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Structural Phases (structural + phase)

Distribution by Scientific Domains
Physics and Astronomy40%
Chemistry40%

Terms modified by Structural Phases

  • structural phase transition
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    Selected Abstracts

    Structural phases of InAs under pressure

    PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2007
    J. López-Solano
    Abstract We present the results of a theoretical study on the structural stability of InAs under high pressure, with a focus on the pressure regime past the first transition from the low-pressure zincblende phase to the rocksalt (NaCl-type) phase. We have examined several candidates proposed for low-enthalpy phases at higher pressures, among them the super-Cmcm structure observed in InSb at moderately high pressure and the B10 structure, which is a distortion of the CsCl structure. Our results reproduce the established sequence of transitions and shed further light on the higher pressure regime of this material. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Structural phases of hexamethylenetetramine,pimelic acid (1/1): a unified description based on a stacking model

    ACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2003
    Gervais Chapuis
    The thermotropic phase diagram of 1:1 co-crystals of hexamethylenetetramine and pimelic acid (heptanedioic acid) is investigated. Three crystalline phases are identified at ambient pressure. Phase I is disordered, as revealed by diffuse rods in its diffraction pattern. When the temperature is lowered the diffuse streaks disappear in Phase II, but superstructure reflections emerge indicating an ordering process of the structure through a non-ferroic, or at least non-ferroelastic, phase transition. Phase II is mainly characterized by an unusual distribution of its reflection intensities. Phase III is reached through a ferroelastic phase transition that induces twinned domains. A model based on the stacking of an elementary layer is proposed with the aim of describing the structures in a unified framework. Depending on the value of the unique stacking parameter ,, each of the different structures observed can be reproduced by this model. Its validity is then tested by a series of simulations reproducing the main features of the diffraction patterns such as the diffuse scattering streaks, the occurrence of superstructure peaks at lower temperature and twinning. [source]

    A new crystal phase of barium nitroprusside trihydrate studied by neutron diffraction at 20,K

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2004
    G. Chevrier
    The crystal of barium penta­cyano­nitro­syl­ferrate trihydrate {barium nitro­prusside trihydrate, Ba[Fe(CN)5(NO)]·3H2O} has been studied by neutron diffraction at 20,K. The study was performed to characterize the structural phase generated by the phase transition undergone by the crystals at 80,K, at which temperature the unit-cell volume doubles. This crystal phase still exists at 20,K. The crystal structure, in space group P1, is completely ordered. The positional changes of the water mol­ecules in the present structure with respect to those of the compound at 105,K are presented. [source]

    Copper impregnated mesoporous activated carbon as a high efficient catalyst for the complete destruction of pathogens in water,

    ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2008
    L. John Kennedy
    Abstract Copper impregnated mesoporous activated carbon catalyst was applied for the elimination of microorganisms in wastewater. The antibacterial activity of the catalyst was determined qualitatively by testing the removal of pathogens in water after contacting with the catalyst. Escherichia coli, Shigella flexneri, Shigella dysenteriae, Shigella sonnei, and Salmonella typhi were taken as the model pathogens in determining the antimicrobial activity of the catalyst. The catalyst developed for this purpose was thoroughly characterized using instrumental techniques such as BET analysis, X-ray diffraction, FTIR spectroscopy, and scanning electron microscope to determine the pore and surface area, structural phases, surface functional groups, and surface morphology respectively. The energy dispersive X-ray analysis carried out confirmed qualitatively the percentage of copper impregnated in the catalyst. The experimental studies revealed that the catalyst was highly efficient and advantageous to be employed for industrial applications because of the nonleacheablity of copper from the catalyst and nonreoccurrence of the pathogens in the treated water. The transmission electron microscopy evidenced the complete cell wall rupture of the microorganisms. All the experimental results revealed that the copper impregnated mesoporous activated carbon exhibited a strong and long term antibacterial activity throughout the studies for repeated cycles. © 2007 American Institute of Chemical Engineers Environ Prog, 2008 [source]

    Photoluminescence depth-profiling of lattice-mismatched InGaN thick film on GaN using inductively coupled plasma etching

    PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006
    Ji-Myon Lee
    Abstract Photoluminescence depth profiling of highly strained In0.1Ga0.9N and In0.15Ga0.85N epitaxial films have been studied employing an inductively coupled Cl2 plasma etching. The photoluminescence measurements showed that thick InGaN films (0.2 ,m) consist of three different structural phases; (i) an InN-rich region near the InGaN film surface, (ii) a region that was free from InN-rich phase under stress-relaxation in the middle of the film, and (iii) an InGaN/GaN interface region. In region (i), a higher wavelength peak from the InN-rich phase was dominant. After removing the surface layer of 500 Å, the PL peaks from InN-rich phases completely disappeared, suggesting that the InN-rich phase region is confined to a depth of 500 Å. In regions of (ii) and (iii), the strain-relaxation between InGaN and GaN had a significant influence on the luminescence properties of InGaN. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]