zircons. Quantitative analytical results by the EMPA indicate that the Naegi and Ohro zircon samples contain a large amount of REE2O3, while REE contents in Saigon zircon are below detection limit. The leaching experiments for the present zircons under the condition of a solvent 1M-HCl, at a room temperature to 250 °C and retention time of 30h resulted in about 100 %, 50 % and 1 % recoveries of REE from the Naegi, Ohro and Saigon zircons, respectively. Leaching experiments for the Naegi zircon under the condition of a solvent 1N-HCl, heating temperature of 50 °C, 100 °C, 150 °C and 200 °C, and retention time 30h, showed that a significant amount of REE was leached out at a temperature above 150 °C. However, the leaching experiments of the Naegi and Ohro zircons at room temperature (about 25 °C) show that REE were hard to be leached. These results indicates that both low crystallinity of zircon and higher leaching temperature are requisite for effective leaching of REE from zircon.

Sol-gel synthesis and characterizations of crystalline NaGd(WO4)2 powder for anisotropic transparent ceramic laser application

NASA Astrophysics Data System (ADS)

Durairajan, A.; Thangaraju, D.; Balaji, D.; Moorthy Babu, S.

2013-02-01

NaGd(WO4)2 powders were synthesized at different pH (3.5, 4.5, 5.5, 6.5 and 7.5) values by conventional Pechini method. Sodium and gadolinium nitrate salts and ammonium paratungstate are used as starting precursors. Metal cations were chelated by citric acid and individual citrates were bound together with ethylene glycol. Synthesized gel was analyzed using differential thermal analysis (DTA), thermo gravimetric (TG) and FT-IR spectroscopy to understand the degradation of gel and formation of metal citrates. Calcined powders (250, 600, 700 and 800 °C) were characterized by powder XRD, FT-IR, Raman and FE-SEM analysis. The temperature dependent phase formation was examined by powder XRD. The morphological changes at different pH derived powders were observed with FE-SEM micrographs. Stepwise organic liberation with respect to temperature and presence of carbon content in the pre-fired powder were analyzed using FT-IR analysis. Raman spectrum reveals disordered tungstate vibrations in the NGW matrix.

New Powder Diffraction File (PDF-4) in relational database format: advantages and data-mining capabilities.

PubMed

Kabekkodu, Soorya N; Faber, John; Fawcett, Tim

2002-06-01

The International Centre for Diffraction Data (ICDD) is responding to the changing needs in powder diffraction and materials analysis by developing the Powder Diffraction File (PDF) in a very flexible relational database (RDB) format. The PDF now contains 136,895 powder diffraction patterns. In this paper, an attempt is made to give an overview of the PDF-4, search/match methods and the advantages of having the PDF-4 in RDB format. Some case studies have been carried out to search for crystallization trends, properties, frequencies of space groups and prototype structures. These studies give a good understanding of the basic structural aspects of classes of compounds present in the database. The present paper also reports data-mining techniques and demonstrates the power of a relational database over the traditional (flat-file) database structures.

High-pressure structural study of MnF 2

DOE PAGES

Stavrou, Elissaios; Yao, Yansun; Goncharov, Alexander F.; ...

2015-02-01

In this study, manganese fluoride (MnF 2) with the tetragonal rutile-type structure has been studied using a synchrotron angle-dispersive powder x-ray diffraction and Raman spectroscopy in a diamond anvil cell up to 60 GPa at room temperature combined with first-principles density functional calculations. The experimental data reveal two pressure-induced structural phase transitions with the following sequence: rutile → SrI 2 type (3 GPa)→ α–PbCl 2 type (13 GPa). Complete structural information, including interatomic distances, has been determined in the case of MnF 2 including the exact structure of the debated first high-pressure phase. First-principles density functional calculations confirm this phasemore » transition sequence, and the two calculated transition pressures are in excellent agreement with the experiment. Lattice dynamics calculations also reproduce the experimental Raman spectra measured for the ambient and high-pressure phases. The results are discussed in line with the possible practical use of rutile-type fluorides in general and specifically MnF 2 as a model compound to reveal the HP structural behavior of rutile-type SiO 2 (Stishovite).« less

Synthesis and characterization of FeSe1-xTex (x=0, 0.5, 1) superconductors

NASA Astrophysics Data System (ADS)

Zargar, Rayees A.; Hafiz, A. K.; Awana, V. P. S.

2015-08-01

In this study, FeTe1-xSex (x=0,0.5,1) samples were prepared by conventional solid state reaction method and investigated by powder XRD, SEM, Raman and resistivity measurement techniques to reveal the effect of tellurium (Te) substitution in FeSe matrix. Rietveld analysis was performed on room temperature recorded, X-ray diffraction (XRD) patterns of pure FeSe, FeTe and FeSe0.5Te0.5 which shows that all the compounds are crystallized in a tetragonal structure. SEM images show the dense surface morphology. Raman spectra recorded in the range from 100 to 700 cm-1 at ambient temperature has been interpreted by P4/nmm space group of the lattice. The variation in intensity and shift in peak positions of some phonon modes has been discussed on the basis of variation in crystalline field effect by substituting Te in FeSe lattice. The resistivity versus temperature curves reveals that FeSe becomes superconductor at 7 K and FeSe0.5Te0.5 shows superconductivity below 14 K while FeTe is non-superconducting compound.

Bioactivity and structural properties of nanostructured bulk composites containing Nb2O5 and natural hydroxyapatite

NASA Astrophysics Data System (ADS)

Bonadio, T. G. M.; Sato, F.; Medina, A. N.; Weinand, W. R.; Baesso, M. L.; Lima, W. M.

2013-06-01

In this work, we investigate the bioactivity and structural properties of nanostructured bulk composites that are composed of Nb2O5 and natural hydroxyapatite (HAp) and are produced by mechanical alloying and powder metallurgy. X-ray diffraction and Raman spectroscopy data showed that the milling process followed by a heat treatment at 1000 °C induced chemical reactions along with the formation of the CaNb2O6, PNb9O25 and Ca3(PO4)2 phases. Rietveld refinement indicated significant changes in each phase weight fraction as a function of HAp concentration. These changes influenced the in vitro bioactivity of the material. XRD and FTIR analyses indicated that the composites exhibited bioactivity characteristics by forming a carbonated apatite layer when the composites were immersed in a simulated body fluid. The formed layers had a maximum thickness of 13 μm, as measured by confocal Raman spectroscopy and as confirmed by scanning electron microscopy. The results of this work suggest that the tested bulk composites are promising biomaterials for use in implants.

Nanostructures formed by cyclodextrin covered procainamide through supramolecular self assembly - Spectral and molecular modeling study

NASA Astrophysics Data System (ADS)

Rajendiran, N.; Mohandoss, T.; Sankaranarayanan, R. K.

2015-02-01

Inclusion complexation behavior of procainamide (PCA) with two cyclodextrins (α-CD and β-CD) were analyzed by absorption, fluorescence, scanning electron microscope (SEM), transmission electron microscope (TEM), Raman image, FT-IR, differential scanning colorimeter (DSC), Powder X ray diffraction (XRD) and 1H NMR. Blue shift was observed in β-CD whereas no significant spectral shift observed in α-CD. The inclusion complex formation results suggest that water molecules also present in the inside of the CD cavity. The present study revealed that the phenyl ring of the PCA drug is entrapped in the CD cavity. Cyclodextrin studies show that PCA forms 1:2 inclusion complex with α-CD and β-CD. PCA:α-CD complex form nano-sized particles (46 nm) and PCA:β-CD complex form self-assembled to micro-sized tubular structures. The shape-shifting of 2D nanosheets into 1D microtubes by simple rolling mechanism were analysed by micro-Raman and TEM images. Thermodynamic parameters (ΔH, ΔG and ΔS) of inclusion process were determined from semiempirical PM3 calculations.

Neutron and X-ray diffraction of plasma-sprayed zirconia-yttria thermal barrier coatings

NASA Technical Reports Server (NTRS)

Shankar, N. R.; Herman, H.; Singhal, S. P.; Berndt, C. C.

1984-01-01

ZrO2-7.8mol. pct. YO1.5, a fused powder, and ZrO2-8.7mol. pct. YO1.5, a prereacted powder, were plasma-sprayed onto steel substrates. Neutron diffraction and X-ray diffraction of the as-received powder, the powder plasma sprayed into water, as-sprayed coatings, and coatings heat-treated for 10 and 100 h were carried out to study phase transformations and ordering of the oxygen ions on the oxygen sublattice. The as-received fused powder has a much lower monoclinic percentage than does the pre-reacted powder, this resulting in a much lower monoclinic percentage in the coating. Heat treatment increases the percentages of the cubic and monoclinic phases, while decreasing the tetragonal content. An ordered tetragonal phase is detected by the presence of extra neutron diffraction peaks. These phase transformations and ordering will result in volume changes. The implications of these transformations on the performance of partially stabilized zirconia thermal barrier coatings is discussed.

Total-scattering pair-distribution function of organic material from powder electron diffraction data

DOE PAGES

Gorelik, Tatiana E.; Billinge, Simon J. L.; Schmidt, Martin U.; ...

2015-04-01

This paper shows for the first time that pair-distribution function analyses can be carried out on organic and organo-metallic compounds from powder electron diffraction data. Different experimental setups are demonstrated, including selected area electron diffraction (SAED) and nanodiffraction in transmission electron microscopy (TEM) or nanodiffraction in scanning transmission electron microscopy (STEM) modes. The methods were demonstrated on organo-metallic complexes (chlorinated and unchlorinated copper-phthalocyanine) and on purely organic compounds (quinacridone). The PDF curves from powder electron diffraction data, called ePDF, are in good agreement with PDF curves determined from X-ray powder data demonstrating that the problems of obtaining kinematical scattering datamore » and avoiding beam-damage of the sample are possible to resolve.« less

High-throughput Raman chemical imaging for evaluating food safety and quality

NASA Astrophysics Data System (ADS)

Qin, Jianwei; Chao, Kuanglin; Kim, Moon S.

2014-05-01

A line-scan hyperspectral system was developed to enable Raman chemical imaging for large sample areas. A custom-designed 785 nm line-laser based on a scanning mirror serves as an excitation source. A 45° dichroic beamsplitter reflects the laser light to form a 24 cm x 1 mm excitation line normally incident on the sample surface. Raman signals along the laser line are collected by a detection module consisting of a dispersive imaging spectrograph and a CCD camera. A hypercube is accumulated line by line as a motorized table moves the samples transversely through the laser line. The system covers a Raman shift range of -648.7-2889.0 cm-1 and a 23 cm wide area. An example application, for authenticating milk powder, was presented to demonstrate the system performance. In four minutes, the system acquired a 512x110x1024 hypercube (56,320 spectra) from four 47-mm-diameter Petri dishes containing four powder samples. Chemical images were created for detecting two adulterants (melamine and dicyandiamide) that had been mixed into the milk powder.

Evaluation of turmeric powder adulterated with metanil yellow using FT-Raman and FT-IR spectroscopy

USDA-ARS?s Scientific Manuscript database

Turmeric powder (Curcuma longa L.) is valued both for its medicinal properties and for its popular culinary use such as being a component in curry powder. Due to its high demand in international trade, turmeric powder has been subject to economically driven, hazardous chemical adulteration. This stu...

Influence of synthesis conditions on the crystal structure of the powder formed in the “HfO2 - CeO2/Ce2O3” system

NASA Astrophysics Data System (ADS)

Popov, V. V.; Menushenkov, A. P.; Khubbutdinov, R. M.; Yastrebtsev, A. A.; Svetogorov, R. D.; Zubavichus, Ya V.; Trigub, A. L.; Sharapov, A. S.; Pisarev, A. A.; Kurilkin, V. V.; Tsarenko, N. A.; Arzhatkina, L. A.

2017-12-01

Influence of synthesis conditions (type of atmosphere: reduction or oxidation, annealing temperature) on the chemical composition and structure of the compounds formed in the “HfO2 - CeO2/Ce2O3” system has been investigated by X-ray absorption fine structure spectroscopy combined with Raman spectroscopy, X-ray diffraction and thermogravimetric analysis. It was revealed that isothermal annealing of precursor at temperatures less than 1000°C in air leads to formation of Ce0.5Hf0.5O2 powders with cubic fluorite-type structure (space group Fm-3m). Further increase of annealing temperatures above 1000°C causes decomposition of formed crystal structure into two phases: cubic and monoclinic. Annealing in reduction hydrogen atmosphere causes formation of Ce4+ 2x Ce3+ 2-2x Hf2O7+x compounds with intermediate oxidation state of cerium, where value of x depends on the reducing conditions and treatment parameters. Annealing in vacuum at 1400°C strongly reduces the content of Ce4+ in a powder samples and leads to formation of pyrochlore structure (space group Fd-3m) with predominant +3 oxidation state of cerium.

Role of initial heat treatment of the ferrite component on magnetic properties in the composite of ferrimagnetic Co1.75Fe1.25O4 ferrite and non-magnetic BaTiO3 oxide

NASA Astrophysics Data System (ADS)

Bhowmik, R. N.; Kazhugasalamoorthy, S.; Sinha, A. K.

2017-12-01

We have prepared a composite of ferrimagnetic ferrite Co1.75Fe1.25O4 and non-magnetic oxide BaTiO3. The ferrite composition Co1.75Fe1.25O4 has been prepared by chemical co-precipitation and subsequently heated at different temperatures. The heat treated ferrite powder has been mixed with BaTiO3 powder with mass ratio 1:1 and the mixed powder has been finally heated at 1000 °C to form composite material. Structural phase of the composite material has been confirmed by high quality Synchrotron X-ray diffraction pattern and Micro-Raman spectra. The grain surface morphology and elemental composition have been studied by Scanning electron microscope and Energy dispersive X-ray analysis. The distribution of magnetic exchange interactions and blocking behavior of the ferrimagnetic grains in composite samples has been understood by analyzing the temperature and magnetic field dependence of dc magnetization. Finally, information on modified micro-structure and ferrimagnetic parameters in composite samples has been obtained as the variation of annealing temperature of the ferrite component before making composite.

Comparison of Physical-chemical and Mechanical Properties of Chlorapatite and Hydroxyapatite Plasma Sprayed Coatings

PubMed Central

Demnati, Imane; Grossin, David; Marsan, Olivier; Bertrand, Ghislaine; Collonges, Gérard; Combes, Christèle; Parco, Maria; Braceras, Inigo; Alexis, Joel; Balcaen, Yannick; Rey, Christian

2015-01-01

Chlorapatite can be considered a potential biomaterial for orthopaedic applications. Its use as plasma-sprayed coating could be of interest considering its thermal properties and particularly its ability to melt without decomposition unlike hydroxyapatite. Chlorapatite (ClA) was synthesized by a high-temperature ion exchange reaction starting from commercial stoichiometric hydroxyapatites (HA). The ClA powder showed similar characteristics as the original industrial HA powder, and was obtained in the monoclinic form. The HA and ClA powders were plasma-sprayed using a low-energy plasma spraying system with identical processing parameters. The coatings were characterized by physical-chemical methods, i.e. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy, including distribution mapping of the main phases detected such as amorphous calcium phosphate (ACP), oxyapatite (OA), and HA or ClA. The unexpected formation of oxyapatite in ClA coatings was assigned to a side reaction with contaminating oxygenated species (O2, H2O). ClA coatings exhibited characteristics different from HA, showing a lower content of oxyapatite and amorphous phase. Although their adhesion strength was found to be lower than that of HA coatings, their application could be an interesting alternative, offering, in particular, a larger range of spraying conditions without formation of massive impurities. PMID:25893015

Graphene oxide as a nanocarrier for controlled release and targeted delivery of an anticancer active agent, chlorogenic acid.

PubMed

Barahuie, Farahnaz; Saifullah, Bullo; Dorniani, Dena; Fakurazi, Sharida; Karthivashan, Govindarajan; Hussein, Mohd Zobir; Elfghi, Fawzi M

2017-05-01

We have synthesized graphene oxide using improved Hummer's method in order to explore the potential use of the resulting graphene oxide as a nanocarrier for an active anticancer agent, chlorogenic acid (CA). The synthesized graphene oxide and chlorogenic acid-graphene oxide nanocomposite (CAGO) were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetry and differential thermogravimetry analysis, Raman spectroscopy, powder X-ray diffraction (PXRD), UV-vis spectroscopy and high resolution transmission electron microscopy (HRTEM) techniques. The successful conjugation of chlorogenic acid onto graphene oxide through hydrogen bonding and π-π interaction was confirmed by Raman spectroscopy, FTIR analysis and X-ray diffraction patterns. The loading of CA in the nanohybrid was estimated to be around 13.1% by UV-vis spectroscopy. The release profiles showed favourable, sustained and pH-dependent release of CA from CAGO nanocomposite and conformed well to the pseudo-second order kinetic model. Furthermore, the designed anticancer nanohybrid was thermally more stable than its counterpart. The in vitro cytotoxicity results revealed insignificant toxicity effect towards normal cell line, with a viability of >80% even at higher concentration of 50μg/mL. Contrarily, CAGO nanocomposite revealed enhanced toxic effect towards evaluated cancer cell lines (HepG2 human liver hepatocellular carcinoma cell line, A549 human lung adenocarcinoma epithelial cell line, and HeLa human cervical cancer cell line) compared to its free form. Copyright © 2016 Elsevier B.V. All rights reserved.

K[AsW{sub 2}O{sub 9}], the first member of the arsenate–tungsten bronze family: Synthesis, structure, spectroscopic and non-linear optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alekseev, Evgeny V., E-mail: e.alekseev@fz-juelich.de; Institut für Kristallographie, RWTH Aachen, Jägerstraße 17–19 D-52066 Aachen; Felbinger, Olivier

K[AsW{sub 2}O{sub 9}], prepared by high-temperature solid-state reaction, is the first member of the arsenate–tungsten bronze family. The structure of K[AsW{sub 2}O{sub 9}] is based on a 3-dimensional (3D) oxotungstate–arsenate framework with the non-centrosymmetric P2{sub 1}2{sub 1}2{sub 1} space group, a=4.9747(3) Å, b=9.1780(8) Å, c=16.681(2) Å. The material was characterized using X-ray diffraction, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Raman and infrared (IR) spectroscopic techniques. The results of DSC demonstrate that this phase is stable up to 1076 K. Second harmonic generation (SHG) measurements performed on a powder sample demonstrate noticeable (0.1 of LiIO{sub 3}) non-linear optical (NLO)more » activity. - Graphical abstract: K[AsW{sub 2}O{sub 9}], the first member of arsenate–tungsten bronze family exhibit new three dimensional structure type, significant thermal stability and NLO properties. Highlights: • K[AsW{sub 2}O{sub 9}], the first member of the arsenate–tungsten bronze family was synthesized with solid state reaction technique. • Structure of this phase was investigated with X-ray diffraction, IR and Raman spectroscopy and electron microscopy. • Thermal stability of the phase was determinate with DSC techniques. • NLO properties were investigated.« less

Environmental Synthesis of Few Layers Graphene Sheets Using Ultrasonic Exfoliation with Enhanced Electrical and Thermal Properties.

PubMed

Noroozi, Monir; Zakaria, Azmi; Radiman, Shahidan; Abdul Wahab, Zaidan

2016-01-01

In this paper, we report how few layers graphene that can be produced in large quantity with low defect ratio from exfoliation of graphite by using a high intensity probe sonication in water containing liquid hand soap and PVP. It was founded that the graphene powder obtained by this simple exfoliation method after the heat treatment had an excellent exfoliation into a single or layered graphene sheets. The UV-visible spectroscopy, FESEM, TEM, X-ray powder diffraction and Raman spectroscopy was used to analyse the graphene product. The thermal diffusivity of the samples was analysed using a highly accurate thermal-wave cavity photothermal technique. The data obtained showed excellent enhancement in the thermal diffusivity of the graphene dispersion. This well-dispersed graphene was then used to fabricate an electrically conductive polymer-graphene film composite. The results demonstrated that this low cost and environmental friendly technique allowed to the production of high quality layered graphene sheets, improved the thermal and electrical properties. This may find use in the wide range of applications based on graphene.

Environmental Synthesis of Few Layers Graphene Sheets Using Ultrasonic Exfoliation with Enhanced Electrical and Thermal Properties

PubMed Central

Noroozi, Monir; Zakaria, Azmi; Radiman, Shahidan; Abdul Wahab, Zaidan

2016-01-01

In this paper, we report how few layers graphene that can be produced in large quantity with low defect ratio from exfoliation of graphite by using a high intensity probe sonication in water containing liquid hand soap and PVP. It was founded that the graphene powder obtained by this simple exfoliation method after the heat treatment had an excellent exfoliation into a single or layered graphene sheets. The UV-visible spectroscopy, FESEM, TEM, X-ray powder diffraction and Raman spectroscopy was used to analyse the graphene product. The thermal diffusivity of the samples was analysed using a highly accurate thermal-wave cavity photothermal technique. The data obtained showed excellent enhancement in the thermal diffusivity of the graphene dispersion. This well-dispersed graphene was then used to fabricate an electrically conductive polymer-graphene film composite. The results demonstrated that this low cost and environmental friendly technique allowed to the production of high quality layered graphene sheets, improved the thermal and electrical properties. This may find use in the wide range of applications based on graphene. PMID:27064575

Europium concentration effect on characteristics and luminescent properties of hydroxyapatite nanocrystalline powders

NASA Astrophysics Data System (ADS)

Nikolaev, Anton; Kolesnikov, Ilya; Frank-Kamenetskaya, Olga; Kuz'mina, Maria

2017-12-01

Series of Eu-apatites were synthesized by precipitation from aqueous solutions with the Eu/Ca atomic ratio from 0.5% to 5% at T = 90 °C. Resulting precipitates were studied using different experimental techniques including X-ray powder diffraction, infrared and raman spectroscopy, scanning elecrton microscopy, EDX and photoluminescent spectroscopy. Eu-doped Ca-deficit nanosized non-stoichiometric hydroxyapatite with high water content has been obtained throughout the experiment. Europium content in the synthesized apatites reaches 0.24 apfu (Eu/Ca = 2.5%). Relations between Eu content is the solution and precipitate have been established. It was shown that Eu-monacite starts to precipitate as secondary phase at Eu/Ca ratio in starting solution 1% or higher. Maximum luminescence is observed in apatite with ∼2% Eu/Ca ratio (which equals to ∼0.2 apfu and corresponds to 3% Eu/Ca ratio in the starting solution). As an important and brand-new result, apatite with 2% Eu/Ca ratio can be considered as the most appropriate material for the producing biolabels for luminescent research in medicine and biology.

Growth, density functional theory (DFT) and spectral studies on L-2-aminobutyric acid -biologically active material

NASA Astrophysics Data System (ADS)

Usha, C.; Santhakumari, R.; Meenakshi, R.; Jayasree, R.; Bhuvaneswari, M.

2017-12-01

Single crystal of L-2-aminobutyric acid (ABA) was grown from water by slow evaporation at room temperature. The crystalline nature of the grown crystal was confirmed using powder X-ray diffraction studies. The grown crystal was subjected to FT-IR, FT-Raman, 1H NMR and 13C NMR spectral analyses to confirm the presence of functional group and molecular structure respectively. Thermal properties were investigated by thermogravimetric and differential thermal analyses. The range and percentage of optical transmission was ascertained by recording UV-vis-NIR spectrum. The electronic charge distribution and reactivity of the molecules within the crystal were studied by HOMO and LUMO analysis and the molecular electrostatic potential (MEP) of the grown crystal was performed using the B3LYP method. The anti-bacterial activities of the crystal were performed by disk diffusion method against the standard bacteria E. coli. The crystal exhibits good anti-bacterial activity. Second harmonic generation efficiency of the powdered ABA crystal was tested using Nd:YAG laser and it is found to be ∼3.3 times that of potassium dihydrogen orthophosphate.

UV-visible spectroscopic estimation of photodegradation of rhodamine-B dye using tin(IV) oxide nanoparticles.

PubMed

Sangami, G; Dharmaraj, N

2012-11-01

Nanocrystalline, tin(IV) oxide (SnO(2)) particles has been prepared by thermal decomposition of tin oxalate precursor obtained from the reactions of tin(IV) chloride and sodium oxalate using eggshell membrane (ESM). The as-prepared SnO(2) nanoparticles were characterized by thermal studies, transmission electron microscopy (TEM), powder X-ray diffraction (XRD), Raman, FT-IR and UV-visible studies and used as a photocatalyst for the degradation of rhodamine-B (Rh-B) dye. The size of the prepared nanoparticles was in the range of 5-12nm as identified from the TEM images. Powder XRD data revealed the presence of a tetragonal, rutile crystalline phase of the tin(IV) oxide nanoparticles. Thermal analysis showed that the decomposition of tin oxalate precursor to yield the titled tin(IV) oxide nanoparticles was completed below 500°C. The extent of degradation of Rh-B in the presence of SnO(2) monitored by absorption spectral measurements demonstrated that 94.48% of the selected dye was degraded upon irradiation with UV light for 60 min. Copyright © 2012 Elsevier B.V. All rights reserved.

Photoluminescent spectroscopy measurements in nanocrystalline praseodymium doped zirconia powders

NASA Astrophysics Data System (ADS)

Ramos-Brito, F.; Murrieta S, H.; Hernández A, J.; Camarillo, E.; García-Hipólito, M.; Martínez-Martínez, R.; Álvarez-Fragoso, O.; Falcony, C.

2006-05-01

Praseodymium doped zirconia powder (ZrO2: (0.53 at%) Pr3+) was prepared by a co-precipitation technique and annealed in air at a temperature Ta = 950 °C. The x-ray diffraction pattern shows a nanocrystalline structure composed of 29.6% monoclinic and 70.4% cubic-tetragonal phases. Medium infrared and Raman analysis confirms the monoclinic/cubic-tetragonal crystalline structure and proves the absence of praseodymium aggregates in the material. Photoluminescent spectroscopy over excitations of 457.9 and 514.9 nm (at 20 K), shows two emission spectra composed of many narrow peaks in the visible-near infrared region (VIS-NIR) of the electromagnetic spectrum, associated with 4f inter-level electronic transitions in praseodymium ions incorporated in the zirconia. Excitation and emission spectra show the different mechanisms of the direct and non-direct excitation of the dopant ion (Pr3+), and the preferential relaxation of the material by charge transfer from the host (zirconia) to the 4f5d band and the 4f inter-level of the dopant ion (Pr3+). No evidence of energy transfer from the host to the dopant was observed.

Sound Velocity and Diffraction Intensity Measurements Based on Raman-Nath Theory of the Interaction of Light and Ultrasound

ERIC Educational Resources Information Center

Neeson, John F.; Austin, Stephen

1975-01-01

Describes a method for the measurement of the velocity of sound in various liquids based on the Raman-Nath theory of light-sound interaction. Utilizes an analog computer program to calculate the intensity of light scattered into various diffraction orders. (CP)

Fabrication and vibration characterization of curcumin extracted from turmeric (Curcuma longa) rhizomes of the northern Vietnam.

PubMed

Van Nong, Hoang; Hung, Le Xuan; Thang, Pham Nam; Chinh, Vu Duc; Vu, Le Van; Dung, Phan Tien; Van Trung, Tran; Nga, Pham Thu

2016-01-01

In this report, we present the research results on using the conventional method and microwave technology to extract curcuminoid from turmeric roots originated in different regions of Northern Vietnam. This method is simple, yet economical, non-toxic and still able to achieve high extraction performance to get curcuminoid from turmeric roots. The detailed results on the Raman vibration spectra combined with X-ray powder diffraction and high-performance liquid chromatography/mass spectrometry allowed the evaluation of each batch of curcumin crystalline powder sample received, under the conditions of applied fabrication technology. Also, the absorption and fluorescence spectroscopies of the samples are presented in the paper. The information to be presented in this paper: absorption and fluorescence spectroscopies of the samples; new experimental study results on applied technology to mass-produce curcumin from turmeric rhizomes; comparative study results between fabricated samples and marketing curcumin products-to state the complexity of co-existing crystalline phase in curcumin powder samples. We noticed that, it is possible to use the vibration line at ~959 cm(-1)-characteristic of the ν C=O vibration, and the ~1625 cm(-1) line-characteristic of the ν C=O and ν C=C vibration in curcumin molecules, for preliminary quality assessment of naturally originated curcumin crystalline powder samples. Data on these new optical spectra will contribute to the bringing of detailed information on natural curcumin in Vietnam, serving research purposes and applications of natural curcumin powder and nanocurcumin in Vietnam, as well as being initial materials for the pharmaceutical, cosmetics or functional food industries.

Investigation of the Sensitivity of Transmission Raman Spectroscopy for Polymorph Detection in Pharmaceutical Tablets.

PubMed

Feng, Hanzhou; Bondi, Robert W; Anderson, Carl A; Drennen, James K; Igne, Benoît

2017-08-01

Polymorph detection is critical for ensuring pharmaceutical product quality in drug substances exhibiting polymorphism. Conventional analytical techniques such as X-ray powder diffraction and solid-state nuclear magnetic resonance are utilized primarily for characterizing the presence and identity of specific polymorphs in a sample. These techniques have encountered challenges in analyzing the constitution of polymorphs in the presence of other components commonly found in pharmaceutical dosage forms. Laborious sample preparation procedures are usually required to achieve satisfactory data interpretability. There is a need for alternative techniques capable of probing pharmaceutical dosage forms rapidly and nondestructively, which is dictated by the practical requirements of applications such as quality monitoring on production lines or when quantifying product shelf lifetime. The sensitivity of transmission Raman spectroscopy for detecting polymorphs in final tablet cores was investigated in this work. Carbamazepine was chosen as a model drug, polymorph form III is the commercial form, whereas form I is an undesired polymorph that requires effective detection. The concentration of form I in a direct compression tablet formulation containing 20% w/w of carbamazepine, 74.00% w/w of fillers (mannitol and microcrystalline cellulose), and 6% w/w of croscarmellose sodium, silicon dioxide, and magnesium stearate was estimated using transmission Raman spectroscopy. Quantitative models were generated and optimized using multivariate regression and data preprocessing. Prediction uncertainty was estimated for each validation sample by accounting for all the main variables contributing to the prediction. Multivariate detection limits were calculated based on statistical hypothesis testing. The transmission Raman spectroscopic model had an absolute prediction error of 0.241% w/w for the independent validation set. The method detection limit was estimated at 1.31% w/w. The results demonstrated that transmission Raman spectroscopy is a sensitive tool for polymorphs detection in pharmaceutical tablets.

Raman analysis of polyethylene glycols and polyethylene oxides

NASA Astrophysics Data System (ADS)

Sagitova, E. A.; Prokhorov, K. A.; Nikolaeva, G. Yu; Baimova, A. V.; Pashinin, P. P.; Yarysheva, A. Yu; Mendeleev, D. I.

2018-04-01

We present Raman study of commercial liquids and powders of polyethylene glycols and polyethylene oxides with the average molecular weight from 400 Da to 10000 kDa. The most significant spectral changes were observed for the range of the molecular weights, where the liquid/semisolid transition has occurred. For the powders we revealed increase in the content of the molecules in the helical conformation and in the content of the monoclinic crystalline phase with growth of the molecular weight.

Mineral and Geochemical Classification From Spectroscopy/Diffraction Through Neural Networks

NASA Astrophysics Data System (ADS)

Ferralis, N.; Grossman, J.; Summons, R. E.

2017-12-01

Spectroscopy and diffraction techniques are essential for understanding structural, chemical and functional properties of geological materials for Earth and Planetary Sciences. Beyond data collection, quantitative insight relies on experimentally assembled, or computationally derived spectra. Inference on the geochemical or geophysical properties (such as crystallographic order, chemical functionality, elemental composition, etc.) of a particular geological material (mineral, organic matter, etc.) is based on fitting unknown spectra and comparing the fit with consolidated databases. The complexity of fitting highly convoluted spectra, often limits the ability to infer geochemical characteristics, and limits the throughput for extensive datasets. With the emergence of heuristic approaches to pattern recognitions though machine learning, in this work we investigate the possibility and potential of using supervised neural networks trained on available public spectroscopic database to directly infer geochemical parameters from unknown spectra. Using Raman, infrared spectroscopy and powder x-ray diffraction from the publicly available RRUFF database, we train neural network models to classify mineral and organic compounds (pure or mixtures) based on crystallographic structure from diffraction, chemical functionality, elemental composition and bonding from spectroscopy. As expected, the accuracy of the inference is strongly dependent on the quality and extent of the training data. We will identify a series of requirements and guidelines for the training dataset needed to achieve consistent high accuracy inference, along with methods to compensate for limited of data.

Growth and characterization of organic material 4-dimethylaminobenzaldehyde single crystal.

PubMed

Jebin, R P; Suthan, T; Rajesh, N P; Vinitha, G; Madhusoodhanan, U

2015-01-25

The organic material 4-dimethylaminobenzaldehyde single crystals were grown by slow evaporation technique. The grown crystal was confirmed by the single crystal and powder X-ray diffraction analyses. The functional groups of the crystal have been identified from the Fourier Transform Infrared (FTIR) and FT-Raman studies. The optical property of the grown crystal was analyzed by UV-Vis-NIR and photoluminescence (PL) spectral measurements. The thermal behavior of the grown crystal was analyzed by thermogravimetric (TG) and differential thermal analyses (DTA). Dielectric measurements were carried out with different frequencies by using parallel plate capacitor method. The third order nonlinear optical properties of 4-dimethylaminobenzaldehyde was measured by the Z-scan technique using 532 nm diode pumped continuous wave (CW) Nd:YAG laser. Copyright © 2014 Elsevier B.V. All rights reserved.

Ba2Mg(BO3)2:Bi3+ - A new phosphor with ultraviolet light emission

NASA Astrophysics Data System (ADS)

Lakshminarasimhan, N.; Jayakiruba, S.; Prabhavathi, K.

2017-10-01

Ultraviolet light emission was observed in a new Ba2Mg(BO3)2:Bi3+ phosphor. Bi3+ substitution for Ba2+ in the lattice was supplemented with K+ to maintain the charge neutrality. The samples of the formula Ba2-2xBixKxMg(BO3)2 [x = 0, 0.001, 0.01, 0.02, and 0.05] synthesized by solid state reaction were characterized using powder X-ray diffraction for their phase formation. Raman and diffuse reflectance UV-Vis spectroscopic techniques were used to obtain information on the vibrational modes and optical properties, respectively. The room temperature photoluminescence measurements revealed an ultraviolet emission at 370 nm when excited using 304 nm wavelength and the Stokes shift is 5868 cm-1.

Phase transition in organic-inorganic perovskite (C9H19NH3)2 PbI2Br2 of long-chain alkylammonium

NASA Astrophysics Data System (ADS)

Abid, H.; Trigui, A.; Mlayah, A.; Hlil, E. K.; Abid, Y.

2012-01-01

Single perovskite slab alkylammonium lead iodides bromides (C9H19NH3)2PbI2Br2 is a new member of the family of hybrid organic-inorganic perovskite compounds. It exhibits a single structural phase transition with changes in the conformation of alkylammonium chains below room temperature. Differential scanning calorimetry (DSC), powder X-ray diffraction and FT-Raman spectroscopy were used to investigate this phase transition. These changes were characterized by a decreased conformational disorder of the methylene units of the alkyl chains. Phase transition was examined in light of the interesting optical properties of this material, as well as the relevance of this system as models for phase transitions in lipid bilayers.

Controlled synthesis of carbon-encapsulated copper nanostructures by using smectite clays as nanotemplates.

PubMed

Tsoufis, Theodoros; Colomer, Jean-François; Maccallini, Enrico; Jankovič, Lubos; Rudolf, Petra; Gournis, Dimitrios

2012-07-23

Rhomboidal and spherical metallic-copper nanostructures were encapsulated within well-formed graphitic shells by using a simple chemical method that involved the catalytic decomposition of acetylene over a copper catalyst that was supported on different smectite clays surfaces by ion-exchange. These metallic-copper nanostructures could be separated from the inorganic support and remained stable for months. The choice of the clay support influenced both the shape and the size of the synthesized Cu nanostructures. The synthesized materials and the supported catalysts from which they were produced were studied in detail by TEM and SEM, powder X-ray diffraction, thermal analysis, as well as by Raman and X-ray photoelectron spectroscopy. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and crystal structure determination of yttrium ultraphosphate YP 5O 14

NASA Astrophysics Data System (ADS)

Mbarek, A.; Graia, M.; Chadeyron, G.; Zambon, D.; Bouaziz, J.; Fourati, M.

2009-03-01

The crystal structure of monoclinic YP 5O 14 (space group C2/ c, a=12.919(2) Å, b=12.796(4) Å, c=12.457(2) Å, β=91.30(1)°, Z=8) has been refined from single-crystal X-ray diffraction data. Full-matrix least-squares refinement on F2 using 2249 independent reflections for 183 refinable parameters results in a final R value of 0.027 ( ωR=0.069). The structure is isotypic with HoP 5O 14. This structure is built up from infinite layers of PO 4 tetrahedra linked through isolated YO 8 polyhedra. The three-dimensional cohesion of the framework results from Y-O-P bridges. This crystal structure refinement leads to the calculated X-ray diffraction powder pattern of this monoclinic polymorph, which has been the starting point of a thorough study of the solid-state synthesis of this ultraphosphate. This investigation further leads to a better outstanding of features observed during the synthesis of powdered samples. The thermal behavior of this ultraphosphate has been studied by DTA and TGA analyses. The infrared and Raman spectroscopic characterizations have been carried out on polycrystalline samples. The luminescence properties of the Eu 3+ ion incorporated in the monoclinic C2/ c polymorph of YP 5O 14 as local structural probe show that in YP 5O 14: 5% Eu 3+ sample, the Eu 3+ ions are distributed over the two Y 3+ crystallographic sites of C 2 symmetry of this structure.

Investigation of La and Al substitution on the spontaneous polarization and lattice dynamics of the Pb(1-x)LaxTi(1-x)AlxO3 ceramics

NASA Astrophysics Data System (ADS)

Yadav, Arun Kumar; Verma, Anita; Kumar, Sunil; Srihari, Velaga; Sinha, A. K.; Reddy, V. Raghavendra; Liu, Shun Wei; Biring, Sajal; Sen, Somaditya

2018-03-01

The phase purity and crystal structure of Pb(1-x)LaxTi(1-x)AlxO3 (0 ≤ x ≤ 0.25) samples (synthesized via the sol-gel process) were confirmed using synchrotron x-ray powder diffraction (XRD) (wavelength, λ = 0.44573 Å). Rietveld analyses of powder x-ray diffraction data confirmed the tetragonal structure for compositions with x ≤ 0.18 and cubic structure for the sample with x = 0.25. Temperature-dependent XRD was performed to investigate the structural change from tetragonal to cubic structure phase transition. Raman spectroscopy at room temperature also confirmed this phase transition with compositions. Field emission scanning electron microscopy (FESEM) provided information about the surface morphology while an energy dispersive x-ray spectrometer attached with FESEM confirmed the chemical compositions of samples. Temperature and frequency dependent dielectric studies showed that the tetragonal to cubic phase transition decreased from 680 K to 175 K with an increase in the x from 0.03 to 0.25, respectively. This is correlated with the structural studies. Electric field dependent spontaneous polarization showed a proper ferroelectric loop for 0.06 ≤ x ≤ 0.18 belonging to a tetragonal phase, while for x ≥ 0.25, the spontaneous polarization vanishes. Bipolar strain versus electric field revealed a butterfly loop for 0.06 ≤ x ≤ 0.18 compositions. Energy storage efficiency initially increases nominally with substitution but beyond x = 0.18 enhances considerably.

Ochres and earths: matrix and chromophores characterization of 19th and 20th century artist materials.

PubMed

Montagner, Cristina; Sanches, Diogo; Pedroso, Joana; Melo, Maria João; Vilarigues, Márcia

2013-02-15

The present paper describes the main results obtained from the characterization of a wide range of natural and synthetic ochre samples used in Portugal from the 19th to the 20th century, including powder and oil painting samples. The powder ochre samples came from several commercial distributors and from the collection of Joaquim Rodrigo (1912-1997), a leading Portuguese artist, particularly active during the sixties and seventies. The micro-samples of oil painting tubes came from the Museu Nacional de Arte Contemporânea-Museu do Chiado (National Museum of Contemporary Art-Chiado Museum) in Lisbon and were used by Columbano Bordalo Pinheiro (1857-1929), one of the most prominent naturalist Portuguese painters. These tubes were produced by the main 19th century colourmen: Winsor & Newton, Morin et Janet, Maison Merlin, and Lefranc. The samples have been studied using μ-Fourier Transform Infrared Spectroscopy (μ-FTIR), Raman microscopy, μ-Energy Dispersive X-ray fluorescence (μ-EDXRF), and X-ray diffraction (XRD). The analyzed ochres were found to be a mixture of several components: iron oxides and hydroxides in matrixes with kaolinite, gypsum and chalk. The results obtained allowed to identify and characterize the ochres according to their matrix and chromophores. The main chromophores where identified by Raman microscopy as being hematite, goethite and magnetite. The infrared analysis of the ochre samples allowed to divide them into groups, according to the composition of the matrix. It was possible to separate ochres containing kaolinite matrix and/or sulfate matrix from ochres where only iron oxides and/or hydroxides were detected. μ-EDXRF and Raman were the best techniques to identify umber, since the presence of elements such as manganese is characteristic of these pigments. μ-EDXRF also revealed the presence of significant amounts of arsenic in all Sienna tube paints. Copyright © 2012 Elsevier B.V. All rights reserved.

Ochres and earths: Matrix and chromophores characterization of 19th and 20th century artist materials

NASA Astrophysics Data System (ADS)

Montagner, Cristina; Sanches, Diogo; Pedroso, Joana; Melo, Maria João; Vilarigues, Márcia

2013-02-01

The present paper describes the main results obtained from the characterization of a wide range of natural and synthetic ochre samples used in Portugal from the 19th to the 20th century, including powder and oil painting samples. The powder ochre samples came from several commercial distributors and from the collection of Joaquim Rodrigo (1912-1997), a leading Portuguese artist, particularly active during the sixties and seventies. The micro-samples of oil painting tubes came from the Museu Nacional de Arte Contemporânea-Museu do Chiado (National Museum of Contemporary Art-Chiado Museum) in Lisbon and were used by Columbano Bordalo Pinheiro (1857-1929), one of the most prominent naturalist Portuguese painters. These tubes were produced by the main 19th century colourmen: Winsor & Newton, Morin et Janet, Maison Merlin, and Lefranc. The samples have been studied using μ-Fourier Transform Infrared Spectroscopy (μ-FTIR), Raman microscopy, μ-Energy Dispersive X-ray fluorescence (μ-EDXRF), and X-ray diffraction (XRD). The analyzed ochres were found to be a mixture of several components: iron oxides and hydroxides in matrixes with kaolinite, gypsum and chalk. The results obtained allowed to identify and characterize the ochres according to their matrix and chromophores. The main chromophores where identified by Raman microscopy as being hematite, goethite and magnetite. The infrared analysis of the ochre samples allowed to divide them into groups, according to the composition of the matrix. It was possible to separate ochres containing kaolinite matrix and/or sulfate matrix from ochres where only iron oxides and/or hydroxides were detected. μ-EDXRF and Raman were the best techniques to identify umber, since the presence of elements such as manganese is characteristic of these pigments. μ-EDXRF also revealed the presence of significant amounts of arsenic in all Sienna tube paints.

Pressure-induced Lifshitz transition in NbP: Raman, x-ray diffraction, electrical transport, and density functional theory

NASA Astrophysics Data System (ADS)

Gupta, Satyendra Nath; Singh, Anjali; Pal, Koushik; Muthu, D. V. S.; Shekhar, C.; Qi, Yanpeng; Naumov, Pavel G.; Medvedev, Sergey A.; Felser, C.; Waghmare, U. V.; Sood, A. K.

2018-02-01

We report high-pressure Raman, synchrotron x-ray diffraction, and electrical transport studies on Weyl semimetals NbP and TaP along with first-principles density functional theoretical (DFT) analysis. The frequencies of first-order Raman modes of NbP harden with increasing pressure and exhibit a slope change at Pc˜9 GPa. The pressure-dependent resistivity exhibits a minimum at Pc. The temperature coefficient of resistivity below Pc is positive as expected for semimetals but changes significantly in the high-pressure phase. Using DFT calculations, we show that these anomalies are associated with a pressure-induced Lifshitz transition, which involves the appearance of electron and hole pockets in its electronic structure. In contrast, the results of Raman and synchrotron x-ray diffraction experiments on TaP and DFT calculations show that TaP is quite robust under pressure and does not undergo any phase transition.

Raman spectroscopic identification of usnic acid in hydrothermal minerals as a potential Martian analogue

NASA Astrophysics Data System (ADS)

Osterrothová, Kateřina; Jehlička, Jan

2009-08-01

Raman spectroscopy using 785 nm excitation was tested as a nondestructive method for determining the presence of the potential biomarker, usnic acid, in experimentally prepared mineral matrices. Investigated samples consisting of usnic acid mixed with powdered hydrothermal minerals, gypsum and calcite were studied. Various concentrations of usnic acid in the mineral matrix were studied to determine the detection limits of this biomarker. Usnic acid was mixed with gypsum (respectively, calcite) and covered by a UV-transparent crystal of gypsum (CaSO 4·2H 2O), thereby creating artificial inclusions similar to those which could be present in Martian minerals. A Raman usnic acid signal at the concentration level as low as 1 g kg -1 was obtained in the powdered mineral matrix and 5 g kg -1 when analyzed through the monocrystal. The number of registered usnic acid key Raman bands was dependent on the particular mineral matrix. If a similar concentration of usnic acid could persist in Martian samples, then Raman spectroscopy will be able to identify it. Obtained results will aid both in situ Raman analyses on Mars and on Earth.

Raman mapping study of the pigments in the dancheong of Korean traditional buildings

NASA Astrophysics Data System (ADS)

Ji, Jeong-Eun; Han, Kiok; Nam, Jiyeon; Kim, Seung; Kang, Dai-Ill; Park, Min-Jung; Lee, Han-Hyoung; Yang, In-Sang

2017-04-01

Korea experienced a tragic loss of most of the Sungnyemun building in an arson attack in 2008. Few scientific records of the pigments originally used in the Korean national treasure exist, thus, the restoration of Sungnyemun was a serious failure. Because the Raman spectroscopic method has the advantage of analyzing the pigment phases in a simple, nondestructive, and noncontact way, it is becoming more important in scientific research on the colors present in cultural assets. In this study, Raman mapping measurements of the pigments in several "dancheong" - color decorations of the surfaces of the wood structure of Korean buildings - samples from Bongjeongsa Geukrakjeon and Sunglimsa Bogwangjeon are presented. The distribution of the pigments, which is difficult to observe with the naked eye, can be found in detail through a high-resolution Raman mapping image. A change of Raman spectrum due to the powderization of some pigments in the colored layer is also observed. The powderization of the pigments is considered to be due to weathering. Our Raman study will be helpful for the preservation and restoration of cultural heritage in general.

Radiation-Induced Changes in Quartz, A Mineral Analog of Nuclear Power Plant Concrete Aggregates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silva, Chinthaka M.; Rosseel, Thomas M.; Kirkegaard, Marie C.

Quartz single-crystal samples consisting of α-quartz crystal structure were neutron irradiated to fluences of 5 × 10 18, 4 × 10 19, and 2 × 10 20 n/cm 2 (E > 0.1 MeV) at two temperatures (52 and 95 °C). The changes in the α-quartz phase as a function of these two conditions (temperature and fluence) were studied using X-ray powder diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM), and the results acquired using these complementary techniques are presented in a single place for the first time. XRD studies showed that the lattice parameters of α-quartz increased with increasingmore » neutron flux. The lattice growth was larger for the samples that were neutron irradiated at 52 °C than at 95 °C. Moreover, an amorphous content was determined in the quartz samples neutron irradiated at 4 × 10 19 n/cm 2, with the greater amount being in the 52 °C irradiated sample. Complete amorphization of quartz was observed at a fluence of 2 × 10 20 n/cm 2 (E > 0.1 MeV) using XRD and confirmed by TEM characterization and Raman spectroscopic studies. In conclusion, the cause for α-quartz lattice expansion and sample amorphization was also explored using XRD and Raman spectroscopic studies.« less

Radiation-Induced Changes in Quartz, A Mineral Analog of Nuclear Power Plant Concrete Aggregates

DOE PAGES

Silva, Chinthaka M.; Rosseel, Thomas M.; Kirkegaard, Marie C.

2018-03-07

Quartz single-crystal samples consisting of α-quartz crystal structure were neutron irradiated to fluences of 5 × 10 18, 4 × 10 19, and 2 × 10 20 n/cm 2 (E > 0.1 MeV) at two temperatures (52 and 95 °C). The changes in the α-quartz phase as a function of these two conditions (temperature and fluence) were studied using X-ray powder diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM), and the results acquired using these complementary techniques are presented in a single place for the first time. XRD studies showed that the lattice parameters of α-quartz increased with increasingmore » neutron flux. The lattice growth was larger for the samples that were neutron irradiated at 52 °C than at 95 °C. Moreover, an amorphous content was determined in the quartz samples neutron irradiated at 4 × 10 19 n/cm 2, with the greater amount being in the 52 °C irradiated sample. Complete amorphization of quartz was observed at a fluence of 2 × 10 20 n/cm 2 (E > 0.1 MeV) using XRD and confirmed by TEM characterization and Raman spectroscopic studies. In conclusion, the cause for α-quartz lattice expansion and sample amorphization was also explored using XRD and Raman spectroscopic studies.« less

Synthesis, growth, structural characterization, Hirshfeld analysis and nonlinear optical studies of a methyl substituted chalcone

NASA Astrophysics Data System (ADS)

Prabhu, Shobha R.; Jayarama, A.; Chandrasekharan, K.; Upadhyaya, V.; Ng, Seik Weng

2017-05-01

A new chalcone compound (2E)-3-(3-methylphenyl)-1-(4-nitrophenyl)prop-2-en-1-one (3MPNP) with molecular formula C16H13NO3 has been synthesized and crystallized by slow solvent evaporation technique. The Fourier transform infrared, Fourier transform Raman and nuclear magnetic resonance techniques were used for structural characterization. UV-visible absorption studies were carried out to study the transparency of the crystal in the visible region. Differential scanning calorimetry study shows thermal stability of crystals up to temperature 122 °C. Single crystal X-ray diffraction and powder X-ray diffraction techniques were used to study crystal structure and cell parameters. The Hirshfeld surface and 2-D fingerprint analysis were performed to study the nature of interactions and their quantitative contributions towards the crystal packing. The third order non-linear optical properties have been studied using single beam Z-scan technique and the results show that the material is a potential candidate for optical device applications such as optical limiters and optical switches.

Screening and structural elucidation of the zwitterionic cocrystal o-picolinic acid with p-nitro aniline

NASA Astrophysics Data System (ADS)

Mekala, R.; Jagdish, P.; Mathammal, R.; Sangeetha, K.

2017-04-01

The cocrystal was screened by solvent drop grinding method and the crystals were grown by slow evaporation method at ambient conditions. The cocrystal formation of o-picolinic acid with p-nitro aniline was initially analysed by powder X-ray diffraction. Further the structural properties of the grown crystal were confirmed by the single X-ray diffraction which indicates that the cocrystal were connected by the strong N+sbnd H-⋯O hydrogen bond interaction. The cell parameters of the grown crystal were a = 14.2144(5) Å, b = 5.7558(2) Å, c = 16.0539(6) Å. The functional groups were identified using Fourier transform infrared and Raman spectral analysis. The excitation and emission state of the sample was analysed by the UV-Visible and Fluorescence studies. The red emission was observed from the Fluorescence studies. NMR studies revealed the chemical shift of the cocrystal. Thermal stability and its melting behaviour were studied by TGA and DSC analytical techniques. Electrical behaviour was studied using the dielectric studies. The intermolecular charge transfer within the molecule were analysed using HOMO- LUMO plots.

Structure and vibrational spectra of melaminium bis(trifluoroacetate) trihydrate: FT-IR, FT-Raman and quantum chemical calculations

NASA Astrophysics Data System (ADS)

Sangeetha, V.; Govindarajan, M.; Kanagathara, N.; Marchewka, M. K.; Gunasekaran, S.; Anbalagan, G.

Melaminium bis(trifluoroacetate) trihydrate (MTFA), an organic material has been synthesized and single crystals of MTFA have been grown by the slow solvent evaporation method at room temperature. X-ray powder diffraction analysis confirms that MTFA crystal belongs to the monoclinic system with space group P2/c. The molecular geometry, vibrational frequencies and intensity of the vibrational bands have been interpreted with the aid of structure optimization based on density functional theory (DFT) B3LYP method with 6-311G(d,p) and 6-311++G(d,p) basis sets. The X-ray diffraction data have been compared with the data of optimized molecular structure. The theoretical results show that the crystal structure can be reproduced by optimized geometry and the vibrational frequencies show good agreement with the experimental values. The nuclear magnetic resonance (NMR) chemical shift of the molecule has been calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. HOMO-LUMO, and other related molecular and electronic properties are calculated. The Mulliken and NBO charges have also been calculated and interpreted.

Identification of different forms of cocaine and substances used in adulteration using near-infrared Raman spectroscopy and infrared absorption spectroscopy.

PubMed

Penido, Ciro A F O; Pacheco, Marcos Tadeu T; Zângaro, Renato A; Silveira, Landulfo

2015-01-01

Identification of cocaine and subsequent quantification immediately after seizure are problems for the police in developing countries such as Brazil. This work proposes a comparison between the Raman and FT-IR techniques as methods to identify cocaine, the adulterants used to increase volume, and possible degradation products in samples seized by the police. Near-infrared Raman spectra (785 nm excitation, 10 sec exposure time) and FT-IR-ATR spectra were obtained from different samples of street cocaine and some substances commonly used as adulterants. Freebase powder, hydrochloride powder, and crack rock can be distinguished by both Raman and FT-IR spectroscopies, revealing differences in their chemical structure. Most of the samples showed characteristic peaks of degradation products such as benzoylecgonine and benzoic acid, and some presented evidence of adulteration with aluminum sulfate and sodium carbonate. Raman spectroscopy is better than FT-IR for identifying benzoic acid and inorganic adulterants in cocaine. © 2014 American Academy of Forensic Sciences.

Raman spectroscopy method for subsurface detection of food powders through plastic layers

USDA-ARS?s Scientific Manuscript database

Turmeric (Curcuma longa L.) powder, valued for both medicinal properties and culinary use, has been subject to economically driven hazardous chemical adulteration by the similarly colored but toxic metanil yellow. Such adulterated food powders in sealed containers can often go undetected due to lack...

Application of focused-beam flat-sample method to synchrotron powder X-ray diffraction with anomalous scattering effect

NASA Astrophysics Data System (ADS)

Tanaka, M.; Katsuya, Y.; Matsushita, Y.

2013-03-01

The focused-beam flat-sample method (FFM), which is a method for high-resolution and rapid synchrotron X-ray powder diffraction measurements by combination of beam focusing optics, a flat shape sample and an area detector, was applied for diffraction experiments with anomalous scattering effect. The advantages of FFM for anomalous diffraction were absorption correction without approximation, rapid data collection by an area detector and good signal-to-noise ratio data by focusing optics. In the X-ray diffraction experiments of CoFe2O4 and Fe3O4 (By FFM) using X-rays near the Fe K absorption edge, the anomalous scattering effect between Fe/Co or Fe2+/Fe3+ can be clearly detected, due to the change of diffraction intensity. The change of observed diffraction intensity as the incident X-ray energy was consistent with the calculation. The FFM is expected to be a method for anomalous powder diffraction.

Structural characterization, electrical conductivity and open circuit voltage studies of the nanocrystalline La10Si6O27 electrolyte material for SOFCs

NASA Astrophysics Data System (ADS)

Jena, Paramananda; Jayasubramaniyan, S.; Patro, P. K.; Lenka, R. K.; Sinha, Amit; Muralidharan, P.; Srinadhu, E. S.; Satyanarayana, N.

2018-02-01

Nanocrystalline La10Si6O27 apatite-type sample was synthesized by the co-precipitation method. Thermal behavior, phase, structure, morphology and elemental composition of La, O and Si of the synthesized La10Si6O27 sample were investigated through TG/DTA, XRD, FTIR, Raman spectroscopy and SEM-EDX measurements respectively. Formation of phase purity of the nanocrystalline La10Si6O27 sample was confirmed by analysing the measured X-ray powder diffraction (XRD) pattern using Rietveld refinement and the calculated average crystallite size of the La10Si6O27 sample was found to be 33 nm. The electrical conductivity of the sintered La10Si6O27 pellet was investigated as a function of temperature ranging from 200 to 800 °C under air and it was found to be 1.92 × 10-3 S cm-1 at 800 °C. The chemical stability of La10Si6O27 powder under oxidizing and reducing atmospheres was confirmed from the analysis of the measured XRD pattern and Raman spectral results. Open circuit potential of a button cell, made up of the La10Si6O27 sample, was tested up to 800 °C with both oxygen and hydrogen at opposite sides of the cell and was found to 1 V. Hence, the results demonstrate that La10Si6O27 could be a promising solid electrolyte material for the solid oxide fuel cell (SOFC) applications.

[Detection of single-walled carbon nanotube bundles by tip-enhanced Raman spectroscopy].

PubMed

Wu, Xiao-Bin; Wang, Jia; Wang, Rui; Xu, Ji-Ying; Tian, Qian; Yu, Jian-Yuan

2009-10-01

Raman spectroscopy is a powerful technique in the characterization of carbon nanotubes (CNTs). However, this spectral method is subject to two obstacles. One is spatial resolution, namely the diffraction limits of light, and the other is its inherent small Raman cross section and weak signal. To resolve these problems, a new approach has been developed, denoted tip-enhanced Raman spectroscopy (TERS). TERS has been demonstrated to be a powerful spectroscopic and microscopic technique to characterize nanomaterial or nanostructures. Excited by a focused laser beam, an enhanced electric field is generated in the vicinity of a metallic tip because of the surface plasmon polariton (SPP) and lightening rod effect. Consequently, Raman signal from the sample area illuminated by the enhanced field nearby the tip is enhanced. At the same time, the topography is obtained in the nanometer scale. The exact corresponding relationship between the localized Raman and the topography makes the Raman identification at the nanometer scale to be feasible. In the present paper, based on an inverted microscope and a metallic AFM tip, a tip-enhanced Raman system was set up. The radius of the Au-coated metallic tip is about 30 nm. The 532 nm laser passes through a high numerical objective (NA0.95) from the bottom to illuminate the tip to excite the enhanced electric field. Corresponding with the AFM image, the tip-enhanced near-field Raman of a 100 nm diameter single-walled carbon nanotube (SWNT) bundles was obtained. The SWNTs were prepared by arc method. Furthermore, the near-field Raman of about 3 SWNTs of the bundles was received with the spatial resolution beyond the diffraction limit. Compared with the far-field Raman, the enhancement factor of the tip-enhanced Raman is more than 230. With the super-diffraction spatial resolution and the tip-enhanced Raman ability, tip-enhanced Raman spectroscopy will play an important role in the nano-material and nano-structure characterization.

Periodic organosilica hollow nanospheres as anode materials for lithium ion rechargeable batteries

NASA Astrophysics Data System (ADS)

Sasidharan, Manickam; Nakashima, Kenichi; Gunawardhana, Nanda; Yokoi, Toshiyuki; Ito, Masanori; Inoue, Masamichi; Yusa, Shin-Ichi; Yoshio, Masaki; Tatsumi, Takashi

2011-11-01

Polymeric micelles with core-shell-corona architecture have been found to be the efficient colloidal templates for synthesis of periodic organosilica hollow nanospheres over a broad pH range from acidic to alkaline media. In alkaline medium, poly (styrene-b-[3-(methacryloylamino)propyl] trimethylammonium chloride-b-ethylene oxide) (PS-PMAPTAC-PEO) micelles yield benzene-silica hollow nanospheres with molecular scale periodicity of benzene groups in the shell domain of hollow particles. Whereas, an acidic medium (pH 4) produces diverse hollow particles with benzene, ethylene, and a mixture of ethylene and dipropyldisulfide bridging functionalities using poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-PVP-PEO) micelles. These hollow particles were thoroughly characterized by powder X-ray diffraction (XRD), dynamic light scattering (DLS), thermogravimetric analysis (TG/DTA), Fourier transformation infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), magic angle spinning-nuclear magnetic resonance (29Si MAS NMR and 13CP-MAS NMR), Raman spectroscopy, and nitrogen adsorption/desorption analyses. The benzene-silica hollow nanospheres with molecular scale periodicity in the shell domain exhibit higher cycling performance of up to 300 cycles in lithium ion rechargeable batteries compared with micron-sized dense benzene-silica particles.Polymeric micelles with core-shell-corona architecture have been found to be the efficient colloidal templates for synthesis of periodic organosilica hollow nanospheres over a broad pH range from acidic to alkaline media. In alkaline medium, poly (styrene-b-[3-(methacryloylamino)propyl] trimethylammonium chloride-b-ethylene oxide) (PS-PMAPTAC-PEO) micelles yield benzene-silica hollow nanospheres with molecular scale periodicity of benzene groups in the shell domain of hollow particles. Whereas, an acidic medium (pH 4) produces diverse hollow particles with benzene, ethylene, and a mixture of ethylene and dipropyldisulfide bridging functionalities using poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-PVP-PEO) micelles. These hollow particles were thoroughly characterized by powder X-ray diffraction (XRD), dynamic light scattering (DLS), thermogravimetric analysis (TG/DTA), Fourier transformation infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), magic angle spinning-nuclear magnetic resonance (29Si MAS NMR and 13CP-MAS NMR), Raman spectroscopy, and nitrogen adsorption/desorption analyses. The benzene-silica hollow nanospheres with molecular scale periodicity in the shell domain exhibit higher cycling performance of up to 300 cycles in lithium ion rechargeable batteries compared with micron-sized dense benzene-silica particles. Electronic supplementary information (ESI) available: FTIR, Raman spectral data, additional TEM pictures, N2 adsorption and physical characteristics of hollow particles data, and cycling performance of dense silica particles. See DOI: 10.1039/c1nr10804b

Raman validity for crystallite size La determination on reticulated vitreous carbon with different graphitization index

NASA Astrophysics Data System (ADS)

Baldan, M. R.; Almeida, E. C.; Azevedo, A. F.; Gonçalves, E. S.; Rezende, M. C.; Ferreira, N. G.

2007-11-01

The graphitization index provided by X-ray diffraction (XRD) and Raman spectrometry for reticulated vitreous carbon (RVC) substrates, carbonized at different heat treatment temperatures (HTT), is investigated. A systematic study of the dependence between the disorder-induced D and G Raman bands is presented. The crystallite size La was obtained for both X-ray diffraction and Raman spectrometry techniques. Particularly, the validity for La determination, from Raman spectra, is pointed out comparing the commonly used formula based on peaks amplitude ratio ( ID/ IG) and the recent proposed equation that uses the integrated intensities of D and G bands. The results discrepancy is discussed taken into account the strong contribution of the line broadening presented in carbon materials heat treated below 2000 °C.

Expected values and variances of Bragg peak intensities measured in a nanocrystalline powder diffraction experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Öztürk, Hande; Noyan, I. Cevdet

A rigorous study of sampling and intensity statistics applicable for a powder diffraction experiment as a function of crystallite size is presented. Our analysis yields approximate equations for the expected value, variance and standard deviations for both the number of diffracting grains and the corresponding diffracted intensity for a given Bragg peak. The classical formalism published in 1948 by Alexander, Klug & Kummer [J. Appl. Phys.(1948),19, 742–753] appears as a special case, limited to large crystallite sizes, here. It is observed that both the Lorentz probability expression and the statistics equations used in the classical formalism are inapplicable for nanocrystallinemore » powder samples.« less

Expected values and variances of Bragg peak intensities measured in a nanocrystalline powder diffraction experiment

DOE PAGES

Öztürk, Hande; Noyan, I. Cevdet

2017-08-24

A rigorous study of sampling and intensity statistics applicable for a powder diffraction experiment as a function of crystallite size is presented. Our analysis yields approximate equations for the expected value, variance and standard deviations for both the number of diffracting grains and the corresponding diffracted intensity for a given Bragg peak. The classical formalism published in 1948 by Alexander, Klug & Kummer [J. Appl. Phys.(1948),19, 742–753] appears as a special case, limited to large crystallite sizes, here. It is observed that both the Lorentz probability expression and the statistics equations used in the classical formalism are inapplicable for nanocrystallinemore » powder samples.« less

Thermal analysis, X-ray powder diffraction and electron microscopy data related with the production of 1:1 Caffeine:Glutaric Acid cocrystals.

PubMed

Duarte, Íris; Andrade, Rita; Pinto, João F; Temtem, Márcio

2016-09-01

The data presented in this article are related to the production of 1:1 Caffeine:Glutaric Acid cocrystals as part of the research article entitled "Green production of cocrystals using a new solvent-free approach by spray congealing" (Duarte et al., 2016) [1]. More specifically, here we present the thermal analysis and the X-ray powder diffraction data for pure Glutaric Acid, used as a raw material in [1]. We also include the X-ray powder diffraction and electron microscopy data obtained for the 1:1 Caffeine:Glutaric Acid cocrystal (form II) produced using the cooling crystallization method reported in "Operating Regions in Cooling Cocrystallization of Caffeine and Glutaric Acid in Acetonitrile" (Yu et al., 2010) [2]. Lastly, we show the X-ray powder diffraction data obtained for assessing the purity of the 1:1 Caffeine:Glutaric cocrystals produced in [1].

Synthesis of nanostructured vanadium powder by high-energy ball milling: X-ray diffraction and high-resolution electron microscopy characterization

NASA Astrophysics Data System (ADS)

Krishnan, Vinoadh Kumar; Sinnaeruvadi, Kumaran

2016-10-01

Vanadium metal powders, ball milled with different surfactants viz., stearic acid, KCl and NaCl, have been studied by X-ray diffraction and transmission electron microscopy. The surfactants alter the microstructural and morphological characteristics of the powders. Ball milling with stearic acid results in solid-state amorphization, while powders milled with KCl yield vanadium-tungsten carbide nanocomposite mixtures. NaCl proved to be an excellent surfactant for obtaining nanostructured fusion-grade vanadium powders. In order to understand the reaction mechanism behind any interstitial addition in the ball-milled powders, CHNOS analysis was performed.

Calibration and testing of a Raman hyperspectral imaging system to reveal powdered food adulteration

USDA-ARS?s Scientific Manuscript database

The potential adulteration of foodstuffs has led to increasing concern regarding food safety and security, in particular for powdered food products where cheap ground materials or hazardous chemicals can be added to increase the quantity of powder or to obtain the desired aesthetic quality. Due to t...

New process of preparation, X-ray characterisation, structure and vibrational studies of a solid solution LiTiOAs 1-xP xO 4 (0⩽ x⩽1)

NASA Astrophysics Data System (ADS)

Chakir, M.; El Jazouli, A.; Chaminade, J. P.; Bouree, F.; de Waal, D.

2006-01-01

LiTiOAs 1-xP xO 4 (0⩽ x⩽1) compounds have been prepared using solutions of Li, Ti, As and P elements as starting products. Selected compositions have been investigated by powder X-ray or neutrons diffraction analysis, Raman and infrared spectroscopy. The structure of LiTiOAs 1-xP xO 4 ( x=0, 0.5 and 1) samples determined by Rietveld analysis is orthorhombic with Pnma space group. It is formed by a 3D network of TiO 6 octahedra and XO 4 ( X=As 1-xP x) tetrahedra where octahedral cavities are occupied by lithium atoms. TiO 6 octahedra are linked together by corners and form infinite chains along a-axis. Ti atoms are displaced from the centre of octahedral units in alternating short (1.700-1.709 Å) and long (2.301-2.275 Å) Ti-O bonds. Raman and infrared studies confirm the existence of Ti-O-Ti chains. Thermal stability of LiTiOAsO 4 has been reported.

Evaluation of physical health effects due to volcanic hazards: crystalline silica in Mount St. Helens volcanic ash.

PubMed

Dollberg, D D; Bolyard, M L; Smith, D L

1986-03-01

This investigation has shown that crystalline silica has been identified as being present in the Mount St. Helens volcanic ash at levels of 3 to 7 per cent by weight. This identification has been established using X-ray powder diffraction, infrared spectrophotometry, visible spectrophotometry, electron microscopy, and Laser Raman spectrophotometry. Quantitative analysis by IR, XRD, and visible spectrophotometry requires a preliminary phosphoric acid digestion of the ash sample to remove the plagioclase silicate material which interferes with the determination by these methods. Electron microscopic analysis as well as Laser Raman spectrophotometric analysis of the untreated ash confirms the presence of silica and at levels found by the XRD and IR analysis of the treated samples. An interlaboratory study of volcanic ash samples by 15 laboratories confirms the presence and levels of crystalline silica. Although several problems with applying the digestion procedure were observed in this hastily organized supply, all laboratories employing the digestion procedure reported the presence of crystalline silica. These results unequivocally put to rest the question of the presence of silica in the volcanic ash from eruptions of Mount St. Helens in 1980.

A combined crystallographic, thermal, Raman and computational study on polymorphism and phase transition in 1-(4-hexyloxy-3-hydroxyphenyl)ethanone.

PubMed

Suárez, Sebastián; Manzano, Veronica E; Fantoni, Adolfo C; Halac, Emilia; Baggio, Ricardo; Cukiernik, Fabio D

2017-12-01

The crystal structure of the triclinic polymorph of 1-(4-hexyloxy-3-hydroxyphenyl)ethanone, C 14 H 20 O 3 , differs markedly from that of the orthorhombic polymorph [Manzano et al. (2015). Acta Cryst. C71, 1022-1027]. The two molecular structures are alike with respect to their bond lengths and angles, but differ in their spatial arrangement. This gives rise to quite different packing schemes, even if built up by similar chains having the hydroxy-ethanone O-H...O hydrogen-bond synthon in common. Both phases were found to be related by a first-order thermally driven phase transformation at 338-340 K, which is discussed in detail. The relative stabilities of both polymorphs are explained on the basis of both the noncovalent interactions operating in each structure and quantum chemical calculations. The polymorphic phase transition has also been studied experimentally by means of differential scanning calorimetry (DSC) experiments, conducted on individual single crystals, Raman spectroscopy and controlled heating under a microscope of individual single crystals, which were further characterized by powder and single-crystal X-ray diffraction.

Thermal and structural characterization of synthetic and natural nanocrystalline hydroxyapatite.

PubMed

Sofronia, Ancuta M; Baies, Radu; Anghel, Elena M; Marinescu, Cornelia A; Tanasescu, Speranta

2014-10-01

The aim of this work was to study the thermal stability on heating and to obtain the processing parameters of synthetic and bone-derived hydroxyapatite over temperatures between room temperature and 1400°C by thermal analysis (thermogravimetry (TG)/differential scanning calorimetry (DSC) and thermo-mechanical analysis-TMA). Structural and surface modifications related to samples origin and calcination temperature were investigated by Fourier transformed infrared (FTIR) and Raman spectroscopy, X-ray diffraction (XRD) and BET method. FTIR spectra indicated that the organic constituents and carbonate are no longer present in the natural sample calcined at 800°C. Raman spectra highlighted the decomposition products of the hydroxyapatite. The calcination treatment modifies the processes kinetics of the synthetic samples, being able to isolate lattice water desorption processes of decarbonization and the dehydroxylation processes. Shrinkage of calcined synthetic sample increases by 10% compared to uncalcined synthetic powder. From the TMA correlated with TG analysis and heat capacity data it can be concluded that sintering temperature of the synthetic samples should be chosen in the temperature range of the onset of dehydroxylation and the temperature at which oxyapatite decomposition begins. Copyright © 2014 Elsevier B.V. All rights reserved.

In situ measurement of magnesium carbonate formation from CO2 using static high-pressure and -temperature 13C NMR.

PubMed

Surface, J Andrew; Skemer, Philip; Hayes, Sophia E; Conradi, Mark S

2013-01-02

We explore a new in situ NMR spectroscopy method that possesses the ability to monitor the chemical evolution of supercritical CO(2) in relevant conditions for geological CO(2) sequestration. As a model, we use the fast reaction of the mineral brucite, Mg(OH)(2), with supercritical CO(2) (88 bar) in aqueous conditions at 80 °C. The in situ conversion of CO(2) into metastable and stable carbonates is observed throughout the reaction. After more than 58 h of reaction, the sample was depressurized and analyzed using in situ Raman spectroscopy, where the laser was focused on the undisturbed products through the glass reaction tube. Postreaction, ex situ analysis was performed on the extracted and dried products using Raman spectroscopy, powder X-ray diffraction, and magic-angle spinning (1)H-decoupled (13)C NMR. These separate methods of analysis confirmed a spatial dependence of products, possibly caused by a gradient of reactant availability, pH, and/or a reaction mechanism that involves first forming hydroxy-hydrated (basic, hydrated) carbonates that convert to the end-product, anhydrous magnesite. This carbonation reaction illustrates the importance of static (unmixed) reaction systems at sequestration-like conditions.

Analysis of Roman age wall paintings found in Pordenone, Trieste and Montegrotto.

PubMed

Mazzocchin, G A; Agnoli, F; Salvadori, M

2004-10-20

The aim of the present work is the study of many fragments of wall painting from archaeological excavations in three different Roman age sites dating back to the I Century before Common Era: Pordenone (località Torre); Trieste (Crosada) and Padova (Montegrotto). The techniques used were optical microscopy, scanning electron microscopy (SEM), equipped with a EDS microanalysis detector, X-rays powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Fourier transform Raman spectroscopy (FT-Raman) and electron paramagnetic resonance (EPR) spectroscopy. The identified pigments were: cinnabar, hematite, celadonite, glauconite, cuprorivaite (Egyptian blue), yellow and red ochre, calcite, limonite, coal black. In general, the mortar preparation did not correspond to the complex procedure suggested by Vitruvius (De Architectura), but generally showed a porous layer, with crushed grains under the pigment layer. In some cases, two superimposed pigment layers were found: yellow superimposed on both red and pink, black on pink, green on black. The slight differences we found in the use of the pigments in the three studied sites might show that the same technology, culture and taste spread all over the Roman Empire in North Eastern Italy (X(a) Regio Venetia et Histria).

Structural, Morphological, Optical and Photocatalytic Properties of Y, N-Doped and Codoped TiO2 Thin Films

PubMed Central

Hamden, Zeineb; Conceição, David; Boufi, Sami; Vieira Ferreira, Luís Filipe; Bouattour, Soraa

2017-01-01

Pure TiO2, Y-N single-doped and codoped TiO2 powders and thin films deposited on glass beads were successfully prepared using dip-coating and sol-gel methods. The samples were analyzed using grazing angle X-ray diffraction (GXRD), Raman spectroscopy, time resolved luminescence, ground state diffuse reflectance absorption and scanning electron microscopy (SEM). According to the GXRD patterns and micro-Raman spectra, only the anatase form of TiO2 was made evident. Ground state diffuse reflectance absorption studies showed that doping with N or codoping with N and Y led to an increase of the band gap. Laser induced luminescence analysis revealed a decrease in the recombination rate of the photogenerated holes and electrons. The photocatalytic activity of supported catalysts, toward the degradation of toluidine, revealed a meaningful enhancement upon codoping samples at a level of 2% (atomic ratio). The photocatalytic activity of the material and its reactivity can be attributed to a reduced, but significant, direct photoexcitation of the semiconductor by the halogen lamp, together with a charge-transfer-complex mechanism, or with the formation of surface oxygen vacancies by the N dopant atoms. PMID:28772962

Structural, Morphological, Optical and Photocatalytic Properties of Y, N-Doped and Codoped TiO₂ Thin Films.

PubMed

Hamden, Zeineb; Conceição, David; Boufi, Sami; Vieira Ferreira, Luís Filipe; Bouattour, Soraa

2017-05-31

Pure TiO₂, Y-N single-doped and codoped TiO₂ powders and thin films deposited on glass beads were successfully prepared using dip-coating and sol-gel methods. The samples were analyzed using grazing angle X-ray diffraction (GXRD), Raman spectroscopy, time resolved luminescence, ground state diffuse reflectance absorption and scanning electron microscopy (SEM). According to the GXRD patterns and micro-Raman spectra, only the anatase form of TiO₂ was made evident. Ground state diffuse reflectance absorption studies showed that doping with N or codoping with N and Y led to an increase of the band gap. Laser induced luminescence analysis revealed a decrease in the recombination rate of the photogenerated holes and electrons. The photocatalytic activity of supported catalysts, toward the degradation of toluidine, revealed a meaningful enhancement upon codoping samples at a level of 2% (atomic ratio). The photocatalytic activity of the material and its reactivity can be attributed to a reduced, but significant, direct photoexcitation of the semiconductor by the halogen lamp, together with a charge-transfer-complex mechanism, or with the formation of surface oxygen vacancies by the N dopant atoms.

Optical and superparamagnetic behavior of ZnFe2O4 nanoparticles

NASA Astrophysics Data System (ADS)

Lal, Ganesh; Punia, Khushboo; Dolia, S. N.; Kumar, Sudhish

2018-05-01

Nanoparticles of zinc ferrite have been synthesized using a low temperature citrate sol-gel route and characterized by powder X-ray diffraction (XRD), Raman & UV-Vis-NIR spectroscopic and SQUID magnetometry measurements. Analysis of XRD pattern and Raman spectrum confirmed that the synthesized ZnFe2O4 sample crystallizes in single phase fcc spinel ferrite structure and the average particle size of nanoparticles is estimated to 24nm. Optical absorption study shows that maximum photo absorption take place in the visible band and peaking in UV band at 206nm and the band gap energy is estimated to Eg = 2.1eV. Zero Field Cooled (ZFC) and Field Cooled (FC) modes of magnetization down to 5K and in fields up to 20kOe shows that ZnFe2O4 nanoparticles exhibits superparamagnetism with high magneto-crystalline anisotropy and high magnetization. Small difference of 9K between the separation temperature TS=˜30K and blocking temperature TB= 21K are suggestive of the formation of ferromagnetic clusters and a narrow particle size distribution of the nanoparticles in superparamagnetic ZnFe2O4 nanoparticles.

The green hydrothermal synthesis of nanostructured Cu2ZnSnSe4 as solar cell material and study of their structural, optical and morphological properties

NASA Astrophysics Data System (ADS)

Vanalakar, S. A.; Agawane, G. L.; Kamble, A. S.; Patil, P. S.; Kim, J. H.

2017-12-01

Cu2ZnSnSe4 (CZTSe) has attracted intensive attention as an absorber material for the thin-film solar cells due to its high absorption coefficient, direct band gap, low toxicity, and abundance of its constituent elements. In this study nanostructured CZTSe nanoparticles are prepared via green hydrothermal synthesis without using toxic solvents, organic amines, catalysts or noxious chemicals. The structural, optical, and morphological properties of CZTSe nanostructured powder were studied using X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectroscopy, and transmission electron microscope (TEM) techniques. Raman peaks at 170, 195, and 232 cm-1 confirm the formation of pure phase CZTSe nanostructured particles. In addition, the EDS and XPS results confirm the appropriate chemical purity of the annealed CZTSe nanoparticles. Meanwhile, the TEM analysis showed the presence of phase pure oval like CZTSe particle with size of about 80-140 nm. The UV-Vis-NIR absorption spectra analysis showed that the optical band gap of CZTSe nanostructured particles is about 1.14 eV. This band gap energy is close to the optimum value of a photovoltaic solar cell absorber material.

Sucrose lyophiles: a semi-quantitative study of residual water content by total X-ray diffraction analysis.

PubMed

Bates, S; Jonaitis, D; Nail, S

2013-10-01

Total X-ray Powder Diffraction Analysis (TXRPD) using transmission geometry was able to observe significant variance in measured powder patterns for sucrose lyophilizates with differing residual water contents. Integrated diffraction intensity corresponding to the observed variances was found to be linearly correlated to residual water content as measured by an independent technique. The observed variance was concentrated in two distinct regions of the lyophilizate powder pattern, corresponding to the characteristic sucrose matrix double halo and the high angle diffuse region normally associated with free-water. Full pattern fitting of the lyophilizate powder patterns suggested that the high angle variance was better described by the characteristic diffraction profile of a concentrated sucrose/water system rather than by the free-water diffraction profile. This suggests that the residual water in the sucrose lyophilizates is intimately mixed at the molecular level with sucrose molecules forming a liquid/solid solution. The bound nature of the residual water and its impact on the sucrose matrix gives an enhanced diffraction response between 3.0 and 3.5 beyond that expected for free-water. The enhanced diffraction response allows semi-quantitative analysis of residual water contents within the studied sucrose lyophilizates to levels below 1% by weight. Copyright © 2013 Elsevier B.V. All rights reserved.

Characterisation of the rare cadmium chromate pigment in a 19th century tube colour by Raman, FTIR, X-ray and EPR

NASA Astrophysics Data System (ADS)

Christiansen, Marie Bitsch; Sørensen, Mikkel Agerbæk; Sanyova, Jana; Bendix, Jesper; Simonsen, Kim Pilkjær

2017-03-01

In an investigation of the artists' materials used by P. S. Krøyer the contents of the tube colours found in Krøyer's painting cabinet were examined. In most cases, the results of the pigment analyses were as expected based on our knowledge of artists' colours used in the late 1800s and early 1900s. However, in one of the tube colours labelled "Jaune de Cadmium Citron" (cadmium lemon yellow) an extremely rare cadmium chromate pigment was found. The pigment was analysed and characterised by Raman microscopy (MRS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), powder X-ray diffraction (PXRD), single-crystal X-ray crystallography, and electron paramagnetic resonance (EPR) spectroscopy. Cadmium chromate was synthesised by precipitation from an aqueous solution of cadmium nitrate and potassium chromate, and the resulting yellow crystals proved identical to the pigment found in the tube colour "Jaune de Cadmium Citron". The structure determined by single-crystal X-ray diffraction identified the pigment as 2CdCrO4·KOH·H2O or more accurately as KCd2(CrO4)2(H3O2) illustrating the μ-H3O2- species. The yellow colour of the paint sample taken from the tube had a greenish hue, which became even more prominent upon storage and drying. EPR analysis of the sample showed the presence of paramagnetic degradation products containing Cr(III) and Cr(V).

Characterisation of the rare cadmium chromate pigment in a 19th century tube colour by Raman, FTIR, X-ray and EPR.

PubMed

Christiansen, Marie Bitsch; Sørensen, Mikkel Agerbæk; Sanyova, Jana; Bendix, Jesper; Simonsen, Kim Pilkjær

2017-03-15

In an investigation of the artists' materials used by P. S. Krøyer the contents of the tube colours found in Krøyer's painting cabinet were examined. In most cases, the results of the pigment analyses were as expected based on our knowledge of artists' colours used in the late 1800s and early 1900s. However, in one of the tube colours labelled "Jaune de Cadmium Citron" (cadmium lemon yellow) an extremely rare cadmium chromate pigment was found. The pigment was analysed and characterised by Raman microscopy (MRS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), powder X-ray diffraction (PXRD), single-crystal X-ray crystallography, and electron paramagnetic resonance (EPR) spectroscopy. Cadmium chromate was synthesised by precipitation from an aqueous solution of cadmium nitrate and potassium chromate, and the resulting yellow crystals proved identical to the pigment found in the tube colour "Jaune de Cadmium Citron". The structure determined by single-crystal X-ray diffraction identified the pigment as 2CdCrO 4 ·KOH·H 2 O or more accurately as KCd 2 (CrO 4 ) 2 (H 3 O 2 ) illustrating the μ-H 3 O 2 - species. The yellow colour of the paint sample taken from the tube had a greenish hue, which became even more prominent upon storage and drying. EPR analysis of the sample showed the presence of paramagnetic degradation products containing Cr(III) and Cr(V). Copyright © 2016 Elsevier B.V. All rights reserved.

Zn2+ in-situ substitution behavior during the formation of BaTiO3 coatings from plasma-sprayed powders collected in liquid nitrogen

NASA Astrophysics Data System (ADS)

Liu, Zhe; Xing, Zhiguo; Wang, Haidou; Xue, Zifan; Chen, Shuying; Cui, Xiufang; Jin, Guo

2018-04-01

The dielectric performance of BaTiO3 ceramic coatings is enhanced significantly by the addition of ZnO. In this study, the maximum relative permittivity value (εr ≈ 923) was measured in BaTiO3 coatings with ZnO added at 6 wt%. The Curie temperature (Tc) was in the range of 111 °C-121 °C for all of the ZnO-modified BaTiO3 coatings. Tc shifted to low temperatures as the ZnO content increased. Detailed analyses were performed to determine the phase composition and optical band gaps of powders collected in liquid nitrogen, which showed that the Zn2+ ions were incorporated into the BaTiO3 lattice where they substituted into the Ti4+ sites, and the composite powders (BaTiO3 + 6 wt% ZnO) tolerated high temperatures in the plasma beam. In addition, some residual Zn accumulated in the grain boundary in the form of ZnO. X-ray diffraction and Raman spectroscopy showed that the substitution led to changes in the compositional and structural properties. The red shift in the optical band gap of BaTiO3 indicated that the ZnTi'' defects caused by the dopants acted as carriers in the doped BaTiO3 coatings.

Influence of Cu substitution on the structural ordering, photocatalytic activity and photoluminescence emission of Ag3-2xCuxPO4 powders

NASA Astrophysics Data System (ADS)

Pereira, Wyllamanney da S.; Sczancoski, Júlio C.; Calderon, Yormary N. C.; Mastelaro, Valmor R.; Botelho, Gleice; Machado, Thales R.; Leite, Edson R.; Longo, Elson

2018-05-01

Materials presenting high photocatalytic performance and interesting photoluminescence emissions are promising candidates for photodegradation of organic pollutants discharged into natural waters as well as for development of new electro-optical devices, respectively. In this study, Ag3-2xCuxPO4 (x = 0.00, 0.01, 0.02, 0.04 and 0.08) powders were synthesized by the precipitation method. The long- and short-range structural ordering was affected when the copper (Cu) content was increased in the lattice, as identified by X-ray diffraction patterns, Fourier transform infrared spectroscopy and Raman spectroscopy, respectively. The field emission scanning electron microscope and transmission electron microscope revealed a particle system composed of irregular spherical-like microcrystals. The presence of Cu as well as its real amount in the samples were confirmed by means of X-ray photoelectron spectroscopy and inductively coupled plasma-atomic emission spectrometry, respectively. On increasing Cu level, a slight variation was noted on the photocatalytic activity of Ag3-2xCuxPO4 powders for degradation of rhodamine B under visible light irradiation. A photodegradation mechanism was proposed in details. The photoluminescence emissions were explained by electronic transitions involving intermediary energy levels in the band gap. The origin these energy levels was related to defects caused by the substitution of Ag by Cu in the crystalline structure.

Luminescent properties under X-ray excitation of Ba(1-x)PbxWO4 disordered solid solution

NASA Astrophysics Data System (ADS)

Bakiz, B.; Hallaoui, A.; Taoufyq, A.; Benlhachemi, A.; Guinneton, F.; Villain, S.; Ezahri, M.; Valmalette, J.-C.; Arab, M.; Gavarri, J.-R.

2018-02-01

A series of polycrystalline barium-lead tungstate Ba1-xPbxWO4 with 0 ≤ x ≤ 1 was synthesized using a classical solid-state method with thermal treatment at 1000 °C. These materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Raman (FT-Raman) spectroscopy. X-ray diffraction profile analyses were performed using Rietveld method. These materials crystallized in the scheelite tetragonal structure and behaved as quasi ideal solid solution. Raman spectroscopy confirmed the formation of the solid solution. Structural distortions were evidenced in X-ray diffraction profiles and in vibration Raman spectra. The scanning electron microscopy experiments showed large and rounded irregular grains. Luminescence experiments were performed under X-ray excitation. The luminescence emission profiles have been interpreted in terms of four Gaussian components, with a major contribution of blue emission. The integrated intensity of luminescence reached a maximum value in the composition range x = 0.3-0.6, in relation with distortions of crystal lattice.

Analysis of Short and Long Range Atomic Order in Nanocrystalline Diamonds with Application of Powder Diffractometry

NASA Technical Reports Server (NTRS)

Palosz, B.; Grzanka, E.; Stelmakh, S.; Pielaszek, R.; Bismayer, U.; Neuefiend, J.; Weber, H.-P.; Proffen, T.; VonDreele, R.; Palosz, W.;

(Zr,Ti)O2 interface structure in ZrO2-TiO2 nanolaminates with ultrathin periodicity

NASA Astrophysics Data System (ADS)

Aita, C. R.; DeLoach, J. D.; Yakovlev, V. V.

2002-07-01

A mixed cation interfacial structure in ZrO2-TiO2 nanolaminate films with ultrathin bilayer periodicity grown by sputter deposition at 297 K was identified by x-ray diffraction and nonresonant Raman spectroscopy. This structure consists of an amorphous phase at a ZrO2-on-TiO2 bilayer interface, followed by an extensive crystalline monoclinic (Zr,Ti)O2 solid solution predicted by Vegard's law. Monoclinic (Zr,Ti)O2 has previously been reported only once, in bulk powder of a single composition (ZrTiO4) at high pressure. Its stabilization in the nanolaminates is explained by the Gibbs-Thomson effect. This complex interfacial structure is shown to be a means of accommodating chemical mixing in the absence of a driving force for heteroepitaxy.

Transformation of hydrazinium azide to molecular N8 at 40 GPa

NASA Astrophysics Data System (ADS)

Duwal, Sakun; Ryu, Young-Jay; Kim, Minseob; Yoo, Choong-Shik; Bang, Sora; Kim, Kyungtae; Hur, Nam Hwi

2018-04-01

Hydrazinium azide (HA) has been investigated at high pressures to 68 GPa using confocal micro-Raman spectroscopy and synchrotron powder x-ray diffraction. The results show that HA undergoes structural phase transitions from solid HA-I to HA-II at 13 GPa, associated with the strengthening of hydrogen bonding, and then to N8 at 40 GPa. The transformation of HA to recently predicted N8 (N≡N+—N-—N=N—-N—+N≡N) is evident by the emergence of new peaks at 2384 cm-1, 1665 cm-1, and 1165 cm-1, arising from the terminal N≡N stretching, the central N=N stretching, and the N—N stretching, respectively. However, upon decompression, N8 decomposes to ɛ-N2 below 25 GPa, but the remnant can be seen as low as 3 GPa.

The lateritic profile of Balkouin, Burkina Faso: Geochemistry, mineralogy and genesis

NASA Astrophysics Data System (ADS)

Giorgis, Ilaria; Bonetto, Sabrina; Giustetto, Roberto; Lawane, Abdou; Pantet, Anne; Rossetti, Piergiorgio; Thomassin, Jean-Hugues; Vinai, Raffaele

2014-02-01

This study reports on the geochemical and mineralogical characterization of a lateritic profile cropping out in the Balkouin area, Central Burkina Faso, aimed at obtaining a better understanding of the processes responsible for the formation of the laterite itself and the constraints to its development. The lateritic profile rests on a Paleoproterozoic basement mostly composed of granodioritic rocks related to the Eburnean magmatic cycle passing upwards to saprolite and consists of four main composite horizons (bottom to top): kaolinite and clay-rich horizons, mottled laterite and iron-rich duricrust. In order to achieve such a goal, a multi-disciplinary analytical approach was adopted, which includes inductively coupled plasma (ICP) atomic emission and mass spectrometries (ICP-AES and ICP-MS respectively), X-ray powder diffraction (XRPD), scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) and micro-Raman spectroscopy.

A New Camera for Powder Diffraction of Macromolecular Crystallography at SPring-8

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miura, Keiko; Inoue, Katsuaki; Goto, Shunji

2004-05-12

A powder diffractometer of Guinier geometry was developed and tested on a beamline, BL40B2, at SPring-8. The long specimen-to-detector distance, 1,000 mm, is advantageous in recording diffraction from Bragg spacing of 20 nm or larger. The angular resolution, 0.012 degrees, was realized together with the focusing optics, the long specimen-to-detector distance and the small pixel size of Blue-type Imaging Plate detector. Such a high resolution makes the peak separation possible in the powder diffraction from microcrystals with large unit cell and low symmetry of biological macromolecules.

Energy research with neutrons (ErwiN) and installation of a fast neutron powder diffraction option at the MLZ, Germany1

PubMed Central

Mühlbauer, Martin J.

2018-01-01

The need for rapid data collection and studies of small sample volumes in the range of cubic millimetres are the main driving forces for the concept of a new high-throughput monochromatic diffraction instrument at the Heinz Maier-Leibnitz Zentrum (MLZ), Germany. A large region of reciprocal space will be accessed by a detector with sufficient dynamic range and microsecond time resolution, while allowing for a variety of complementary sample environments. The medium-resolution neutron powder diffraction option for ‘energy research with neutrons’ (ErwiN) at the high-flux FRM II neutron source at the MLZ is foreseen to meet future demand. ErwiN will address studies of energy-related systems and materials with respect to their structure and uniformity by means of bulk and spatially resolved neutron powder diffraction. A set of experimental options will be implemented, enabling time-resolved studies, rapid parametric measurements as a function of external parameters and studies of small samples using an adapted radial collimator. The proposed powder diffraction option ErwiN will bridge the gap in functionality between the high-resolution powder diffractometer SPODI and the time-of-flight diffractometers POWTEX and SAPHiR at the MLZ. PMID:29896055

Raman spectroscopy method for subsurface detection of food powders through plastic layers

NASA Astrophysics Data System (ADS)

Dhakal, Sagar; Chao, Kuanglin; Qin, Jianwei; Schmidt, Walter F.; Kim, Moon S.; Chan, Diane E.; Bae, Abigail

2017-05-01

Proper chemical analyses of materials in sealed containers are important for quality control purpose. Although it is feasible to detect chemicals at top surface layer, it is relatively challenging to detect objects beneath obscuring surface. This study used spatially offset Raman spectroscopy (SORS) method to detect urea, ibuprofen and acetaminophen powders contained within one or more (up to eight) layers of gelatin capsules to demonstrate subsurface chemical detection and identification. A 785 nm point-scan Raman spectroscopy system was used to acquire spatially offset Raman spectra for an offset range of 0 to 10 mm from the surfaces of 24 encapsulated samples, using a step size of 0.1 mm to obtain 101 spectral measurements per sample. With increasing offset distance, the fraction of information from the deeper subsurface material increased compared to that from the top surface material. The series of measurements was analyzed to differentiate and identify the top surface and subsurface materials. Containing mixed contributions from the powder and capsule, the SORS of each sample was decomposed using self modeling mixture analysis (SMA) to obtain pure component spectra of each component and corresponding components were identified using spectral information divergence values. Results show that SORS technique together with SMA method has a potential for non-invasive detection of chemicals at deep subsurface layer.

Structural, morphological and dielectric properties of BiNbO{sub 4} ceramics prepared by the sol-gel method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Devesa, S.; Graça, M.P.; Costa, L.C., E-mail: kady@ua.pt

2016-06-15

Highlights: • The thermal treatment at 1200 °C generates a non-stoichiometric secondary phase. • The secondary phase Bi{sub 3.54}Nb{sub 7.09}O{sub 22.7}, is responsible for the highest Q × f and density. • The samples with triclinic BiNbO{sub 4} have the highest ε′. - Abstract: BiNbO{sub 4} ceramic powders were prepared using the sol-gel method. The fine particles were pressed into cylinders and, then, they were treated at temperatures between 500 and 1150 °C. The structure was studied by X-ray diffraction and Raman spectroscopy and the morphology was observed by scanning electron microscopy. The measurements of the complex permittivity were mademore » in a resonant cavity operating at 2.7 GHz, using the small perturbation method. The reversible phase transformation between β-BiNbO{sub 4} and α-BiNbO{sub 4} was observed. The density, dielectric constant (ε') and the dielectric loss (tg δ) of the prepared powders increase with the sintering temperature, and the sample treated at 1150 °C shows the highest ε' and the highest Q × f.« less

Studies on the mechanism of printing film-coated tablets containing titanium dioxide in the film by using UV laser irradiation.

PubMed

Kato, Yoshiteru; Nakashima, Yasuhiko; Shino, Naoki; Sasaki, Koichi; Hosokawa, Akihiro; Ishihara, Hiroshi

2010-04-01

The purpose of this article is to study a detailed mechanism of printing when film-coated tablets were irradiated by UV laser at a wavelength of 355 nm. Hydroxypropylmethylcellulose (HPMC) film containing titanium dioxide (TiO(2)) and the film not containing TiO(2) and TiO(2) powder were lirradiated by the UV laser and estimated by the morphological observation by zoom stereo microscope, thermogravimetric analysis (TGA), total color difference (dE), X-ray powder diffraction (XRD), and dispersive Raman microscopy. In the case of the film containing TiO(2), the film showed a visible change in its color from white to gray by the UV laser irradiation. By zoom stereo microscope, it was found that the entire UV laser-irradiated area was not grayed uniformly, but many black particles, whose diameter was about 2 microm, were observed on the film. When TiO(2) powder was irradiated by the UV laser, a visible change in its color from white to gray was observed similar to the case of the film containing TiO(2). There were many black particles locally in the UV laser-treated TiO(2) powder by the morphological observation, and these black particles, agglomerates of the grayed oxygen-defected TiO(2), were associated with the visible change of the TiO(2). It was found that the film-coated tablets were printed utilizing the formation of the black particles by the agglomeration of the grayed oxygen-defected TiO(2) by the UV laser irradiation.

Double diffraction in an atomic gravimeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malossi, N.; Bodart, Q.; Merlet, S.

2010-01-15

We demonstrate the realization of a scheme for cold-atom gravimetry based on the recently demonstrated use of double-diffraction beam splitters [T. Leveque, A. Gauguet, F. Michaud, F. Pereira Dos Santos, and A. Landragin, Phys. Rev. Lett. 103, 080405 (2009)], where the use of two retro-reflected Raman beams allows symmetric diffraction in +-(Planck constant/2pi)k{sub eff} momenta. Although in principle restricted to the case of zero Doppler shift, for which the two pairs of Raman beams are simultaneously resonant, such diffraction pulses can remain efficient on atoms with nonzero velocity, such as in a gravimeter, when the frequency of one of themore » two Raman laser sources is modulated. Such pulses are used to realize an interferometer insensitive to laser phase noise and some of the dominant systematics. This approach reduces the technical requirements and would allow the realization of a simple atomic gravimeter. A sensitivity of 1.2x10{sup -7}g per shot is demonstrated.« less

High-resolution neutron diffraction study of microstructural changes in nanocrystalline ball-milled niobium carbide NbC{sub 0.93}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balagurov, Anatoly M.; Bobrikov, Ivan A.; Bokuchava, Gizo D.

2015-11-15

High resolution neutron diffraction was applied for elucidating of the microstructural evolution of nanocrystalline niobium carbide NbC{sub 0.93} powders subjected to high-energy ball milling. The diffraction patterns were collected with the high resolution Fourier diffractometer HRFD by using the reverse time-of-flight (RTOF) mode of data acquisition. The traditional single diffraction line analysis, the Rietveld method and more advanced Whole Powder Pattern Modeling technique were applied for the data analysis. The comparison of these techniques was performed. It is established that short-time milling produces a non-uniform powder, in which two distinct fractions with differing microstructure can be identified. Part of themore » material is in fact milled efficiently, with a reduction in grain size, an increase in the quantity of defects, and a corresponding tendency to decarburize reaching a composition NbC{sub 0.80} after 15 h of milling. The rest of the powder is less efficiently processed and preserves its composition and lower defect content. Larger milling times should have homogenized the system by increasing the efficiently milled fraction, but the material is unable to reach a uniform and homogeneous state. It is definitely shown that RTOF neutron diffraction patterns can provide the very accurate data for microstructure analysis of nanocrystalline powders. - Highlights: • The NbC{sub 0.93} powder was processed by high-energy ball milling. • The microstrain and dislocation density increase with milling time increase. • The corresponding decrease in crystallite size with milling time was observed. • The material exhibits the presence of two fractions after ball milling. • The RTOF neutron diffraction data are suitable for accurate microstructure analysis.« less

Digital Image Correlation of 2D X-ray Powder Diffraction Data for Lattice Strain Evaluation

PubMed Central

Zhang, Hongjia; Sui, Tan; Daisenberger, Dominik; Fong, Kai Soon

2018-01-01

High energy 2D X-ray powder diffraction experiments are widely used for lattice strain measurement. The 2D to 1D conversion of diffraction patterns is a necessary step used to prepare the data for full pattern refinement, but is inefficient when only peak centre position information is required for lattice strain evaluation. The multi-step conversion process is likely to lead to increased errors associated with the ‘caking’ (radial binning) or fitting procedures. A new method is proposed here that relies on direct Digital Image Correlation analysis of 2D X-ray powder diffraction patterns (XRD-DIC, for short). As an example of using XRD-DIC, residual strain values along the central line in a Mg AZ31B alloy bar after 3-point bending are calculated by using both XRD-DIC and the conventional ‘caking’ with fitting procedures. Comparison of the results for strain values in different azimuthal angles demonstrates excellent agreement between the two methods. The principal strains and directions are calculated using multiple direction strain data, leading to full in-plane strain evaluation. It is therefore concluded that XRD-DIC provides a reliable and robust method for strain evaluation from 2D powder diffraction data. The XRD-DIC approach simplifies the analysis process by skipping 2D to 1D conversion, and opens new possibilities for robust 2D powder diffraction data analysis for full in-plane strain evaluation. PMID:29543728

Structure determination of Ba5AlF13 by coupling electron, synchrotron and neutron powder diffraction, solid-state NMR and ab initio calculations.

PubMed

Martineau, Charlotte; Allix, Mathieu; Suchomel, Matthew R; Porcher, Florence; Vivet, François; Legein, Christophe; Body, Monique; Massiot, Dominique; Taulelle, Francis; Fayon, Franck

2016-10-04

The room temperature structure of Ba 5 AlF 13 has been investigated by coupling electron, synchrotron and neutron powder diffraction, solid-state high-resolution NMR ( 19 F and 27 Al) and first principles calculations. An initial structural model has been obtained from electron and synchrotron powder diffraction data, and its main features have been confirmed by one- and two-dimensional NMR measurements. However, DFT GIPAW calculations of the 19 F isotropic shieldings revealed an inaccurate location of one fluorine site (F3, site 8a), which exhibited unusual long F-Ba distances. The atomic arrangement was reinvestigated using neutron powder diffraction data. Subsequent Fourier maps showed that this fluorine atom occupies a crystallographic site of lower symmetry (32e) with partial occupancy (25%). GIPAW computations of the NMR parameters validate the refined structural model, ruling out the presence of local static disorder and indicating that the partial occupancy of this F site reflects a local motional process. Visualisation of the dynamic process was then obtained from the Rietveld refinement of neutron diffraction data using an anharmonic description of the displacement parameters to account for the thermal motion of the mobile fluorine. The whole ensemble of powder diffraction and NMR data, coupled with first principles calculations, allowed drawing an accurate structural model of Ba 5 AlF 13 , including site-specific dynamical disorder in the fluorine sub-network.

A new theory for X-ray diffraction.

PubMed

Fewster, Paul F

2014-05-01

This article proposes a new theory of X-ray scattering that has particular relevance to powder diffraction. The underlying concept of this theory is that the scattering from a crystal or crystallite is distributed throughout space: this leads to the effect that enhanced scatter can be observed at the `Bragg position' even if the `Bragg condition' is not satisfied. The scatter from a single crystal or crystallite, in any fixed orientation, has the fascinating property of contributing simultaneously to many `Bragg positions'. It also explains why diffraction peaks are obtained from samples with very few crystallites, which cannot be explained with the conventional theory. The intensity ratios for an Si powder sample are predicted with greater accuracy and the temperature factors are more realistic. Another consequence is that this new theory predicts a reliability in the intensity measurements which agrees much more closely with experimental observations compared to conventional theory that is based on `Bragg-type' scatter. The role of dynamical effects (extinction etc.) is discussed and how they are suppressed with diffuse scattering. An alternative explanation for the Lorentz factor is presented that is more general and based on the capture volume in diffraction space. This theory, when applied to the scattering from powders, will evaluate the full scattering profile, including peak widths and the `background'. The theory should provide an increased understanding of the reliability of powder diffraction measurements, and may also have wider implications for the analysis of powder diffraction data, by increasing the accuracy of intensities predicted from structural models.

Phase equilibria in the NaF-CdO-NaPO3 system at 873 K and crystal structure and physico-chemical characterizations of the new Na2CdPO4F fluorophosphate

NASA Astrophysics Data System (ADS)

Aboussatar, Mohamed; Mbarek, Aïcha; Naili, Houcine; El-Ghozzi, Malika; Chadeyron, Geneviève; Avignant, Daniel; Zambon, Daniel

2017-04-01

Isothermal sections of the diagram representing phase relationships in the NaF-CdO-NaPO3 system have been investigated by solid state reactions and powder X-ray diffraction. This phase diagram investigation confirms the polymorphism of the NaCdPO4 side component and the structure of the ß high temperature polymorph (orthorhombic, space group Pnma and unit cell parameters a=9.3118(2), b=7.0459(1), c=5.1849(1) Å has been refined. A new fluorophosphate, Na2CdPO4F, has been discovered and its crystal structure determined and refined from powder X-ray diffraction data. It exhibits a new 3D structure with orthorhombic symmetry, space group Pnma and unit cell parameters a=5.3731(1), b=6.8530(1), c=12.2691(2) Å. The structure is closely related to those of the high temperature polymorph of the nacaphite Na2CaPO4F and the fluorosilicate Ca2NaSiO4F but differs essentially in the cationic repartition since the structure is fully ordered with one Na site (8d) and one Cd site (4c). Relationships with other Na2MIIPO4F (MII=Mg, Ca, Mn, Fe, Co, Ni) have been examined and the crystal-chemical and topographical analysis of these fluorophosphates is briefly reviewed. IR, Raman, optical and 19F, 23Na, 31P MAS NMR characterizations of Na2CdPO4F have been investigated.

Investigation of nanocrystalline zinc chromite obtained by two soft chemical routes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gingasu, Dana; Mindru, Ioana, E-mail: imandru@yahoo.com; Culita, Daniela C.

2014-01-01

Graphical abstract: - Highlights: • Two soft chemical routes to synthesize zinc chromites are described. • Glycine is used as chelating agent (precursor method) and fuel (solution combustion method). • The synthesized chromites have crystallite size in the range of 18–27 nm. • An antiferromagnetic (AFM) transition is observed at about T{sub N} ∼ 18 K. - Abstract: Zinc chromite (ZnCr{sub 2}O{sub 4}) nanocrystalline powders were obtained by two different chemical routes: the precursor method and the solution combustion method involving glycine-nitrates. The complex compound precursors, [ZnCr{sub 2}(NH{sub 2}CH{sub 2}COO){sub 8}]·9H{sub 2}O and [ZnCr{sub 2}(NH{sub 2}CH{sub 2}COOH){sub 4.5}]·(NO{sub 3}){sub 8}·6H{submore » 2}O, were characterized by chemical analysis, infrared spectroscopy (IR), ultraviolet–visible spectroscopy (UV–vis) and thermal analysis. The structure, morphology, surface chemistry and magnetic properties of ZnCr{sub 2}O{sub 4} powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), infrared and Raman spectroscopy (RS), ultraviolet–visible spectroscopy (UV–vis) and magnetic measurements. X-ray diffraction patterns indicated the chromite spinel phase with good crystallinity and an average crystallite size of approximately 18–27 nm. The band gap values ranged between 3.31 and 3.33 eV. The magnetic measurements indicated an antiferromagnetic transition at T{sub N} ∼ 17.5/18 K.« less

Raman correlation spectroscopy: A feasibility study of a new optical correlation technique and development of multi-component nanoparticles using the reprecipitation method

NASA Astrophysics Data System (ADS)

Nishida, Maki

The feasibility of Raman correlation spectroscopy (RCS) is investigated as a new temporal optical fluctuation spectroscopy in this dissertation. RCS analyzes the correlations of the intensity fluctuations of Raman scattering from particles in a suspension that undergo Brownian motion. Because each Raman emission line arises from a specific molecular bond, the RCS method could yield diffusion behavior of specific chemical species within a dispersion. Due to the nature of Raman scattering as a coherent process, RCS could provide similar information as acquired in dynamic light scattering (DLS) and be practical for various applications that requires the chemical specificity in dynamical information. The theoretical development is discussed, and four experimental implementations of this technique are explained. The autocorrelation of the intensity fluctuations from a beta-carotene solution is obtained using the some configurations; however, the difficulty in precise alignment and weak nature of Raman scattering prevented the achievement of high sensitivity and resolution. Possible fluctuations of the phase of Raman scattering could also be affecting the results. A possible explanation of the observed autocorrelation in terms of number fluctuations of particles is also examined to test the feasibility of RCS as a new optical characterization method. In order to investigate the complex systems for which RCS would be useful, strategies for the creation of a multicomponent nanoparticle system are also explored. Using regular solution theory along with the concept of Hansen solubility parameters, an analytical model is developed to predict whether two or more components will form single nanoparticles, and what effect various processing conditions would have. The reprecipitation method was used to demonstrate the formation of the multi-component system of the charge transfer complex perylene:TCNQ (tetracyanoquinodimethane) and the active pharmaceutical ingredient cocrystal of CBZ:NCT (carbamazepine:nicotinamide). The experimental results with various characterization methods including DLS, absorption spectroscopy, powder x-ray diffraction, and SEM imaging, verify formation of the multicomponent cocrystals. The observation of the self-assembly of TCNQ crystals is also discussed.

Chromatographic separation and detection of contaminants from whole milk powder using a chitosan-modified silver nanoparticles surface-enhanced Raman scattering device.

PubMed

Li, Dan; Lv, Di Y; Zhu, Qing X; Li, Hao; Chen, Hui; Wu, Mian M; Chai, Yi F; Lu, Feng

2017-06-01

Methods for the on-site analysis of food contaminants are in high demand. Although portable Raman spectroscopy is commonly used to test food on-site, it can be challenge to achieve this goal with rapid detection and inexpensive substrate. In this study, we detected trace food contaminants in samples of whole milk powder using the methods that combined chromatography with surface-enhanced Raman scattering detection (SERS). We developed a simple and efficient technique to fabricate the paper with chitosan-modified silver nanoparticles as a SERS-active substrate. The soaking time of paper and the concentration of chitosan solution were optimized for chromatographic separation and SERS detection. We then studied the separation properties for real applications including complex sample matrices, and detected melamine at 1mg/L, dicyandiamide at 100mg/L and sodium sulfocyanate at 10mg/L in whole milk powder. As such, our methods have great potential for field-based detection of milk contaminants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Noninvasive deep Raman detection with 2D correlation analysis

NASA Astrophysics Data System (ADS)

Kim, Hyung Min; Park, Hyo Sun; Cho, Youngho; Jin, Seung Min; Lee, Kang Taek; Jung, Young Mee; Suh, Yung Doug

2014-07-01

The detection of poisonous chemicals enclosed in daily necessaries is prerequisite essential for homeland security with the increasing threat of terrorism. For the detection of toxic chemicals, we combined a sensitive deep Raman spectroscopic method with 2D correlation analysis. We obtained the Raman spectra from concealed chemicals employing spatially offset Raman spectroscopy in which incident line-shaped light experiences multiple scatterings before being delivered to inner component and yielding deep Raman signal. Furthermore, we restored the pure Raman spectrum of each component using 2D correlation spectroscopic analysis with chemical inspection. Using this method, we could elucidate subsurface component under thick powder and packed contents in a bottle.

Evidence from x-ray and neutron powder diffraction patterns that the so-called icosahedral and decagonal quasicrystals of MnAl(6) and other alloys are twinned cubic crystals.

PubMed

Pauling, L

1987-06-01

It is shown that the x-ray powder diffraction patterns of rapidly quenched MnAl(6) and Mg(32)(Al,Zn)(49) and the neutron powder diffraction pattern of MnAl(6) are compatible with the proposed 820-atom primitive cubic structure [Pauling, L. (1987) Phys. Rev. Lett. 58, 365-368]. The values found for the edge of the unit cube are 23.365 A (x-ray) and 23.416 A (neutron) for MnAl(6) and 24.313 A (x-ray) for Mg(32)(Al,Zn)(49).

Evidence from x-ray and neutron powder diffraction patterns that the so-called icosahedral and decagonal quasicrystals of MnAl6 and other alloys are twinned cubic crystals

PubMed Central

Pauling, Linus

1987-01-01

It is shown that the x-ray powder diffraction patterns of rapidly quenched MnAl6 and Mg32(Al,Zn)49 and the neutron powder diffraction pattern of MnAl6 are compatible with the proposed 820-atom primitive cubic structure [Pauling, L. (1987) Phys. Rev. Lett. 58, 365-368]. The values found for the edge of the unit cube are 23.365 Å (x-ray) and 23.416 Å (neutron) for MnAl6 and 24.313 Å (x-ray) for Mg32(Al,Zn)49. PMID:16593841

New high- and low-temperature apparatus for synchrotron polycrystalline X-ray diffraction.

PubMed

Tang, C C; Bushnell-Wye, G; Cernik, R J

1998-05-01

A high-temperature furnace with an induction heater coil and a cryogenic system based on closed-cycle refrigeration have been assembled to enhance the non-ambient powder diffraction facilities at the Synchrotron Radiation Source, Daresbury Laboratory. The commissioning of the high- and low-temperature devices on the high-resolution powder diffractometer of Station 2.3 is described. The combined temperature range provided by the furnace/cryostat is 10-1500 K. Results from Fe and NH(4)Br powder samples are presented to demonstrate the operation of the apparatus. The developments presented in this paper are applicable to a wide range of other experiments and diffraction geometries.

Improved camera for better X-ray powder photographs

NASA Technical Reports Server (NTRS)

Parrish, W.; Vajda, I. E.

1969-01-01

Camera obtains powder-type photographs of single crystals or polycrystalline powder specimens. X-ray diffraction photographs of a powder specimen are characterized by improved resolution and greater intensity. A reasonably good powder pattern of small samples can be produced for identification purposes.

Speciation of residual carbon contained in UO{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ziouane, Yannis; Arab-Chapelet, Bénédicte; Tamain, Christelle

2016-12-15

UO{sub 2} powders were synthesized thanks to oxalic precipitation (platelet morphology) and sol-gel route and completely characterized. A secondary phase was found depending on the calcination atmospheres. This phase has been identified by Raman spectroscopy as graphitic material (i.e. carbon-based secondary compound) and quantified by thermogravimetric analyses. Its amount varies with the calcination atmosphere. The presence of this secondary phase has no significant effect on the lattice parameter and its specific surface area. - Graphical abstract: Figure 2: Raman spectroscopy of the three UO{sub 2} powders and of the dissolution residues.

Rapid quantitation of atorvastatin in process pharmaceutical powder sample using Raman spectroscopy and evaluation of parameters related to accuracy of analysis.

PubMed

Lim, Young-Il; Han, Janghee; Woo, Young-Ah; Kim, Jaejin; Kang, Myung Joo

2018-07-05

The purpose of this study was to determine the atorvastatin (ATV) content in process pharmaceutical powder sample using Raman spectroscopy. To establish the analysis method, the influence of the type of Raman measurements (back-scattering or transmission mode), preparation of calibration sample (simple admixing or granulation), sample pre-treatment (pelletization), and spectral pretreatment on the Raman spectra was investigated. The characteristic peak of the active compound was more distinctively detected in transmission Raman mode with a laser spot size of 4mm than in the back-scattering method. Preparation of calibration samples by wet granulation, identical to the actual manufacturing process, provided unchanged spectral patterns for the in process sample, with no changes and/or shifts in the spectrum. Pelletization before Raman analysis remarkably improved spectral reproducibility by decreasing the difference in density between the samples. Probabilistic quotient normalization led to accurate and consistent quantification of the ATV content in the calibration samples (standard error of cross validation: 1.21%). Moreover, the drug content in the granules obtained from five commercial batches were reliably quantified, with no statistical difference (p=0.09) with that obtained by HPLC assay. From these findings, we suggest that transmission Raman analysis may be a fast and non-invasive method for the quantification of ATV in actual manufacturing processes. Copyright © 2018 Elsevier B.V. All rights reserved.

Rapid quantitation of atorvastatin in process pharmaceutical powder sample using Raman spectroscopy and evaluation of parameters related to accuracy of analysis

NASA Astrophysics Data System (ADS)

Lim, Young-Il; Han, Janghee; Woo, Young-Ah; Kim, Jaejin; Kang, Myung Joo

2018-07-01

The purpose of this study was to determine the atorvastatin (ATV) content in process pharmaceutical powder sample using Raman spectroscopy. To establish the analysis method, the influence of the type of Raman measurements (back-scattering or transmission mode), preparation of calibration sample (simple admixing or granulation), sample pre-treatment (pelletization), and spectral pretreatment on the Raman spectra was investigated. The characteristic peak of the active compound was more distinctively detected in transmission Raman mode with a laser spot size of 4 mm than in the back-scattering method. Preparation of calibration samples by wet granulation, identical to the actual manufacturing process, provided unchanged spectral patterns for the in process sample, with no changes and/or shifts in the spectrum. Pelletization before Raman analysis remarkably improved spectral reproducibility by decreasing the difference in density between the samples. Probabilistic quotient normalization led to accurate and consistent quantification of the ATV content in the calibration samples (standard error of cross validation: 1.21%). Moreover, the drug content in the granules obtained from five commercial batches were reliably quantified, with no statistical difference (p = 0.09) with that obtained by HPLC assay. From these findings, we suggest that transmission Raman analysis may be a fast and non-invasive method for the quantification of ATV in actual manufacturing processes.

Anisotropic stress in narrow sGe fin field-effect transistor channels measured using nano-focused Raman spectroscopy

NASA Astrophysics Data System (ADS)

Nuytten, T.; Bogdanowicz, J.; Witters, L.; Eneman, G.; Hantschel, T.; Schulze, A.; Favia, P.; Bender, H.; De Wolf, I.; Vandervorst, W.

2018-05-01

The continued importance of strain engineering in semiconductor technology demands fast and reliable stress metrology that is non-destructive and process line-compatible. Raman spectroscopy meets these requirements but the diffraction limit prevents its application in current and future technology nodes. We show that nano-focused Raman scattering overcomes these limitations and can be combined with oil-immersion to obtain quantitative anisotropic stress measurements. We demonstrate accurate stress characterization in strained Ge fin field-effect transistor channels without sample preparation or advanced microscopy. The detailed analysis of the enhanced Raman response from a periodic array of 20 nm-wide Ge fins provides direct access to the stress levels inside the nanoscale channel, and the results are validated using nano-beam diffraction measurements.

Depth of penetration of a 785nm wavelength laser in food powders

NASA Astrophysics Data System (ADS)

Chao, Kuanglin; Dhakal, Sagar; Qin, Jianwei; Kim, Moon S.; Peng, Yankun; Schmidt, Walter F.

2015-05-01

Raman spectroscopy is a useful, rapid, and non-destructive method for both qualitative and quantitative evaluation of chemical composition. However it is important to measure the depth of penetration of the laser light to ensure that chemical particles at the very bottom of a sample volume is detected by Raman system. The aim of this study was to investigate the penetration depth of a 785nm laser (maximum power output 400mw) into three different food powders, namely dry milk powder, corn starch, and wheat flour. The food powders were layered in 5 depths between 1 and 5 mm overtop a Petri dish packed with melamine. Melamine was used as the subsurface reference material for measurement because melamine exhibits known and identifiable Raman spectral peaks. Analysis of the sample spectra for characteristics of melamine and characteristics of milk, starch and flour allowed determination of the effective penetration depth of the laser light in the samples. Three laser intensities (100, 200 and 300mw) were used to study the effect of laser intensity to depth of penetration. It was observed that 785nm laser source was able to easily penetrate through every point in all three food samples types at 1mm depth. However, the number of points that the laser could penetrate decreased with increasing depth of the food powder. ANOVA test was carried out to study the significant effect of laser intensity to depth of penetration. It was observed that laser intensity significantly influences the depth of penetration. The outcome of this study will be used in our next phase of study to detect different chemical contaminants in food powders and develop quantitative analysis models for detection of chemical contaminants.

A spatially offset Raman spectroscopy method for non-destructive detection of gelatin-encapsulated powders

USDA-ARS?s Scientific Manuscript database

Non-destructive subsurface detection of encapsulated, coated, or seal-packaged foods and pharmaceuticals can help prevent distribution and consumption of counterfeit or hazardous products. This study used a Spatially Offset Raman Spectroscopy (SORS) method to detect and identify urea, ibuprofen, and...

Raman spectroscopy-based detection of chemical contaminants in food powders

USDA-ARS?s Scientific Manuscript database

Raman spectroscopy technique has proven to be a reliable method for qualitative detection of chemical contaminants in food ingredients and products. For quantitative imaging-based detection, each contaminant particle in a food sample must be detected and it is important to determine the necessary sp...

Purchase of a Raman and Photoluminescence Imaging System for Characterization of Advanced Electrochemical and Electronic Materials

DTIC Science & Technology

2016-01-05

regularly used the Raman imaging system to characterize the doping chemistry of colloidal indium nitride nanoparticles . This material shows an interesting...regularly used the Raman imaging system to characterize the doping chemistry of colloidal indium nitride nanoparticles . This material shows an...analysis of thin film coatings, bulk materials, powders and nanoparticles . The instrument is extensively used to characterize advanced electrochemical and

New Coll-HA/BT composite materials for hard tissue engineering.

PubMed

Zanfir, Andrei Vlad; Voicu, Georgeta; Busuioc, Cristina; Jinga, Sorin Ion; Albu, Madalina Georgiana; Iordache, Florin

2016-05-01

The integration of ceramic powders in composite materials for bone scaffolds can improve the osseointegration process. This work was aimed to the synthesis and characterization of new collagen-hydroxyapatite/barium titanate (Coll-HA/BT) composite materials starting from barium titanate (BT) nanopowder, hydroxyapatite (HA) nanopowder and collagen (Coll) gel. BT nanopowder was produced by combining two wet-chemical approaches, sol-gel and hydrothermal methods. The resulting materials were characterized in terms of phase composition and microstructure by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. Moreover, the biocompatibility and bioactivity of the composite materials were assessed by in vitro tests. The synthesized BT particles exhibit an average size of around 35 nm and a spherical morphology, with a pseudo-cubic or tetragonal symmetry. The diffraction spectra of Coll-HA and Coll-HA/BT composite materials indicate a pronounced interaction between Col and the mineral phases, meaning a good mineralization of Col fibres. As well, the in vitro tests highlight excellent osteoinductive properties for all biological samples, especially for Coll-HA/BT composite materials, fact that can be attributed to the ferromagnetic properties of BT. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigation on synthesis, growth and characterization of CdIn2S2Se2 single crystal grown by vertical Bridgman method

NASA Astrophysics Data System (ADS)

Vijayakumar, P.; Ramasamy, P.

2017-06-01

CdIn2S2Se2 polycrystalline material has been synthesized by melt oscillation method. Vertical Bridgman method was used to grow a good quality CdIn2S2Se2 single crystal. The crystalline phase and growth orientation were confirmed by powder X-ray diffraction pattern and unit cell parameters were determined by single crystal X-ray diffraction analysis. The structural uniformity of CdIn2S2Se2 was studied using Raman scattering spectroscopy at room temperature. The stoichiometric composition variation along the CdIn2S2Se2 was measured using energy dispersive spectrometry. The transmission spectra of CdIn2S2Se2 single crystal gave 42% transmission in the NIR region. Thermal property of CdIn2S2Se2 has been studied using differential thermal analysis. Thermal diffusivity, specific heat capacity and thermal conductivity were also measured. Electrical property was measured using Hall Effect measurement and it confirms the n-type semiconducting nature. The hardness behavior has been measured using Vickers micro hardness measurement and the indentation size effect has been observed.

X-ray diffraction, vibrational and quantum chemical investigations of 2-methyl-4-nitroanilinium trichloroacetate trichloroacetic acid

NASA Astrophysics Data System (ADS)

Arjunan, V.; Marchewka, Mariusz K.; Pietraszko, A.; Kalaivani, M.

2012-11-01

The structural investigations of the molecular complex of 2-methyl-4-nitroaniline with trichloroacetic acid, namely 2-methyl-4-nitroanilinium trichloroacetate trichloroacetic acid (C11H10Cl6N2O6) have been performed by means of single crystal and powder X-ray diffraction method. The complex was formed with accompanying proton transfer from trichloroacetic acid molecule to 2-methyl-4-nitroaniline. The studied crystal is built up of singly protonated 2-methyl-4-nitroanilinium cations, trichloroacetate anions and neutral trichloroacetic acid molecules. The crystals are monoclinic, space group P21/c, with a = 14.947 Å, b = 6.432 Å, c = 19.609 Å and Z = 4. The vibrational assignments and analysis of 2-methyl-4-nitroanilinium trichloroacetate trichloroacetic acid have also been performed by FTIR, FT-Raman and far-infrared spectral studies. More support on the experimental findings were added from the quantum chemical studies performed with DFT (B3LYP) method using 6-31G**, cc-pVDZ, 6-31G and 6-31++G basis sets. The structural parameters, energies, thermodynamic parameters and the NBO charges of 2M4NATCA were also determined by the DFT methods.

Structure and vibrational spectra of melaminium bis(trifluoroacetate) trihydrate: FT-IR, FT-Raman and quantum chemical calculations.

PubMed

Sangeetha, V; Govindarajan, M; Kanagathara, N; Marchewka, M K; Gunasekaran, S; Anbalagan, G

2014-05-05

Melaminium bis(trifluoroacetate) trihydrate (MTFA), an organic material has been synthesized and single crystals of MTFA have been grown by the slow solvent evaporation method at room temperature. X-ray powder diffraction analysis confirms that MTFA crystal belongs to the monoclinic system with space group P2/c. The molecular geometry, vibrational frequencies and intensity of the vibrational bands have been interpreted with the aid of structure optimization based on density functional theory (DFT) B3LYP method with 6-311G(d,p) and 6-311++G(d,p) basis sets. The X-ray diffraction data have been compared with the data of optimized molecular structure. The theoretical results show that the crystal structure can be reproduced by optimized geometry and the vibrational frequencies show good agreement with the experimental values. The nuclear magnetic resonance (NMR) chemical shift of the molecule has been calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. HOMO-LUMO, and other related molecular and electronic properties are calculated. The Mulliken and NBO charges have also been calculated and interpreted. Copyright © 2014 Elsevier B.V. All rights reserved.

Fabrication and testing of a newly designed slit system for depth-resolved X-ray diffraction measurements

DOE PAGES

Sinsheimer, John; Bouet, Nathalie; Ghose, Sanjit; ...

2016-10-06

A new system of slits called `spiderweb slits' have been developed for depth-resolved powder or polycrystalline X-ray diffraction measurements. The slits act on diffracted X-rays to select a particular gauge volume of sample, while absorbing diffracted X-rays from outside of this volume. Although the slit geometry is to some extent similar to that of previously developed conical slits or spiral slits, this new design has advantages over the previous ones in use for complex heterogeneous materials and in situ and operando diffraction measurements. For example, the slits can measure a majority of any diffraction cone for any polycrystalline material, overmore » a continuous range of diffraction angles, and work for X-ray energies of tens to hundreds of kiloelectronvolts. In addition, the design is generated and optimized using ray-tracing simulations, and fabricated through laser micromachining. The first prototype was successfully tested at the X17A beamline at the National Synchrotron Light Source, and shows similar performance to simulations, demonstrating gauge volume selection for standard powders, for all diffraction peaks over angles of 2–10°. A similar, but improved, design will be implemented at the X-ray Powder Diffraction beamline at the National Synchrotron Light Source II.« less

A new theory for X-ray diffraction

PubMed Central

Fewster, Paul F.

2014-01-01

This article proposes a new theory of X-ray scattering that has particular relevance to powder diffraction. The underlying concept of this theory is that the scattering from a crystal or crystallite is distributed throughout space: this leads to the effect that enhanced scatter can be observed at the ‘Bragg position’ even if the ‘Bragg condition’ is not satisfied. The scatter from a single crystal or crystallite, in any fixed orientation, has the fascinating property of contributing simultaneously to many ‘Bragg positions’. It also explains why diffraction peaks are obtained from samples with very few crystallites, which cannot be explained with the conventional theory. The intensity ratios for an Si powder sample are predicted with greater accuracy and the temperature factors are more realistic. Another consequence is that this new theory predicts a reliability in the intensity measurements which agrees much more closely with experimental observations compared to conventional theory that is based on ‘Bragg-type’ scatter. The role of dynamical effects (extinction etc.) is discussed and how they are suppressed with diffuse scattering. An alternative explanation for the Lorentz factor is presented that is more general and based on the capture volume in diffraction space. This theory, when applied to the scattering from powders, will evaluate the full scattering profile, including peak widths and the ‘background’. The theory should provide an increased understanding of the reliability of powder diffraction measurements, and may also have wider implications for the analysis of powder diffraction data, by increasing the accuracy of intensities predicted from structural models. PMID:24815975

Influence of Oxygen Content in Oriented LaCoO3-δ Thin Films: Probed by X-ray diffraction and Raman Spectroscopy

NASA Astrophysics Data System (ADS)

Mishra, D. K.; Ahlawat, Anju; Sathe, V. G.

2011-07-01

Nonstoichiometric oriented thin films of LaCoO3-δ of equal thickness and varying oxygen content has been deposited on STO (001) substrate by pulsed laser deposition. X-ray diffraction results show that all films are single phase and c-axis oriented in the (001) direction with in plane tensile strain. In these films strain reduces with increasing oxygen content and Raman study also support this result. Low temperature Raman study shows no change in spin state of Co3+ in temperature range from 300 K to down to 80 K.

Analysis of Wilhelm Ostwald's "Colour Organ" with Raman microspectroscopy

NASA Astrophysics Data System (ADS)

Bridarolli, Alexandra; Atak, Sefkan; Herm, Christoph

2016-11-01

The "Scientific Colour Organ" is a collection of 680 pigment powders, created by the chemist Wilhelm Ostwald in 1925 as a means to represent his colour system. Today, it remains a leading part of colour theory. Analysis of these materials was undertaken to understand how the colour system was realised and to gain indications for preservation of the collection to which it belongs. Dispersive Raman microspectroscopy was applied directly to the powders, as well as using alternative techniques to suppress fluorescence. Barium sulphate was detected in all of the samples with one exception. Portable X-ray fluorescence revealed that this compound was a constituent of lithopone pigment. Raman spectroscopy furthermore revealed synthetic ultramarine (C.I. PB 29) as well as six different synthetic organic pigments and dyes (C.I. PY3; C.I. PO5; C.I. PR81:1; C.I. PV2 and two different triarylmethane dyes). Thin-layer chromatography was applied to determine the exact combination of dyes causing the gradual change in colour of each powder compared to the adjacent samples. With the exception of triarylmethane, the synthetic organic dyes could be identified with Raman spectroscopy directly on the chromatographic plate. The efficiency of thin-layer chromatography combined with Raman spectroscopy for identification of organic pigments could thus be shown. X-ray fluorescence indicated the presence of tungsten-molybdenum lakes in some samples. Comparison of the analytical results to information published by Oswald in 1917 showed that he switched to more light-stable synthetic organic pigments used for his "Scientific Colour Organ".

SERS-active Au/SiO2 clouds in powder for rapid ex vivo breast adenocarcinoma diagnosis

PubMed Central

Cepeda-Pérez, Elisa; López-Luke, Tzarara; Salas, Pedro; Plascencia-Villa, Germán; Ponce, Arturo; Vivero-Escoto, Juan; José-Yacamán, Miguel; de la Rosa, Elder

2016-01-01

In the present work, we report a dry-based application technique of Au/SiO2 clouds in powder for rapid ex vivo adenocarcinoma diagnosis through surface-enhanced Raman scattering (SERS); using low laser power and an integration time of one second. Several characteristic Raman peaks frequently used for the diagnosis of breast adenocarcinoma in the range of the amide III are successfully enhanced by breading the tissue with Au/SiO2 powder. The SERS activity of these Au/SiO2 powders is attributed to their rapid rehydration upon contact with the wet tissues, which promotes the formation of gold nanoparticle aggregates. The propensity of the Au/SiO2 cloud structures to adsorb biomolecules in the vicinity of the gold nanoparticle clusters promotes the necessary conditions for SERS detection. In addition, electron microscopy, together with elemental analysis, have been used to confirm the structure of the new Au/SiO2 cloud material and to investigate its distribution in breast tissues. PMID:27375955

Study of the structural, vibrational and thermodynamic properties of natroxalate mineral using density functional theory

NASA Astrophysics Data System (ADS)

Colmenero, Francisco; Timón, Vicente

2018-07-01

Natroxalate mineral, Na2C2O4, is a fundamental oxalate mineral widespread in nature, present in humans, animals and plants, as well as in naturally occurring minerals. The characterization of oxalate minerals is extraordinarily important since these organic minerals are indicators of environmental events and of the presence of biological activity, because they are commonly of biological origin. These minerals are currently under study to investigate the possible biological activity on Mars. The identification of these compounds is usually performed by X-ray diffraction and Raman spectroscopy. Theoretical calculations are of great value for the study and interpretation of the results of these experimental techniques. In this work, natroxalate mineral structure and Raman spectrum was studied by first principle calculations based on the density functional theory. The computed structure of natroxalate reproduces the one determined experimentally by X-ray diffraction (monoclinic symmetry, space group P21/c; lattice parameters a = 3.449 Å, b = 5.243 Å; c = 10.375 Å). Lattice parameters, bond lengths, bond angles and X-ray powder pattern were found to be in very good agreement with their experimental counterparts. Raman spectrum was then computed by means of density functional perturbation theory and compared with the experimental spectrum. Since the results were also found in agreement with the experimental data, a normal mode analysis of the theoretical spectra was carried out and used in order to assign the main bands of the Raman spectrum. The band found at about 567 cm-1, described as a single peak in previous experimental works, is shown clearly to have two contributing bands. Finally, two bands of the observed spectrum, located at the wavenumbers 1750 and 1358 cm-1, were not found in the theoretical spectrum. This is because these bands correspond to an overtone, 2ν1 (ν1 = 875 cm-1), and a combination band, ν1 + ν2 (ν1,ν2 = 875, 481 cm-1), respectively. Finally, the fundamental thermodynamic properties of natroxalate mineral were determined. The calculated specific heat at 298.15 K is in excellent agreement with the experimental value, the difference being less than 1%. Since for most of these properties there are not experimental values to compare with, their values were predicted.

Pressure-induced ferroelectric to paraelectric transition in LiTaO 3 and (Li,Mg)TaO 3

DOE PAGES

Yamanaka, Takamitsu; Nakamoto, Yuki; Takei, Fumihiko; ...

2016-02-16

X-ray powder diffraction and Raman scattering of LiTaO 3 (LT) and (Li,Mg)TaO 3 (LMT) have been measured under pressure up to 46 GPa. Above 30 GPa, the ferroelectric rhombohedral phase (R3c, Z – 6) of LiTaO 3 transforms to a paraelectric orthorhombic phase (Pnma with Z – 4) with a large hysteresis. Rietveld profile fitting analysis shows that the Li-O bond is compressed and approaches that of Ta-O with pressure. The cation distribution analysis of the orthorhombic perovskite structure shows that Li and Ta are located in the octahedral 8-fold coordination sites. Difference Fourier |F obs(hkl)| - |F cal(hkl)| mapsmore » of LiTaO 3 and (Li,Mg)TaO 3 indicate polarization in the c axis direction and a more distinct electron density distribution around the Ta position for (Li,Mg)TaO 3 compared to LiTaO 3. The observed effective charges indicate that for (Li,Mg)TaO 3 without vacancies Ta 5+ becomes less ionized as a function of Mg substitution. Considering both site occupancy and effective charge analysis, Ta 5+ is reduced to Ta 4.13+. Mg 2+ and O 2- change to Mg 1.643+ and O 1.732 -, respectively. The space- and time-averaged structures of the dynamical vibration of atoms can be elucidated from the electron density analysis by difference Fourier and temperature factors T(hkl) in the structure refinement. The refinement of the temperature factor is consistent with the cation distribution assuming full stoichiometry. The residual electron density induced from the excess electron in (Li,Mg)TaO 3 indicates more electrons around the Ta site, as confirmed by the effective charge analysis. Raman spectra of LiTaO 3 and (Li,Mg)TaO 3 show notable changes over the measured pressure range. Raman peaks centered at 250 cm –1 and 350 cm –1 at ambient pressure merge above 8 GPa, which we associate with the diminishing of difference in distances between Li-O and Ta-O bonds with pressure in both materials. Finally, Raman spectra show significant changes at 28 GPa and 33 GPa for LT and LMT, respectively, due to the structural transition from R3c to Pnma consistent with the x-ray diffraction results.« less

Investigation and Characterization of Water-Recrystallized Croconic Acid

DTIC Science & Technology

2016-12-01

high- pressure synthesis. Thermal analysis, bomb calorimetry, X-ray diffraction, and Raman spectroscopy were performed on water- recrystallized...3.2.3 Raman Spectroscopy and X-ray Diffraction 12 3.2.4 Bomb Calorimetry 13 4. Conclusions 15 5. References 16 List of Symbols, Abbreviations, and...and is called the β-phase (the as-received [AR] material is also known as the α-phase). Bomb calorimeter testing of the β-CA indicated a heat of

Investigation of the optical property and photocatalytic activity of mixed phase nanocrystalline titania

NASA Astrophysics Data System (ADS)

Paul, Susmita; Choudhury, Amarjyoti

2014-10-01

Mixed phase nanocrystalline titania are prepared by simple sol-gel method. The physico-chemical characteristics of the prepared nanoparticles are studied with X-ray diffraction, high-resolution transmission electron microscopy, RAMAN, BET, UV-Vis, steady state and time resolved photoluminescence. X-ray diffraction and Raman spectra clearly demarcate the anatase and rutile phase as both the phases give different diffraction patterns and Raman peaks. A comparison in the band gap indicates that pure anatase and rutile phase have band gap in the UV region, whereas a mixture of these phases has lower band gap and corresponds to the visible region. Steady state and time resolved photoluminescence are employed to understand the emissivity and carrier lifetime. The photocatalytic activity is evaluated by monitoring the degradation of phenol under visible light illumination. Due to the synergistic effect of mixed anatase and rutile phases, mixed phase nanocrystalline titania exhibit superior photocatalytic activity.

Demonstration of the ExoMars sample preparation and distribution system jointly with an optical instrument head

NASA Astrophysics Data System (ADS)

Schulte, Wolfgang; Thiele, Hans; Hofmann, Peter; Baglioni, Pietro

The ExoMars program will search for past and present life on Mars. ExoMars will address important scientific goals and demonstrate key in-situ enabling technologies. Among such technologies are the acquisition, preparation, distribution and analysis of samples from Mars surface rocks and from the subsurface. The 2018 mission will land an ESA rover on Mars which carries a sample preparation and distribution system (SPDS) and a suite of analytical instruments, the Pasteur Payload with its Analytical Laboratory Drawer (ALD). Kayser-Threde GmbH (Germany) will be responsible for the SPDS as a subcontractor under the mission prime Thales Alenia Space. The SPDS comprises a number of complex mechanisms and mechanical devices designed to transport drill core samples within the rover analytical laboratory, to crush them to powder with a fine grain size, to portion discrete amounts of powdered sample material, to distribute and fill the material into sample containers and to prepare flat sample surfaces for scientific analysis. Breadboards of the crushing mechanism, the dosing mechanism and a distribution carousel with sample containers and a powder sample surface flattening mechanism were built and tested. Kayser-Threde, as a member of the Spanish led ExoMars Raman Instrument team, is also responsible for development of the Raman optical head, which will be mounted inside ALD and will inspect the crushed samples, when they are presented to the instrument by the distribution carousel. Within this activity, which is performed under contract with the Institute of Physical Chemistry of the University of Jena (Germany) and funded by the German DLR, Kayser-Threde can demonstrate Raman measurements with the optical head and a COTS laser and spectrometer and thus simulate the full Raman instrument optical path. An autofocus system with actuator and feedback optics is also part of this activity, which allows focusing the 50 m Raman spot on the surface of the powdered sample. Availability of both, the SPDS mechanisms and the Raman Spectrometer optical head at Kayser-Threde facilities allowed to demonstrate for the first time a sample preparation chain with a joint operation of the optical head. Mineral samples were crushed, dosed into sample containers on the carousel, flattened and then inspected by the Raman optical head. The samples were provided by the University of Jena, a member of the ExoMars Raman science team. This paper will give an overview of the breadboards developed so far for the ExoMars SPDS and the Raman optical head and illustrate the joint demonstration test setup of the SPDS with the instrument. The different behavior of different sample materials will be highlighted and first conclusions will be drawn on what could be learned from test setups combining the ExoMars SPDS and analytical instruments.

Synthesis and electrochemical sodium-storage of few-layered MoS2/nitrogen, phosphorus-codoped graphene

NASA Astrophysics Data System (ADS)

Xu, Limei; Ma, Lin; Li, Wenyan; Yang, Xinxin; Ling, Yan

2018-07-01

Few-layered molybdenum disulfide/nitrogen, phosphorus co-doped graphene composites are synthesized by a quaternary phosphonium salt-assisted hydrothermal and annealing procedure. The prepared composites are analyzed by x-ray powder diffraction, x-ray photoelectron spectra, scanning electronic microscopy, transmission electronic microscopy, Raman spectra and nitrogen adsorption and desorption. Experimental results indicate that the MoS2 nanosheets are of few-layered and defective structures and are well anchored on flexible conductive nitrogen, phosphorus co-doped graphene to constitute mesoporous composites with increased surface areas. Benefiting from the structural merits as well as surface-dominated pseudocapacitive contribution, the composite electrode presents a high electrochemical sodium storage capacity that arrives at 542 mAh g‑1 at a current density of 100 mA g‑1 with an excellent cyclability. Moreover, a superior high-rate capability can also be achieved.

Synthesis, crystal growth, structural, thermal, optical and mechanical properties of solution grown 4-methylpyridinium 4-hydroxybenzoate single crystal.

PubMed

Sudhahar, S; Krishna Kumar, M; Sornamurthy, B M; Mohan Kumar, R

2014-01-24

Organic nonlinear optical material, 4-methylpyridinium 4-hydroxybenzoate (4MPHB) was synthesized and single crystal was grown by slow evaporation solution growth method. Single crystal and powder X-ray diffraction analyses confirm the structure and crystalline perfection of 4MPHB crystal. Infrared, Raman and NMR spectroscopy techniques were used to elucidate the functional groups present in the compound. TG-DTA analysis was carried out in nitrogen atmosphere to study the decomposition stages, endothermic and exothermic reactions. UV-visible and Photoluminescence spectra were recorded for the grown crystal to estimate the transmittance and band gap energy respectively. Linear refractive index, birefringence, and SHG efficiency of the grown crystal were studied. Laser induced surface damage threshold and mechanical properties of grown crystal were studied to assess the suitability of the grown crystals for device applications. Copyright © 2013 Elsevier B.V. All rights reserved.

Electrical relaxation, optical and magnetic studies of nanocrystalline lithium ferrite synthesized by different chemical routes

NASA Astrophysics Data System (ADS)

Cheruku, Rajesh; Govindaraj, G.; Vijayan, Lakshmi

2017-12-01

The nanocrystalline lithium ferrite was synthesized by wet chemical methods such as solution combustion technique, sol-gel, and hydrothermal for a comparative study. Different characterization techniques like x-ray powder diffraction and thermal analysis were employed to confirm the structure and phase. Temperature-dependent Raman analysis was employed to classify the phonon modes associated with precise atomic motions existing in the synthesized materials. Morphology of sample surface was explored by scanning electron microscopy, and elemental analysis was done by energy dispersive spectroscopy analysis. The nanocrystalline nature of the materials was confirmed through transmission electron microscopy. Magnetic properties of these samples were explored through a vibrating sample magnetometer. Ac electrical impedance spectroscopy data were investigated using two Cole-Cole functions, and activation energies were calculated for all materials. Among them, solution combustion prepared lithium ferrite shows the highest conductivity and lowest activation energy.

Crystal growth and physical characterization of picolinic acid cocrystallized with dicarboxylic acids

NASA Astrophysics Data System (ADS)

Somphon, Weenawan; Haller, Kenneth J.

2013-01-01

Pharmaceutical cocrystals are multicomponent materials containing an active pharmaceutical ingredient with another component in well-defined stoichiometry within the same unit cell. Such cocrystals are important in drug design, particularly for improving physicochemical properties such as solubility, bioavailability, or chemical stability. Picolinic acid is an endogenous metabolite of tryptophan and is widely used for neuroprotective, immunological, and anti-proliferative effects within the body. In this paper we present cocrystallization experiments of a series of dicarboxylic acids, oxalic acid, succinic acid, DL-tartaric acid, pimelic acid, and phthalic acid, with picolinic acid. Characterization by FT-IR and Raman spectroscopy, DSC and TG/DTG analysis, and X-ray powder diffraction show that new compounds are formed, including a 1:1 picolinium tartrate monohydrate, a 2:1 monohydrate adduct of picolinic acid and oxalic acid, and a 2:1 picolinic acid-succinic acid monohydrate cocrystal.

Titan's Lakes in a Beaker

NASA Astrophysics Data System (ADS)

Hodyss, R. P.

2017-12-01

The surface of Titan presents a complex, varied surfaced, with mountains, plains, dunes, rivers, lakes and seas, composed of a layer of organics over a water ice bedrock. Over the past 10 years, our group at JPL has developed a variety of techniques to study the chemistry of Titan's organic surface under relevant temperature and pressure conditions (90-100 K, 1.5 bar). Dissolution, precipitation, and both covalent and non-covalent chemical processes are examined using Raman and infrared spectroscopy, mass spectrometry, optical microscopy, and synchrotron X-ray powder diffraction. Despite the low temperatures, our experiments are revealing that a rich and active organic chemistry is possible on Titan's surface. Laboratory experiments like these can provide crucial insights into the geological processes occurring Titan's surface, and help explain the wealth of observational data returned by the Cassini/Huygens mission. This type of data is also critical for the development of future missions to Titan.

Development of nanosized lanthanum strontium aluminum manganite as electrodes for potentiometric oxygen sensor

DOE PAGES

Mullen, Max R.; Spirig, John V.; Hoy, Julia; ...

2014-11-01

Nanocrystalline La0.8Sr0.2Al0.9Mn0.1O3 (LSAM) was synthesized by a microwave-assisted citrate method, and characterized by electron microscopy and X-ray diffraction. Electrical behavior of LSAM was investigated by impedance spectroscopy and activation energy of conduction was obtained. Joining of sintered bodies of LSAM and yttria-stabilized tetragonal zirconia polycrystals (YTZP), an extensively studied oxygen ion conducting electrolyte, was examined by isostatic hot pressing methods. Characteristics of the joining region were evaluated with microprobe Raman spectroscopy, and products formed at the interface, primarily strontium zirconate, was confirmed by examination of high temperature chemical reaction between LSAM and YTZP powders. Finally, the electrical properties of themore » LSAM were exploited for development of a high temperature oxygen sensor in which LSAM functioned as the electrode and YTZP as electrolyte.« less

Enhanced photoelectrocatalytic performance of heterostructured TiO2-based nanoparticles decorated nanotubes

NASA Astrophysics Data System (ADS)

Wu, Liangpeng; Yang, Xu; Huang, Yanqin; Li, Xinjun

2017-06-01

Titanium oxide nanotubes were prepared by hydrothermal treatment of TiO2 powder in NaOH aqueous solution and subsequently calcined. Titanium oxide nanotubes were further decorated by TiO2 nanoparticles through in situ hydrolysis of titanium isopropoxide containing alcohol and ammonia in an aqueous medium to form the composite catalyst (TNP/TiO2NTs). The morphology and structure of TNP/TiO2NTs were characterized by scanning and transmission electron microscopy, X-ray diffraction, UV-Vis, and Raman spectra. The separation efficiency of photo-excited carriers was investigated by photoluminescence technique and photoelectrochemical behavior. The photocatalytic activity was evaluated by the photocatalytic degradation of methyl orange. Due to the synergy effect caused by the interaction of titanium oxide nanotubes and TiO2 nanoparticles, the TNP/TiO2NTs composite shows efficient photogenerated carriers' separation and the increased light absorption. The photocatalytic activity was enhanced.

Facile synthesis of Ni/NiO@GO nanocomposites and its enhanced dielectric constant

NASA Astrophysics Data System (ADS)

Sarkar, S.; Giri, N.; Mondal, A.; Ray, R.

2018-05-01

Ni/NiO embedded Graphene Oxide (GO): Ni/NiO@GO is synthesized by citric acid assisted Pechini-type method. Structural and morphological characterizations are performed by X-ray powdered diffraction (XRD), field emission scanning electron microscopy (FESEM) and tunneling electron microscopy (TEM). Defects in GO sheets are probed by RAMAN spectroscopy. The temperature variation of dielectric constant (ɛR) and dielectric loss (tan δ) are investigated in the temperature range 300 - 400 K. Decoration of GO with Ni/NiO nanoparticles enhances its ɛR by˜55 times. Moreover, its dielectric constant measured at 5 MHz is found to be˜430 times to that of Ni/NiO along with the reduction of dielectric loss by a factor˜0.5. The enhanced dielectric constant makes the composite Ni/NiO@GO a potential candidate for using in ecologically friendly energy storage devices.

Analytical Characterization of Erythritol Tetranitrate, an Improvised Explosive.

PubMed

Matyáš, Robert; Lyčka, Antonín; Jirásko, Robert; Jakový, Zdeněk; Maixner, Jaroslav; Mišková, Linda; Künzel, Martin

2016-05-01

Erythritol tetranitrate (ETN), an ester of nitric acid and erythritol, is a solid crystalline explosive with high explosive performance. Although it has never been used in any industrial or military application, it has become one of the most prepared and misused improvise explosives. In this study, several analytical techniques were explored to facilitate analysis in forensic laboratories. FTIR and Raman spectrometry measurements expand existing data and bring more detailed assignment of bands through the parallel study of erythritol [(15) N4 ] tetranitrate. In the case of powder diffraction, recently published data were verified, and (1) H, (13) C, and (15) N NMR spectra are discussed in detail. The technique of electrospray ionization tandem mass spectrometry was successfully used for the analysis of ETN. Described methods allow fast, versatile, and reliable detection or analysis of samples containing erythritol tetranitrate in forensic laboratories. © 2016 American Academy of Forensic Sciences.

Possible Roles of Fluoride and Carbonate in Biochemical Carbonated Apatite Formation

NASA Astrophysics Data System (ADS)

Meouch, Orysia; Omelon, Sidney

2016-04-01

Marine phosphorites are predominantly composed of carbonated fluorapatite (CFA = Ca10-a-b-cNaaMgb(PO4)6-x(CO3)x-y-z(CO3.F)y(SO4)zF2, where x=y+a+2c, and c represents the number of Ca vacancies, with a P2O5 content that ranges from 18-40 %. Sulphur-oxidizing bacteria of the Beggiatoa genus concentration phosphorous as intracellular polyphosphate ((PO3-)n) which is depolymerized into inorganic orthophosphate (Pi). Consequently, an increase in pore water Pi concentration favours carbonated apatite precipitation. The carbonate and fluoride that is characteristic of phosphorite CFA is also located in the vertebrate skeleton. This similarity suggests a biochemical pathway for CFA precipitation. Preliminary Raman spectroscopy and powder x-ray diffraction results that suggest a role for fluoride, and possibly carbonate, in the biochemical depolymerisation of polyphosphates with alkaline phosphatase will be presented.

Synthesis and electrochemical sodium-storage of few-layered MoS2/nitrogen, phosphorus-codoped graphene.

PubMed

Xu, Limei; Ma, Lin; Li, Wenyan; Yang, Xinxin; Ling, Yan

2018-07-27

Few-layered molybdenum disulfide/nitrogen, phosphorus co-doped graphene composites are synthesized by a quaternary phosphonium salt-assisted hydrothermal and annealing procedure. The prepared composites are analyzed by x-ray powder diffraction, x-ray photoelectron spectra, scanning electronic microscopy, transmission electronic microscopy, Raman spectra and nitrogen adsorption and desorption. Experimental results indicate that the MoS 2 nanosheets are of few-layered and defective structures and are well anchored on flexible conductive nitrogen, phosphorus co-doped graphene to constitute mesoporous composites with increased surface areas. Benefiting from the structural merits as well as surface-dominated pseudocapacitive contribution, the composite electrode presents a high electrochemical sodium storage capacity that arrives at 542 mAh g -1 at a current density of 100 mA g -1 with an excellent cyclability. Moreover, a superior high-rate capability can also be achieved.

Synthesis and Optical Properties of MnS–ZnS and MnS–CdS Nanoparticles in Montmorillonite.

PubMed

Kabilaphat, Jirabhorn; Poosimma, Poonsuk; Khaorapapong, Nithima; Intachai, Sonchai; Ogawa, Makoto

2017-02-01

The incorporation of metal sulfide mixture, manganese sulfide and zinc sulfide (MnS–ZnS) or manganese sulfide and cadmium sulfide (MnS–CdS), in two types of montmorillonites (sodium montmorillonite and cetyltrimethylammonium modified montmorillonite) was investigated. The hybrids were characterized by powder X-ray diffraction, thermogravimetric-differential thermal analysis, transmission electron microscopy (TEM), and Raman, UV-visible and photoluminescence spectroscopies. The experimental evidences such as the expansion of the interlayer spaces and the presence of the absorption and photoluminescence due to MnS, ZnS and/or CdS revealed that the mixed metal sulfides formed in the interlayer space of montmorillonites. TEM images of the hybrids showed diskor plate-shaped nanoparticles with a mean diameter of ca. 2 nm. The increase of the luminescence intensities of the hybrids was assumed to be caused by quantum confinement effect in the interlayer space of montmorillonite.

Study on the hydration and microstructure of Portland cement containing diethanol-isopropanolamine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Suhua, E-mail: yc982@163.com; Li, Weifeng; Zhang, Shenbiao

2015-01-15

Diethanol-isopropanolamine (DEIPA) is a tertiary alkanolamine used in the formulation of cement grinding-aid additives and concrete early-strength agents. In this research, isothermal calorimetry was used to study the hydration kinetics of Portland cement with DEIPA. A combination of X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC)–thermogravimetric (TG) analysis and micro-Raman spectroscopy was used to investigate the phase development in the process of hydration. Mercury intrusion porosimetry was used to study the pore size distribution and porosity. The results indicate that DEIPA promotes the formation of ettringite (AFt) and enhances the second hydration rate of the aluminatemore » and ferrite phases, the transformation of AFt into monosulfoaluminate (AFm) and the formation of microcrystalline portlandite (CH) at early stages. At later stages, DEIPA accelerates the hydration of alite and reduces the pore size and porosity.« less

Flux growth and characterization of cuprorivaite: the influence of temperature, flux, and silica source

NASA Astrophysics Data System (ADS)

Bloise, A.; Abd El Salam, S.; De Luca, R.; Crisci, G. M.; Miriello, D.

2016-07-01

Single crystals of cuprorivaite (CaCuSi4O10), one of the oldest synthetic color pigments of Egyptian history, have been synthesized by slow-cooling flux method. Several runs were carried out at temperatures between 800 and 960 °C and with reaction times ranging from 10 to 72 h. The starting materials and run products were characterized by binocular microscope, X-ray powder diffraction, scanning electron microscopy with annexed energy-dispersive spectrometry, and μ-Raman spectroscopy. The effects of growth parameters (temperature, flux, silica source) on yield and size of crystals were studied. The growth of cuprorivaite depends greatly on the starting materials: they are observed as run products only using natron as flux. Furthermore, colorimetric analysis performed on the synthesizing pigment was compared with the archeological samples present in the literature in order to value similarities and differences.

Synthesis and characterization of ligational behavior of curcumin drug towards some transition metal ions: Chelation effect on their thermal stability and biological activity

NASA Astrophysics Data System (ADS)

Refat, Moamen S.

2013-03-01

Complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with curcumin ligand as antitumor activity were synthesized and characterized by elemental analysis, conductometry, magnetic susceptibility, UV-Vis, IR, Raman, ESR, 1H-NMR spectroscopy, X-ray diffraction analysis of powdered samples and thermal analysis, and screened for antimicrobial activity. The IR spectral data suggested that the ligand behaves as a monobasic bidentate ligand towards the central metal ion with an oxygen's donor atoms sequence of both sbnd OH and Cdbnd O groups under keto-enol structure. From the microanalytical data, the stoichiometry of the complexes 1:2 (metal:ligand) was found. The ligand and their metal complexes were screened for antibacterial activity against Escherichia Coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa and fungicidal activity against Aspergillus flavus and Candida albicans.

High-throughput continuous hydrothermal synthesis of nanomaterials (part II): unveiling the as-prepared CexZryYzO2-δ phase diagram.

PubMed

Quesada-Cabrera, Raul; Weng, Xiaole; Hyett, Geoff; Clark, Robin J H; Wang, Xue Z; Darr, Jawwad A

2013-09-09

High-throughput continuous hydrothermal flow synthesis was used to manufacture 66 unique nanostructured oxide samples in the Ce-Zr-Y-O system. This synthesis approach resulted in a significant increase in throughput compared to that of conventional batch or continuous hydrothermal synthesis methods. The as-prepared library samples were placed into a wellplate for both automated high-throughput powder X-ray diffraction and Raman spectroscopy data collection, which allowed comprehensive structural characterization and phase mapping. The data suggested that a continuous cubic-like phase field connects all three Ce-Zr-O, Ce-Y-O, and Y-Zr-O binary systems together with a smooth and steady transition between the structures of neighboring compositions. The continuous hydrothermal process led to as-prepared crystallite sizes in the range of 2-7 nm (as determined by using the Scherrer equation).

Growth and characterization of chalcostibite CuSbSe2 thin films for photovoltaic application

NASA Astrophysics Data System (ADS)

Tiwari, Kunal J.; Vinod, Vijay; Subrahmanyam, A.; Malar, P.

2017-10-01

Bulk copper antimony selenide was synthesized using mechanical alloying from the elemental precursors. Phase formation in milled powders was studied using x-ray diffraction (XRD) and Raman spectroscopy studies. The synthesized bulk source after cold compaction was used as source material for thin film deposition by e-beam evaporation. Thin film deposition was carried out at various e-beam current values (Ib ∼30, 40 and 50 mA) and at a substrate temperature of 200 °C. Near stoichiometric CuSbSe2 thin films were obtained for Ib values closer to 50 mA and post annealing at a temperature of 380 °C for 1 h. Thin films deposited using above conditions were found to exhibit an absorption coefficient (α) values of >105 cm-1 and a band gap value ∼1.18 eV that is closer to the reported band gap for CuSbSe2 compound.

Catalytic growth of carbon nanofibers on Cr nanoparticles on a carbon substrate: adsorbents for organic dyes in water

NASA Astrophysics Data System (ADS)

de Oliveira, Luiz Carlos Alves; da Silva, Adilson Cândido; Machado, Alan Rodrigues Teixeira; Diniz, Renata; Pereira, Márcio César

2013-05-01

We have produced carbon nanofibers (CNFs) using leather waste that had been tanned with a chromium bath, and when dried contained Cr2O3. Suitable reduction processing produced a carbon substrate with supported nanoparticles of chromium metal. Powder X-ray diffraction showed that the Cr2O3 is reduced on the carbon surface to produce CrC and metal Cr, which is the effective catalyst for the CNFs growth. The CNF arrays were confirmed by TEM images. Raman data revealed that the synthesized CNFs have a poor-quality graphite structure which favors their use in adsorption processes. These CNFs presented higher affinity to adsorb anionic dyes, whereas the cationic dyes are better adsorbed on the carbon substrate. The low-cost and availability of the carbon precursor makes their potential use to produce CNFs of interest.

Progressing the analysis of Improvised Explosive Devices: Comparative study for trace detection of explosive residues in handprints by Raman spectroscopy and liquid chromatography.

PubMed

Zapata, Félix; de la Ossa, Mª Ángeles Fernández; Gilchrist, Elizabeth; Barron, Leon; García-Ruiz, Carmen

2016-12-01

Concerning the dreadful global threat of terrorist attacks, the detection of explosive residues in biological traces and marks is a current need in both forensics and homeland security. This study examines the potential of Raman microscopy in comparison to liquid chromatography (ion chromatography (IC) and reversed-phase high performance liquid chromatography (RP-HPLC)) to detect, identify and quantify residues in human handmarks of explosives and energetic salts commonly used to manufacture Improvised Explosive Devices (IEDs) including dynamite, ammonium nitrate, single- and double-smokeless gunpowders and black powder. Dynamite, ammonium nitrate and black powder were detected through the identification of the energetic salts by Raman spectroscopy, their respective anions by IC, and organic components by RP-HPLC. Smokeless gunpowders were not detected, either by Raman spectroscopy or the two liquid chromatography techniques. Several aspects of handprint collection, sample treatment and a critical comparison of the identification of compounds by both techniques are discussed. Raman microscopy and liquid chromatography were shown to be complementary to one another offering more comprehensive information for trace explosives analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous detection of multiple adulterants in dry milk using macro-scale Raman chemical imaging

USDA-ARS?s Scientific Manuscript database

The potential of Raman chemical imaging for simultaneously detecting multiple adulterants in milk powder was investigated. Potential chemical adulterants, including ammonium sulfate, dicyandiamide, melamine, and urea, were mixed together into skim dry milk in the concentration range of 0.1–5.0% for ...

1D hetero-bimetallic regularly alternated 4f-3d coordination polymers based on N-oxide-4,4'-bipyridine (bipyMO) as a linker: photoluminescence and magnetic properties.

PubMed

Armelao, Lidia; Belli Dell'Amico, Daniela; Bottaro, Gregorio; Bellucci, Luca; Labella, Luca; Marchetti, Fabio; Mattei, Carlo Andrea; Mian, Federica; Pineider, Francesco; Poneti, Giordano; Samaritani, Simona

2018-06-13

Heterotopic divergent ligand N-oxide-4,4'-bipyridine (bipyMO) has been herein exploited for the preparation of hetero-bimetallic coordination polymers where Ln(hfac)3 and M(hfac)2 nodes regularly alternate (Hhfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione), bipyMO being able to selectively use its two potential coordination sites to discriminate the metal ions. The synthesis of three coordination polymers, [Ln(hfac)3M(hfac)2(bipyMO)2]n (Ln = Eu, M = Zn, 1; Ln = Eu, M = Cu, 2, Ln = Dy, M = Co, 3), was carried out by reacting the appropriate [M(hfac)2(bipyMO)]n and [Ln(hfac)3] precursors in toluene in the presence of a given stoichiometric amount of bipyMO. The products were characterized by elemental analysis, X-ray powder diffraction, and FTIR spectroscopy. Single crystal X-ray diffraction studies carried out on 2 showed that it was formed by chains containing the hexa-coordinated 3d metal (Cu(hfac)2[N]2) and the octa-coordinated lanthanide (Eu(hfac)3[O]2) nodes, where [N] and [O] stand for the donor atom of the bridging divergent ligand. The X-ray powder diffraction patterns of the three compounds and the comparison of their cell constant values allowed establishing that the derivatives were isotypic. Photoluminescence (PL) studies on microcrystalline sample powders evidenced a bright red emission for 1 with an absolute PL quantum yield of 0.24. The sensitized emission of Eu3+ can be excited in a wide wavelength range, from UV to visible, up to ≈450 nm. Conversely, europium emissions are not detectable in 2 due to the presence of Cu(hfac)2(bipyMO) moieties whose strong absorption overlaps Eu3+ transitions. Magnetic measurements conducted on 3 revealed the presence of a weak ferromagnetic interaction below 2.1 K. An ac susceptibility study highlighted a slow relaxation of the magnetization of 3 with an applied static magnetic field of 0.1 T, which could be equally fitted with a Orbach-direct or a Raman-direct mechanism. No relaxation dynamics was detected without the application of a static magnetic field.

Synchrotron X-ray powder diffraction data of LASSBio-1515: A new N-acylhydrazone derivative compound

NASA Astrophysics Data System (ADS)

Costa, F. N.; Braz, D.; Ferreira, F. F.; da Silva, T. F.; Barreiro, E. J.; Lima, L. M.; Colaço, M. V.; Kuplich, L.; Barroso, R. C.

2014-02-01

In this work, synchrotron X-ray powder diffraction data allowed for a successful indexing of LASSBio-1515 compound, candidate to analgesic and anti-inflammatory activity. X-ray powder diffraction data collected in transmission and high-throughput geometries were used to analyze this compound. The X-ray wavelength of the synchrotron radiation used in this study was determined to be λ=1.55054 Å. LASSBio-1515 was found to be monoclinic with space group P21/c and unit cell parameters a=11.26255(16) Å, b=12.59785(16) Å, c=8.8540(1) Å, β=90.5972(7)° and V=1256.17(3) Å3.

Low-temperature route to metal titanate perovskite nanoparticles for photocatalytic applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alammar, Tarek; Hamm, Ines; Wark, Michael

MTiO 3 (M = Ca, Sr, Ba) nanoparticles were synthesized by a one-step room-temperature ultrasound synthesis in ionic liquid. The samples we gathered are characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, UV–vis diffuse reflectance, Raman and IR spectroscopy and their capability in photocatalytic hydrogen evolution and methylene blue degradation was tested. Powder X-ray diffraction and Raman spectroscopic investigations revealed the products to crystallize in the cubic perovskite structure. SEM observations showed that the obtained CaTiO 3 consists of nanospheres, BaTiO 3 of raspberry-like shaped particles of 20 nm in diameter. SrTiO 3 particles have cubic-like morphology with anmore » edge length varying from 100 to 300 nm. SrTiO 3 exhibited the highest catalytic activity for photocatalytic H 2 evolution using only 0.025 wt.% Rh as co-catalyst and for the degradation of methylene blue under UV irradiation. The influence of parameters such as synthesis method, calcination temperature, and doping with nitrogen on the morphology, crystallinity, chemical composition, and photocatalytic acivity of SrTiO 3 was studied. Heating the as-prepared SrTiO 3 to 700 °C for extended time leads to a decrease in surface area and catalytic activity. Ionothermal prepared SrTiO 3 exhibits a higher activity than sonochemically prepared one without co-catalyst due to a synergistic effect of anatase which is present in small amount as a by-phase. Furthermore, after photodeposition of Rh, however, the activity is lower than that of the sonochemically prepared SrTiO 3. Nitrogen-doped SrTiO 3 showed photocatalytic acivity under visible light irradiation.« less

Low-temperature route to metal titanate perovskite nanoparticles for photocatalytic applications

DOE PAGES

Alammar, Tarek; Hamm, Ines; Wark, Michael; ...

2014-11-13

MTiO 3 (M = Ca, Sr, Ba) nanoparticles were synthesized by a one-step room-temperature ultrasound synthesis in ionic liquid. The samples we gathered are characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, UV–vis diffuse reflectance, Raman and IR spectroscopy and their capability in photocatalytic hydrogen evolution and methylene blue degradation was tested. Powder X-ray diffraction and Raman spectroscopic investigations revealed the products to crystallize in the cubic perovskite structure. SEM observations showed that the obtained CaTiO 3 consists of nanospheres, BaTiO 3 of raspberry-like shaped particles of 20 nm in diameter. SrTiO 3 particles have cubic-like morphology with anmore » edge length varying from 100 to 300 nm. SrTiO 3 exhibited the highest catalytic activity for photocatalytic H 2 evolution using only 0.025 wt.% Rh as co-catalyst and for the degradation of methylene blue under UV irradiation. The influence of parameters such as synthesis method, calcination temperature, and doping with nitrogen on the morphology, crystallinity, chemical composition, and photocatalytic acivity of SrTiO 3 was studied. Heating the as-prepared SrTiO 3 to 700 °C for extended time leads to a decrease in surface area and catalytic activity. Ionothermal prepared SrTiO 3 exhibits a higher activity than sonochemically prepared one without co-catalyst due to a synergistic effect of anatase which is present in small amount as a by-phase. Furthermore, after photodeposition of Rh, however, the activity is lower than that of the sonochemically prepared SrTiO 3. Nitrogen-doped SrTiO 3 showed photocatalytic acivity under visible light irradiation.« less

Corrosion behavior of magnetic ferrite coating prepared by plasma spraying

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Yi; Wei, Shicheng, E-mail: wsc33333@163.com; Tong, Hui

Graphical abstract: The saturation magnetization (M{sub s}) of the ferrite coating is 34.417 emu/g while the M{sub s} value of the ferrite powder is 71.916 emu/g. It can be seen that plasma spray process causes deterioration of the room temperature soft magnetic properties. - Highlights: • Spinel ferrite coatings have been prepared by plasma spraying. • The coating consists of nanocrystalline grains. • The saturation magnetization of the ferrite coating is 34.417 emu/g. • Corrosion behavior of the ferrite coating was examined in NaCl solution. - Abstract: In this study, spray dried spinel ferrite powders were deposited on the surfacemore » of mild steel substrate through plasma spraying. The structure and morphological studies on the ferrite coatings were carried out using X-ray diffraction, scanning electron microscope and Raman spectroscopy. It was showed that spray dried process was an effective method to prepare thermal spraying powders. The coating showed spinel structure with a second phase of LaFeO{sub 3}. The magnetic property of the ferrite samples were measured by vibrating sample magnetometer. The saturation magnetization (M{sub s}) of the ferrite coating was 34.417 emu/g. The corrosion behavior of coating samples was examined by electrochemical impedance spectroscopy. EIS diagrams showed three corrosion processes as the coating immersed in 3.5 wt.% NaCl solution. The results suggested that plasma spraying was a promising technology for the production of magnetic ferrite coatings.« less

Formation of silicon nanowire packed films from metallurgical-grade silicon powder using a two-step metal-assisted chemical etching method.

PubMed

Ouertani, Rachid; Hamdi, Abderrahmen; Amri, Chohdi; Khalifa, Marouan; Ezzaouia, Hatem

2014-01-01

In this work, we use a two-step metal-assisted chemical etching method to produce films of silicon nanowires shaped in micrograins from metallurgical-grade polycrystalline silicon powder. The first step is an electroless plating process where the powder was dipped for few minutes in an aqueous solution of silver nitrite and hydrofluoric acid to permit Ag plating of the Si micrograins. During the second step, corresponding to silicon dissolution, we add a small quantity of hydrogen peroxide to the plating solution and we leave the samples to be etched for three various duration (30, 60, and 90 min). We try elucidating the mechanisms leading to the formation of silver clusters and silicon nanowires obtained at the end of the silver plating step and the silver-assisted silicon dissolution step, respectively. Scanning electron microscopy (SEM) micrographs revealed that the processed Si micrograins were covered with densely packed films of self-organized silicon nanowires. Some of these nanowires stand vertically, and some others tilt to the silicon micrograin facets. The thickness of the nanowire films increases from 0.2 to 10 μm with increasing etching time. Based on SEM characterizations, laser scattering estimations, X-ray diffraction (XRD) patterns, and Raman spectroscopy, we present a correlative study dealing with the effect of the silver-assisted etching process on the morphological and structural properties of the processed silicon nanowire films.

Formation of silicon nanowire packed films from metallurgical-grade silicon powder using a two-step metal-assisted chemical etching method

PubMed Central

2014-01-01

In this work, we use a two-step metal-assisted chemical etching method to produce films of silicon nanowires shaped in micrograins from metallurgical-grade polycrystalline silicon powder. The first step is an electroless plating process where the powder was dipped for few minutes in an aqueous solution of silver nitrite and hydrofluoric acid to permit Ag plating of the Si micrograins. During the second step, corresponding to silicon dissolution, we add a small quantity of hydrogen peroxide to the plating solution and we leave the samples to be etched for three various duration (30, 60, and 90 min). We try elucidating the mechanisms leading to the formation of silver clusters and silicon nanowires obtained at the end of the silver plating step and the silver-assisted silicon dissolution step, respectively. Scanning electron microscopy (SEM) micrographs revealed that the processed Si micrograins were covered with densely packed films of self-organized silicon nanowires. Some of these nanowires stand vertically, and some others tilt to the silicon micrograin facets. The thickness of the nanowire films increases from 0.2 to 10 μm with increasing etching time. Based on SEM characterizations, laser scattering estimations, X-ray diffraction (XRD) patterns, and Raman spectroscopy, we present a correlative study dealing with the effect of the silver-assisted etching process on the morphological and structural properties of the processed silicon nanowire films. PMID:25349554

Observations on online educational materials for powder diffraction crystallography software.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toby, B. H.

2010-10-01

This article presents a series of approaches used to educate potential users of crystallographic software for powder diffraction. The approach that has been most successful in the author's opinion is the web lecture, where an audio presentation is coupled to a video-like record of the contents of the presenter's computer screen.

Ultraviolet Raman Wide-Field Hyperspectral Imaging Spectrometer for Standoff Trace Explosive Detection.

PubMed

Hufziger, Kyle T; Bykov, Sergei V; Asher, Sanford A

2017-02-01

We constructed the first deep ultraviolet (UV) Raman standoff wide-field imaging spectrometer. Our novel deep UV imaging spectrometer utilizes a photonic crystal to select Raman spectral regions for detection. The photonic crystal is composed of highly charged, monodisperse 35.5 ± 2.9 nm silica nanoparticles that self-assemble in solution to produce a face centered cubic crystalline colloidal array that Bragg diffracts a narrow ∼1.0 nm full width at half-maximum (FWHM) UV spectral region. We utilize this photonic crystal to select and image two different spectral regions containing resonance Raman bands of pentaerythritol tetranitrate (PETN) and NH 4 NO 3 (AN). These two deep UV Raman spectral regions diffracted were selected by angle tuning the photonic crystal. We utilized this imaging spectrometer to measure 229 nm excited UV Raman images containing ∼10-1000 µg/cm 2 samples of solid PETN and AN on aluminum surfaces at 2.3 m standoff distances. We estimate detection limits of ∼1 µg/cm 2 for PETN and AN films under these experimental conditions.

Frequency analysis for modulation-enhanced powder diffraction.

PubMed

Chernyshov, Dmitry; Dyadkin, Vadim; van Beek, Wouter; Urakawa, Atsushi

2016-07-01

Periodic modulation of external conditions on a crystalline sample with a consequent analysis of periodic diffraction response has been recently proposed as a tool to enhance experimental sensitivity for minor structural changes. Here the intensity distributions for both a linear and nonlinear structural response induced by a symmetric and periodic stimulus are analysed. The analysis is further extended for powder diffraction when an external perturbation changes not only the intensity of Bragg lines but also their positions. The derived results should serve as a basis for a quantitative modelling of modulation-enhanced diffraction data measured in real conditions.

Fabrication, characterization, and photocatalytic property of α-Fe2O3/graphene oxide composite

NASA Astrophysics Data System (ADS)

Li, Hong; Zhao, Qidong; Li, Xinyong; Zhu, Zhengru; Tade, Moses; Liu, Shaomin

2013-06-01

Spindle-shaped microstructure of α-Fe2O3 was successfully synthesized by a simple hydrothermal method. The α-Fe2O3/graphene oxide (GO) composites was prepared using a modified Hummers' strategy. The properties of the samples were systematically investigated by X-ray powder diffraction (XRD), UV-Vis diffuse reflectance spectrophotometer, transmission electron microscope, atomic force microscope, X-ray photoelectron spectroscopy, and Raman spectroscopy (Raman) techniques. GO nanosheets act as supporting materials for anchoring the α-Fe2O3 particles. The average crystallite sizes of the α-Fe2O3 and α-Fe2O3/GO samples are ca. 27 and 24 nm, respectively. The possible growth of α-Fe2O3 onto GO layers led to a higher absorbance capacity for visible light by α-Fe2O3/GO than α-Fe2O3 composite. The photocatalytic degradation of toluene over the α-Fe2O3 and α-Fe2O3/GO samples under xenon-lamp irradiation was comparatively studied by in situ FTIR technique. The results indicate that the α-Fe2O3/GO sample synthesized exhibited a higher capacity for the degradation of toluene. The composite of α-Fe2O3/GO could be promisingly applied in photo-driven air purification.

Carbon-encapsulated cobalt nanoparticles: synthesis, properties, and magnetic particle hyperthermia efficiency

NASA Astrophysics Data System (ADS)

Kotoulas, A.; Dendrinou-Samara, C.; Sarafidis, C.; Kehagias, Th.; Arvanitidis, J.; Vourlias, G.; Angelakeris, M.; Kalogirou, Orestis

2017-12-01

A facile and low-cost method for structuring carbon-encapsulated cobalt nanoparticles (Co@C) is presented. Three samples were solvothermally prepared in one step at 220 °C and one in two steps at 200 °C. Three different polyols such as propylene glycol, triethylene glycol, and tetraethylene glycol were used as carbon sources, solvents, and reducing agents. The samples were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy. Concerning the crystal structure of the particles, a mixture of hcp/ fcc Co phases was obtained in three of the samples, independently of the polyol used. The coexistence of cubic and hexagonal phases was revealed both from XRD and high-resolution TEM (HRTEM). The formation of the cubic fcc structure, despite the relatively low reaction temperature, is attributed to the role of the interface between carbon coating and metallic core. The presence of carbon coating was demonstrated by Raman spectrometry, exhibiting the characteristic D and G graphitic bands, and by HRTEM observations. All samples showed ferromagnetic behavior with saturation magnetization up to 158 emu/g and coercivity up to 206 Oe. From the magnetic particle hyperthermia measurements recorded at a frequency of 765 kHz, a maximum SLP value of 241 W/g was obtained.

Effect of Zn doping on structural and dielectric properties of tetragonal Ni{sub 1-x}Zn{sub x}Fe{sub 2}O{sub 4} (0.0 ≤ x ≤ 0.5)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lone, S. A.; Dar, M. A.; Kumar, A.

2015-06-24

A series of Ni-Zn ferrite with compositional formula Ni{sub 1-x}Zn{sub x}Fe{sub 2}O{sub 4} (0.0 ≤ x ≤ 0.5) were prepared by solid-state reaction route. The influence of the Zn content on the structural and dielectric properties of NiFe{sub 2}O{sub 4} was investigated using X-ray powder diffraction (XRD), Raman spectroscopy and dielectric measurements. XRD analysis reveals that the samples are polycrystalline single-phase cubic spinel in structure excluding the presence of any secondary phase corresponding to any structure. Slight variation in the lattice parameter of Zn doped NiFe{sub 2}O{sub 4} has been observed due to difference in ionic radii of cations. Ramanmore » analysis reveals the doublet like nature of A{sub 1g} mode for all synthesized samples. Small shift in Raman modes and increment in the line width has been observed with the doping ions. Furthermore, room temperature dielectric properties of all the prepared samples have been reported. It is observed that for each sample the dielectric constant decreases with an increase of frequency and becomes constant at higher frequencies.« less

Spectroscopic characterization, antioxidant and antitumour studies of novel bromo substituted thiosemicarbazone and its copper(II), nickel(II) and palladium(II) complexes

NASA Astrophysics Data System (ADS)

Jagadeesh, M.; Lavanya, M.; Kalangi, Suresh K.; Sarala, Y.; Ramachandraiah, C.; Varada Reddy, A.

2015-01-01

A new, slightly distorted octahedral complex of copper(II), square planar complexes of nickel(II) and palladium(II) with 2,4‧-dibromoacetophenone thiosemicarbazone (DBAPTSC) are synthesized. The ligand and the complexes are characterized by FT-IR, FT-Raman, powder X-ray diffraction studies. The IR and Raman data are correlated for the presence of the functional groups which specifically helped in the confirmation of the compounds. In addition, the free ligand is unambiguously characterized by 1H and 13C NMR spectroscopy while the copper(II) complex is characterized by electron paramagnetic resonance spectroscopy (EPR). The g values for the same are found to be 2.246 (g1), 2.012 (g2) and 2.005 (g3) which suggested rhombic distortions. The HOMO-LUMO band gap calculations for these compounds are found to be in between 0.5 and 4.0 eV and these compounds are identified as semiconducting materials. The synthesized ligand and its copper(II), nickel(II) and palladium(II) complexes are subjected to antitumour activity against the HepG2 human hepatoblastoma cell lines. Among all the compounds, nickel(II) complex is found to exert better antitumour activity with 57.6% of cytotoxicity.

Investigation of polymorphic transitions of piracetam induced during wet granulation.

PubMed

Potter, Catherine B; Kollamaram, Gayathri; Zeglinski, Jacek; Whitaker, Darren A; Croker, Denise M; Walker, Gavin M

2017-10-01

Piracetam was investigated as a model API which is known to exhibit a number of different polymorphic forms. It is freely soluble in water so the possibility exists for polymorphic transformations to occur during wet granulation. Analysis of the polymorphic form present during lab-scale wet granulation, using water as a granulation liquid, was studied with powder X-ray diffraction and Raman spectroscopy as off-line and inline analysis tools respectively. Different excipients with a range of hydrophilicities, aqueous solubilities and molecular weights were investigated to examine their influence on these solution-mediated polymorphic transitions and experimental results were rationalised using molecular modelling. Our results indicated that as an increasing amount of water was added to the as-received piracetam FIII, a greater amount of the API dissolved which recrystallised upon drying to the metastable FII(6.403) via a monohydrate intermediary. Molecular level analysis revealed that the observed preferential transformation of monohydrate to FII is linked with a greater structural similarity between the monohydrate and FII polymorph in comparison to FIII. The application of Raman spectroscopy as a process analytical technology (PAT) tool to monitor the granulation process for the production of the monohydrate intermediate as a precursor to the undesirable metastable form was demonstrated. Copyright © 2017 Elsevier B.V. All rights reserved.

Raman, SEM-EDS and XRPD investigations on pre-Columbian Central America "estucado" pottery

NASA Astrophysics Data System (ADS)

Casanova Municchia, Annalaura; Micheli, Mario; Ricci, Maria Antonietta; Toledo, Michelle; Bellatreccia, Fabio; Lo Mastro, Sergio; Sodo, Armida

2016-03-01

Seventeen different colored fragments from six selected pre-Columbian estucado ceramics from El Salvador have been investigated by Raman spectroscopy, scanning electron microscope coupled to an energy dispersive spectrometer (SEM/EDS) and X-ray powder diffraction (XRPD). The peculiarity of this kind of ceramics consist of the unusual presence of a white engobe, traditionally termed stucco, between the ceramic body and the decoration elements, hence the name estucado ceramics. The aim of this work was to study the unusual manufacturing technique and to identify the chemical composition of the engobe and of the pigment palette. The results showed that the stucco layer is made of clay (kaolinite) with traces of titanium oxide (anatase). Remarkably, this is the same composition of the white pigments used for the decoration layer, thus excluding an early use of natural titanium oxide as a white pigment in the estucado productions as suggested in previous investigations. Moreover, the presence of kaolinite and anatase both in the stucco and in the decoration layer suggests a cold-working or low temperature technique. The red, yellow and green decorations were realized by the use of natural ochre, while in all the blue and gray decorations Maya blue pigment was identified. Finally, an amorphous carbon pigment of vegetal origin and manganese oxide were used to obtain black pigments.

Growth and characterization of Melaminium bis (trichloroacetate) dihydrate

NASA Astrophysics Data System (ADS)

Kanagathara, N.; Renganathan, N. G.; Marchewka, M. K.; Sivakumar, N.; Gayathri, K.; Krishnan, P.; Gunasekaran, S.; Anbalagan, G.

2013-01-01

Single crystals of melaminium bis (trichloroacetate) dihydrate have been grown successfully by slow evaporation solution growth technique at room temperature. Single crystal X-ray diffraction analysis reveals that the compound crystallizes in monoclinic system with non -centrosymmetric space group C2 with lattice parameters a = 17.70 Å, b = 8.44 Å, c = 6.09 Å, α = 90°, β = 100.24°, γ = 90° and V = 900 (Å)3. The UV-Vis transmittance spectrum shows that the crystal has a good optical transmittance in the entire visible region with lower cutoff wavelength of 351 nm. The vibrational frequencies of various functional groups present in the crystal have been derived from FI-IR, FT-Raman and Confocal Raman analyses. The chemical structure of the compound was established by 1H and 13C NMR spectrum. TGA-DTA analysis reveals that the materials have good thermal stability and the melting point of the crystal is found to be 195 °C. The dielectric response of the crystals was studied in the frequency range 50 Hz to 5 MHz at different temperatures and the results are discussed. Etching studies show the growth pattern of the crystals. The second harmonic generation efficiency was measured in comparison with KDP by employing powder Kurtz method.

Fabrication and testing of a newly designed slit system for depth-resolved X-ray diffraction measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sinsheimer, John; Bouet, Nathalie; Ghose, Sanjit

2016-10-06

A new system of slits called `spiderweb slits' have been developed for depth-resolved powder or polycrystalline X-ray diffraction measurements. The slits act on diffracted X-rays to select a particular gauge volume of sample, while absorbing diffracted X-rays from outside of this volume. Although the slit geometry is to some extent similar to that of previously developed conical slits or spiral slits, this new design has advantages over the previous ones in use for complex heterogeneous materials andin situandoperandodiffraction measurements. For example, the slits can measure a majority of any diffraction cone for any polycrystalline material, over a continuous range ofmore » diffraction angles, and work for X-ray energies of tens to hundreds of kiloelectronvolts. The design is generated and optimized using ray-tracing simulations, and fabricated through laser micromachining. The first prototype was successfully tested at the X17A beamline at the National Synchrotron Light Source, and shows similar performance to simulations, demonstrating gauge volume selection for standard powders, for all diffraction peaks over angles of 2–10°. A similar, but improved, design will be implemented at the X-ray Powder Diffraction beamline at the National Synchrotron Light Source II.« less

Physicochemical characterization and aerosol dispersion performance of organic solution advanced spray-dried cyclosporine A multifunctional particles for dry powder inhalation aerosol delivery

PubMed Central

Wu, Xiao; Zhang, Weifen; Hayes, Don; Mansour, Heidi M

2013-01-01

In this systematic and comprehensive study, inhalation powders of the polypeptide immunosuppressant drug – cyclosporine A – for lung delivery as dry powder inhalers (DPIs) were successfully designed, developed, and optimized. Several spray drying pump rates were rationally chosen. Comprehensive physicochemical characterization and imaging was carried out using scanning electron microscopy, hot-stage microscopy, differential scanning calorimetry, powder X-ray diffraction, Karl Fischer titration, laser size diffraction, and gravimetric vapor sorption. Aerosol dispersion performance was conducted using a next generation impactor with a Food and Drug Administration-approved DPI device. These DPIs displayed excellent aerosol dispersion performance with high values in emitted dose, respirable fraction, and fine particle fraction. In addition, novel multifunctional inhalation aerosol powder formulations of cyclosporine A with lung surfactant-mimic phospholipids were also successfully designed and developed by advanced organic solution cospray drying in closed mode. The lung surfactantmimic phospholipids were 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1,2-dipalmitoyl-snglycero- 3-(phosphor-rac-1-glycerol). These cyclosporine A lung surfactant-mimic aerosol powder formulations were comprehensively characterized. Powder X-ray diffraction and differential scanning calorimetry confirmed that the phospholipid bilayer structure in the solid state was preserved following advanced organic solution spray drying in closed mode. These novel multifunctional inhalation powders were optimized for DPI delivery with excellent aerosol dispersion performance and high aerosol performance parameters. PMID:23569375

The High Resolution Powder Diffraction Beam Line at ESRF.

PubMed

Fitch, A N

2004-01-01

The optical design and performance of the high-resolution powder diffraction beam line BM16 at ESRF are discussed and illustrated. Some recent studies carried out on BM16 are described, including crystal structure solution and refinement, anomalous scattering, in situ measurements, residual strain in engineering components, investigation of microstructure, and grazing-incidence diffraction from surface layers. The beam line is built on a bending magnet, and operates in the energy range from 5 keV to 40 keV. After the move to an undulator source in 2002, it will benefit from an extented energy range up to 60 keV and increased flux and resolution. It is anticipated that enhancements to the data quality will be achieved, leading to the solution of larger crystal structures, and improvements in the accuracy of refined structures. The systematic exploitation of anisotropic thermal expansion will help reduce the effects of peak overlap in the analysis of powder diffraction data.

The miniaturized Raman system and detection of traces of life in halite from the Atacama Desert: some considerations for the search for life signatures on Mars.

PubMed

Vítek, Petr; Jehlička, Jan; Edwards, Howell G M; Hutchinson, Ian; Ascaso, Carmen; Wierzchos, Jacek

2012-12-01

Raman spectroscopy is being adopted as a nondestructive instrumentation for the robotic exploration of Mars to search for traces of life in the geological record. Here, miniaturized Raman spectrometers of two different types equipped with 532 and 785 nm lasers for excitation, respectively, were compared for the detection of microbial biomarkers in natural halite from the hyperarid region of the Atacama Desert. Measurements were performed directly on the rock as well as on the homogenized, powdered samples prepared from this material-the effects of this sample preparation and the excitation wavelength employed in the analysis are compared and discussed. From these results, 532 nm excitation was found to be superior for the analysis of powdered specimens due to its high sensitivity toward carotenoids and hence a higher capability for their detection at relatively low concentration in bulk powdered specimens. For the same reason, this wavelength was a better choice for the detection of carotenoids in direct measurements made on the rock samples. The 785 nm excitation wavelength, in contrast, proved to be more sensitive toward the detection of scytonemin.

Application of powder X-ray diffraction in studying the compaction behavior of bulk pharmaceutical powders.

PubMed

Bandyopadhyay, Rebanta; Selbo, Jon; Amidon, Gregory E; Hawley, Michael

2005-11-01

This study investigates the effects of crystal lattice deformation on the powder X-ray diffraction (PXRD) patterns of compressed polycrystalline specimen (compacts/tablets) made from molecular, crystalline powders. The displacement of molecules and the corresponding adjustment of interplanar distances (d-spacings) between diffracting planes of PNU-288034 and PNU-177553, which have crystal habits with a high aspect ratio favoring preferred orientation during tableting, are demonstrated by shifts in the diffracted peak positions. The direction of shift in diffracted peak positions suggests a reduction of interplanar d-spacing in the crystals of PNU-288034 and PNU-177553 following compaction. There is also a general reduction of peak intensities following compression at the different compressive loads. The lattice strain representing the reduction in d-spacing is proportional to the original d-spacing of the uncompressed sample suggesting that, as with systems that obey a simple Hooke's law relationship, the further apart the planes of atoms/molecules within the lattice are, the easier it is for them to approach each other under compressive stresses. For a third model compound comprising more equant-shaped crystals of PNU-141659, the shift in diffracted peak positions are consistent with an expansion of lattice spacing after compression. This apparent anomaly is supported by the PXRD studies of the bulk powder consisting of fractured crystals where also, the shift in peak position suggests expansion of the lattice planes. Thus the crystals of PNU-141659 may be fracturing under the compressive loads used to produce the compacts. Additional studies are underway to relate the PXRD observations with the bulk tableting properties of these model compounds.

Test of Equivalence Principle at 10(-8) Level by a Dual-Species Double-Diffraction Raman Atom Interferometer.

PubMed

Zhou, Lin; Long, Shitong; Tang, Biao; Chen, Xi; Gao, Fen; Peng, Wencui; Duan, Weitao; Zhong, Jiaqi; Xiong, Zongyuan; Wang, Jin; Zhang, Yuanzhong; Zhan, Mingsheng

2015-07-03

We report an improved test of the weak equivalence principle by using a simultaneous 85Rb-87Rb dual-species atom interferometer. We propose and implement a four-wave double-diffraction Raman transition scheme for the interferometer, and demonstrate its ability in suppressing common-mode phase noise of Raman lasers after their frequencies and intensity ratios are optimized. The statistical uncertainty of the experimental data for Eötvös parameter η is 0.8×10(-8) at 3200 s. With various systematic errors corrected, the final value is η=(2.8±3.0)×10(-8). The major uncertainty is attributed to the Coriolis effect.

Enhancing the Area of a Raman Atom Interferometer Using a Versatile Double-Diffraction Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leveque, T.; Gauguet, A.; Michaud, F.

2009-08-21

In this Letter, we demonstrate a new scheme for Raman transitions which realize a symmetric momentum-space splitting of 4(Planck constant/2pi)k, deflecting the atomic wave packets into the same internal state. Combining the advantages of Raman and Bragg diffraction, we achieve a three pulse state labeled an interferometer, intrinsically insensitive to the main systematics and applicable to all kinds of atomic sources. This splitting scheme can be extended to 4N(Planck constant/2pi)k momentum transfer by a multipulse sequence and is implemented on a 8(Planck constant/2pi)k interferometer. We demonstrate the area enhancement by measuring inertial forces.

Phase equilibria in the NaF-CdO-NaPO{sub 3} system at 873 K and crystal structure and physico-chemical characterizations of the new Na{sub 2}CdPO{sub 4}F fluorophosphate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aboussatar, Mohamed; Laboratoire de Physico-Chimie de l’État Solide, Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000 Sfax; Mbarek, Aïcha

Isothermal sections of the diagram representing phase relationships in the NaF-CdO-NaPO{sub 3} system have been investigated by solid state reactions and powder X-ray diffraction. This phase diagram investigation confirms the polymorphism of the NaCdPO{sub 4} side component and the structure of the ß high temperature polymorph (orthorhombic, space group Pnma and unit cell parameters a=9.3118(2), b=7.0459(1), c=5.1849(1) Å has been refined. A new fluorophosphate, Na{sub 2}CdPO{sub 4}F, has been discovered and its crystal structure determined and refined from powder X-ray diffraction data. It exhibits a new 3D structure with orthorhombic symmetry, space group Pnma and unit cell parameters a=5.3731(1), b=6.8530(1),more » c=12.2691(2) Å. The structure is closely related to those of the high temperature polymorph of the nacaphite Na{sub 2}CaPO{sub 4}F and the fluorosilicate Ca{sub 2}NaSiO{sub 4}F but differs essentially in the cationic repartition since the structure is fully ordered with one Na site (8d) and one Cd site (4c). Relationships with other Na{sub 2}M{sup II}PO{sub 4}F (M{sup II}=Mg, Ca, Mn, Fe, Co, Ni) have been examined and the crystal-chemical and topographical analysis of these fluorophosphates is briefly reviewed. IR, Raman, optical and {sup 19}F, {sup 23}Na, {sup 31}P MAS NMR characterizations of Na{sub 2}CdPO{sub 4}F have been investigated. - Graphical abstract: The structure of the compound Na{sub 2}CdPO{sub 4}F, discovered during the study of the phase relationships in the NaF-CdO-NaPO{sub 3} system, has been determined and compared with other Na{sub 2}M{sup II}PO{sub 4}F fluorophosphates. - Highlights: • XRD analysis of the isothermal section of the NaF-CdO-NaPO{sub 3} system at 923 K. • Rietveld refinement of the high temperature polymorph β-NaCdPO{sub 4}. • Crystal structure of the new Na{sub 2}CdPO{sub 4}F fluorophosphate determined from powder XRD. • Crystal structure - composition relationships of Na{sub 2}M{sup II}PO{sub 4}F compounds are reviewed. • IR, Raman, optical and {sup 19}F, {sup 23}Na, {sup 31}P MAS NMR characterizations of Na{sub 2}CdPO{sub 4}F.« less

Detecting multiple adulterants in dry milk using Raman chemical imaging

USDA-ARS?s Scientific Manuscript database

A Raman chemical imaging method was developed for detecting the presence of multiple chemical adulterants in dry milk powder. Four chemicals (ammonium sulfate, dicyandiamide, melamine, and urea) were added in equal concentrations, between 0.1% and 5.0%, to nonfat dry milk. An area of 25×25 mm2 for e...

Depth of penetration of a 785nm laser for Raman spectral measurement in food powders.

USDA-ARS?s Scientific Manuscript database

Raman spectroscopy is a useful, rapid, and non-destructive method for both qualitative and quantitative evaluation of chemical composition. However it is important to measure the depth of penetration of the laser light to ensure that chemical particles at the very bottom of a sample volume are detec...

A parameter selection for Raman spectroscopy-based detection of chemical contaminants in food powders

USDA-ARS?s Scientific Manuscript database

Raman spectroscopy technique has proven to be a reliable method for detection of chemical contaminants in food ingredients and products. To detect each contaminant particle in a food sample, it is important to determine the effective depth of penetration of laser through the food sample and the corr...

Vibrational modes in thymine molecule from an ab initio MO calculation

NASA Astrophysics Data System (ADS)

Aida, Misako; Kaneko, Motohisa; Dupuis, Michel; Ueda, Toyotoshi; Ushizawa, Koichi; Ito, Gen; Kumakura, Akiko; Tsuboi, Masamichi

1997-03-01

Ab initio self-consistent field molecular orbital (SCF MO) calculations have been made of the thymine molecule for the equilibrium geometry, harmonic force constants, vibrational frequencies, vibrational modes, infrared intensities, and Raman intensities. The results have been correlated with the observed Raman and infrared spectra of thymine crystalline powder.

Near-Ir surface-enhanced Raman spectrum of lignin

Treesearch

Umesh P. Agarwal; Richard S. Reiner

2009-01-01

Compacted powders of commercially available nano- and microparticles of silver were used to successfully induce the surface enhanced Raman scattering (SERS) effect in spruce milled-wood lignin (MWL). For the two silver particle sizes used in this investigation, the spectra were mostly similar. Some general characteristics of the lignin SERS spectrum are described. The...

Diffraction-controlled backscattering threshold and application to Raman gap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rose, Harvey A.; Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87544; Mounaix, Philippe

2011-04-15

In most classic analytical models of linear stimulated scatter, light diffraction is omitted, a priori. However, modern laser optic typically includes a variant of the random phase plate [Y. Kato et al., Phys. Rev. Lett. 53, 1057 (1984)], resulting in diffraction limited laser intensity fluctuations - or localized speckles - which may result in explosive reflectivity growth as the average laser intensity approaches a critical value [H. A. Rose and D. F. DuBois, Phys. Rev. Lett. 72, 2883 (1994)]. Among the differences between stimulated Raman scatter (SRS) and stimulated Brillouin scatter is that the SRS scattered light diffracts more stronglymore » than the laser light with increase of electron density. This weakens the tendency of the SRS light to closely follow the most amplified paths, diminishing gain. Let G{sub 0} be the one-dimensional power gain exponent of the stimulated scatter. In this paper we show that differential diffraction gives rise to an increase of G{sub 0} at the SRS physical threshold with increase of electron density up to a drastic disruption of SRS as electron density approaches one fourth of its critical value from below. For three wave interaction lengths not small compared to a speckle length, this is a physically robust Raman gap mechanism.« less

An Inquiry-Based Project Focused on the X-Ray Powder Diffraction Analysis of Common Household Solids

ERIC Educational Resources Information Center

Hulien, Molly L.; Lekse, Jonathan W.; Rosmus, Kimberly A.; Devlin, Kasey P.; Glenn, Jennifer R.; Wisneski, Stephen D.; Wildfong, Peter; Lake, Charles H.; MacNeil, Joseph H.; Aitken, Jennifer A.

2015-01-01

While X-ray powder diffraction (XRPD) is a fundamental analytical technique used by solid-state laboratories across a breadth of disciplines, it is still underrepresented in most undergraduate curricula. In this work, we incorporate XRPD analysis into an inquiry-based project that requires students to identify the crystalline component(s) of…

Using Variable Temperature Powder X-Ray Diffraction to Determine the Thermal Expansion Coefficient of Solid MgO

ERIC Educational Resources Information Center

Corsepius, Nicholas C.; DeVore, Thomas C.; Reisner, Barbara A.; Warnaar, Deborah L.

2007-01-01

A laboratory exercise was developed by using variable temperature powder X-ray diffraction (XRD) to determine [alpha] for MgO (periclase)and was tested in the Applied Physical Chemistry and Materials Characterization Laboratories at James Madison University. The experiment which was originally designed to provide undergraduate students with a…

Analysis of macromolecules, ligands and macromolecule-ligand complexes

DOEpatents

Von Dreele, Robert B [Los Alamos, NM

2008-12-23

A method for determining atomic level structures of macromolecule-ligand complexes through high-resolution powder diffraction analysis and a method for providing suitable microcrystalline powder for diffraction analysis are provided. In one embodiment, powder diffraction data is collected from samples of polycrystalline macromolecule and macromolecule-ligand complex and the refined structure of the macromolecule is used as an approximate model for a combined Rietveld and stereochemical restraint refinement of the macromolecule-ligand complex. A difference Fourier map is calculated and the ligand position and points of interaction between the atoms of the macromolecule and the atoms of the ligand can be deduced and visualized. A suitable polycrystalline sample of macromolecule-ligand complex can be produced by physically agitating a mixture of lyophilized macromolecule, ligand and a solvent.

Design, physicochemical characterization, and optimization of organic solution advanced spray-dried inhalable dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylethanolamine poly(ethylene glycol) (DPPE-PEG) microparticles and nanoparticles for targeted respiratory nanomedicine delivery as dry powder inhalation aerosols

PubMed Central

Meenach, Samantha A; Vogt, Frederick G; Anderson, Kimberly W; Hilt, J Zach; McGarry, Ronald C; Mansour, Heidi M

2013-01-01

Novel advanced spray-dried and co-spray-dried inhalable lung surfactant-mimic phospholipid and poly(ethylene glycol) (PEG)ylated lipopolymers as microparticulate/nanoparticulate dry powders of biodegradable biocompatible lipopolymers were rationally formulated via an organic solution advanced spray-drying process in closed mode using various phospholipid formulations and rationally chosen spray-drying pump rates. Ratios of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylethanolamine PEG (DPPE-PEG) with varying PEG lengths were mixed in a dilute methanol solution. Scanning electron microscopy images showed the smooth, spherical particle morphology of the inhalable particles. The size of the particles was statistically analyzed using the scanning electron micrographs and SigmaScan® software and were determined to be 600 nm to 1.2 μm in diameter, which is optimal for deep-lung alveolar penetration. Differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) were performed to analyze solid-state transitions and long-range molecular order, respectively, and allowed for the confirmation of the presence of phospholipid bilayers in the solid state of the particles. The residual water content of the particles was very low, as quantified analytically via Karl Fischer titration. The composition of the particles was confirmed using attenuated total-reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy and confocal Raman microscopy (CRM), and chemical imaging confirmed the chemical homogeneity of the particles. The dry powder aerosol dispersion properties were evaluated using the Next Generation Impactor™ (NGI™) coupled with the HandiHaler® dry powder inhaler device, where the mass median aerodynamic diameter from 2.6 to 4.3 μm with excellent aerosol dispersion performance, as exemplified by high values of emitted dose, fine particle fraction, and respirable fraction. Overall, it was determined that the pump rates defined in the spray-drying process had a significant effect on the solid-state particle properties and that a higher pump rate produced the most optimal system. Advanced dry powder inhalers of inhalable lipopolymers for targeted dry powder inhalation delivery were successfully achieved. PMID:23355776

Raman and dielectric studies of GdMnO3 bulk ceramics synthesized from nano powders

NASA Astrophysics Data System (ADS)

Samantaray, S.; Mishra, D. K.; Roul, B. K.

2017-05-01

Nanocrystalline GdMnO3 (GMO) powders has been synthesized by a simple chemical route i. e. pyrophoric reaction technique and then sintered in the form of bulk pellet at 850°C for 24 hours by adopting slow step sintering schedule. It is observed that by reducing the particles size, chemical route enhances the mixing process as well as decreasing the sintering temperature to get single phase material system in compared to the polycrystalline sample prepared directly from the micron sized commercial powder. Raman spectroscopic studies confirm that the sample is in single phase without any detectable impurity. Frequency dependent dielectric properties i.e., dielectric constant (K) and dielectric loss (tanδ) of GMO ceramics sintered at 850°C for 24 hours were studied at room temperature. The sample showed high K value (˜2736) in the frequency of 100 Hz at room temperature.

High-pressure behavior of CaMo O4

NASA Astrophysics Data System (ADS)

Panchal, V.; Garg, N.; Poswal, H. K.; Errandonea, D.; Rodríguez-Hernández, P.; Muñoz, A.; Cavalli, E.

2017-09-01

We report a high-pressure study of tetragonal scheelite-type CaMo O4 up to 29 GPa. In order to characterize its high-pressure behavior, we have combined Raman and optical-absorption measurements with density functional theory calculations. We have found evidence of a pressure-induced phase transition near 15 GPa. Experiments and calculations agree in assigning the high-pressure phase to a monoclinic fergusonite-type structure. The reported results are consistent with previous powder x-ray-diffraction experiments, but are in contradiction with the conclusions obtained from earlier Raman measurements, which support the existence of more than one phase transition in the pressure range covered by our studies. The observed scheelite-fergusonite transition induces significant changes in the electronic band gap and phonon spectrum of CaMo O4 . We have determined the pressure evolution of the band gap for the low- and high-pressure phases as well as the frequencies and pressure dependencies of the Raman-active and infrared-active modes. In addition, based on calculations of the phonon dispersion of the scheelite phase, carried out at a pressure higher than the transition pressure, we propose a possible mechanism for the reported phase transition. Furthermore, from the calculations we determined the pressure dependence of the unit-cell parameters and atomic positions of the different phases and their room-temperature equations of state. These results are compared with previous experiments showing a very good agreement. Finally, information on bond compressibility is reported and correlated with the macroscopic compressibility of CaMo O4 . The reported results are of interest for the many technological applications of this oxide.

Study the chemical composition and biological outcomes resulting from the interaction of the hormone adrenaline with heavy elements: Infrared, Raman, electronic, 1H NMR, XRD and SEM studies

NASA Astrophysics Data System (ADS)

Ibrahim, Omar B.; Mohamed, Mahmoud A.; Refat, Moamen S.

2014-01-01

Heavy metal adrenaline complexes formed from the reaction of adrenaline with Al3+, Zn2+, Sn2+, Sb3+, Pb2+and Bi3+ ions in methanolic solvent at 60 °C. The final reaction products have been isolated and characterization using elemental analyses (% of carbon, hydrogen and nitrogen), conductivity measurements, mid infrared, Raman laser, UV-Vis, 1H NMR spectra, X-ray powder diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDX). Upon the spectroscopic, conductivity and elemental analyses, the stoichiometric reactions indicated that the data obtained refer to 1:2 (M:L) for Zn2+, Sn2+, Pb2+and Bi3+ complexes [Zn(Adr)2(Cl)2], [Sn(Adr)2]Cl2, [Pb(Adr)2](NO3)2 and [Bi(Adr)2(Cl)2]Cl, while the molar ratio 1:3 (M:L) for Al3+ and Sb3+ with formulas [Al(Adr)3](NO3)3 and [Sb(Adr)3]Cl3. The infrared and Raman laser spectra interpreted the mode of interactions which associated through the two phenolic groups of catechol moiety. The adrenaline chelates have been screened for their in vitro antibacterial activity against four bacteria, Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and two strains of fungus (Aspergillus flavus and Candida albicans). The metal chelates were shown to possess more antibacterial and antifungal activities than the free adrenaline chelate.

Structural and spectroscopic study of mechanically synthesized SnO2 nanostructures

NASA Astrophysics Data System (ADS)

Vij, Ankush; Kumar, Ravi

2016-05-01

We report the single step synthesis of SnO2 nanostructures using high energy mechanical attrition method. X-ray diffraction (XRD) pattern reveals the single phase rutile structure with appreciable broadening of diffraction peaks, which is a signature of nanostructure formation. The average crystallite size of SnO2 nanostructures has been calculated to be ~15 nm. The micro-Raman study reveals the shifting of A1g Raman mode towards lower wave number, which is correlated with the nanostructure formation.

Synthesis and Characterization of Yttria-Stabilized Zirconia Nanoparticles Doped with Ytterbium and Gadolinium: ZrO2 9.5Y2O3 5.6Yb2O3 5.2Gd2O3

NASA Astrophysics Data System (ADS)

Bahamirian, M.; Hadavi, S. M. M.; Rahimipour, M. R.; Farvizi, M.; Keyvani, A.

2018-06-01

Defect cluster thermal barrier coatings (TBCs) are attractive alternatives to Yttria-stabilized zirconia (YSZ) in advanced applications. In this study, YSZ nanoparticles doped with ytterbium and gadolinium (ZrO2 9.5Y2O3 5.6Yb2O3 5.2Gd2O3 (ZGYbY)) were synthesized through a chemical co-precipitation and calcination method, and characterized by in situ high-temperature X-ray diffraction analysis in the temperature range of 25 °C to 1000 °C (HTK-XRD), thermogravimetric analysis, differential thermal analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, and field emission scanning electron microscopy (FE-SEM). Precise cell parameters of t-prime phase and the best zirconia phase for TBC applications were calculated by Cohen's and Rietveld refinement methods. Optimum crystallization temperature of the precursor powder was found to be 1000 °C. Furthermore, FE-SEM results for the calcined ZGYbY powders indicated orderly particles of uniform shape and size with a small tendency toward agglomeration. Average lattice thermal expansion coefficient in the temperature range of 25 °C to 1000 °C was determined to be 31.71 × 10-6 K-1.

Synthesis and Characterization of Yttria-Stabilized Zirconia Nanoparticles Doped with Ytterbium and Gadolinium: ZrO2 9.5Y2O3 5.6Yb2O3 5.2Gd2O3

NASA Astrophysics Data System (ADS)

Bahamirian, M.; Hadavi, S. M. M.; Rahimipour, M. R.; Farvizi, M.; Keyvani, A.

2018-03-01

Defect cluster thermal barrier coatings (TBCs) are attractive alternatives to Yttria-stabilized zirconia (YSZ) in advanced applications. In this study, YSZ nanoparticles doped with ytterbium and gadolinium (ZrO2 9.5Y2O3 5.6Yb2O3 5.2Gd2O3 (ZGYbY)) were synthesized through a chemical co-precipitation and calcination method, and characterized by in situ high-temperature X-ray diffraction analysis in the temperature range of 25 °C to 1000 °C (HTK-XRD), thermogravimetric analysis, differential thermal analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, and field emission scanning electron microscopy (FE-SEM). Precise cell parameters of t-prime phase and the best zirconia phase for TBC applications were calculated by Cohen's and Rietveld refinement methods. Optimum crystallization temperature of the precursor powder was found to be 1000 °C. Furthermore, FE-SEM results for the calcined ZGYbY powders indicated orderly particles of uniform shape and size with a small tendency toward agglomeration. Average lattice thermal expansion coefficient in the temperature range of 25 °C to 1000 °C was determined to be 31.71 × 10-6 K-1.

Microwave-assisted synthesis of iron oxide nanoparticles in biocompatible organic environment

NASA Astrophysics Data System (ADS)

Aivazoglou, E.; Metaxa, E.; Hristoforou, E.

2018-04-01

The development of magnetite and maghemite particles in uniform nanometer size has triggered the interest of the research community due to their many interesting properties leading to a wide range of applications, such as catalysis, nanomedicine-nanobiology and other engineering applications. In this study, a simple, time-saving and low energy-consuming, microwave-assisted synthesis of iron oxide nanoparticles, is presented. The nanoparticles were prepared by microwave-assisted synthesis using polyethylene glycol (PEG) or PEG and β-cyclodextrin (β-CD)/water solutions of chloride salts of iron in the presence of ammonia solution. The prepared nano-powders were characterized using X-Ray Diffraction (XRD), Transition Electron Microscopy (TEM), Fourier-transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, Vibrating Sample Magnetometer (VSM), X-Ray Photoelectron Spectroscopy (XPS) and Thermal analysis (TG/DSC). The produced nanoparticles are crystallized mostly in the magnetite and maghemite lattice exhibiting very similar shape and size, with indications of partial PEG coating. Heating time, microwave power and presence of PEG, are the key factors shaping the size properties of nanoparticles. The average size of particles ranges from 10.3 to 19.2 nm. The nanoparticles exhibit a faceted morphology, with zero contamination levels. The magnetic measurements indicate that the powders are soft magnetic materials with negligible coercivity and remanence, illustrating super-paramagnetic behavior.

Compressibility of Cs2SnBr6 by X-ray diffraction and Raman spectroscopy

NASA Astrophysics Data System (ADS)

Yuan, Guan; Huang, Shengxuan; Niu, Jingjing; Qin, Shan; Wu, Xiang; Ding, Hongrui; Lu, Anhuai

2018-07-01

Cs2SnBr6, one promising material applied in perovskite solar cells, has been investigated up to 20 GPa by synchrotron X-ray diffraction and Raman spectroscopy. Both experimental data demonstrate that no phase transition occurs up to 20 GPa. By fitting the third-order Birch-Murnaghan equation of state, we have obtained V0 = 1288 (14) Å3, K0 = 11 (1) GPa and K0‧ = 7 (1). The ultralow value of bulk modulus K0 demonstrates the soft nature of Cs2SnBr6. Combining calculated values with experimental results, we find that x coordinate of Sn (x,0,0) atoms increases and Snsbnd Br bond lengths get shortened on compression. We have assigned vibrational peaks of Cs2SnBr6 in Raman measurements, and all the three Raman bands present nonlinear correlations with pressure.

Raman spectroscopy as a PAT for pharmaceutical blending: Advantages and disadvantages.

PubMed

Riolo, Daniela; Piazza, Alessandro; Cottini, Ciro; Serafini, Margherita; Lutero, Emilio; Cuoghi, Erika; Gasparini, Lorena; Botturi, Debora; Marino, Iari Gabriel; Aliatis, Irene; Bersani, Danilo; Lottici, Pier Paolo

2018-02-05

Raman spectroscopy has been positively evaluated as a tool for the in-line and real-time monitoring of powder blending processes and it has been proved to be effective in the determination of the endpoint of the mixing, showing its potential role as process analytical technology (PAT). The aim of this study is to show advantages and disadvantages of Raman spectroscopy with respect to the most traditional HPLC analysis. The spectroscopic results, obtained directly on raw powders, sampled from a two-axis blender in real case conditions, were compared with the chromatographic data obtained on the same samples. The formulation blend used for the experiment consists of active pharmaceutical ingredient (API, concentrations 6.0% and 0.5%), lactose and magnesium stearate (as excipients). The first step of the monitoring process was selecting the appropriate wavenumber region where the Raman signal of API is maximal and interference from the spectral features of excipients is minimal. Blend profiles were created by plotting the area ratios of the Raman peak of API (A API ) at 1598cm -1 and the Raman bands of excipients (A EXC ), in the spectral range between 1560 and 1630cm -1 , as a function of mixing time: the API content can be considered homogeneous when the time-dependent dispersion of the area ratio is minimized. In order to achieve a representative sampling with Raman spectroscopy, each sample was mapped in a motorized XY stage by a defocused laser beam of a micro-Raman apparatus. Good correlation between the two techniques has been found only for the composition at 6.0% (w/w). However, standard deviation analysis, applied to both HPLC and Raman data, showed that Raman results are more substantial than HPLC ones, since Raman spectroscopy enables generating data rich blend profiles. In addition, the relative standard deviation calculated from a single map (30 points) turned out to be representative of the degree of homogeneity for that blend time. Copyright © 2017 Elsevier B.V. All rights reserved.

Application of Powder Diffraction Methods to the Analysis of the Atomic Structure of Nanocrystals: The Concept of the Apparent Lattice Parameter (ALP)

NASA Technical Reports Server (NTRS)

Palosz, B.; Grzanka, E.; Gierlotka, S.; Stelmakh, S.; Pielaszek, R.; Bismayer, U.; Weber, H.-P.; Palosz, W.; Curreri, Peter A. (Technical Monitor)

2002-01-01

The applicability of standard methods of elaboration of powder diffraction data for determination of the structure of nano-size crystallites is analysed. Based on our theoretical calculations of powder diffraction data we show, that the assumption of the infinite crystal lattice for nanocrystals smaller than 20 nm in size is not justified. Application of conventional tools developed for elaboration of powder diffraction data, like the Rietveld method, may lead to erroneous interpretation of the experimental results. An alternate evaluation of diffraction data of nanoparticles, based on the so-called 'apparent lattice parameter' (alp) is introduced. We assume a model of nanocrystal having a grain core with well-defined crystal structure, surrounded by a surface shell with the atomic structure similar to that of the core but being under a strain (compressive or tensile). The two structural components, the core and the shell, form essentially a composite crystal with interfering, inseparable diffraction properties. Because the structure of such a nanocrystal is not uniform, it defies the basic definitions of an unambiguous crystallographic phase. Consequently, a set of lattice parameters used for characterization of simple crystal phases is insufficient for a proper description of the complex structure of nanocrystals. We developed a method of evaluation of powder diffraction data of nanocrystals, which refers to a core-shell model and is based on the 'apparent lattice parameter' methodology. For a given diffraction pattem, the alp values are calculated for every individual Bragg reflection. For nanocrystals the alp values depend on the diffraction vector Q. By modeling different a0tomic structures of nanocrystals and calculating theoretically corresponding diffraction patterns using the Debye functions we showed, that alp-Q plots show characteristic shapes which can be used for evaluation of the atomic structure of the core-shell system. We show, that using a simple model of a nanocrystal with spherical shape and centro-symmetric strain at the surface shell we obtain theoretical alp-Q values which match very well the alp-Q plots determined experimentally for Sic, GaN, and diamond nanopowders. The theoretical models are defined by the lattice parameter of the grain core, thickness of the surface shell, and the magnitude and distribution of the strain field in the surface shell. According to our calculations, the part of the diffraction pattern measured at relatively low diffraction vectors Q (below 10/angstrom) provides information on the surface strain, whle determination of the lattice parameters in the grain core requires measurements at large Q-values (above 15 - 20/angstrom).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frølich, S.; Leemreize, H.; Jakus, A.

A model sample consisting of two different hydroxyapatite (hAp) powders was used as a bone phantom to investigate the extent to which X-ray diffraction tomography could map differences in hAp lattice constants and crystallite size. The diffraction data were collected at beamline 1-ID, the Advanced Photon Source, using monochromatic 65 keV X-radiation, a 25 × 25 µm pinhole beam and translation/rotation data collection. The diffraction pattern was reconstructed for each volume element (voxel) in the sample, and Rietveld refinement was used to determine the hAp lattice constants. The crystallite size for each voxel was also determined from the 00.2 hApmore » diffraction peak width. The results clearly show that differences between hAp powders could be measured with diffraction tomography.« less

Crystallinity and compositional changes in carbonated apatites: Evidence from 31P solid-state NMR, Raman, and AFM analysis

NASA Astrophysics Data System (ADS)

McElderry, John-David P.; Zhu, Peizhi; Mroue, Kamal H.; Xu, Jiadi; Pavan, Barbara; Fang, Ming; Zhao, Guisheng; McNerny, Erin; Kohn, David H.; Franceschi, Renny T.; Holl, Mark M. Banaszak; Tecklenburg, Mary M. J.; Ramamoorthy, Ayyalusamy; Morris, Michael D.

2013-10-01

Solid-state (magic-angle spinning) NMR spectroscopy is a useful tool for obtaining structural information on bone organic and mineral components and synthetic model minerals at the atomic-level. Raman and 31P NMR spectral parameters were investigated in a series of synthetic B-type carbonated apatites (CAps). Inverse 31P NMR linewidth and inverse Raman PO43-ν1 bandwidth were both correlated with powder XRD c-axis crystallinity over the 0.3-10.3 wt% CO32- range investigated. Comparison with bone powder crystallinities showed agreement with values predicted by NMR and Raman calibration curves. Carbonate content was divided into two domains by the 31P NMR chemical shift frequency and the Raman phosphate ν1 band position. These parameters remain stable except for an abrupt transition at 6.5 wt% carbonate, a composition which corresponds to an average of one carbonate per unit cell. This near-binary distribution of spectroscopic properties was also found in AFM-measured particle sizes and Ca/P molar ratios by elemental analysis. We propose that this transition differentiates between two charge-balancing ion-loss mechanisms as measured by Ca/P ratios. These results define a criterion for spectroscopic characterization of B-type carbonate substitution in apatitic minerals.

Structured illumination for wide-field Raman imaging of cell membranes

NASA Astrophysics Data System (ADS)

Chen, Houkai; Wang, Siqi; Zhang, Yuquan; Yang, Yong; Fang, Hui; Zhu, Siwei; Yuan, Xiaocong

2017-11-01

Although the diffraction limit still restricts their lateral resolution, conventional wide-field Raman imaging techniques offer fast imaging speeds compared with scanning schemes. To extend the lateral resolution of wide-field Raman microscopy using filters, standing-wave illumination technique is used, and an improvement of lateral resolution by a factor of more than two is achieved. Specifically, functionalized surface enhanced Raman scattering nanoparticles are employed to strengthen the desired scattering signals to label cell membranes. This wide-field Raman imaging technique affords various significant opportunities in the biological applications.

Entrainment of lactose inhalation powders: a study using laser diffraction.

PubMed

Watling, C P; Elliott, J A; Cameron, R E

2010-07-11

We have investigated the mechanism of entrainment of lactose inhalation blends released from a dry powder inhaler using a diffraction particle size analyser (Malvern Spraytec). Whether a powder blend entrains as a constant stream of powder (the "erosion" mechanism) or as a few coarse plugs (the "fracture" mechanism) was found by comparing transmission data with particle size information. This technique was then applied to a lactose grade with 0, 5 and 10wt% added fine particles. As the wt% fines increased, the entrainment mechanism was found to change from a mild fracture, consisting of multiple small plugs, to more severe fracture with fewer plugs. The most severe fracture mechanism consisted of either the powder reservoir emptying as a single plug, or of the reservoir emptying after a delay of the order of 0.1s due to the powder sticking to its surroundings. Further to this, three different inhalation grades were compared, and the severity of the fracture was found to be inversely proportional to the flowability of the powder (measured using an annular ring shear tester). By considering the volume of aerosolised fine particles in different blends it was determined that the greater the volume of fines added to a powder, the smaller the fraction of fines that were aerosolised. This was attributed to different behaviour when fines disperse from carrier particles compared with when they disperse from agglomerates of fines. In summary, this paper demonstrates how laser diffraction can provide a more detailed analysis of an inhalation powder than just its size distribution. 2010. Published by Elsevier B.V. All rights reserved.

Real-time powder diffraction studies of energy materials under non-equilibrium conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peterson, Vanessa K.; Auckett, Josie E.; Pang, Wei-Kong

Energy materials form the central part of energy devices. An essential part of their function is the ability to reversibly host charge or energy carriers, and analysis of their phase composition and structure in real time under non-equilibrium conditions is mandatory for a full understanding of their atomic-scale functional mechanism. Real-time powder diffraction is increasingly being applied for this purpose, forming a critical step in the strategic chemical engineering of materials with improved behaviour. This topical review gives examples of real-time analysis using powder diffraction of rechargeable battery electrodes and porous sorbent materials used for the separation and storage ofmore » energy-relevant gases to demonstrate advances in the insights which can be gained into their atomic-scale function.« less

Real-time powder diffraction studies of energy materials under non-equilibrium conditions

PubMed Central

Peterson, Vanessa K.; Auckett, Josie E.; Pang, Wei-Kong

2017-01-01

Energy materials form the central part of energy devices. An essential part of their function is the ability to reversibly host charge or energy carriers, and analysis of their phase composition and structure in real time under non-equilibrium conditions is mandatory for a full understanding of their atomic-scale functional mechanism. Real-time powder diffraction is increasingly being applied for this purpose, forming a critical step in the strategic chemical engineering of materials with improved behaviour. This topical review gives examples of real-time analysis using powder diffraction of rechargeable battery electrodes and porous sorbent materials used for the separation and storage of energy-relevant gases to demonstrate advances in the insights which can be gained into their atomic-scale function. PMID:28989711

Structural phase transition in d-benzil characterised by capacitance measurements and neutron powder diffraction

NASA Astrophysics Data System (ADS)

Goossens, D. J.; Wu, Xiaodong; Prior, M.

2005-12-01

The ferroelectric phase transition in deuterated benzil, C 14H 10O 2, has been studied using capacitance measurements and neutron powder diffraction. Hydrogenous benzil shows a phase transition at 83.5 K from a high temperature P3 121 phase to a cell-doubled P2 1 phase. The phase transition in d-benzil occurs at 88.1 K, a small isotope effect. Neutron powder diffraction was consistent with a low temperature phase of space group P2 1. Upon deuteration the transition remained first-order and the dynamics of the phenyl ring dominated the behaviour. The isotope effect can be attributed to the difference in mass and moment of inertia between C 6H 5 and C 6D 5.

Synthesis and characterization of Mn-Bi alloy

NASA Astrophysics Data System (ADS)

Mishra, Ashutosh; Patil, Harsha; Jain, G.; Mishra, N.

2012-06-01

High purity MnBi low temperature phase has been prepared and analyzed using X-ray diffraction, Lorentz-Polarization Factor and Fourier transforms infrared measurement. After synthesis of samples structural characterization has done on samples by X-ray diffraction, which shows that after making the bulk sample is in no single phase MnBi has been prepared by sintering Mn and Bi powders. By Lorentz-Polarization Factor is affecting the relative intensity of diffraction lines on a powder form. And by FTIR which shows absorption peaks of MnBi alloys.

Room Temperature Ferromagnetism of Fe Doped Indium Tin Oxide Based on Dispersed Fe3O4 Nanoparticles

NASA Astrophysics Data System (ADS)

Okada, Koichi; Kohiki, Shigemi; Nishi, Sachio; Shimooka, Hirokazu; Deguchi, Hiroyuki; Mitome, Masanori; Bando, Yoshio; Shishido, Toetsu

2007-09-01

Transmission electron microscopy revealed that Fe3O4 nanoparticles with diameter of ≈200 nm dispersed in Fe doped indium tin oxide (Fe@ITO) powders exhibiting co-occurrence of room temperature ferromagnetism and superparamagnetism. Although we observed no X-ray diffraction peak from Fe related compounds for Fe0.19@ITO (ITO: In1.9Sn0.1O3) powders, the powders showed both hysteresis loop in field dependent magnetization at 300 K and divergence of zero-field-cooled magnetization from field-cooled magnetization. Scanning transmission electron microscopy with energy dispersive X-ray spectroscopy demonstrated that the nanoparticle with diameter of ≈200 nm consists of Fe and oxygen. Transmission electron diffraction revealed that crystal structure of the nanoparticle is inverse spinel type Fe3O4. The Fe3O4 crystalline phase by electron diffraction is consistent with the saturation magnetization of 1.3 μB/Fe and magnetic anomaly at ≈110 K observed for the powders.

Miniature Spatial Heterodyne Raman Spectrometer with a Cell Phone Camera Detector.

PubMed

Barnett, Patrick D; Angel, S Michael

2017-05-01

A spatial heterodyne Raman spectrometer (SHRS) with millimeter-sized optics has been coupled with a standard cell phone camera as a detector for Raman measurements. The SHRS is a dispersive-based interferometer with no moving parts and the design is amenable to miniaturization while maintaining high resolution and large spectral range. In this paper, a SHRS with 2.5 mm diffraction gratings has been developed with 17.5 cm -1 theoretical spectral resolution. The footprint of the SHRS is orders of magnitude smaller than the footprint of charge-coupled device (CCD) detectors typically employed in Raman spectrometers, thus smaller detectors are being explored to shrink the entire spectrometer package. This paper describes the performance of a SHRS with 2.5 mm wide diffraction gratings and a cell phone camera detector, using only the cell phone's built-in optics to couple the output of the SHRS to the sensor. Raman spectra of a variety of samples measured with the cell phone are compared to measurements made using the same miniature SHRS with high-quality imaging optics and a high-quality, scientific-grade, thermoelectrically cooled CCD.

Combined synchrotron X-ray tomography and X-ray powder diffraction using a fluorescing metal foil.

PubMed

Kappen, P; Arhatari, B D; Luu, M B; Balaur, E; Caradoc-Davies, T

2013-06-01

This study realizes the concept of simultaneous micro-X-ray computed tomography and X-ray powder diffraction using a synchrotron beamline. A thin zinc metal foil was placed in the primary, monochromatic synchrotron beam to generate a divergent wave to propagate through the samples of interest onto a CCD detector for tomographic imaging, thus removing the need for large beam illumination and high spatial resolution detection. Both low density materials (kapton tubing and a piece of plant) and higher density materials (Egyptian faience) were investigated, and elemental contrast was explored for the example of Cu and Ni meshes. The viability of parallel powder diffraction using the direct beam transmitted through the foil was demonstrated. The outcomes of this study enable further development of the technique towards in situ tomography∕diffraction studies combining micrometer and crystallographic length scales, and towards elemental contrast imaging and reconstruction methods using well defined fluorescence outputs from combinations of known fluorescence targets (elements).

Structural and Spectral Characterization of Co2+- and Ni2+-DOPED CdO Powder Prepared From Solution at Room Temperature

NASA Astrophysics Data System (ADS)

Reddy, C. V.; Rao, L. V. Krishna; Satish, D. V.; Shim, J.; Ravikumar, R. V. S. S. N.

2015-11-01

The mild and simple solution method was used for the synthesis of Co2+- and Ni2+-doped CdO powders at room temperature. The prepared powders were characterized using powder X-ray diffraction, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), optical absorption, and Fourier transform infrared spectroscopy (FTIR). From the powder X-ray diffraction patterns, it has been observed that the prepared Co2+ and Ni2+ ion-doped CdO powders belong to the cubic phase, and the evaluated average crystalline sizes of the powders are 20 and 14 nm, respectively. The SEM images and the EDS spectra show that the prepared powders are distributed over different sizes in the grain boundaries. Optical absorption studies allow determination of site symmetry of the metal ion with its ligands. The crystal field (Dq) and inter-electronic repulsion (B and C) parameters have been evaluated from the optical absorption spectra. The FTIR spectra show the characteristic fundamental vibrations of the metal oxide and CdO.

The adsorption of cationic and amphoteric copolymers on glass surfaces: zeta potential measurements, adsorption isotherm determination, and FT Raman characterization.

PubMed

Tartakovsky, Alla; Drutis, Dane M; Carnali, Joseph O

2003-07-15

The adsorption of cationic and amphoteric copolymers onto controlled pore glass (CPG) powders has been studied by measurement of the powder particle zeta (zeta) potential, by determination of the adsorption isotherm, and by FT Raman measurements of the polymer-coated powder. The cationic polymers consisted chiefly of homopolymers of dimethyldiallylammonium chloride (DMDAAC) or copolymers of DMDAAC and acrylamide. The amphoteric polymers studied included copolymers of DMDAAC and acrylic acid. The comonomer ratio was varied to explore the dependence of cationic charge density on the extent and effect of adsorption. Both types of polymers adsorb onto the anionic glass surface via an ion-exchange mechanism. Consequently, a correspondingly higher mass of a low-charge-density copolymer adsorbs than of a cationic homopolymer. The presence of the anionic portion in the amphoteric polymers does not significantly alter this picture. The zeta potential, however, reflects the overall nature of the polymer. Cationic polymers effectively neutralize the glass surface, while amphoteric polymers leave the zeta potential net negative. Adsorption isotherms, determined via the depletion technique using colloidal titration, were used to "calibrate" a FT Raman method. The latter was used to determined the amount of adsorbed polymer under solution conditions in which colloidal titration could not be performed.

The Miniaturized Raman System and Detection of Traces of Life in Halite from the Atacama Desert: Some Considerations for the Search for Life Signatures on Mars

PubMed Central

Jehlička, Jan; Edwards, Howell G.M.; Hutchinson, Ian; Ascaso, Carmen; Wierzchos, Jacek

2012-01-01

Abstract Raman spectroscopy is being adopted as a nondestructive instrumentation for the robotic exploration of Mars to search for traces of life in the geological record. Here, miniaturized Raman spectrometers of two different types equipped with 532 and 785 nm lasers for excitation, respectively, were compared for the detection of microbial biomarkers in natural halite from the hyperarid region of the Atacama Desert. Measurements were performed directly on the rock as well as on the homogenized, powdered samples prepared from this material—the effects of this sample preparation and the excitation wavelength employed in the analysis are compared and discussed. From these results, 532 nm excitation was found to be superior for the analysis of powdered specimens due to its high sensitivity toward carotenoids and hence a higher capability for their detection at relatively low concentration in bulk powdered specimens. For the same reason, this wavelength was a better choice for the detection of carotenoids in direct measurements made on the rock samples. The 785 nm excitation wavelength, in contrast, proved to be more sensitive toward the detection of scytonemin. Key Words: Miniaturized portable Raman—Atacama—Mars—Biomarker detection. Astrobiology 12, 1095–1099. PMID:23151300

Stereospecific growth of densely populated rutile mesoporous TiO2 nanoplate films: a facile low temperature chemical synthesis approach

NASA Astrophysics Data System (ADS)

Lee, Go-Woon; Ambade, Swapnil B.; Cho, Young-Jin; Mane, Rajaram S.; Shashikala, V.; Yadav, Jyotiprakash; Gaikwad, Rajendra S.; Lee, Soo-Hyoung; Jung, Kwang-Deog; Han, Sung-Hwan; Joo, Oh-Shim

2010-03-01

We report for the first time, using a simple and environmentally benign chemical method, the low temperature synthesis of densely populated upright-standing rutile TiO2 nanoplate films onto a glass substrate from a mixture of titanium trichloride, hydrogen peroxide and thiourea in triply distilled water. The rutile TiO2 nanoplate films (the phase is confirmed from x-ray diffraction analysis, selected area electron diffraction, energy-dispersive x-ray analysis, and Raman shift) are 20-35 nm wide and 100-120 nm long. The chemical reaction kinetics for the growth of these upright-standing TiO2 nanoplate films is also interpreted. Films of TiO2 nanoplates are optically transparent in the visible region with a sharp absorption edge close to 350 nm, confirming an indirect band gap energy of 3.12 eV. The Brunauer-Emmet-Teller surface area, Barret-Joyner-Halenda pore volume and pore diameter, obtained from N2 physisorption studies, are 82 m2 g - 1, 0.0964 cm3 g - 1 and 3.5 nm, respectively, confirming the mesoporosity of scratched rutile TiO2 nanoplate powder that would be ideal for the direct fabrication of nanoscaled devices including upcoming dye-sensitized solar cells and gas sensors.

Establishment of the structural and enhanced physicochemical properties of the cocrystal-2-benzyl amino pyridine with oxalic acid

NASA Astrophysics Data System (ADS)

Sangeetha, M.; Mathammal, R.

2017-09-01

We report on a cocrystal of 2-(benzyl amino) pyridine (BAP) with oxalic acid (OA) in the ratio 1:1. The cocrystal was synthesised and single crystals were grown under slow evaporation technique at room temperature. Single crystal X-ray diffraction (SCXRD) analysis determined the structure of the cocrystal formed and it belongs to orthorhombic system with Cc space group. It was also subjected to X-ray Powder diffraction (XRPD) to confirm the cocrystal structure. Hirshfeld surfaces and fingerprints were plotted to analyze the intermolecular interactions. Spectroscopic techniques such as FTIR, FT-Raman and NMR were carried out to identify the functional groups present in the cocrystal. The bioactivity of the cocrystal was revealed from the UV-Vis analysis. Computational Density Functional Theory (DFT) was adopted at the B3LYP/6-31+G** level to calculate the optimized geometrical parameters and the vibrational frequencies of the cocrystal. The non-linear optical property of the cocrystal was revealed from the SHG test. The different types of interactions and delocalization of charge were analysed from Natural Bond Orbital (NBO) calculations. The HOMO-LUMO energies and MEP surface maps confirmed the pharmaceutical importance of the (1:1) BAPOA cocrystal. The cocrystal has been explored for the invitro antioxidant activity and insilico molecular docking studies.

Novel furosemide cocrystals and selection of high solubility drug forms.

PubMed

Goud, N Rajesh; Gangavaram, Swarupa; Suresh, Kuthuru; Pal, Sharmistha; Manjunatha, Sulur G; Nambiar, Sudhir; Nangia, Ashwini

2012-02-01

Furosemide was screened in cocrystallization experiments with pharmaceutically acceptable coformer molecules to discover cocrystals of improved physicochemical properties, that is high solubility and good stability. Eight novel equimolar cocrystals of furosemide were obtained by liquid-assisted grinding with (i) caffeine, (ii) urea, (iii) p-aminobenzoic acid, (iv) acetamide, (v) nicotinamide, (vi) isonicotinamide, (vii) adenine, and (viii) cytosine. The product crystalline phases were characterized by powder x-ray diffraction, differential scanning calorimetry, infrared, Raman, near IR, and (13) C solid-state NMR spectroscopy. Furosemide-caffeine was characterized as a neutral cocrystal and furosemide-cytosine an ionic salt by single crystal x-ray diffraction. The stability of furosemide-caffeine, furosemide-adenine, and furosemide-cytosine was comparable to the reference drug in 10% ethanol-water slurry; there was no evidence of dissociation of the cocrystal to furosemide for up to 48 h. The other five cocrystals transformed to furosemide within 24 h. The solubility order for the stable forms is furosemide-cytosine > furosemide-adenine > furosemide-caffeine, and their solubilities are approximately 11-, 7-, and 6-fold higher than furosemide. The dissolution rates of furosemide cocrystals were about two times faster than the pure drug. Three novel furosemide compounds of higher solubility and good phase stability were identified in a solid form screen. Copyright © 2011 Wiley Periodicals, Inc.

X-ray diffraction, vibrational and quantum chemical investigations of 2-methyl-4-nitroanilinium trichloroacetate trichloroacetic acid.

PubMed

Arjunan, V; Marchewka, Mariusz K; Pietraszko, A; Kalaivani, M

2012-11-01

The structural investigations of the molecular complex of 2-methyl-4-nitroaniline with trichloroacetic acid, namely 2-methyl-4-nitroanilinium trichloroacetate trichloroacetic acid (C(11)H(10)Cl(6)N(2)O(6)) have been performed by means of single crystal and powder X-ray diffraction method. The complex was formed with accompanying proton transfer from trichloroacetic acid molecule to 2-methyl-4-nitroaniline. The studied crystal is built up of singly protonated 2-methyl-4-nitroanilinium cations, trichloroacetate anions and neutral trichloroacetic acid molecules. The crystals are monoclinic, space group P2(1)/c, with a=14.947Å, b=6.432Å, c=19.609Å and Z=4. The vibrational assignments and analysis of 2-methyl-4-nitroanilinium trichloroacetate trichloroacetic acid have also been performed by FTIR, FT-Raman and far-infrared spectral studies. More support on the experimental findings were added from the quantum chemical studies performed with DFT (B3LYP) method using 6-31G, cc-pVDZ, 6-31G and 6-31++G basis sets. The structural parameters, energies, thermodynamic parameters and the NBO charges of 2M4NATCA were also determined by the DFT methods. Copyright © 2012 Elsevier B.V. All rights reserved.

X-ray diffraction studies of shocked lunar analogs

NASA Technical Reports Server (NTRS)

Hanss, R. E.

1979-01-01

The X-ray diffraction experiments on shocked rock and mineral analogs of particular significance to lunar geology are described. Materials naturally shocked by meteorite impact, nuclear-shocked, or artificially shocked in a flat plate accelerator were utilized. Four areas were outlined for investigation: powder diffractometer studies of shocked single crystal silicate minerals (quartz, orthoclase, oligoclase, pyroxene), powder diffractometer studies of shocked polycrystalline monomineralic samples (dunite), Debye-Scherrer studies of single grains of shocked granodiorite, and powder diffractometer studies of shocked whole rock samples. Quantitative interpretation of peak shock pressures experienced by materials found in lunar or terrestrial impact structures is presented.

Dissolution and storage stability of nanostructured calcium carbonates and phosphates for nutrition

NASA Astrophysics Data System (ADS)

Posavec, Lidija; Knijnenburg, Jesper T. N.; Hilty, Florentine M.; Krumeich, Frank; Pratsinis, Sotiris E.; Zimmermann, Michael B.

2016-10-01

Rapid calcium (Ca) dissolution from nanostructured Ca phosphate and carbonate (CaCO3) powders may allow them to be absorbed in much higher fraction in humans. Nanosized Ca phosphate and CaCO3 made by flame-assisted spray pyrolysis were characterized by nitrogen adsorption, X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy. As-prepared nanopowders contained both CaCO3 and CaO, but storing them under ambient conditions over 130 days resulted in a complete transformation into CaCO3, with an increase in both crystal and particle sizes. The small particle size could be stabilized against such aging by cation (Mg, Zn, Sr) and anion (P) doping, with P and Mg being most effective. Calcium phosphate nanopowders made at Ca:P ≤ 1.5 were XRD amorphous and contained γ-Ca2P2O7 with increasing hydroxyapatite content at higher Ca:P. Aging of powders with Ca:P = 1.0 and 1.5 for over 500 days gradually increased particle size (but less than for CaCO3) without a change in phase composition or crystallinity. In 0.01 M H3PO4 calcium phosphate nanopowders dissolved ≈4 times more Ca than micronsized compounds and about twice more Ca than CaCO3 nanopowders, confirming that nanosizing and/or amorphous structuring sharply increases Ca powder dissolution. Because higher Ca solubility in vitro generally leads to greater absorption in vivo, these novel FASP-made Ca nanostructured compounds may prove useful for nutrition applications, including supplementation and/or food fortification.

Study of structural and optical properties of YAG and Nd:YAG single crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kostić, S.; Lazarević, Z.Ž., E-mail: lzorica@yahoo.com; Radojević, V.

2015-03-15

Highlights: • Transparent YAG and pale pink Nd:YAG single crystals were produced by the Czochralski technique. • Growth mechanisms and shape of the liquid/solid interface and incorporation of Nd{sup 3+} were studied. • The structure of the crystals was investigated by X-ray diffraction, Raman and IR spectroscopy. • The 15 Raman and 17 IR modes were observed. • The obtained YAG and Nd:YAG single crystals were without core and of good optical quality. - Abstract: Yttrium aluminum garnet (YAG, Y{sub 3}Al{sub 5}O{sub 12}) and yttrium aluminum garnet doped with neodymium (Nd:YAG) single crystals were grown by the Czochralski technique. Themore » critical diameter and the critical rate of rotation were calculated. Suitable polishing and etching solutions were determined. As a result of our experiments, the transparent YAG and pale pink Nd:YAG single crystals were produced. The obtained crystals were studied by X-ray diffraction, Raman and IR spectroscopy. The crystal structure was confirmed by XRD. The 15 Raman and 17 IR modes were observed. The Raman and IR spectroscopy results are in accordance with X-ray diffraction analysis. The obtained YAG and Nd:YAG single crystals were without core and of good optical quality. The absence of a core was confirmed by viewing polished crystal slices. Also, it is important to emphasize that the obtained Nd:YAG single crystal has a concentration of 0.8 wt.% Nd{sup 3+} that is characteristic for laser materials.« less

Structural and spectroscopic study of mechanically synthesized SnO{sub 2} nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vij, Ankush, E-mail: vij-anx@yahoo.com; Kumar, Ravi; Presently at Beant College of Engineering and Technology, Gurdaspur-143521

2016-05-23

We report the single step synthesis of SnO{sub 2} nanostructures using high energy mechanical attrition method. X-ray diffraction (XRD) pattern reveals the single phase rutile structure with appreciable broadening of diffraction peaks, which is a signature of nanostructure formation. The average crystallite size of SnO{sub 2} nanostructures has been calculated to be ~15 nm. The micro-Raman study reveals the shifting of A{sub 1g} Raman mode towards lower wave number, which is correlated with the nanostructure formation.

In situ Raman and X-ray diffraction studies on the high pressure and temperature stability of methane hydrate up to 55 GPa.

PubMed

Kadobayashi, Hirokazu; Hirai, Hisako; Ohfuji, Hiroaki; Ohtake, Michika; Yamamoto, Yoshitaka

2018-04-28

High-temperature and high-pressure experiments were performed under 2-55 GPa and 298-653 K using in situ Raman spectroscopy and X-ray diffraction combined with externally heated diamond anvil cells to investigate the stability of methane hydrate. Prior to in situ experiments, the typical C-H vibration modes of methane hydrate and their pressure dependence were measured at room temperature using Raman spectroscopy to make a clear discrimination between methane hydrate and solid methane which forms through the decomposition of methane hydrate at high temperature. The sequential in situ Raman spectroscopy and X-ray diffraction revealed that methane hydrate survives up to 633 K and 40.3 GPa and then decomposes into solid methane and ice VII above the conditions. The decomposition curve of methane hydrate estimated by the present experiments is >200 K lower than the melting curves of solid methane and ice VII, and moderately increases with increasing pressure. Our result suggests that although methane hydrate may be an important candidate for major constituents of cool exoplanets and other icy bodies, it is unlikely to be present in the ice mantle of Neptune and Uranus, where the temperature is expected to be far beyond the decomposition temperatures.

In situ Raman and X-ray diffraction studies on the high pressure and temperature stability of methane hydrate up to 55 GPa

NASA Astrophysics Data System (ADS)

Kadobayashi, Hirokazu; Hirai, Hisako; Ohfuji, Hiroaki; Ohtake, Michika; Yamamoto, Yoshitaka

2018-04-01

High-temperature and high-pressure experiments were performed under 2-55 GPa and 298-653 K using in situ Raman spectroscopy and X-ray diffraction combined with externally heated diamond anvil cells to investigate the stability of methane hydrate. Prior to in situ experiments, the typical C-H vibration modes of methane hydrate and their pressure dependence were measured at room temperature using Raman spectroscopy to make a clear discrimination between methane hydrate and solid methane which forms through the decomposition of methane hydrate at high temperature. The sequential in situ Raman spectroscopy and X-ray diffraction revealed that methane hydrate survives up to 633 K and 40.3 GPa and then decomposes into solid methane and ice VII above the conditions. The decomposition curve of methane hydrate estimated by the present experiments is >200 K lower than the melting curves of solid methane and ice VII, and moderately increases with increasing pressure. Our result suggests that although methane hydrate may be an important candidate for major constituents of cool exoplanets and other icy bodies, it is unlikely to be present in the ice mantle of Neptune and Uranus, where the temperature is expected to be far beyond the decomposition temperatures.

Raman spectroscopy-based detection of chemical contaminants in food powders

NASA Astrophysics Data System (ADS)

Chao, Kuanglin; Dhakal, Sagar; Qin, Jianwei; Kim, Moon; Bae, Abigail

2016-05-01

Raman spectroscopy technique has proven to be a reliable method for qualitative detection of chemical contaminants in food ingredients and products. For quantitative imaging-based detection, each contaminant particle in a food sample must be detected and it is important to determine the necessary spatial resolution needed to effectively detect the contaminant particles. This study examined the effective spatial resolution required for detection of maleic acid in tapioca starch and benzoyl peroxide in wheat flour. Each chemical contaminant was mixed into its corresponding food powder at a concentration of 1% (w/w). Raman spectral images were collected for each sample, leveled across a 45 mm x 45 mm area, using different spatial resolutions. Based on analysis of these images, a spatial resolution of 0.5mm was selected as effective spatial resolution for detection of maleic acid in starch and benzoyl peroxide in flour. An experiment was then conducted using the 0.5mm spatial resolution to demonstrate Raman imaging-based quantitative detection of these contaminants for samples prepared at 0.1%, 0.3%, and 0.5% (w/w) concentrations. The results showed a linear correlation between the detected numbers of contaminant pixels and the actual concentrations of contaminant.

Single-shot stand-off chemical identification of powders using random Raman lasing

PubMed Central

Hokr, Brett H.; Bixler, Joel N.; Noojin, Gary D.; Thomas, Robert J.; Rockwell, Benjamin A.; Yakovlev, Vladislav V.; Scully, Marlan O.

2014-01-01

The task of identifying explosives, hazardous chemicals, and biological materials from a safe distance is the subject we consider. Much of the prior work on stand-off spectroscopy using light has been devoted to generating a backward-propagating beam of light that can be used drive further spectroscopic processes. The discovery of random lasing and, more recently, random Raman lasing provide a mechanism for remotely generating copious amounts of chemically specific Raman scattered light. The bright nature of random Raman lasing renders directionality unnecessary, allowing for the detection and identification of chemicals from large distances in real time. In this article, the single-shot remote identification of chemicals at kilometer-scale distances is experimentally demonstrated using random Raman lasing. PMID:25114231

On the possibility of using polycrystalline material in the development of structure-based generic assays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allaire, Marc, E-mail: allaire@bnl.gov; Moiseeva, Natalia; Botez, Cristian E.

The correlation coefficients calculated between raw powder diffraction profiles can be used to identify ligand-bound/unbound states of lysozyme. The discovery of ligands that bind specifically to a targeted protein benefits from the development of generic assays for high-throughput screening of a library of chemicals. Protein powder diffraction (PPD) has been proposed as a potential method for use as a structure-based assay for high-throughput screening applications. Building on this effort, powder samples of bound/unbound states of soluble hen-egg white lysozyme precipitated with sodium chloride were compared. The correlation coefficients calculated between the raw diffraction profiles were consistent with the known bindingmore » properties of the ligands and suggested that the PPD approach can be used even prior to a full description using stereochemically restrained Rietveld refinement.« less

Pressure-induced structural transition in chalcopyrite ZnSiP2

NASA Astrophysics Data System (ADS)

Bhadram, Venkata S.; Krishna, Lakshmi; Toberer, Eric S.; Hrubiak, Rostislav; Greenberg, Eran; Prakapenka, Vitali B.; Strobel, Timothy A.

2017-05-01

The pressure-dependent phase behavior of semiconducting chalcopyrite ZnSiP2 was studied up to 30 GPa using in situ X-ray diffraction and Raman spectroscopy in a diamond-anvil cell. A structural phase transition to the rock salt type structure was observed between 27 and 30 GPa, which is accompanied by soft phonon mode behavior and simultaneous loss of Raman signal and optical transmission through the sample. The high-pressure rock salt type phase possesses cationic disorder as evident from broad features in the X-ray diffraction patterns. The behavior of the low-frequency Raman modes during compression establishes a two-stage, order-disorder phase transition mechanism. The phase transition is partially reversible, and the parent chalcopyrite structure coexists with an amorphous phase upon slow decompression to ambient conditions.

Addressing the amorphous content issue in quantitative phase analysis: the certification of NIST standard reference material 676a.

PubMed

Cline, James P; Von Dreele, Robert B; Winburn, Ryan; Stephens, Peter W; Filliben, James J

2011-07-01

A non-diffracting surface layer exists at any boundary of a crystal and can comprise a mass fraction of several percent in a finely divided solid. This has led to the long-standing issue of amorphous content in standards for quantitative phase analysis (QPA). NIST standard reference material (SRM) 676a is a corundum (α-Al(2)O(3)) powder, certified with respect to phase purity for use as an internal standard in powder diffraction QPA. The amorphous content of SRM 676a is determined by comparing diffraction data from mixtures with samples of silicon powders that were engineered to vary their specific surface area. Under the (supported) assumption that the thickness of an amorphous surface layer on Si was invariant, this provided a method to control the crystalline/amorphous ratio of the silicon components of 50/50 weight mixtures of SRM 676a with silicon. Powder diffraction experiments utilizing neutron time-of-flight and 25 keV and 67 keV X-ray energies quantified the crystalline phase fractions from a series of specimens. Results from Rietveld analyses, which included a model for extinction effects in the silicon, of these data were extrapolated to the limit of zero amorphous content of the Si powder. The certified phase purity of SRM 676a is 99.02% ± 1.11% (95% confidence interval). This novel certification method permits quantification of amorphous content for any sample of interest, by spiking with SRM 676a.

Effect of the Chemical State of the Surface on the Relaxation of the Surface Shell Atoms in SiC and GaN Nanocrystals

NASA Technical Reports Server (NTRS)

Palosz, B.; Grzanka, E.; Stelmakh, S.; Pielaszek, R.; Bismayer, U.; Weber, H. P.; Janik, J. F.; Palosz, W.; Curreri, Peter A. (Technical Monitor)

2002-01-01

The effect of the chemical state of the surface of nanoparticles on the relaxation in the near-surface layer was examined using the concept of the apparent lattice parameter (alp) determined for different diffraction vectors Q. The apparent lattice parameter is a lattice parameter determined either from an individual Bragg reflection, or from a selected region of the diffraction pattern. At low diffraction vectors the Bragg peak positions are affected mainly by the structure of the near-surface layer, while at high Q-values only the interior of the nano-grain contributes to the diffraction pattern. Following the measurements on raw (as prepared) powders we investigated powders cleaned by annealing at 400C under vacuum, and the same powders wetted with water. Theoretical alp-Q plots showed that the structure of the surface layer depends on the sample treatment. Semi-quantitative analysis based on the comparison of the experimental and theoretical alp-Q plots was performed. Theoretical alp-Q relations were obtained from the diffraction patterns calculated for models of nanocrystals with a strained surface layer using the Debye functions.

In Situ Monitoring and Modeling of the Solution-Mediated Polymorphic Transformation of Rifampicin: From Form II to Form I.

PubMed

Guo, Nannan; Hou, Baohong; Wang, Na; Xiao, Yan; Huang, Jingjing; Guo, Yanmei; Zong, Shuyi; Hao, Hongxun

2018-01-01

In this article, the solution-mediated polymorphic transformation of rifampicin was investigated and simulated in 3 solvents at 30°C. The solid-state form I and form II of rifampicin was characterized by powder X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR). To explore the relative stability, solubility data of form I and form II of rifampicin in butan-1-ol were determined using a dynamical method. In addition, Raman spectroscopy and focused beam reflectance measurement were used to in situ monitor the transformation of rifampicin from form II to form I. The liquid state concentration of rifampicin was measured by UV spectroscopic method. To investigate the effect of solvent on transformation, the transformation experiments were carried out in 3 solvents. Furthermore, a mathematical model was built to describe the kinetics of dissolution, nucleation, and growth processes during transformation by using experimental data. By combination of experimental and simulation results, it was found that the transformation process of rifampicin is controlled by dissolution of form II in heptane, whereas the transformation in hexane and octane was firstly controlled by dissolution of solid-state form and then controlled by growth of form I. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Growth, characterization and estimation of lattice strain and size in CdS nanoparticles: X-ray peak profile analysis

NASA Astrophysics Data System (ADS)

Solanki, Rekha Garg; Rajaram, Poolla; Bajpai, P. K.

2018-05-01

This work is based on the growth, characterization and estimation of lattice strain and crystallite size in CdS nanoparticles by X-ray peak profile analysis. The CdS nanoparticles were synthesized by a non-aqueous solvothermal method and were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman and UV-visible spectroscopy. XRD confirms that the CdS nanoparticles have the hexagonal structure. The Williamson-Hall (W-H) method was used to study the X-ray peak profile analysis. The strain-size plot (SSP) was used to study the individual contributions of crystallite size and lattice strain from the X-rays peaks. The physical parameters such as strain, stress and energy density values were calculated using various models namely, isotropic strain model, anisotropic strain model and uniform deformation energy density model. The particle size was estimated from the TEM images to be in the range of 20-40 nm. The Raman spectrum shows the characteristic optical 1LO and 2LO vibrational modes of CdS. UV-visible absorption studies show that the band gap of the CdS nanoparticles is 2.48 eV. The results show that the crystallite size estimated from Scherrer's formula, W-H plots, SSP and the particle size calculated by TEM images are approximately similar.

Studies of phase transitions in the aripiprazole solid dosage form.

PubMed

Łaszcz, Marta; Witkowska, Anna

2016-01-05

Studies of the phase transitions in an active substance contained in a solid dosage form are very complicated but essential, especially if an active substance is classified as a BCS Class IV drug. The purpose of this work was the development of sensitive methods for the detection of the phase transitions in the aripiprazole tablets containing initially its form III. Aripiprazole exhibits polymorphism and pseudopolymorphism. Powder diffraction, Raman spectroscopy and differential scanning calorimetry methods were developed for the detection of the polymorphic transition between forms III and I as well as the phase transition of form III into aripiprazole monohydrate in tablets. The study involved the initial 10 mg and 30 mg tablets, as well as those stored in Al/Al blisters, a triplex blister pack and HDPE bottles (with and without desiccant) under accelerated and long term conditions. The polymorphic transition was not observed in the initial and stored tablets but it was visible on the DSC curve of the Abilify(®) 10 mg reference tablets. The formation of the monohydrate was observed in the diffractograms and Raman spectra in the tablets stored under accelerated conditions. The monohydrate phase was not detected in the tablets stored in the Al/Al blisters under long term conditions. The results showed that the Al/Al blisters can be recommended as the packaging of the aripiprazole tablets containing form III. Copyright © 2015 Elsevier B.V. All rights reserved.

Investigating the effect of moisture protection on solid-state stability and dissolution of fenofibrate and ketoconazole solid dispersions using PXRD, HSDSC and Raman microscopy.

PubMed

Kanaujia, Parijat; Lau, Grace; Ng, Wai Kiong; Widjaja, Effendi; Schreyer, Martin; Hanefeld, Andrea; Fischbach, Matthias; Saal, Christoph; Maio, Mario; Tan, Reginald B H

2011-09-01

Enhanced dissolution of poorly soluble active pharmaceutical ingredients (APIs) in amorphous solid dispersions often diminishes during storage due to moisture-induced re-crystallization. This study aims to investigate the influence of moisture protection on solid-state stability and dissolution profiles of melt-extruded fenofibrate (FF) and ketoconazole (KC) solid dispersions. Samples were kept in open, closed and Activ-vials(®) to control the moisture uptake under accelerated conditions. During 13-week storage, changes in API crystallinity were quantified using powder X-ray diffraction (PXRD) (Rietveld analysis) and high sensitivity differential scanning calorimetry (HSDSC) and compared with any change in dissolution profiles. Trace crystallinity was observed by Raman microscopy, which otherwise was undetected by PXRD and HSDSC. Results showed that while moisture protection was ineffective in preventing the re-crystallization of amorphous FF, KC remained X-ray amorphous despite 5% moisture uptake. Regardless of the degree of crystallinity increase in FF, the enhanced dissolution properties were similarly diminished. Moisture uptake above 10% in KC samples also led to re-crystallization and significant decrease in dissolution rates. In conclusion, eliminating moisture sorption may not be sufficient in ensuring the stability of solid dispersions. Analytical quantification of API crystallinity is crucial in detecting subtle increase in crystallinity that can diminish the enhanced dissolution properties of solid dispersions.

Spectroscopic study of the degradation products in the holy water fonts in Santa Maria della Steccata Church in Parma (Italy).

PubMed

Bersani, D; Campani, E; Casoli, A; Lottici, P P; Marino, I-G

2008-03-03

Two holy water fonts (dated at the beginning of the XVII century) in the Santa Maria della Steccata Church in Parma (Italy) have recently been restored. Before the intervention, a detailed investigation on their degradation products was carried out to understand the mechanisms of alteration of the materials and to suggest appropriate restoration procedures. The analyses were performed by means of powder X-ray diffraction (XRD), micro-Fourier transform infrared (FTIR) and micro-Raman spectroscopies. Calcite, iron oxides, silicates and sodium chloride (from salted holy water) were found in the red coloured calcarenite. On and under the lead coverings, different lead oxides (mainly massicot), other lead salts (lead basic carbonate, cerussite, plumbonacrite Pb10O(OH)6(CO3)6 and lead-chlorine compounds as laurionite PbOHCl and phosgenite Pb2CO3Cl2) were identified by Raman spectroscopy and XRD. Haematite alpha-Fe2O3, goethite alpha-FeO(OH) and lepidocrocite gamma-FeO(OH) were found on and around the iron hinges. Lead compounds and sodium chloride, through crystallization and solubilization cycles, were responsible for the stone's degradation, whereas the iron corrosion materials on the hinges produced mechanical stress and cracks in the stone. Various suggestions have been given on how to restore these fonts and to remove the causes of damage.

Shape- and Size-Controlled Synthesis of Silver Nanoparticles Using Aloe vera Plant Extract and Their Antimicrobial Activity

NASA Astrophysics Data System (ADS)

Logaranjan, Kaliyaperumal; Raiza, Anasdass Jaculin; Gopinath, Subash C. B.; Chen, Yeng; Pandian, Kannaiyan

2016-11-01

Biogenic synthesis of silver nanoparticles (AgNP) was performed at room temperature using Aloe vera plant extract in the presence of ammoniacal silver nitrate as a metal salt precursor. The formation of AgNP was monitored by UV-visible spectroscopy at different time intervals. The shape and size of the synthesized particle were visualized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. These results were confirmed by X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses and further supported by surface-enhanced Raman spectroscopy/Raman scattering (SERS) study. UV-visible spectrum has shown a sharp peak at 420 nm and further evidenced by FTIR peak profile (at 1587.6, 1386.4, and 1076 cm-1 with corresponding compounds). The main band position with SERS was noticed at 1594 cm-1 (C-C stretching vibration). When samples were heated under microwave radiation, AgNP with octahedron shapes with 5-50 nm were found and this method can be one of the easier ways to synthesis anisotropic AgNP, in which the plant extract plays a vital role to regulate the size and shape of the nanoparticles. Enhanced antibacterial effects (two- to fourfold) were observed in the case of Aloe vera plant protected AgNP than the routinely synthesized antibiotic drugs.

Study of structural, electrical, and dielectric properties of phosphate-borate glasses and glass-ceramics

NASA Astrophysics Data System (ADS)

Melo, B. M. G.; Graça, M. P. F.; Prezas, P. R.; Valente, M. A.; Almeida, A. F.; Freire, F. N. A.; Bih, L.

2016-08-01

In this work, phosphate-borate based glasses with molar composition 20.7P2O5-17.2Nb2O5-13.8WO3-34.5A2O-13.8B2O3, where A = Li, Na, and K, were prepared by the melt quenching technique. The as-prepared glasses were heat-treated in air at 800 °C for 4 h, which led to the formation of glass-ceramics. These high chemical and thermal stability glasses are good candidates for several applications such as fast ionic conductors, semiconductors, photonic materials, electrolytes, hermetic seals, rare-earth ion host solid lasers, and biomedical materials. The present work endorses the analysis of the electrical conductivity of the as-grown samples, and also the electrical, dielectric, and structural changes established by the heat-treatment process. The structure of the samples was analyzed using X-Ray powder Diffraction (XRD), Raman spectroscopy, and density measurements. Both XRD and Raman analysis confirmed crystals formation through the heat-treatment process. The electrical ac and dc conductivities, σac and σdc, respectively, and impedance spectroscopy measurements as function of the temperature, varying from 200 to 380 K, were investigated for the as-grown and heat-treated samples. The impedance spectroscopy was measured in the frequency range of 100 Hz-1 MHz.

Rapid and field-deployable biological and chemical Raman-based identification

NASA Astrophysics Data System (ADS)

Botonjic-Sehic, Edita; Paxon, Tracy L.; Boudries, Hacene

2011-06-01

Pathogen detection using Raman spectroscopy is achieved through the use of a sandwich immunoassay. Antibody-modified magnetic beads are used to capture and concentrate target analytes in solution and surface-enhanced Raman spectroscopy (SERS) tags are conjugated with antibodies and act as labels to enable specific detection of biological pathogens. The rapid detection of biological pathogens is critical to first responders, thus assays to detect E.Coli and Anthrax have been developed and will be reported. The problems associated with pathogen detection resulting from the spectral complexity and variability of microorganisms are overcome through the use of SERS tags, which provide an intense, easily recognizable, and spectrally consistent Raman signal. The developed E. coli assay has been tested with 5 strains of E. coli and shows a low limit of detection, on the order of 10 and 100 c.f.u. per assay. Additionally, the SERS assay utilizes magnetic beads to collect the labeled pathogens into the focal point of the detection laser beam, making the assay robust to commonly encountered white powder interferants such as flour, baking powder, and corn starch. The reagents were also found to be stable at room temperature over extended periods of time with testing conducted over a one year period. Finally, through a specialized software algorithm, the assays are interfaced to the Raman instrument, StreetLab Mobile, for rapid-field-deployable biological identification.

Characterization of composite materials based on cement-ceramic powder blended binder

NASA Astrophysics Data System (ADS)

Kulovaná, Tereza; Pavlík, Zbyšek

2016-06-01

Characterization of newly developed composite mortars with incorporated ceramic powder coming from precise brick cutting as partial Portland cement replacement up to 40 mass% is presented in the paper. Fine ceramic powder belongs to the pozzolanic materials. Utilization of pozzolanic materials is accompanied by lower request on energy needed for Portland clinker production which generally results in lower production costs of blended binder and lower CO2 emission. In this paper, the ceramic powder is used in cement based mortar composition in amount of 8, 16, 24, 32, and 40 mass% of cement. Chemical composition of ceramic powder is analyzed by X-Ray Fluorescence and X-Ray Diffraction. The particle size distribution of ceramics is accessed on laser diffraction principle. For 28 days cured mortar samples, basic physical and mechanical properties are experimentally determined. The obtained results demonstrate that ceramic powder has potential to replace a part of Portland cement in composition of cement based composites and to reduce negative environmental impact of their production.

Phase analysis of ZrO2-SiO2 systems synthesized through Ball milling mechanical activations

NASA Astrophysics Data System (ADS)

Nurlaila, Rizka; Musyarofah, Muwwaqor, Nibras Fuadi; Triwikantoro, Kuswoyo, Anton; Pratapa, Suminar

2017-01-01

Zircon powders have been produced from raw materials of amorphous zirconia and amorphous silica powders obtained from natural zircon sand of Kalimantan Tengah, Indonesia. Synthesis process was started with the extraction of zircon powder to produce sodium silicate solution and pure zircon powder. The amorphous zirconia and silica powders were prepared by alkali fusion and co-precipitation techniques. The powders were mixed using a planetary ball mill, followed by a calcination of various holding time of 3, 10, and 15 h. Phase characterization was done using X-Ray Diffraction (XRD) technique and analysis of the diffraction data was carried out using Rietica and MAUD software. The identified phases after the calcination were zircon, tetragonal zirconia, and cristobalite. The highest zircon content was obtained in the sample calcinated for15 hours - reaching 99.66 %wt. Crystallite size analysis revealed that the samples calcinated for 3, 10, and 15 h exhibited zircon crystal size of 176 (1) nm, 191 (1) nm and 233 (1) nm respectively.

Characterization of composite materials based on cement-ceramic powder blended binder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kulovaná, Tereza; Pavlík, Zbyšek

Characterization of newly developed composite mortars with incorporated ceramic powder coming from precise brick cutting as partial Portland cement replacement up to 40 mass% is presented in the paper. Fine ceramic powder belongs to the pozzolanic materials. Utilization of pozzolanic materials is accompanied by lower request on energy needed for Portland clinker production which generally results in lower production costs of blended binder and lower CO{sub 2} emission. In this paper, the ceramic powder is used in cement based mortar composition in amount of 8, 16, 24, 32, and 40 mass% of cement. Chemical composition of ceramic powder is analyzedmore » by X-Ray Fluorescence and X-Ray Diffraction. The particle size distribution of ceramics is accessed on laser diffraction principle. For 28 days cured mortar samples, basic physical and mechanical properties are experimentally determined. The obtained results demonstrate that ceramic powder has potential to replace a part of Portland cement in composition of cement based composites and to reduce negative environmental impact of their production.« less

Performance Characteristics of Waste Glass Powder Substituting Portland Cement in Mortar Mixtures

NASA Astrophysics Data System (ADS)

Kara, P.; Csetényi, L. J.; Borosnyói, A.

2016-04-01

In the present work, soda-lime glass cullet (flint, amber, green) and special glass cullet (soda-alkaline earth-silicate glass coming from low pressure mercury-discharge lamp cullet and incandescent light bulb borosilicate glass waste cullet) were ground into fine powders in a laboratory planetary ball mill for 30 minutes. CEM I 42.5N Portland cement was applied in mortar mixtures, substituted with waste glass powder at levels of 20% and 30%. Characterisation and testing of waste glass powders included fineness by laser diffraction particle size analysis, specific surface area by nitrogen adsorption technique, particle density by pycnometry and chemical analysis by X-ray fluorescence spectrophotometry. Compressive strength, early age shrinkage cracking and drying shrinkage tests, heat of hydration of mortars, temperature of hydration, X-ray diffraction analysis and volume stability tests were performed to observe the influence of waste glass powder substitution for Portland cement on physical and engineering properties of mortar mixtures.

Fabrication, characterization and fracture study of a machinable hydroxyapatite ceramic.

PubMed

Shareef, M Y; Messer, P F; van Noort, R

1993-01-01

In this study the preparation of a machinable hydroxyapatite from mixtures of a fine, submicrometer powder and either a coarse powder composed of porous aggregates up to 50 microns or a medium powder composed of dense particles of 3 microns median size is described. These were characterized using X-ray diffraction, transmission and scanning electron microscopy and infra-red spectroscopy. Test-pieces were formed by powder pressing and slip casting mixtures of various combinations of the fine, medium and coarse powders. The fired test-pieces were subjected to measurements of firing shrinkage, porosity, bulk density, tensile strength and fracture toughness. The microstructure and composition were examined using scanning electron microscopy and X-ray diffraction. For both processing methods, a uniform interconnected microporous structure was produced of a high-purity hydroxyapatite. The maximum tensile strength and fracture toughness that could be attained while retaining machinability were 37 MPa and 0.8 MPa m1/2 respectively.

Polymorphism of Alprazolam (Xanax): a review of its crystalline phases and identification, crystallographic characterization, and crystal structure of a new polymorph (form III).

PubMed

de Armas, Héctor Novoa; Peeters, Oswald M; Van den Mooter, Guy; Blaton, Norbert

2007-05-01

A new polymorphic form of Alprazolam (Xanax), 8-chloro-1-methyl-6-phenyl-4H-[1,2,4]triazolo-[4,3-alpha][1,4]benzodiazepine, C(17)H(13)ClN(4), has been investigated by means of X-ray powder diffraction (XRPD), single crystal X-ray diffraction, and differential scanning calorimetry (DSC). This polymorphic form (form III) was obtained during DSC experiments after the exothermic recrystallization of the melt of form I. The crystal unit cell dimensions for form III were determined from diffractometer methods. The monoclinic unit cell found for this polymorph using XRPD after indexing the powder diffractogram was confirmed by the cell parameters obtained from single crystal X-ray diffractometry on a crystal isolated from the DSC pans. The single crystal unit cell parameters are: a = 28.929(9), b = 13.844(8), c = 7.361(3) angstroms, beta = 92.82(3) degrees , V = 2944(2) angstroms(3), Z = 8, space group P2(1) (No.4), Dx = 1.393 Mg/m(3). The structure obtained from single crystal X-ray diffraction was used as initial model for Rietveld refinement on the powder diffraction data of form III. The temperature phase transformations of alprazolam were also studied using high temperature XRPD. A review of the different phases available in the Powder Diffraction File (PDF) database for this drug is described bringing some clarification and corrections. (c) 2007 Wiley-Liss, Inc. and the American Pharmacists Association.

Electron paramagnetic resonance and FT-IR spectroscopic studies of glycine anhydride and betaine hydrochloride

NASA Astrophysics Data System (ADS)

Halim Başkan, M.; Kartal, Zeki; Aydın, Murat

2015-12-01

Gamma irradiated powders of glycine anhydride and betaine hydrochloride have been investigated at room temperature by electron paramagnetic resonance (EPR). In these compounds, the observed paramagnetic species were attributed to the R1 and R2 radicals, respectively. It was determined that the free electron interacted with environmental protons and 14N nucleus in both radicals. The EPR spectra of gamma irradiated powder samples remained unchanged at room temperature for two weeks after irradiation. Also, the Fourier Transform Infrared (FT-IR), FT-Raman and thermal analyses of both compounds were investigated. The functional groups in the molecular structures of glycine anhydride and betaine hydrochloride were identified by vibrational spectroscopies (FT-IR and FT-Raman).

Evaluation of Raman spectroscopy for the trace analysis of biomolecules for Mars exobiology

NASA Astrophysics Data System (ADS)

Jehlicka, Jan; Edwards, Howell G. M.; Vitek, Petr; Culka, Adam

2010-05-01

Raman spectroscopy is an ideal technique for the identification of biomolecules and minerals for astrobiological applications. Raman spectroscopic instrumentation has been shown to be potentially valuable for the in-situ detection of spectral biomarkers originating from rock samples containing remnants of terrestrial endolithic colonisation. Within the future payloads designed by ESA and NASA for several missions focussing on life detection on Mars, Raman spectroscopy has been proposed as an important non-destructive analytical tool for the in-situ identification of organic compounds relevant to life detection on planetary and moon surfaces or near sub-surfaces. Portable Raman systems equipped with 785 nm lasers permit the detection of pure organic minerals, aminoacids, carboxylic acids, as well as NH-containing compounds outdoors at -20°C and at an altitude of 3300 m. A potential limitation for the use of Raman spectroscopic techniques is the detection of very low amounts of biomolecules in rock matrices. The detection of beta-carotene and aminoacids has been achieved in the field using a portable Raman system in admixture with crystalline powders of sulphates and halite. Relatively low detection limits less than 1 % for detecting beta-carotene, aminoacids using a portable Raman system were obtained analysing traces of these compounds in crystalline powders of sulphates and halite. Laboratory systems permit the detection of these biomolecules at even lower concentrations at sub-ppm level of the order of 0.1 to 1 mg kg-1. The comparative evaluation of laboratory versus field measurements permits the identification of critical issues for future field applications and directs attention to the improvements needed in the instrumentation . A comparison between systems using different laser excitation wavelengths shows excellent results for 785 nm laser excitation . The results of this study will inform the acquisition parameters necessary for the deployment of robotic miniaturised Raman spectrosocpic instrumentation intended for the detection of spectral signatures of extant or relict life on Mars.

Mg(1 + x)Ir(1 - x) (x = 0, 0.037 and 0.054), a binary intermetallic compound with a new orthorhombic structure type determined from powder and single-crystal X-ray diffraction.

PubMed

Cerný, Radovan; Renaudin, Guillaume; Favre-Nicolin, Vincent; Hlukhyy, Viktor; Pöttgen, Rainer

2004-06-01

The new binary compound Mg(1 + x)Ir(1 - x) (x = 0-0.054) was prepared by melting the elements in the Mg:Ir ratio 2:3 in a sealed tantalum tube under an argon atmosphere in an induction furnace (single crystals) or by annealing cold-pressed pellets of the starting composition Mg:Ir 1:1 in an autoclave under an argon atmosphere (powder sample). The structure was independently solved from high-resolution synchrotron powder and single-crystal X-ray data: Pearson symbol oC304, space group Cmca, lattice parameters from synchrotron powder data a = 18.46948 (6), b = 16.17450 (5), c = 16.82131 (5) A. Mg(1 + x)Ir(1 - x) is a topologically close-packed phase, containing 13 Ir and 12 Mg atoms in the asymmetric unit, and has a narrow homogeneity range. Nearly all the atoms have Frank-Kasper-related coordination polyhedra, with the exception of two Ir atoms, and this compound contains the shortest Ir-Ir distances ever observed. The solution of a rather complex crystal structure from powder diffraction, which was fully confirmed by the single-crystal method, shows the power of powder diffraction in combination with the high-resolution data and the global optimization method.

Roller compaction of different pseudopolymorphic forms of theophylline: Effect on compressibility and tablet properties.

PubMed

Hadzović, Ervina; Betz, Gabriele; Hadzidedić, Seherzada; El-Arini, Silvia Kocova; Leuenberger, Hans

2010-08-30

The effect of roller compaction on disintegration time, dissolution rate and compressibility of tablets prepared from theophylline anhydrate powder, theophylline anhydrate fine powder and theophylline monohydrate was studied. In addition, the influence of adding microcrystalline cellulose, a commonly used excipient, in mixtures with these materials was investigated. Theophylline anhydrate powder was used as a model drug to investigate the influence of different compaction pressures on the tablet properties. Tablets with same porosity were prepared by direct compaction and by roller compaction/re-compaction. Compressibility was characterized by Heckel and modified Heckel equations. Due to the property of polymorphic materials to change their form during milling and compression, X-ray diffraction analysis of theophylline anhydrate powder, theophylline anhydrate fine powder and theophylline monohydrate powders and granules was carried out. After roller compaction the disintegration time and the dissolution rate of the tablets were significantly improved. Compressibility of theophylline anhydrate powder and theophylline anhydrate fine powder was decreased, while theophylline monohydrate showed higher compressibility after roller compaction. Microcrystalline cellulose affected compressibility of theophylline anhydrate powder, theophylline anhydrate fine powder and theophylline monohydrate whereby the binary mixtures showed higher compressibility than the individual materials. X-ray diffraction analyses confirmed that there were no polymorphic/pseudopolymorphic changes after roller compaction. Copyright 2010 Elsevier B.V. All rights reserved.

Synchrotron X-ray diffraction and Raman spectroscopy of Ln{sub 3}NbO{sub 7} (Ln=La, Pr, Nd, Sm-Lu) ceramics obtained by molten-salt synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siqueira, K.P.F.; Soares, J.C.; Granado, E.

2014-01-15

Ln{sub 3}NbO{sub 7} (Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) ceramics were obtained by molten-salt synthesis and their structures were systematically investigated by synchrotron X-ray diffraction (SXRD), second harmonic generation (SHG) and Raman spectroscopy. It was observed that ceramics with the largest ionic radii (La, Pr, Nd) crystallized into the Pmcn space group, while the ceramics with intermediate ionic radii (Sm-Gd) exhibited a different crystal structure belonging to the Ccmm space group. For this last group of ceramics, this result was corroborated by SHG and Raman scattering and ruled out any possibility formore » the non-centrosymmetric C 222{sub 1} space group, solving a recent controversy in the literature. Finally, according to SXRD, Tb-Lu containing samples exhibited an average defect fluorite structure (Fm3{sup ¯}m space group). Nonetheless, broad scattering at forbidden Bragg reflections indicates the presence of short-range domains with lower symmetry. Vibrational spectroscopy showed the presence of six Raman-active modes, inconsistent with the average cubic fluorite structure, and in line with the existence of lower-symmetry nano-domains immersed in the average fluorite structure of these ceramics. - Graphical abstract: Raman spectrum for Sm{sub 3}NbO{sub 7} ceramics showing their 27 phonon modes adjusted through Lorentzian lines. According to synchrotron X-ray diffraction and Raman scattering, this material belongs to the space group Cmcm. Display Omitted - Highlights: • Ln{sub 3}NbO{sub 7} ceramics were obtained by molten-salt synthesis. • SXRD, SHG and Raman scattering confirmed orthorhombic and cubic structures. • Ccmm instead of C222{sub 1} is the correct structure for Sm–Gd ceramics. • Pmcn space group was confirmed for La-, Pr- and Nd-based ceramics. • For Tb–Lu ceramics, ordered domains of a pyrochlore structure were observed.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

S. Dong; N. Paterson; S.G. Kazarian

A suite of tuyere-level coke samples have been withdrawn from a working blast furnace during coal injection, using the core-drilling technique. The samples have been characterized by size exclusion chromatography (SEC), Fourier transform Raman spectroscopy (FT-RS), and X-ray powder diffraction (XRD) spectroscopy. The 1-methyl-2-pyrrolidinone (NMP) extracts of the cokes sampled from the 'bosh', the rear of the 'bird's nest', and the 'dead man' zones were found by SEC to contain heavy soot-like materials (ca. 10{sup 7}-10{sup 8} apparent mass units). In contrast, NMP extracts of cokes taken from the raceway and the front of the 'bird's nest' only contained amore » small amount of material of relatively lower apparent molecular mass (up to ca. 10{sup 5} u). Since the feed coke contained no materials extractable by the present method, the soot-like materials are thought to have formed during the reactions of volatile matter released from the injectant coal, probably via dehydrogenation and repolymerization of the tars. The Raman spectra of the NMP-extracted core-drilled coke samples showed variations reflecting their temperature histories. Area ratios of D-band to G-band decreased as the exposure temperature increased, while intensity ratios of D to G band and those of 2D to G bands increased with temperature. The graphitic (G), defect (D), and random (R) fractions of the carbon structure of the cokes were also derived from the Raman spectra. The R fractions decreased with increasing temperature, whereas G fractions increased, while the D fractions showed a more complex variation with temperature. These data appear to give clues regarding the graphitization mechanism of tuyere-level cokes in the blast furnace. 41 refs., 9 figs., 6 tabs.« less

Selective Encaging of N2O in N2O-N2 Binary Gas Hydrates via Hydrate-Based Gas Separation.

PubMed

Yang, Youjeong; Shin, Donghoon; Choi, Seunghyun; Woo, Yesol; Lee, Jong-Won; Kim, Dongseon; Shin, Hee-Young; Cha, Minjun; Yoon, Ji-Ho

2017-03-21

The crystal structure and guest inclusion behaviors of nitrous oxide-nitrogen (N 2 O-N 2 ) binary gas hydrates formed from N 2 O/N 2 gas mixtures are determined through spectroscopic analysis. Powder X-ray diffraction results indicate that the crystal structure of all the N 2 O-N 2 binary gas hydrates is identified as the structure I (sI) hydrate. Raman spectra for the N 2 O-N 2 binary gas hydrate formed from N 2 O/N 2 (80/20, 60/40, 40/60 mol %) gas mixtures reveal that N 2 O molecules occupy both large and small cages of the sI hydrate. In contrast, there is a single Raman band of N 2 O molecules for the N 2 O-N 2 binary gas hydrate formed from the N 2 O/N 2 (20/80 mol %) gas mixture, indicating that N 2 O molecules are trapped in only large cages of the sI hydrate. From temperature-dependent Raman spectra and the Predictive Soave-Redlich-Kwong (PSRK) model calculation, we confirm the self-preservation of N 2 O-N 2 binary gas hydrates in the temperature range of 210-270 K. Both the experimental measurements and the PSRK model calculations demonstrate the preferential occupation of N 2 O molecules rather than N 2 molecules in the hydrate cages, leading to a possible process for separating N 2 O from gas mixtures via hydrate formation. The phase equilibrium conditions, pseudo-pressure-composition (P-x) diagram, and gas storage capacity of N 2 O-N 2 binary gas hydrates are discussed in detail.

Raman-spectroscopy-based chemical contaminant detection in milk powder

NASA Astrophysics Data System (ADS)

Dhakal, Sagar; Chao, Kuanglin; Qin, Jianwei; Kim, Moon S.

2015-05-01

Addition of edible and inedible chemical contaminants in food powders for purposes of economic benefit has become a recurring trend. In recent years, severe health issues have been reported due to consumption of food powders contaminated with chemical substances. This study examines the effect of spatial resolution used during spectral collection to select the optimal spatial resolution for detecting melamine in milk powder. Sample depth of 2mm, laser intensity of 200mw, and exposure time of 0.1s were previously determined as optimal experimental parameters for Raman imaging. Spatial resolution of 0.25mm was determined as the optimal resolution for acquiring spectral signal of melamine particles from a milk-melamine mixture sample. Using the optimal resolution of 0.25mm, sample depth of 2mm and laser intensity of 200mw obtained from previous study, spectral signal from 5 different concentration of milk-melamine mixture (1%, 0.5%, 0.1%, 0.05%, and 0.025%) were acquired to study the relationship between number of detected melamine pixels and corresponding sample concentration. The result shows that melamine concentration has a linear relation with detected number of melamine pixels with correlation coefficient of 0.99. It can be concluded that the quantitative analysis of powder mixture is dependent on many factors including physical characteristics of mixture, experimental parameters, and sample depth. The results obtained in this study are promising. We plan to apply the result obtained from this study to develop quantitative detection model for rapid screening of melamine in milk powder. This methodology can also be used for detection of other chemical contaminants in milk powders.

Heterogeneous distribution of dye-labelled biomineralizaiton proteins in calcite crystals

NASA Astrophysics Data System (ADS)

Liu, Chuang; Xie, Liping; Zhang, Rongqing

2015-12-01

Biominerals are highly ordered crystals mediated by organic matters especially proteins in organisms. However, how specific proteins are distributed inside biominerals are not well understood. In the present study, we use fluorescein isothiocyanate (FITC) to label extracted proteins from the shells of bivalve Pinctada fucata. By confocal laser scanning microscopy (CLSM), we observe a heterogeneous distribution of dye-labelled proteins inside synthetic calcite at the microscale. Proteins from the prismatic calcite layers accumulate at the edge of crystals while proteins from the nacreous aragonite layers accumulate at the center of crystals. Raman and X-ray powder diffraction show that both the proteins cannot alter the crystal phase. Scanning electron microscope demonstrates both proteins are able to affect the crystal morphology. This study may provide a direct approach for the visualization of protein distributions in crystals by small-molecule dye-labelled proteins as the additives in the crystallization process and improve our understanding of intracrystalline proteins distribution in biogenic calcites.

Tetra-n-butylammonium borohydride semiclathrate: a hybrid material for hydrogen storage.

PubMed

Shin, Kyuchul; Kim, Yongkwan; Strobel, Timothy A; Prasad, P S R; Sugahara, Takeshi; Lee, Huen; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A

2009-06-11

In this study, we demonstrate that tetra-n-butylammonium borohydride [(n-C(4)H(9))(4)NBH(4)] can be used to form a hybrid hydrogen storage material. Powder X-ray diffraction measurements verify the formation of tetra-n-butylammonium borohydride semiclathrate, while Raman spectroscopic and direct gas release measurements confirm the storage of molecular hydrogen within the vacant cavities. Subsequent to clathrate decomposition and the release of physically bound H(2), additional hydrogen was produced from the hybrid system via a hydrolysis reaction between the water host molecules and the incorporated BH(4)(-) anions. The additional hydrogen produced from the hydrolysis reaction resulted in a 170% increase in the gravimetric hydrogen storage capacity, or 27% greater storage than fully occupied THF + H(2) hydrate. The decomposition temperature of tetra-n-butylammonium borohydride semiclathrate was measured at 5.7 degrees C, which is higher than that for pure THF hydrate (4.4 degrees C). The present results reveal that the BH(4)(-) anion is capable of stabilizing tetraalkylammonium hydrates.

Influences of annealing temperature on structural characterization and magnetic properties of Mn-doped BaTiO3 ceramics

NASA Astrophysics Data System (ADS)

Phan, The-Long; Zhang, P.; Grinting, D.; Yu, S. C.; Nghia, N. X.; Dang, N. V.; Lam, V. D.

2012-07-01

Polycrystalline samples of BaTiO3 doped with 2.0 at. % Mn were prepared by solid-state reaction at various temperatures (Tan) ranging from 500 to 1350 °C, used high-pure powders of BaCO3, TiO2, and MnCO3 as precursors. Experimental results obtained from x-ray diffraction patterns and Raman scattering spectra reveal that tetragonal Mn-doped BaTiO3 starts constituting as Tan ≈ 500 °C. The Tan increase leads to the development of this phase. Interestingly, there is the tetragonal-hexagonal transformation in the crystal structure of BaTiO3 as Tan ≈ 1100 °C. Such the variations influence directly magnetic properties of the samples. Besides paramagnetic contributions of Mn2+ centers traced to electron spin resonance, the room-temperature ferromagnetism found in the samples is assigned to exchange interactions taking place between Mn3+ and Mn4+ ions located in tetragonal BaTiO3 crystals.

Structural, chemical and physical properties of pure and La3+ doped L-Threonine acetate crystals

NASA Astrophysics Data System (ADS)

Senthamizhan, A.; Sambathkumar, K.; Nithiyanantham, S.; Venkatachalapathy, M.; Rajkamal, N.

2017-12-01

The pure and La3+ doped L- Threonine crystals can be grown by slow evaporation techniques. The crystal structure were examined through X-Ray diffraction (XRD) analysis, confirmed the P212121 system. The quantitative nature of dopant can be analyzed with Inductively Coupled Plasma (ICP) study. The Fourier Transform Infra-Red (FTIR) and Fourier Transform (FT- Raman) investigations yields the possible stretching/bonding with their functional groups and the qualitative/quantitative nature of both crystals is analyzed. The optical behavior of crystals can be studied through Ultra Violet (UV) - Visible spectrometer. The mechanical, thermal and decomposition studies can be carried out through Vickers hardness test, Thermo Gravometric Analysis (TGA) and Differential Thermal Analysis (DTA). The Non Linear Optical (NLO) properties are found more than Potassium Phosphate (KDP) through Kurtz powders technique. The dielectric and optical absorption studies for both pure and L-doped crystals were studied and interpreted all the properties. The La3+ dopant increases the properties are investigated.

Effect of Co doping on structural and mechanical properties of CeO2

NASA Astrophysics Data System (ADS)

Tiwari, Saurabh; Balasubramanian, Nivedha; Biring, Sajal; Sen, Somaditya

2018-05-01

Sol-gel synthesized nanocrystalline Co doped CeO2 powders [(Ce1-xCoxO2; x=0, 0.03)] were made into cylindrical discs by uniaxial pressing and sintered at 1500°C for 24h to measure mechanical properties. The pure phase formation of undoped and Co doped samples were confirmed by X-ray diffraction and Raman analysis. The scanning electron microscopy (SEM) was used for observing the microstructure of sintered samples to investigate density, porosity, and grain size. The grains size observed for 1500°C sintered samples 5-8 µm. Vickers indentation method used for investigating the micro-hardness. For undoped CeO2 micro-hardness was found 6.2 GPa which decreased with Co doping. It was found that samples follow indentation size effect (ISE) and follow elastic than plastic deformation. Enhanced ductile nature with Co doping in CeO2 made it more promising material for optoelectronic device applications.

Crystal growth, spectral, structural and optical studies of π-conjugated stilbazolium crystal: 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate.

PubMed

Krishna Kumar, M; Sudhahar, S; Bhagavannarayana, G; Mohan Kumar, R

2014-05-05

Nonlinear optical (NLO) organic compound, 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate was synthesized by reflux method. The formation of molecular complex was confirmed from (1)H NMR, FT-IR and FT-Raman spectral analyses. The single crystals were grown by slow evaporation solution growth method and the crystal structure and atomic packing of grown crystal was identified. The morphology and growth axis of grown crystal were determined. The crystal perfection was analyzed using high resolution X-ray diffraction study on (001) plane. Thermal stability, decomposition stages and melting point of the grown crystal were analyzed. The optical absorption coefficient (α) and energy band gap (E(g)) of the crystal were determined using UV-visible absorption studies. Second harmonic generation efficiency of the grown crystal was examined by Kurtz powder method with different particle size using 1064 nm laser. Laser induced damage threshold study was carried out for the grown crystal using Nd:YAG laser. Copyright © 2014 Elsevier B.V. All rights reserved.

Systematic investigation on Cadmium-incorporation in Li₂FeSiO₄/C cathode material for lithium-ion batteries.

PubMed

Zhang, Lu-Lu; Duan, Song; Yang, Xue-Lin; Liang, Gan; Huang, Yun-Hui; Cao, Xing-Zhong; Yang, Jing; Ni, Shi-Bing; Li, Ming

2014-05-27

Cadmium-incorporated Li2FeSiO4/C composites have been successfully synthesized by a solid-state reaction assisted with refluxing. The effect and mechanism of Cd-modification on the electrochemical performance of Li2FeSiO4/C were investigated in detail by X-ray powder diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, Raman spectra, transmission electron microscopy, positron annihilation lifetime spectroscopy and Doppler broadening spectrum, and electrochemical measurements. The results show that Cd not only exists in an amorphous state of CdO on the surface of LFS particles, but also enters into the crystal lattice of LFS. Positron annihilation lifetime spectroscopy and Doppler broadening spectrum analyses verify that Cd-incorporation increases the defect concentration and the electronic conductivity of LFS, thus improve the Li(+)-ion diffusion process. Furthermore, our electrochemical measurements verify that an appropriate amount of Cd-incorporation can achieve a satisfied electrochemical performance for LFS/C cathode material.

Electrical conductivity and dielectric behavior in sodium zinc divanadates

NASA Astrophysics Data System (ADS)

Sallemi, F.; Louati, B.; Guidara, K.

2014-11-01

The Na2ZnV2O7 compound was obtained by the conventional solid-state reaction. The sample was characterized by X-ray powder diffraction, Raman and impedance spectroscopy. The ac electrical conductivity and dielectric properties have been investigated in the frequency and temperature range of 200 Hz-1 MHz and 513 K-729 K, respectively. The direct current conductivity process is thermally activated. The frequency dependence of the conductivity is interpreted using the power law. The close values of activation energies obtained from the analysis of hopping frequency and dc conductivity implies that the transport is due to Na+ cation displacement parallel to (0 0 1) plane located between ZnO4 and VO4 tetrahedra. The evolution of the complex permittivity as a function of angular frequency was investigated. Several important parameters such as charge carrier concentration, ionic mobility and diffusion coefficient were determined. Thermodynamic parameters such as the free energy of activation ∆F, the enthalpy ∆H, and the change in entropy ∆S have been calculated.

Fabrication of ZnO nanoparticles based sensitive methanol sensor and efficient photocatalyst

NASA Astrophysics Data System (ADS)

Faisal, M.; Khan, Sher Bahadar; Rahman, Mohammed M.; Jamal, Aslam; Abdullah, M. M.

2012-07-01

ZnO nanoparticles (NPs) were prepared by hydrothermal treatment with starting materials (zinc chloride and urea) in the presence of ammonium hydroxide and characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and UV-vis spectroscopy. The synthesized nanoparticles are crystalline with wurtzite hexagonal phase having average particle size in the range of 80-130 nm. Photocatalytic activity of the prepared ZnO NPs was evaluated by the degradation of methylene blue and almost complete degradation (91.0%) takes place within 85 min of irradiation time. Prepared ZnO nanostructures possessed high photocatalytic activity when compared with TiO2-UV100. Additionally, the sensing properties of the ZnO films were investigated for various concentrations of methanol in liquid phase by simple I-V technique at room conditions. It was observed that ZnO thin film exhibits good sensitivity (0.9554 μA cm-2 mM-1) towards detection of methanol at room conditions.

Natural precursor based hydrothermal synthesis of sodium carbide for reactor applications

NASA Astrophysics Data System (ADS)

Swapna, M. S.; Saritha Devi, H. V.; Sebastian, Riya; Ambadas, G.; Sankararaman, S.

2017-12-01

Carbides are a class of materials with high mechanical strength and refractory nature which finds a wide range of applications in industries and nuclear reactors. The existing synthesis methods of all types of carbides have problems in terms of use of toxic chemical precursors, high-cost, etc. Sodium carbide (Na2C2) which is an alkali metal carbide is the least explored one and also that there is no report of low-cost and low-temperature synthesis of sodium carbide using the eco-friendly, easily available natural precursors. In the present work, we report a simple low-cost, non-toxic hydrothermal synthesis of refractory sodium carbide using the natural precursor—Pandanus. The formation of sodium carbide along with boron carbide is evidenced by the structural and morphological characterizations. The sample thus synthesized is subjected to field emission scanning electron microscopy (FESEM), x-ray powder diffraction (XRD), ultraviolet (UV)—visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), Raman, and photoluminescent (PL) spectroscopic techniques.

The structure feature of layered M1/3TiNbO5 (M=Fe, Ce) and their photocatalytic oxidization performance for ethyl mercaptan

NASA Astrophysics Data System (ADS)

Dong, Rui; Wang, Yuan; Wang, Ningning; Xu, Lei; He, Jie; Wu, Shanshan; Lan, Yunxiang; Hu, Jinsong

2016-09-01

Layered photocatalytic materials M1/3TiNbO5 (M = Fe, Ce) were prepared by ion-exchange of KTiNbO5 with M(NO3)3. The parent KTiNbO5 was synthesized with titanium (IV) isopropoxide and niobium oxalate by a novel polymerized complex (PC) method. The micro-structures and spectral response features of the as-prepared samples were characterized by powder X-ray diffraction (XRD), transmission electron microscope (TEM), laser Raman spectroscopy (LRS) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The results revealed that there was a significant interaction between the interlayer cation and the terminal Nbdbnd O (Tidbnd O) bond in the NbO6 (TiO6) unit of the laminates. Photocatalytic performance was evaluated in oxidation of ethyl mercaptan under natural and UV light irradiation. It can be deduced that the photocatalytic oxidization performance can be directly affected by the characteristics of the interlayer cations.

Advanced Microstructural Study of Suspension Plasma Sprayed Hydroxyapatite Coatings

NASA Astrophysics Data System (ADS)

Podlesak, Harry; Pawlowski, Lech; D'Haese, Romain; Laureyns, Jacky; Lampke, Thomas; Bellayer, Severine

2010-03-01

Fine, home-synthesized, hydroxyapatite powder was formulated with water and alcohol to obtain a suspension used to plasma spray coatings onto a titanium substrate. The deposition process was optimized using statistical design of 2 n experiments with two variables: spray distance and electric power input to plasma. X-ray diffraction (XRD) was used to determine quantitatively the phase composition of obtained deposits. Raman microscopy and electron probe microanalysis (EPMA) enabled localization of the phases in different positions of the coating cross sections. Transmission electron microscopic (TEM) study associated with energy-dispersive x-ray spectroscopy (EDS) enabled visualization and analysis of a two-zone microstructure. One zone contained crystals of hydroxyapatite, tetracalcium phosphate, and a phase rich in calcium oxide. This zone included lamellas, usually observed in thermally sprayed coatings. The other zone contained fine hydroxyapatite grains that correspond to nanometric and submicrometric solids from the suspension that were agglomerated and sintered in the cold regions of plasma jet and on the substrate.

Systematic investigation on Cadmium-incorporation in Li2FeSiO4/C cathode material for lithium-ion batteries

PubMed Central

Zhang, Lu-Lu; Duan, Song; Yang, Xue-Lin; Liang, Gan; Huang, Yun-Hui; Cao, Xing-Zhong; Yang, Jing; Ni, Shi-Bing; Li, Ming

2014-01-01

Cadmium-incorporated Li2FeSiO4/C composites have been successfully synthesized by a solid-state reaction assisted with refluxing. The effect and mechanism of Cd-modification on the electrochemical performance of Li2FeSiO4/C were investigated in detail by X-ray powder diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, Raman spectra, transmission electron microscopy, positron annihilation lifetime spectroscopy and Doppler broadening spectrum, and electrochemical measurements. The results show that Cd not only exists in an amorphous state of CdO on the surface of LFS particles, but also enters into the crystal lattice of LFS. Positron annihilation lifetime spectroscopy and Doppler broadening spectrum analyses verify that Cd-incorporation increases the defect concentration and the electronic conductivity of LFS, thus improve the Li+-ion diffusion process. Furthermore, our electrochemical measurements verify that an appropriate amount of Cd-incorporation can achieve a satisfied electrochemical performance for LFS/C cathode material. PMID:24860942

Spectroscopic, Homo-Lumo and NLO studies of tetra fluoro phthalate doped Coumarin crystals using DFT method

NASA Astrophysics Data System (ADS)

Latha, B.; Kumaresan, P.; Nithiyanantham, S.; Sampathkumar, K.

2017-08-01

In the present examination, a methodical study has been done on the development of unadulterated and Coumarin doped Tetrafluoro Phthalate precious stones. Powder X-beam diffraction studies were done and the cross section parameters were computed by minimum square technique in pure and doped crystals. FT-IR, UV-Vis, Thermal, Micro-hardness and Dielectric studies were additionally done for the pure and doped crystals. The tentatively watched FT-IR and FT-Raman groups were allotted to various ordinary methods of the atom. The steadiness and charge delocalization of the particle were likewise concentrations were done by characteristic security orbital (NBO) examination. The HOMO-LUMO energies depict the charge exchange happens inside the particle. Atomic electrostatic potential has been broken down the electronic properties such as excitation energies, oscillator quality, wavelengths and HOMO-LUMO energies were acquired by time-subordinate DFT (TD-DFT) approach. The SHG of pure and doped TFP stones were examined through Nd:YAG Q-exchanged laser.

Synthesis, growth, spectral, electrical, mechanical and thermal characterization of a potential optical material: γ-glycine single crystal

NASA Astrophysics Data System (ADS)

Sivakumar, N.; Jayavel, R.; Anbalagan, G.; Yadav, R. R.

2018-06-01

Gamma glycine, an organic material was grown by slow solvent evaporation method. Conventional polythermal method was employed in the temperature range, 30-50 °C to obtain the solubility and the metastable zonewidth. The crystal and molecular structures were analyzed by X-ray powder diffraction, FT-IR and FT-Raman spectral studies. Optical refractive index was determined by prism coupling technique and was found to be 1.4488. Electrical properties such as ac conductivity and activation energy were studied for different temperatures in the frequency range from 40 Hz to 6 MHz. The dc electrical conductivity was estimated from the Cole-Cole plot and the values were found to be 2.19 × 10-6 Sm-1 at 353K and 1.46 × 10-6 Sm-1 at 373K respectively. Mechanical studies on the grown crystal revealed that the material belongs to soft materials category. Thermal conductivity and specific heat capacities were estimated by Hot Disk Thermal Constants Analyzer.

Efficient photodegradation of methylthioninium chloride dye in aqueous using barium tungstate nanoparticles

NASA Astrophysics Data System (ADS)

AlShehri, Saad M.; Ahmed, Jahangeer; Ahamad, Tansir; Almaswari, Basheer M.; Khan, Aslam

2017-08-01

BaWO4 nanoparticles were successfully used as the photocatalysts in the degradation of methylthioninium chloride (MTC) dye at different pH levels of aqueous solution. Pure phase of barium tungstate (BaWO4) nanoparticles was synthesized by modified molten salt process at 500 °C for 6 h. Structural and morphological characterizations of BaWO4 nanoparticles (average particle size of 40 nm) were studied in details using powder x-ray diffraction (XRD), FTIR, Raman, energy-dispersive, electron microscopic, and x-ray photoelectron spectroscopy (XPS) techniques. Direct band gap energy of BaWO4 nanoparticles was found to be 3.06 eV from the UV-visible absorption spectroscopy followed by Tauc's model. Photocatalytic properties of the nanoparticles were also investigated systematically for the degradation of MTC dye solution in various mediums. BaWO4 nanoparticles claim the significant enhancement of the photocatalytic degradation of aqueous MTC dye to non-hazardous inorganic constitutes under alkaline, neutral, and acidic mediums. [Figure not available: see fulltext.

Mesoporous hollow carbon spheres for lithium–sulfur batteries: distribution of sulfur and electrochemical performance

PubMed Central

Juhl, Anika C; Schneider, Artur; Ufer, Boris; Brezesinski, Torsten

2016-01-01

Summary Hollow carbon spheres (HCS) with a nanoporous shell are promising for the use in lithium–sulfur batteries because of the large internal void offering space for sulfur and polysulfide storage and confinement. However, there is an ongoing discussion whether the cavity is accessible for sulfur. Yet no valid proof of cavity filling has been presented, mostly due to application of unsuitable high-vacuum methods for the analysis of sulfur distribution. Here we describe the distribution of sulfur in hollow carbon spheres by powder X-ray diffraction and Raman spectroscopy along with results from scanning electron microscopy and nitrogen physisorption. The results of these methods lead to the conclusion that the cavity is not accessible for sulfur infiltration. Nevertheless, HCS/sulfur composite cathodes with areal sulfur loadings of 2.0 mg·cm−2 were investigated electrochemically, showing stable cycling performance with specific capacities of about 500 mAh·g−1 based on the mass of sulfur over 500 cycles. PMID:27826497

Synthesis and Characterization of Highly Intercalated Graphite Bisulfate

NASA Astrophysics Data System (ADS)

Salvatore, Marcella; Carotenuto, Gianfranco; De Nicola, Sergio; Camerlingo, Carlo; Ambrogi, Veronica; Carfagna, Cosimo

2017-03-01

Different chemical formulations for the synthesis of highly intercalated graphite bisulfate have been tested. In particular, nitric acid, potassium nitrate, potassium dichromate, potassium permanganate, sodium periodate, sodium chlorate, and hydrogen peroxide have been used in this synthesis scheme as the auxiliary reagent (oxidizing agent). In order to evaluate the presence of delamination, and pre-expansion phenomena, and the achieved intercalation degree in the prepared samples, the obtained graphite intercalation compounds have been characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), infrared spectroscopy (FT-IR), micro-Raman spectroscopy ( μ-RS), and thermal analysis (TGA). Delamination and pre-expansion phenomena were observed only for nitric acid, sodium chlorate, and hydrogen peroxide, while the presence of strong oxidizers (KMnO4, K2Cr2O7) led to stable graphite intercalation compounds. The largest content of intercalated bisulfate is achieved in the intercalated compounds obtained from NaIO4 and NaClO3.

Five novel lanthanide complexes with 2-chloroquinoline-4-carboxylic acid and 1,10-phenanthroline: Crystal structures, molecular spectra, thermal properties and bacteriostatic activities

NASA Astrophysics Data System (ADS)

Wang, Ye; Jin, Cheng-Wei; He, Shu-Mei; Ren, Ning; Zhang, Jian-Jun

2016-12-01

Five novel lanthanide complexes [Ln2(2-ClQL)6(phen)2(H2O)2]·2H2O (Ln = Pr(1), Sm(2), Eu(3), Ho(4), Er(5)); 2-ClQL: 2-chloroquinoline-4-carboxylate; phen: 1,10-phenanthroline; were synthesized by conventional solution method at room temperature and characterized via elemental analysis, powder x-ray diffraction, Infrared spectroscopy and Raman spectrometry. The results indicate that complexes 1-5 are isostructural, and each Ln3+ ion is eight-coordinated adopting a distorted square antiprismatic molecular geometry. Binuclear complex 1 are stitched together via hydrogen bonding interactions to form 1D chains, and further to form 2D sheets by the π-π interactions. Luminescence investigation reveals that complex 3 displays strong red emission. TG/DTG-FTIR, reveal the thermal decomposition processes and products of title complexes. The bacteriostatic activities of the complexes were evaluated against Candida albicans, Escherichia coli, and Staphylococcus aureus.

The application of inelastic neutron scattering to explore the significance of a magnetic transition in an iron based Fischer-Tropsch catalyst that is active for the hydrogenation of CO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warringham, Robbie; McFarlane, Andrew R.; Lennon, David, E-mail: David.Lennon@Glasgow.ac.uk

2015-11-07

An iron based Fischer-Tropsch synthesis catalyst is evaluated using CO hydrogenation at ambient pressure as a test reaction and is characterised by a combination of inelastic neutron scattering (INS), powder X-ray diffraction, temperature-programmed oxidation, Raman scattering, and transmission electron microscopy. The INS spectrum of the as-prepared bulk iron oxide pre-catalyst (hematite, α-Fe{sub 2}O{sub 3}) is distinguished by a relatively intense band at 810 cm{sup −1}, which has previously been tentatively assigned as a magnon (spinon) feature. An analysis of the neutron scattering intensity of this band as a function of momentum transfer unambiguously confirms this assignment. Post-reaction, the spinon featuremore » disappears and the INS spectrum is characterised by the presence of a hydrocarbonaceous overlayer. A role for the application of INS in magnetic characterisation of iron based FTS catalysts is briefly considered.« less

Usefulness of charge-transfer complexation for the assessment of sympathomimetic drugs: Spectroscopic properties of drug ephedrine hydrochloride complexed with some π-acceptors

NASA Astrophysics Data System (ADS)

Refat, Moamen S.; Ibrahim, Omar B.; Saad, Hosam A.; Adam, Abdel Majid A.

2014-05-01

Recently, ephedrine (Eph) assessment in food products, pharmaceutical formulations, human fluids of athletes and detection of drug toxicity and abuse, has gained a growing interest. To provide basic data that can be used to assessment of Eph quantitatively based on charge-transfer (CT) complexation, the CT complexes of Eph with 7‧,8,8‧-tetracyanoquinodimethane (TCNQ), dichlorodicyanobenzoquinone (DDQ), 1,3-dinitrobenzene (DNB) or tetrabromothiophene (TBT) were synthesized and spectroscopically investigated. The newly synthesized complexes have been characterized via elemental analysis, IR, Raman, 1H NMR, and UV-visible spectroscopy. The formation constant (KCT), molar extinction coefficient (εCT) and other spectroscopic data have been determined using the Benesi-Hildebrand method and its modifications. The sharp, well-defined Bragg reflections at specific 2θ angles have been identified from the powder X-ray diffraction patterns. Thermal decomposition behavior of these complexes was also studied, and their kinetic thermodynamic parameters were calculated with Coats-Redfern and Horowitz-Metzger equations.

Spectroscopic, microchemical and petrographic analyses of plasters from ancient buildings in Lamezia Terme (Calabria, Southern Italy)

NASA Astrophysics Data System (ADS)

De Luca, Raffaella; Gigliotti, Valentina; Panarello, Mario; Bloise, Andrea; Crisci, Gino M.; Miriello, Domenico

2016-01-01

This work shows the results of the spectroscopic, microchemical and petrographic study carried out on six plasters coming from three important residential buildings of the 18th century, located in Lamezia Terme (Catanzaro, Southern Italy). To study the provenance of the raw materials used to make the plasters, one sample of limestone and two samples of sand were also collected from the quarries near Lamezia Terme and compared with the historical plasters. Samples were studied by polarized optical microscopy (OM), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. The results of these analyses allowed to determine the mineralogical, petrographical and chemical characteristics of the plasters, identify the pigments used for their coloration and provide useful information about the building techniques, the raw materials employed and the production technology of plasters during the 18th century in Lamezia Terme. SEM-EDS microanalysis also revealed the presence of gold and silver on the surface of two samples.

Formation of CaB6 in the thermal decomposition of the hydrogen storage material Ca(BH4)2.

PubMed

Sahle, Christoph J; Sternemann, Christian; Giacobbe, Carlotta; Yan, Yigang; Weis, Christopher; Harder, Manuel; Forov, Yury; Spiekermann, Georg; Tolan, Metin; Krisch, Michael; Remhof, Arndt

2016-07-20

Using a combination of high resolution X-ray powder diffraction and X-ray Raman scattering spectroscopy at the B K- and Ca L2,3-edges, we analyzed the reaction products of Ca(BH4)2 after annealing at 350 °C and 400 °C under vacuum conditions. We observed the formation of nanocrystalline/amorphous CaB6 mainly and found only small contributions from amorphous B for annealing times larger than 2 h. For short annealing times of 0.5 h at 400 °C we observed neither CaB12H12 nor CaB6. The results indicate a reaction pathway in which Ca(BH4)2 decomposes to B and CaH2 and finally reacts to form CaB6. These findings confirm the potential of using Ca(BH4)2 as a hydrogen storage medium and imply the desired cycling capabilities for achieving high-density hydrogen storage materials.

Growth, structural, optical, thermal and dielectric properties of lanthanum chloride—thiourea—L tartaric acid coordinated complex

NASA Astrophysics Data System (ADS)

Slathia, Goldy; Bamzai, K. K.

2017-11-01

Lanthanum chloride—thiourea—l tartaric acid coordinated complex was grown in the form of single crystal by slow evaporation of supersaturated solutions at room temperature. This coordinated complex crystallizes in orthorhombic crystal system having space group P nma. The crystallinity and purity was tested by powder x-ray diffraction. Fourier transform infra red and Raman spectroscopy analysis provide the evidences on structure and mode of coordination. The scanning electron microscopy (SEM) analysis shows the morphology evolution as brought by the increase in composition of lanthanum chloride. The band transitions due to C=O and C=S chromophores remain active in grown complexes and are recorded in the UV-vis optical spectrum. The thermal effects such as dehydration, melting and decomposition were observed by the thermogravimetric and differential thermo analytical (TGA/DTA) analysis. Electrical properties were studied by dielectric analysis in frequency range 100-30 MHz at various temperatures. Increase in values of dielectric constant was observed with change in lanthanum concentration in the coordinated complex.

Temperature- and pressure-dependent structural transformation of methane hydrates in salt environments

NASA Astrophysics Data System (ADS)

Shin, Donghoon; Cha, Minjun; Yang, Youjeong; Choi, Seunghyun; Woo, Yesol; Lee, Jong-Won; Ahn, Docheon; Im, Junhyuck; Lee, Yongjae; Han, Oc Hee; Yoon, Ji-Ho

2017-03-01

Understanding the stability of volatile species and their compounds under various surface and subsurface conditions is of great importance in gaining insights into the formation and evolution of planetary and satellite bodies. We report the experimental results of the temperature- and pressure-dependent structural transformation of methane hydrates in salt environments using in situ synchrotron X-ray powder diffraction, solid-state nuclear magnetic resonance, and Raman spectroscopy. We find that under pressurized and concentrated brine solutions methane hydrate forms a mixture of type I clathrate hydrate, ice, and hydrated salts. Under a low-pressure condition, however, the methane hydrates are decomposed through a rapid sublimation of water molecules from the surface of hydrate crystals, while NaCl · 2H2O undergoes a phase transition into a crystal growth of NaCl via the migration of salt ions. In ambient pressure conditions, the methane hydrate is fully decomposed in brine solutions at temperatures above 252 K, the eutectic point of NaCl · 2H2O.

Synthesis and Characterization of Highly Intercalated Graphite Bisulfate.

PubMed

Salvatore, Marcella; Carotenuto, Gianfranco; De Nicola, Sergio; Camerlingo, Carlo; Ambrogi, Veronica; Carfagna, Cosimo

2017-12-01

Different chemical formulations for the synthesis of highly intercalated graphite bisulfate have been tested. In particular, nitric acid, potassium nitrate, potassium dichromate, potassium permanganate, sodium periodate, sodium chlorate, and hydrogen peroxide have been used in this synthesis scheme as the auxiliary reagent (oxidizing agent). In order to evaluate the presence of delamination, and pre-expansion phenomena, and the achieved intercalation degree in the prepared samples, the obtained graphite intercalation compounds have been characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), infrared spectroscopy (FT-IR), micro-Raman spectroscopy (μ-RS), and thermal analysis (TGA). Delamination and pre-expansion phenomena were observed only for nitric acid, sodium chlorate, and hydrogen peroxide, while the presence of strong oxidizers (KMnO 4 , K 2 Cr 2 O 7 ) led to stable graphite intercalation compounds. The largest content of intercalated bisulfate is achieved in the intercalated compounds obtained from NaIO 4 and NaClO 3 .

Microstructural Analysis of TiAl x N y O z Coatings Fabricated by DC Reactive Sputtering

NASA Astrophysics Data System (ADS)

García-González, L.; Hernández-Torres, J.; Flores-Ramírez, N.; Martínez-Castillo, J.; García-Ramírez, P. J.; Muñoz-Saldaña, J.; Espinoza-Beltrán, F. J.

2009-02-01

TiAl x N y O z coatings were prepared by DC reactive sputtering on AISI D2 tool steel substrates, using a target of Ti-Al-O fabricated from a mixture of powders of Ti (22.60 wt.%), Al (24.77 wt.%), and O (52.63 wt.%). The coatings were deposited on substrates at room temperature in a reactive atmosphere of nitrogen and argon under a pressure of 8.5 × 10-3 mbar. X-ray diffraction, electron dispersive spectroscopy, Raman scattering, and nanoindentation techniques were employed to investigate the coatings. The results show that the increment in the nitrogen flow affects the structure and the mechanical properties of the coatings. The sample with the lowest nitrogen flow presented the highest hardness (10.5 GPa) and the Young’s modulus (179.5 GPa). The hardness of the coatings TiAl x N y O z as a function of crystalline grain size shows a behavior consistent with the Hall-Petch relation.

Charge-transfer interaction of drug quinidine with quinol, picric acid and DDQ: Spectroscopic characterization and biological activity studies towards understanding the drug-receptor mechanism.

PubMed

Eldaroti, Hala H; Gadir, Suad A; Refat, Moamen S; Adam, Abdel Majid A

2014-04-01

Investigation of charge-transfer (CT) complexes of drugs has been recognized as an important phenomenon in understanding of the drug-receptor binding mechanism. Structural, thermal, morphological and biological behavior of CT complexes formed between drug quinidine (Qui) as a donor and quinol (QL), picric acid (PA) or dichlorodicyanobenzoquinone (DDQ) as acceptors were reported. The newly synthesized CT complexes have been spectroscopically characterized via elemental analysis; infrared (IR), Raman, 1 H NMR and electronic absorption spectroscopy; powder X-ray diffraction (PXRD); thermogravimetric (TG) analysis and scanning electron microscopy (SEM). It was found that the obtained complexes are nanoscale, semi-crystalline particles, thermally stable and spontaneous. The molecular composition of the obtained complexes was determined using spectrophotometric titration method and was found to be 1:1 ratios (donor:acceptor). Finally, the biological activities of the obtained CT complexes were tested for their antibacterial activities. The results obtained herein are satisfactory for estimation of drug Qui in the pharmaceutical form.

The Fabrication and High-Efficiency Electromagnetic Wave Absorption Performance of CoFe/C Core-Shell Structured Nanocomposites

NASA Astrophysics Data System (ADS)

Wan, Gengping; Luo, Yongming; Wu, Lihong; Wang, Guizhen

2018-03-01

CoFe/C core-shell structured nanocomposites (CoFe@C) have been fabricated through the thermal decomposition of acetylene with CoFe2O4 as precursor. The as-prepared CoFe@C was characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and thermogravimetric analysis. The results demonstrate that the carbon shell in CoFe@C has a poor crystallization with a thickness about 5-30 nm and a content approximately 48.5 wt.%. Due to a good combination between intrinsic magnetic properties and high-electrical conductivity, the CoFe@C exhibits not only excellent absorption intensity but also wide frequency bandwidth. The minimum RL value of CoFe@C can reach - 44 dB at a thickness of 4.0 mm, and RL values below - 10 dB is up to 4.3 GHz at a thickness of 2.5 mm. The present CoFe@C may be a potential candidate for microwave absorption application.

Vibrational microspectroscopic identification of powdered traditional medicines: Chemical micromorphology of Poria observed by infrared and Raman microspectroscopy

NASA Astrophysics Data System (ADS)

Chen, Jian-bo; Sun, Su-qin; Ma, Fang; Zhou, Qun

2014-07-01

Microscopic identification using optical microscopes is a simple and effective method to identify powdered traditional medicines made from plants, animals and fungi. Sometimes, the criteria based on physical properties of the microscopic characteristics of drug powder may be ambiguous, which makes the microscopic identification method subjective and empirical to some extent. In this research, the vibrational microspectroscopic identification method is proposed for more explicit discrimination of powdered traditional medicines. The chemical micromorphology, i.e., chemical compositions and related physical morphologies, of the drug powder can be profiled objectively and quantitatively by infrared and Raman microspectroscopy, leading to better understanding about the formation mechanisms of microscopic characteristics and more accurate identification criteria. As an example, the powder of Poria, which is one of the most used traditional Chinese medicines, is studied in this research. Three types of hyphae are classified according to their infrared spectral features in the region from 1200 to 900 cm-1. Different kinds of polysaccharides indicate that these hyphae may be in different stages of the growth. The granular and branched clumps observed by the optical microscope may be formed from the aggregation of the mature hyphae with β-D-glucan reserves. The newfound spherical particles may originate from the exuded droplets in the fresh Poria because they are both composed of α-D-glucan. The results are helpful to understand the development of the hyphae and the formation of active polysaccharides in Poria and to establish accurate microspectroscopic identification criteria.

Crystal structure of hydrocortisone acetate, C23H32O6

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaduk, James A.; Gindhart, Amy M.; Blanton, Thomas N.

The crystal structure of hydrocortisone acetate has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Hydrocortisone acetate crystallizes in space groupP2 1(#4) witha= 8.85173(3) Å,b= 13.53859(3) Å,c= 8.86980(4) Å,β= 101.5438(3)°,V= 1041.455(6) Å 3, andZ= 2. Both hydroxyl groups form hydrogen bonds to the ketone oxygen atom on the steroid ring system, resulting in a three-dimensional hydrogen bond network. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™.

Vibrations and reorientations of H2O molecules in [Sr(H2O)6]Cl2 studied by Raman light scattering, incoherent inelastic neutron scattering and proton magnetic resonance.

PubMed

Hetmańczyk, Joanna; Hetmańczyk, Lukasz; Migdał-Mikuli, Anna; Mikuli, Edward; Florek-Wojciechowska, Małgorzata; Harańczyk, Hubert

2014-04-24

Vibrational-reorientational dynamics of H2O ligands in the high- and low-temperature phases of [Sr(H2O)6]Cl2 was investigated by Raman Spectroscopy (RS), proton magnetic resonance ((1)H NMR), quasielastic and inelastic incoherent Neutron Scattering (QENS and IINS) methods. Neutron powder diffraction (NPD) measurements, performed simultaneously with QENS, did not indicated a change of the crystal structure at the phase transition (detected earlier by differential scanning calorimetry (DSC) at TC(h)=252.9 K (on heating) and at TC(c)=226.5K (on cooling)). Temperature dependence of the full-width at half-maximum (FWHM) of νs(OH) band at ca. 3248 cm(-1) in the RS spectra indicated small discontinuity in the vicinity of phase transition temperature, what suggests that the observed phase transition may be associated with a change of the H2O reorientational dynamics. However, an activation energy value (Ea) for the reorientational motions of H2O ligands in both phases is nearly the same and equals to ca. 8 kJ mol(-1). The QENS peaks, registered for low temperature phase do not show any broadening. However, in the high temperature phase a small QENS broadening is clearly visible, what implies that the reorientational dynamics of H2O ligands undergoes a change at the phase transition. (1)H NMR line is a superposition of two powder Pake doublets, differentiated by a dipolar broadening, suggesting that there are two types of the water molecules in the crystal lattice of [Sr(H2O)6]Cl2 which are structurally not equivalent average distances between the interacting protons are: 1.39 and 1.18 Å. However, their reorientational dynamics is very similar (τc=3.3⋅10(-10) s). Activation energies for the reorientational motion of these both kinds of H2O ligands have nearly the same values in an experimental error limit: and equal to ca. 40 kJ mole(-1). The phase transition is not seen in the (1)H NMR spectra temperature dependencies. Infrared (IR), Raman (RS) and inelastic incoherent neutron scattering (IINS) spectra were calculated by the DFT method and quite a good agreement with the experimental data was obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

Two-dimensional strain-mapping by electron backscatter diffraction and confocal Raman spectroscopy

NASA Astrophysics Data System (ADS)

Gayle, Andrew J.; Friedman, Lawrence H.; Beams, Ryan; Bush, Brian G.; Gerbig, Yvonne B.; Michaels, Chris A.; Vaudin, Mark D.; Cook, Robert F.

2017-11-01

The strain field surrounding a spherical indentation in silicon is mapped in two dimensions (2-D) using electron backscatter diffraction (EBSD) cross-correlation and confocal Raman spectroscopy techniques. The 200 mN indentation created a 4 μm diameter residual contact impression in the silicon (001) surface. Maps about 50 μm × 50 μm area with 128 pixels × 128 pixels were generated in several hours, extending, by comparison, assessment of the accuracy of both techniques to mapping multiaxial strain states in 2-D. EBSD measurements showed a residual strain field dominated by in-surface normal and shear strains, with alternating tensile and compressive lobes extending about three to four indentation diameters from the contact and exhibiting two-fold symmetry. Raman measurements showed a residual Raman shift field, dominated by positive shifts, also extending about three to four indentation diameters from the contact but exhibiting four-fold symmetry. The 2-D EBSD results, in combination with a mechanical-spectroscopic analysis, were used to successfully predict the 2-D Raman shift map in scale, symmetry, and shift magnitude. Both techniques should be useful in enhancing the reliability of microelectromechanical systems (MEMS) through identification of the 2-D strain fields in MEMS devices.

Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mangum, John S.; Chan, Lisa H.; Schmidt, Ute

Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In thismore » work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice.« less

Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs.

PubMed

Mangum, John S; Chan, Lisa H; Schmidt, Ute; Garten, Lauren M; Ginley, David S; Gorman, Brian P

2018-05-01

Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In this work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice. Copyright © 2018 Elsevier B.V. All rights reserved.

Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs

DOE PAGES

Mangum, John S.; Chan, Lisa H.; Schmidt, Ute; ...

2018-02-23

Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In thismore » work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice.« less

Neutron and X-ray powder diffraction study of skutterudite thermoelectrics

DOE PAGES

Wang, H.; Kirkham, M. J.; Watkins, T. R.; ...

2016-02-17

N- and p-type filled-skutterudite materials prepared for thermoelectric power generation modules were analyzed by neutron diffraction at the POWGEN beam line of the Spallation Neutron Source (SNS) and X-ray diffraction (XRD). The skutterudite powders were processed by melt spinning, followed by ball milling and annealing. The n-type material consists of Ba–Yb–Co–Sb and the p-type material consists of Di–Fe–Ni–Sb or Di–Fe–Co–Sb (Di = didymium, an alloy of Pr and Nd). Powders for prototype module fabrication from General Motors and Marlow Industries were analyzed in this study. XRD and neutron diffraction studies confirm that both the n- and p-type materials have cubicmore » symmetry. Structural Rietveld refinements determined the lattice parameters and atomic parameters of the framework and filler atoms. The cage filling fraction was found to depend linearly on the lattice parameter, which in turn depends on the average framework atom size. Ultimately, this knowledge may allow the filling fraction of these skutterudite materials to be purposefully adjusted, thereby tuning the thermoelectric properties.« less

Synthesis of cerium oxide (CeO 2) by co-precipitation for application as a reference material for X-ray powder diffraction peak widths

DOE Office of Scientific and Technical Information (OSTI.GOV)

de Lima Batista, Anderson Márcio; Miranda, Marcus Aurélio Ribeiro; Martins, Fátima Itana Chaves Custódio

Several methods can be used to obtain, from powder diffraction patterns, crystallite size and lattice strain of polycrystalline samples. Some examples are the Scherrer equation, Williamson–Hall plots, Warren/Averbach Fourier decomposition, Whole Powder Pattern Modeling, and Debye function analysis. To apply some of these methods, it is necessary to remove the contribution of the instrument to the widths of the diffraction peaks. Nowadays, one of the main samples used for this purpose is the LaB6 SRM660b commercialized by the National Institute of Standard Technology; the width of the diffraction peak of this sample is caused only by the instrumental apparatus. However,more » this sample can be expensive for researchers in developing countries. In this work, the authors present a simple route to obtain micron-sized polycrystalline CeO 2that have a full width at half maximum comparable with the SRM660b and therefore it can be used to remove instrumental broadening.« less

Pressure-induced structural transition in chalcopyrite ZnSiP 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhadram, Venkata S.; Krishna, Lakshmi; Toberer, Eric S.

The pressure-dependent phase behavior of semiconducting chalcopyrite ZnSiP 2 was studied up to 30 GPa using in situ X-ray diffraction and Raman spectroscopy in a diamond-anvil cell. A structural phase transition to the rock salt type structure was observed between 27 and 30 GPa, which is accompanied by soft phonon mode behavior and simultaneous loss of Raman signal and optical transmission through the sample. The high-pressure rock salt type phase possesses cationic disorder as evident from broad features in the X-ray diffraction patterns. The behavior of the low-frequency Raman modes during compression establishes a two-stage, order-disorder phase transition mechanism. Themore » phase transition is partially reversible, and the parent chalcopyrite structure coexists with an amorphous phase upon slow decompression to ambient conditions.« less

N-Sulfinylimine compounds, R-NSO: a chemistry family with strong temperament

NASA Astrophysics Data System (ADS)

Romano, R. M.; Della Védova, C. O.

2000-04-01

In this review, an update on the structural properties and theoretical studies of N-sulfinylimine compounds (R-NSO) is reported. They were deduced using several experimental techniques: gas-electron diffraction (GED), X-ray diffraction, 17O NMR, ultraviolet-visible absorption spectroscopy (UV-Vis), FTIR (including matrix studies of molecular randomisation) and Raman (including pre-resonant Raman spectra). Data are compared with those obtained by theoretical calculations. With these tools, excited state geometry using the time-dependent theory was calculated for these kinds of compounds. The existence of pre-resonant Raman effect was reported recently for R-NSO compounds. The configuration of R-NSO compounds was checked for this series confirming the existence of only one syn configuration. This finding is corroborated by theoretical calculations. The method of preparation is also summarised.

Direct and continuous synthesis of VO2 nanoparticles

NASA Astrophysics Data System (ADS)

Powell, M. J.; Marchand, P.; Denis, C. J.; Bear, J. C.; Darr, J. A.; Parkin, I. P.

2015-11-01

Monoclinic VO2 nanoparticles are of interest due to the material's thermochromic properties, however, direct synthesis routes to VO2 nanoparticles are often inaccessible due to the high synthesis temperatures or long reaction times required. Herein, we present a two-step synthesis route for the preparation of monoclinic VO2 nanoparticles using Continuous Hydrothermal Flow Synthesis (CHFS) followed by a short post heat treatment step. A range of particle sizes, dependent on synthesis conditions, were produced from 50 to 200 nm by varying reaction temperatures and the residence times in the process. The nanoparticles were characterised by powder X-ray diffraction, Raman and UV/Vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The nanoparticles were highly crystalline with rod and sphere-like morphologies present in TEM micrographs, with the size of both the rod and spherical particles being highly dependent on both reaction temperature and residence time. SEM micrographs showed the surface of the powders produced from the CHFS process to be highly uniform. The samples were given a short post synthesis heat treatment to ensure that they were phase pure monoclinic VO2, which led to them exhibiting a large and reversible switch in optical properties (at near-IR wavelengths), which suggests that if such materials can be incorporated into coatings or in composites, they could be used for fenestration in architectural applications.

Direct and continuous synthesis of VO2 nanoparticles.

PubMed

Powell, M J; Marchand, P; Denis, C J; Bear, J C; Darr, J A; Parkin, I P

2015-11-28

Monoclinic VO2 nanoparticles are of interest due to the material's thermochromic properties, however, direct synthesis routes to VO2 nanoparticles are often inaccessible due to the high synthesis temperatures or long reaction times required. Herein, we present a two-step synthesis route for the preparation of monoclinic VO2 nanoparticles using Continuous Hydrothermal Flow Synthesis (CHFS) followed by a short post heat treatment step. A range of particle sizes, dependent on synthesis conditions, were produced from 50 to 200 nm by varying reaction temperatures and the residence times in the process. The nanoparticles were characterised by powder X-ray diffraction, Raman and UV/Vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The nanoparticles were highly crystalline with rod and sphere-like morphologies present in TEM micrographs, with the size of both the rod and spherical particles being highly dependent on both reaction temperature and residence time. SEM micrographs showed the surface of the powders produced from the CHFS process to be highly uniform. The samples were given a short post synthesis heat treatment to ensure that they were phase pure monoclinic VO2, which led to them exhibiting a large and reversible switch in optical properties (at near-IR wavelengths), which suggests that if such materials can be incorporated into coatings or in composites, they could be used for fenestration in architectural applications.

Earth, soil and environmental science research facility at sector 13 of the Advanced Photon Source. II. Scientific program and experimental instrumentation (abstract)

NASA Astrophysics Data System (ADS)

Sutton, S.; Eng., P. J.; Jaski, Y. R.; Lazaraz, N.; Pluth, J.; Murray, P.; Rarback, H.; Rivers, M.

1996-09-01

The GSECARS (APS sector 13) scientific program will provide fundamental new information on the deep structure and composition of the Earth and other planets, the formation of economic mineral deposits, the cycles and fate of toxic metals in the environment, and the mechanisms of nutrient uptake and disease in plants. In the four experimental stations (2 per beamline), scientists will have access to three main x-ray techniques: diffraction (microcrystal, powder, diamond anvil cell, and large volume press), fluorescence microprobe, and spectroscopy (conventional, microbeam, liquid and solid surfaces). The high pressure facilities will be capable of x-ray crystallography at P≳360 GPa and T˜6000 K with the diamond anvil cell and P˜25 GPa and T˜2500 °C with the large volume press. Diffractometers will allow study of 1 micrometer crystals and micro-powders. The microprobe (1 micrometer focused beam) will be capable of chemical analyses in the sub-ppm range using wavelength and energy dispersive detectors. Spectroscopy instrumentation will be available for XANES and EXAFS with microbeams as well as high sensitivity conventional XAS and studies of liquid and solid interfaces. Visiting scientists will be able to setup, calibrate, and test experiments in off-line laboratories with equipment such as micromanipulators, optical microscopes, clean bench, glove boxes, high powered optical and Raman spectrometers.

On the synthesis of tailored biomimetic hydroxyapatite nanoplates through a bioinspired approach in the presence of collagen or chitosan and L-arginine.

PubMed

Tsetsekou, A; Brasinika, D; Vaou, V; Chatzitheodoridis, E

2014-10-01

Controlling the structure of hydroxyapatite nanocrystals is vital for acquiring a consistent product. In an effort to synthesize crystals mimicking the morphology of natural bone's apatite, a bioinspired process was developed based on the use of a natural biomacromolecule, collagen or chitosan, in conjunction with l-arginine to direct the formation of hydroxyapatite from H3PO4 and Ca(OH)2. Different cases were investigated by employing various concentrations of the precursors and two molar ratios of Ca/P 1/1 and 10/6. The reaction was carried out at basic pH conditions and at biomimetic temperature (40°C). The resulting aqueous suspensions were characterized in terms of their rheological behavior, whereas the derived powders were fully evaluated by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis and Raman spectroscopy. The analysis showed that in all cases, the only phase detected was hydroxyapatite of a plate-like morphology very similar to that of natural apatite. The homogeneity of the morphology and the crystal size distribution depend on the precursors' final concentration with the mean size ranging from 5 nm up to 20 nm. The powder that demonstrated the best characteristics in terms of homogeneity was that produced in the presence of collagen for molar ratio of Ca/P 1/1. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of magnetic domain state of carbon coated iron nanoparticles via 57Fe zero-external-field NMR

NASA Astrophysics Data System (ADS)

Manjunatha, M.; Kumar, Rajeev; Sahoo, Balaram; Damle, Ramakrishna; Ramesh, K. P.

2018-05-01

The magnetic domain state of carbon coated iron nanopowder (Fe@C) was studied by the internal field nuclear magnetic resonance (IFNMR) at 77 K using the spin echo technique. The structure and magnetic properties of the sample were further characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Mössbauer spectroscopy, vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA) and Raman Spectroscopy. The obtained IFNMR results of Fe@C powder were compared with that of micron sized carbonyl iron (CI) and electrolytic iron (EI) powders. The calculated critical size of the single domain iron particles in Fe@C is ∼ 16 nm. A higher enhancement in echo amplitude was observed due to better response of the domain walls of multidomain particles in comparison to the single domain particles. The echo signal of CI and EI particles exhibit a single narrow intense peak corresponding to the domain walls, whereas Fe@C exhibits two low amplitude peaks at two different frequencies: a low frequency (46.6 MHz) peak corresponds to the response of the domain walls of the multidomain particles and the other high frequency (47.2 MHz) signal (a shoulder) corresponding to the response of the magnetic nuclei inside the domain. Our results help in determining the domain state of iron-based magnetic particles using 57Fe-IFNMR.

A comparative structural study of wet and dried ettringite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Renaudin, G.; CNRS, UMR 6002, LMI, F-63177 Aubiere; Filinchuk, Y.

2010-03-15

Two different techniques were used to compare structural characteristics of 'wet' ettringite (stored in the synthesis mother liquid) and 'dried' ettringite (dried to 35% relative humidity over saturated CaCl{sub 2} solution). Lattice parameters and the water content in the channel region of the structure (site occupancy factor of the water molecule not bonded to cations) as well as microstructure parameters (size and strain) were determined from a Rietveld refinement on synchrotron powder diffraction data. Local environment of sulphate anions and of the hydrogen bonding network was characterized by Raman spectroscopy. Both techniques led to the same conclusion: the 'wet' ettringitemore » sample immersed in the mother solution from the synthesis presents similar structural features as ettringite dried to 35% relative humidity. An increase of the a lattice parameter combined with a decrease of the c lattice parameter occurs on drying. The amount of structural water, the point symmetry of sulphate and the hydrogen bond network are unchanged when passing from the wet to the dried ettringite powder. Ettringite does not form a high-hydrate polymorph in equilibrium with alkaline solution, in contrast to the AFm phases that lose water molecules on drying. According to these results we conclude that ettringite precipitated in aqueous solution at the early hydration stages is of the same chemical composition as ettringite present in the hardening concrete.« less

Formation of graphitic carbon nitride and boron carbon nitride film on sapphire substrate

NASA Astrophysics Data System (ADS)

Kosaka, Maito; Urakami, Noriyuki; Hashimoto, Yoshio

2018-02-01

As a novel production method of boron carbon nitride (BCN) films, in this paper, we present the incorporation of B into graphitic carbon nitride (g-C3N4). First, we investigated the formation of g-C3N4 films via chemical vapor deposition (CVD) using melamine powder as the precursor. The formation of g-C3N4 films on a c-plane sapphire substrate was confirmed by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman spectroscopy measurements. The deposition temperature of g-C3N4 films was found to be suitable between 550 and 600 °C since the degradation and desorption of hexagonal C-N bonds should be suppressed. As for BCN films, we prepared BCN films via two-zone extended CVD using ammonia borane as the B precursor. Several XPS signals from B, C, and N core levels were detected from B-incorporated g-C3N4 films. While the N composition was almost constant, the marked tendencies for increasing B composition and decreasing C composition were achieved with the increase in the B incorporation, indicating the incorporation of B atoms by the substitution for C atoms. Optical absorptions were shifted to the high-energy side by B incorporation, which indicates the successful formation of BCN films using melamine and ammonia borane powders as precursors.

High-Yield Preparation and Electrochemical Properties of Few-Layer MoS2 Nanosheets by Exfoliating Natural Molybdenite Powders Directly via a Coupled Ultrasonication-Milling Process

NASA Astrophysics Data System (ADS)

Dong, Huina; Chen, Deliang; Wang, Kai; Zhang, Rui

2016-09-01

Cost-effective and scalable preparation of two-dimensional (2D) molybdenum disulfide (MoS2) has been the bottleneck that limits their applications. This paper reports a novel coupled ultrasonication-milling (CUM) process to exfoliate natural molybdenite powders to achieve few-layer MoS2 (FL-MoS2) nanosheets in the solvent of N-methyl-2-pyrrolidone (NMP) with polyvinylpyrrolidone (PVP) molecules. The synergistic effect of ultrasonication and sand milling highly enhanced the exfoliation efficiency, and the precursor of natural molybdenite powders minimizes the synthetic cost of FL-MoS2 nanosheets. The exfoliation of natural molybdenite powders was conducted in a home-made CUM system, mainly consisting of an ultrasonic cell disruptor and a ceramic sand mill. The samples were characterized by X-ray diffraction, UV-vis spectra, Raman spectra, FT-IR, SEM, TEM, AFM, and N2 adsorption-desorption. The factors that influence the exfoliation in the CUM process, including the initial concentration of natural molybdenite powders ( C in, 15-55 g L-1), ultrasonic power ( P u, 200-350 W), rotation speed of sand mill ( ω s, 1500-2250 r.p.m), exfoliation time ( t ex, 0.5-6 h), and the molar ratio of PVP unit to MoS2 ( R pm, 0-1), were systematically investigated. Under the optimal CUM conditions (i.e., C in = 45 g L-1, P u = 280 W, ω s = 2250 r.p.m and R pm = 0.5), the yield at t ex = 6 h reaches 21.6 %, and the corresponding exfoliation rate is as high as 1.42 g L-1 h-1. The exfoliation efficiency of the CUM mode is much higher than that of either the ultrasonication (U) mode or the milling (M) mode. The synergistic mechanism and influencing rules of the CUM process in exfoliating natural molybdenite powders were elaborated. The as-obtained FL-MoS2 nanosheets have a high specific surface area of 924 m2 g-1 and show highly enhanced electrocatalytic performance in hydrogen evolution reaction and good electrochemical sensing property in detecting ascorbic acid. The CUM process developed has paved a low-cost, green, and highly efficient way towards FL-MoS2 nanosheets from natural molybdenite powders.

Addressing the amorphous content issue in quantitative phase analysis : the certification of NIST SRM 676a.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cline, J. P.; Von Dreele, R. B.; Winburn, R.

2011-07-01

A non-diffracting surface layer exists at any boundary of a crystal and can comprise a mass fraction of several percent in a finely divided solid. This has led to the long-standing issue of amorphous content in standards for quantitative phase analysis (QPA). NIST standard reference material (SRM) 676a is a corundum ({alpha}-Al{sub 2}O{sub 3}) powder, certified with respect to phase purity for use as an internal standard in powder diffraction QPA. The amorphous content of SRM 676a is determined by comparing diffraction data from mixtures with samples of silicon powders that were engineered to vary their specific surface area. Undermore » the (supported) assumption that the thickness of an amorphous surface layer on Si was invariant, this provided a method to control the crystalline/amorphous ratio of the silicon components of 50/50 weight mixtures of SRM 676a with silicon. Powder diffraction experiments utilizing neutron time-of-flight and 25 keV and 67 keV X-ray energies quantified the crystalline phase fractions from a series of specimens. Results from Rietveld analyses, which included a model for extinction effects in the silicon, of these data were extrapolated to the limit of zero amorphous content of the Si powder. The certified phase purity of SRM 676a is 99.02% {+-} 1.11% (95% confidence interval). This novel certification method permits quantification of amorphous content for any sample of interest, by spiking with SRM 676a.« less

Addressing the Amorphous Content Issue in Quantitative Phase Analysis: The Certification of NIST Standard Reference Material 676a

DOE Office of Scientific and Technical Information (OSTI.GOV)

J Cline; R Von Dreele; R Winburn

2011-12-31

A non-diffracting surface layer exists at any boundary of a crystal and can comprise a mass fraction of several percent in a finely divided solid. This has led to the long-standing issue of amorphous content in standards for quantitative phase analysis (QPA). NIST standard reference material (SRM) 676a is a corundum ({alpha}-Al{sub 2}O{sub 3}) powder, certified with respect to phase purity for use as an internal standard in powder diffraction QPA. The amorphous content of SRM 676a is determined by comparing diffraction data from mixtures with samples of silicon powders that were engineered to vary their specific surface area. Undermore » the (supported) assumption that the thickness of an amorphous surface layer on Si was invariant, this provided a method to control the crystalline/amorphous ratio of the silicon components of 50/50 weight mixtures of SRM 676a with silicon. Powder diffraction experiments utilizing neutron time-of-flight and 25 keV and 67 keV X-ray energies quantified the crystalline phase fractions from a series of specimens. Results from Rietveld analyses, which included a model for extinction effects in the silicon, of these data were extrapolated to the limit of zero amorphous content of the Si powder. The certified phase purity of SRM 676a is 99.02% {+-} 1.11% (95% confidence interval). This novel certification method permits quantification of amorphous content for any sample of interest, by spiking with SRM 676a.« less

Additional evidence from x-ray powder diffraction patterns that icosahedral quasi-crystals of intermetallic compounds are twinned cubic crystals

PubMed Central

Pauling, Linus

1988-01-01

Analysis of the measured values of Q for the weak peaks (small maxima, usually considered to be background fluctuations, “noise”) on the x-ray powder diffraction curves for 17 rapidly quenched alloys leads directly to the conclusion that they are formed by an 820-atom or 1012-atom primitive cubic structure that by icosahedral twinning produces the so-called icosahedral quasi-crystals. PMID:16593948

Test and Delivery of the Chemin Mineralogical Instrument for Mars Science Laboratory

NASA Technical Reports Server (NTRS)

Blake, D. F.; Vaniman, D.; Anderson, R.; Bish, D.; Chipera, S.; Chemtob, S.; Crisp, J.; DesMarais, D. J.; Downs, R.; Feldman, S.;

Melting point suppression in new lanthanoid(III) ionic liquids by trapping of kinetic polymorphs: an in situ synchrotron powder diffraction study.

PubMed

Chesman, Anthony S R; Yang, Mei; Mallick, Bert; Ross, Tamsyn M; Gass, Ian A; Deacon, Glen B; Batten, Stuart R; Mudring, Anja-Verena

2012-01-04

The complexes (N(4444))(3)[Ln(dcnm)(6)] (Ln = La-Nd, Sm; N(4444) = tetrabutylammonium) display a decrease in the melting point upon fast cooling from a melt, which is shown by in situ synchrotron based X-ray powder diffraction to be due to the formation of a second, less thermodynamically stable, polymorph. This journal is © The Royal Society of Chemistry 2012

Identification of copper phthalocyanine blue polymorphs in unaged and aged paint systems by means of micro-Raman spectroscopy and Random Forest.

PubMed

Anghelone, Marta; Jembrih-Simbürger, Dubravka; Schreiner, Manfred

2015-10-05

Copper phthalocyanine (CuPc) blues (PB15) are largely used in art and industry as pigments. In these fields mainly three different polymorphic modifications of PB15 are employed: alpha, beta and epsilon. Differentiating among these CuPc forms can give important information for developing conservation strategy and can help in relative dating, since each form was introduced in the market in different time periods. This study focuses on the classification of Raman spectra measured using 532 nm excitation wavelength on: (i) dry pigment powders, (ii) unaged mock-ups of self-made paints, (iii) unaged commercial paints, and (iv) paints subjected to accelerated UV ageing. The ratios among integrated Raman bands are taken in consideration as features to perform Random Forest (RF). Features selection based on Gini Contrast score was carried out on the measured dataset to determine the Raman bands ratios with higher predictive power. These were used as polymorphic markers, in order to establish an easy and accessible method for the identification. Three different ratios and the presence of a characteristic vibrational band allowed the identification of the crystal modification in pigments powder as well as in unaged and aged paint films. Copyright © 2015 Elsevier B.V. All rights reserved.

Structural and Spectral Properties of Curcumin and Metal- Curcumin Complex Derived from Turmeric (Curcuma longa)

NASA Astrophysics Data System (ADS)

Bich, Vu Thi; Thuy, Nguyen Thi; Binh, Nguyen Thanh; Huong, Nguyen Thi Mai; Yen, Pham Nguyen Dong; Luong, Tran Thanh

Structural and spectral properties of curcumin and metal- curcumin complex derived from turmeric (Curcuma longa) were studied by SEM and vibrational (FTIR and Raman) techniques. By comparison between curcumin commercial, fresh turmeric and a yellow powder obtained via extraction and purification of turmeric, we have found that this insoluble powder in water is curcumin. The yellow compound could complex with certain ion metal and this metal-curcumin coloring complex is water soluble and capable of producing varying hues of the same colors and having antimicrobial, cytotoxicity activities for use in foodstuffs and pharmacy. The result also demonstrates that Micro-Raman spec-troscopy is a valuable non-destructive tool and fast for investigation of a natural plant even when occurring in low concentrations.

Raman spectroscopic analysis of real samples: Brazilian bauxite mineralogy

NASA Astrophysics Data System (ADS)

Faulstich, Fabiano Richard Leite; Castro, Harlem V.; de Oliveira, Luiz Fernando Cappa; Neumann, Reiner

2011-10-01

In this investigation, Raman spectroscopy with 1064 and 632.8 nm excitation was used to investigate real mineral samples of bauxite ore from mines of Northern Brazil, together with Raman mapping and X-rays diffraction. The obtained results show clearly that the use of microRaman spectroscopy is a powerful tool for the identification of all the minerals usually found in bauxites: gibbsite, kaolinite, goethite, hematite, anatase and quartz. Bulk samples can also be analysed, and FT-Raman is more adequate due to better signal-to-noise ratio and representativity, although not efficient for kaolinite. The identification of fingerprinting vibrations for all the minerals allows the acquisition of Raman-based chemical maps, potentially powerful tools for process mineralogy applied to bauxite ores.

Clifford G. Shull, Neutron Diffraction, Hydrogen Atoms, and Neutron

Science.gov Websites

Analysis of NaH and NaD, DOE Technical Report, April 1947 The Diffraction of Neutrons by Crystalline Powders; DOE Technical Report; 1948 Neutron Diffraction Studies, DOE Technical Report, 1948 Laue Structure of Thorium and Zirconium Dihydrides by X-ray and Neutron Diffraction, DOE Technical Report, April

Near-Field Scanning Optical Microscopy and Raman Microscopy.

NASA Astrophysics Data System (ADS)

Harootunian, Alec Tate

1987-09-01

Both a one dimensional near-field scanning optical microscope and Raman microprobe were constructed. In near -field scanning optical microscopy (NSOM) a subwavelength aperture is scanned in the near-field of the object. Radiation transmitted through the aperture is collected to form an image as the aperture scans over the object. The resolution of an NSOM system is essentially wavelength independent and is limited by the diameter of the aperture used to scan the object. NSOM was developed in an effort to provide a nondestructive in situ high spatial resolution probe while still utilizing photons at optical wavelengths. The Raman microprobe constructed provided vibrational Raman information with spatial resolution equivalent that of a conventional diffraction limited microscope. Both transmission studies and near-field diffration studies of subwavelength apertures were performed. Diffraction theories for a small aperture in an infinitely thin conducting screen, a slit in a thick conducting screen, and an aperture in a black screen were examined. All three theories indicate collimation of radiation to the size to the size of the subwavelength aperture or slit in the near-field. Theoretical calculations and experimental results indicate that light transmitted through subwavelength apertures is readily detectable. Light of wavelength 4579 (ANGSTROM) was transmitted through apertures with diameters as small as 300 (ANGSTROM). These studies indicate the feasibility of constructing an NSOM system. One dimensional transmission and fluorescence NSOM systems were constructed. Apertures in the tips of metallized glass pipettes width inner diameters of less than 1000 (ANGSTROM) were used as a light source in the NSOM system. A tunneling current was used to maintain the aperture position in the near-field. Fluorescence NSOM was demonstrated for the first time. Microspectroscopic and Raman microscopic studies of turtle cone oil droplets were performed. Both the Raman vibrational frequencies and the Raman excitation data indicate that the carotenoids are unaggregated. The carotenoid astaxanthin was identified in the orange and red droplets by Raman microscopy. Future applications for both Raman microscopy and near-field microscopy were proposed. Four methods of near-field distance regulation were also examined. Finally, theoretical exposure curves for near-field lithography were calculated. Both the near-field lithographic results and the near field diffraction studies indicate essentially wavelength independent resolution. (Abstract shortened with permission of author.).

Effects of Zr/Ce molar ratio and water content on thermal stability and structure of ZrO{sub 2}–CeO{sub 2} mixed oxides prepared via sol–gel process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Wenzhi; Yang, Jili; Wang, Chunjie

2012-09-15

Highlights: ► Tetragonal t″ phase was stabilized in Zr{sub 0.5}Ce{sub 0.5}O{sub 2} solid solution at temperature as high as 1000 °C. ► Specific surface area of powders decreased with the increase of water addition and the Ce content. ► The single stable phase was controlled by adjusting the volume ratio of water and ethanol. ► Tetragonal (t″) phase dissociated into cubic and tetragonal (t′) phases at 1200 °C. -- Abstract: ZrO{sub 2}–CeO{sub 2} mixed oxides were synthesized via sol–gel process. Thermal stability, structure and morphology of samples were investigated by powder X-ray diffraction, FT-Raman spectroscopy, X-ray photoelectron spectroscopy and scanningmore » electron microscopy. In this approach, the solvent composition and Zr/Ce molar ratio have great influences on the structure and morphology of final products. With decreasing water content in the mixed solvent, specific surface area of powders increased and the single tetragonal phase was obtained. Only when the volume ratio of water and ethanol and the Zr/Ce molar ratio were 1:1, tetragonal t″-Zr{sub 0.5}Ce{sub 0.5}O{sub 2} could be stabilized in powders at temperature as high as 1000 °C. Meanwhile, tetragonal (t′) and (t″) phases coexisted in Zr{sub 0.5}Ce{sub 0.5}O{sub 2} solid solution without peak splitting after calcination at 1100 °C, further transforming into cubic and tetragonal (t′) phases at 1200 °C. The effective activation energy for Zr{sub 0.5}Ce{sub 0.5}O{sub 2} nanocrystallite growth during annealing is about 5.24 ± 0.15 kJ/mol.« less

Effect of powder compaction on radiation-thermal synthesis of lithium-titanium ferrites

NASA Astrophysics Data System (ADS)

Surzhikov, A. P.; Lysenko, E. N.; Vlasov, V. A.; Malyshev, A. V.; Korobeynikov, M. V.; Mikhailenko, M. A.

2017-01-01

Effect of powder compaction on the efficiency of thermal and radiation-thermal synthesis of lithium-substituted ferrites was investigated by X-Ray diffraction and specific magnetization analysis. It was shown that the radiation-thermal heating of compacted powder reagents mixture leads to an increase in efficiency of lithium-titanium ferrites synthesis.

Synthesis of nano-forsterite powder by making use of natural silica sand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nurbaiti, Upik, E-mail: upik-nurbaiti@mail.unnes.ac.id; Department of Physics, Faculty of Mathematics and Natural Sciences Semarang State University Jl. Raya Sekaran GunungPati, Semarang 50221; Suud, Fikriyatul Azizah

2016-02-08

Nano-forsterite powder with natural silica sand and magnesium powder as the raw materials have been succesfully synthesized. The silica sand was purified followed by a coprecipitation process to obtain colloidal silica. The magnesium powder was dissolved in a chloric acid solution to obtain MgCl{sub 2} solution. The nanoforsterite powder was synthesised using a sol-gel method which included the mixing the colloidal silica and the MgCl{sub 2} solution with various aging and filtering processes. The samples were dried at 100 °C using a hot plate and then the dried powders were calcinated at 900 °C for 2 hours. The samples weremore » characetised for their elements and phase compositions using X-ray Flourescence (XRF) and X-ray Diffraction (XRD) methods, respectively. The diffraction data were qualitatively analyzed using Match!2 software and quantitatively using Rietica software. The crystallite size was verified using Transmission Electron Microscopy (TEM). Results of XRD data analysis showed that the forsterite content reached up to 90.5% wt. The TEM average crystallite size was approximately 53(6) nm.« less