Search results for "metastable phase"

showing 3 items of 3 documents

Ab Initio Structure Determination of Vaterite by Automated Electron Diffraction

2012

tion that is fundamental for understanding material properties. Still, a number of compounds have eluded such kinds of analysis because they are nanocrystalline, highly disordered, with strong pseudosymmetries or available only in small amounts in polyphasic or polymorphic systems. These materials are crystallographically intractable with conventional Xray or synchrotron radiation diffraction techniques. Single nanoparticles can be visualized by high-resolution transmission electron microscopy (HR-TEM) up to sub�ngstrom resolution, [2] but obtaining 3D information is still a difficult task, especially for highly beam-sensitive materials and crystal structures with long cell parameters. Elec…

DiffractionReflection high-energy electron diffractionmetastable phaseElectron crystallographyChemistryResolution (electron density)Analytical chemistrybiomineralization; calcium carbonate; electron crystallography; metastable phase; structure determinationElectronsGeneral ChemistrybiomineralizationCatalysisNanocrystalline materialstructure determinationAutomationCrystallographyelectron crystallographyX-Ray DiffractionElectron diffractionMicroscopy Electron ScanningNanoparticlescalcium carbonateAntacidsPowder diffractionElectron backscatter diffraction
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Co-precipitation synthesis of neodymium-doped yttrium aluminium oxides nanopowders: Quantitative phase investigation as a function of joint isotherma…

2007

Abstract Neodymium-doped yttrium aluminium nanopowders with nominal Nd:Y:Al ratio equal to X:3–X:5 (where X = 0, 0.006, 0.012, 0.024, 0.048, 0.081, 0.096, 0.171, 0.192, 0.384, 0.540 and 0.720) were prepared by the co-precipitation method and subjected to five cumulative stages of isothermal treatment in the temperature range from 900 to 1050 °C. The phase evolution of the oxides were investigated quantitatively by the X-ray powder diffraction approach using the Rietveld method of analysis. An almost single phase cubic garnet structure was attained at temperatures as low as 900 °C for specimens with neodymium loading less than ca. 6 at.% with respect to total (Nd + Y) atoms. Isothermal treat…

Materials scienceXRDAnalytical chemistrychemistry.chemical_elementNeodymiumIsothermal processInorganic ChemistryYttrium aluminium oxides powdersPhase (matter)Electrical and Electronic EngineeringPhysical and Theoretical ChemistrySpectroscopySettore CHIM/02 - Chimica FisicaPerovskite (structure)Aluminium oxidesYAG nanopowderOrganic ChemistryMetallurgyRietveld methodMetastable phaseAtomic and Molecular Physics and OpticsElectronic Optical and Magnetic MaterialschemistryOrthorhombic crystal systemPowder diffractionMonoclinic crystal systemOptical Materials
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Nucleation and cavitation in parahydrogen

2012

We have used a density functional approach to investigate thermal homogeneous nucleation and cavitation in parahydrogen. The effect of electrons as seeds of heterogeneous cavitation in liquid parahydrogen is also discussed within the capillary model. (C) 2011 Elsevier B.V. All rights reserved.

CavitationMetastable phasesChemistryCapillary actionPhysics::Medical PhysicsNucleationGeneral Physics and AstronomyElectronPhysics::Classical PhysicsSpin isomers of hydrogenPhysics::Fluid DynamicsPhysics::Plasma PhysicsHomogeneousChemical physicsCavitationThermalPhysics::Atomic and Molecular ClustersNucleationPhysical chemistryPhysical and Theoretical ChemistryLiquid parahydrogen
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