A5052744619- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Crystallography and molecular interactions
- Solid-state spectroscopy and crystallography
- Advanced Condensed Matter Physics
- Nuclear Physics and Applications
- Ferroelectric and Piezoelectric Materials
- Magnetic and transport properties of perovskites and related materials
- Rare-earth and actinide compounds
- Crystal Structures and Properties
- High-pressure geophysics and materials
- Chemical Thermodynamics and Molecular Structure
- Microwave Dielectric Ceramics Synthesis
- Inorganic Fluorides and Related Compounds
- Physics of Superconductivity and Magnetism
- Inorganic Chemistry and Materials
- Fullerene Chemistry and Applications
- Multiferroics and related materials
- Material Dynamics and Properties
- Chemical Synthesis and Characterization
- Magnetic Properties of Alloys
- Nuclear materials and radiation effects
- Layered Double Hydroxides Synthesis and Applications
- Advanced Battery Materials and Technologies
- Advancements in Battery Materials
Oak Ridge National Laboratory
2015-2021
NIST Center for Neutron Research
2013-2018
National Institute of Standards and Technology
2013-2018
Rutherford Appleton Laboratory
2003-2017
Fluor (United States)
2009-2010
University of Southampton
2009
University of Oxford
1996-2009
University of Edinburgh
1998-2009
University of Strathclyde
2009
University of Glasgow
2009
High-resolution powder neutron diffraction has been used to study the crystal structure of fullerence C60 in temperature range 5 K 320 K. Solid adopts a cubic at all temperatures. The experimental data provide clear evidence continuous phase transition ca. 90 and confirm existence first-order 260 In high-temperature face-centred-cubic (T > K), molecules are completely orientationally disordered, undergoing reorientation. Below K, interpretation is consistent with uniaxial jump reorientation...
Lithium iron arsenide phases with compositions close to LiFeAs exhibit superconductivity at temperatures least as high 16 K, demonstrating that superconducting [FeAs](-) anionic layers the anti-PbO structure type occur in three different types and a wide range of As-Fe-As bond angles.
Perfect single grains of the AlPdMn icosahedral phase have been used for structure determination by X-ray and neutron diffraction. Owing to large difference between scattering factors, information is gained on atomic positions three elements. A model proposed as deduced from a six-dimensional (6D) Patterson analysis. Six different hypersurfaces are located node body-centre sites 6D lattice. The superstructure that leads face-centred lattice mainly due strong chemical ordering, all palladium...
We show that the Mott transition in orbitally degenerate systems can, and often does, proceed not standard ``Mott insulator---weakly correlated metal'' sequence, but via a novel intermediate phase with charge (rather than orbital) ordering. Lifting an orbital degeneracy this way can be viewed as alternative to Jahn-Teller distortion. This may occur crossover between localized itinerant regimes, if Hund's rule coupling overcomes on site Coulomb repulsion. both by calculations experiment...
Mesoscopic (500-2000 Angstrom) and microscopic (5-20 phase segregation with temperature magnetic field was studied in the model manganite Pr0.7Ca0.3MnO3 by high-resolution neutron diffraction inelastic scattering. Intra-granular strain-driven mesoscopic between two insulating phases, one of which is charge ordered (CO), sets below CO zero field. The orders antiferromagnetically, while other shows spin-glass behavior. After field-induced metallization, coexists a ferromagnetic metallic phase.
High resolution time-of-flight neutron powder diffraction has been used to determine the detailed structure of C 60 as a function temperature. Rapid data collection coupled with high enabled subtle aspects 86 K orientational glass transition and precursor effects 260 order-disorder be observed. This surveying capability complements traditional single crystal methods. The power Rietveld method profile refinement is demonstrated in elucidation orientationally-ordered low temperature phase...
Other| February 01, 1997 Structural behavior, crystal chemistry, and phase transitions in substituted leucite: High-resolution neutron powder diffraction studies David C. Palmer; Palmer University of Cambridge, Department Earth Sciences, United Kingdom Search for other works by this author on: GSW Google Scholar Martin T. Dove; Dove Richard M. Ibberson; Ibberson Brian Powell American Mineralogist (1997) 82 (1-2): 16–29. https://doi.org/10.2138/am-1997-1-203 Article history first online: 02...
Proton conducting oxides such as BaCe0.9Y0.1O3−δ have considerable promise for intermediate temperature fuel cells. Unfortunately these tend to be unstable, e.g. attack by carbonation. Previous work has highlighted the possibility of utilising barium zirconate provide a chemically stable electrolyte; however materials are difficult sinter yielding very high overall resistances. Whilst this sintering problem is soluble, there still significant questions about intrinsic grain conductivity,...
Details of the synthesis and structural physical characterization oxides with nominal composition NaTiO2 are presented. The highest sodium loading we have achieved is Na0.99(2)TiO2 determined using diffraction methods. results not consistent a localized moment d1 system. High-resolution neutron shows that transition observed previously between 200 250 K in magnetic susceptibility has structural, rather than purely magnetic, origin. At room temperature α-NaFeO2 structure, space group R3̄m...
High resolution neutron powder diffraction studies were performed on Nd2Fe17Nx and Y2Fe17Nx. A strong preferential site occupation of the N atoms 9e position rhombohedral compound was observed. In hexagonal Y2Fe17Nx occupy primarily 6h sites (82%) only a small fraction goes into 12i (12%). The refined nitrogen numbers correspond to formula compositions Nd2Fe17N2.6 Y2Fe17N2.9.
We have applied a combination of spectroscopic and diffraction methods to study the adduct formed between squaric acid bypridine, which has been postulated exhibit proton transfer associated with single-crystal phase transition at ca. 450 K. A X-ray very-high flux powder neutron data confirmed that does from base in high-temperature form. Powder measurements demonstrated was reversible but significant kinetic energy barrier must be overcome revert original structure. Computational modeling...
Not so simple: It is normally assumed that deuteration has only a minor effect on the stabilities of crystal structures. This assumption wrong for pyridine. A low-temperature polymorph exists [D5]pyridine, but not [H5]pyridine, which adds further twist to already unusual structural chemistry one simplest and most familiar laboratory chemicals.
The perovskite Ba3ZnTa2O9 (BZT) is the parent of a family high dielectric constant, low-loss oxides currently applied in mobile telecommunications base stations. preparation BZT microwave resonators with optimal properties requires careful attention to thermal treatment control formation domains which Ta and Zn cations order on octahedral sites structure. In this paper we use powder X-ray neutron diffraction together fluorescence electron microscopy demonstrate strong correlation between...
The ZrW2O8 family of materials has been shown to display the unusual property an isotropic bulk contraction in volume as a function temperature. We report here on negative thermal expansion properties and oxygen migration at very low temperatures ZrW2-xMoxO8 phases. ZrWMoO8 shows significant (αl = −8.7 × 10-6 K-1) 200 K with activation energy 0.23 eV. are unaware such other electronic insulators. low-temperature is associated order−disorder transition between α β forms material ΔVdisorder...