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Structural, Magnetic, And Defect Properties Of Co-Pt-Type Magnetic-Storage Alloys: Density-Functional Theory Study Of Thermal Processing Effects, Aftab Alam, Brent Kraczek, Duane D. Johnson
Structural, Magnetic, And Defect Properties Of Co-Pt-Type Magnetic-Storage Alloys: Density-Functional Theory Study Of Thermal Processing Effects, Aftab Alam, Brent Kraczek, Duane D. Johnson
Duane D. Johnson
Using an optimized-basis Korringa-Kohn-Rostoker-coherent-potential approximation method, we calculate formation enthalpies ΔEf, structural, and magnetic properties of paramagnetic (PM) and ferromagnetic, disordered A1 and ordered L10 CoPt, FePd, and FePt systems that are of interest for high-density magnetic-recording media. To address processing effects, we focus on the point defects that dictate thermal properties and planar defects (e.g., c domain and antiphase boundaries) which can serve as pinning centers for magnetic domains and affect storage properties. We determine bulk Curie (Tc) and order-disorder (To-d) transition temperatures within 4% of observed values, and estimates for nanoparticles. Planar-defect energies γhklx show that the favorable …
Isogeometric Shell Analysis: The Reissner–Mindlin Shell, D. J. Benson, Y. Bazilevs, Ming-Chen Hsu, T.J.R. Hughes
Isogeometric Shell Analysis: The Reissner–Mindlin Shell, D. J. Benson, Y. Bazilevs, Ming-Chen Hsu, T.J.R. Hughes
Ming-Chen Hsu
A Reissner–Mindlin shell formulation based on a degenerated solid is implemented for NURBS-based isogeometric analysis. The performance of the approach is examined on a set of linear elastic and nonlinear elasto-plastic benchmark examples. The analyses were performed with LS-DYNA, an industrial, general-purpose finite element code, for which a user-defined shell element capability was implemented. This new feature, to be reported on in subsequent work, allows for the use of NURBS and other non-standard discretizations in a sophisticated nonlinear analysis framework.
[Ni(Tmen)(Acac)][B(Ph)4] A Probe For The Anion Basicity Of Ionic Liquids, Joanna Bartosik, Anja V. Mudring
[Ni(Tmen)(Acac)][B(Ph)4] A Probe For The Anion Basicity Of Ionic Liquids, Joanna Bartosik, Anja V. Mudring
Anja V. Mudring
An optical basicity scale of various ionic liquids (IL) anions has been determined by UV-Vis absorption spectroscopy. The indicator complex [Ni(tmen)(acac)][B(Ph)4] (tmen = tetramethylethylendiamine, acac = acetylacetonate) shows to be a sensitive probe as the position of the 3A2g(F) → 3T1g(F) absorption maximum of square planar to octahedral Ni2+ shifts distinctly depending on the electron donor ability of the respective ionic liquid anion. If the Lewis basicity of the anion becomes stronger a change to a tetrahedral coordination around Ni2+ is observed. Here the 3T1(F) → 3T2(F) and 3T1(F) → 3T1(P) transitions are helpful for monitoring the IL anion basicity. …
On The Dissolution Of Non-Metallic Solid Elements (Sulfur, Selenium, Tellurium And Phosphorus) In Ionic Liquids, Eva Boros, Martyn J. Earle, Manuela A. Gilea, Andreas Metlen, Anja V. Mudring, Franziska Rieger, Allan J. Robertson, Kenneth R. Seddon, Alina A. Tomaszowska, Lev Trusov, Joseph S. Vyle
On The Dissolution Of Non-Metallic Solid Elements (Sulfur, Selenium, Tellurium And Phosphorus) In Ionic Liquids, Eva Boros, Martyn J. Earle, Manuela A. Gilea, Andreas Metlen, Anja V. Mudring, Franziska Rieger, Allan J. Robertson, Kenneth R. Seddon, Alina A. Tomaszowska, Lev Trusov, Joseph S. Vyle
Anja V. Mudring
Ionic liquids are shown to be good solvents for elemental sulfur, selenium, phosphorus and tellurium, and can be designed to maximise the solubility of these elements. The presence of the [S3]˙− radical anion in diluted solutions of sulfur in some ionic liquids has been confirmed, and is the origin of their intense blue colour (cf. lapis lazuli).
Communication Prev. Article Next Article Table Of Contents Chains Of Face-Sharing {Zpr6} Octahedra With Alternating Endohedral Iridium Atoms And Chloride Ions In {(Ir,Cl)Pr6}Cl10, Nina Herzmann, Matthias Bruhmann, Anja V. Mudring, Gerd Meyer
Communication Prev. Article Next Article Table Of Contents Chains Of Face-Sharing {Zpr6} Octahedra With Alternating Endohedral Iridium Atoms And Chloride Ions In {(Ir,Cl)Pr6}Cl10, Nina Herzmann, Matthias Bruhmann, Anja V. Mudring, Gerd Meyer
Anja V. Mudring
The most impressive feature of the crystal structure of IrPr6Cl11 is chains of face-sharing {Pr6} octahedra that encapsulate, alternatingly, iridium atoms and chloride ions, according to the formulation {(Ir,Cl)Pr6}Cl10. An alternative description of the structure is the connection of isolated {IrPr6} clusters that are surrounded in a mixed {ZR6}Xi12/{ZR6}Xi8 type by chlorido ligands with a rather complex connectivity, {IrPr6}(Cli−a−a4/3Cla−i−a8/3Cli−a6/2Cla−i6/2)e(Cli−i2/2)f, to a three-dimensional structure of tetragonally packed cluster-complex chains.
Facile Preparation Of Quantum Cutting Gdf3 : Eu3+ Nanoparticles From Ionic Liquids, Chantal Lorbeer, Joanna Cybinska, Anja V. Mudring
Facile Preparation Of Quantum Cutting Gdf3 : Eu3+ Nanoparticles From Ionic Liquids, Chantal Lorbeer, Joanna Cybinska, Anja V. Mudring
Anja V. Mudring
Microwave reaction of Ln(OAc)3·xH2O, Ln = Gd, Eu; OAc = acetate) with and in the ionic liquid [C4mim][BF4] (C4mim = 1-butyl-3-methylimidazolium) allows the fast and efficient synthesis of small, uniform, oxygen-free lanthanide nanofluorides with excellent photophysical behaviour. For GdF3 : Eu3+ nanoparticles a quantum efficiency of up to 145% was determined.
Electronic And Magnetic Structure Of (Crcl 3 ) 3, M. Grodzicki, B. Mallick, Anja V. Mudring
Electronic And Magnetic Structure Of (Crcl 3 ) 3, M. Grodzicki, B. Mallick, Anja V. Mudring
Anja V. Mudring
Electronic structure calculations in the local spin-density approximation have been carried out on the recently synthesized trimer (CrCl 3 ) 3 exhibiting antiferromagnetic ordering below T N =55 K. The calculated magnetic coupling constant, the paramagnetic Curie temperature, and the decrease of the magnetic moment below T N are well reproduced by the calculations. An interpretation of the spin structure is given that is consistent with all experimental data currently available.
Preparation And Characterization Of Pt/Γ-Al2o3 Model Catalyst On Nial Alloy, Zhongfan Zhang, Long Li, Lin-Lin Wang, Sergio I. Sanchez, Ross V. Grieshaber, Qi Wang, Duane D. Johnson, Anatoly I. Frenkel, Ralph G. Nuzzo, Judith C. Yang
Preparation And Characterization Of Pt/Γ-Al2o3 Model Catalyst On Nial Alloy, Zhongfan Zhang, Long Li, Lin-Lin Wang, Sergio I. Sanchez, Ross V. Grieshaber, Qi Wang, Duane D. Johnson, Anatoly I. Frenkel, Ralph G. Nuzzo, Judith C. Yang
Duane D. Johnson
Numerous studies of heterogeneous catalysis systems clearly demonstrate that the metal nanoparticle (NPs)/support interaction is significant in determining the catalytic chemistry. Theoretical simulations have been performed to understand the metal/support interactions [1,2]. For example, theorists discovered that electronic and oxygen defects of γ-Al2O3 anchor the active particles [1]. Platinum NPs dispersed on γ-alumina is one of the most widely used heterogeneous catalysts and Pt performs extremely well as a catalyst for the oxygen-reduction reaction used in fuel cell industries. Hence, we chose Pt/γ-Al2O3 as a model heterogeneous catalyst system to investigate the metal NPs/support interface by electron microscopy methods with …
Interphase Energies Of Hcp Precipitates In Fcc Metals: A Density-Functional Theory Study In Al-Ag, Daniel Finkenstadt, Duane D. Johnson
Interphase Energies Of Hcp Precipitates In Fcc Metals: A Density-Functional Theory Study In Al-Ag, Daniel Finkenstadt, Duane D. Johnson
Duane D. Johnson
Density-functional theory (DFT) calculations of interphase boundary energies relevant to hexagonal-close-packed (hcp) γ-precipitate formation were performed within approximate unit cells that mirror the experimental conditions in face-centered-cubic (fcc) Al-Ag solid solutions. In Al-rich, fcc Al-Ag, γ precipitates are observed to form rapidly with large (300+) aspect ratios even though the Al stacking-fault energy is high (approximately 130 mJ/m2), which should suppress hcp ribbon formation according to standard arguments. Our DFT results show why high-aspect ratio plates occur and why previous estimates based on Wulff construction were orders of magnitude less than observed values. Using DFT, we obtain a Gibbs free-energy …
Easy Access To Ultra Long-Time Stable, Luminescent Europium(Ii) Fluoride Nanoparticles In Ionic Liquids, Nina Von Prondzinski, Joanna Cybinska, Anja V. Mudring
Easy Access To Ultra Long-Time Stable, Luminescent Europium(Ii) Fluoride Nanoparticles In Ionic Liquids, Nina Von Prondzinski, Joanna Cybinska, Anja V. Mudring
Anja V. Mudring
Physical vapour deposition into ionic liquids allows for the first time the synthesis of a reduced lanthanide halide on the nanoscale. The obtained EuF2 nanoparticles show a bright blue luminescence and form long-time stable-colloidal solutions in the ionic liquids.
Optical Basicity Of Ionic Liquids, Slawomir Pitula, Anja V. Mudring
Optical Basicity Of Ionic Liquids, Slawomir Pitula, Anja V. Mudring
Anja V. Mudring
The concept of optical basicities initially developed by Duffy for solid oxides was successfully transferred to low melting salts such as ionic liquids (ILs). Several ionic liquids (ILs) were doped with Mn(NTf2)2 (NTf2 = bis(trifluoromethanesulfonyl)imide) as a probe to investigate the IL anion basicity by means of UV-Vis spectroscopy. The 6A1 → 4A, 4E(G) transition band of Mn2+ is influenced by the electron donor properties, i.e., Lewis basicity, of the coordinating ligands but remains—to the first order—independent from the ligand field. The change in the optical spectra for various Mn(NTf2)2 doped ILs is predominantly dependent on the anion. No significant …