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Search Publications by: Craig Brown (Fed)

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Displaying 101 - 125 of 160

Quasi-Elastic Neutron Scattering Studies of Hydrogen Dynamics for Nanoconfined NaAlH 4

July 14, 2016
Author(s)
Shathabish NaraseGowda, Craig Brown, Madhu Sudan Tyagi, Tabbetha A. Dobbins
The hydrogen dynamics of nano-confined sodium alanate (NaAlH 4) has been studied using quasi-elastic neutron scattering (QENS). Results indicate thermodynamic destabilization is responsible for reduced desorption temperatures of NaAlH 4 upon confinement

Adsorption of Two Gas Molecules at a Single Metal Site in a Metal-Organic Framework

July 7, 2016
Author(s)
Tomce Runcevski, Matthew T. Kapelewski, Rodolfo M. Torres-Gavosto, Jacob Daniel Tarver, Craig Brown, Jeffrey R. Long
One strategy to markedly increase the gas storage capacity of metal-organic frameworks, is to introduce coordinatively-unsaturated metal centers capable of binding multiple gas molecules. Herein, we provide an initial demonstration that a single mental

High-Pressure Synthesis of Manganese Oxyhydride with Partial Anion Order

July 1, 2016
Author(s)
Cedric Tassel, Yoshinori Goto, Daichi Watabe, Ya Tang, Honcheng Lu, Yoshinori Kuno, Fumitaka Takeiri, Takafumi Yamamoto, Craig Brown, James Hester, Yoji Kobayashi, Hiroshi Kageyama
We report the high-pressure synthesis of a manganese oxyhydride LaSrMnO 3.3H 0.7. Neutron and X-ray Rietveld analyses showed this compound adopts the K 2NiF 4 structure, with H -positioned exclusively at the equatorial site. This result makes a striking

Physical Properties of the Ce 2 MAl 7 Ge 4 Heavy-Fermion Compounds (M = C0, Ir,Ni,Pd)

May 23, 2016
Author(s)
N. J. Ghimire, S. K. Cary, S. Eley, N. A. Wakeham, P. F. S. Rosa, T. Albrecht-Schmitt, Y. Lee, M. Janoschek, Craig Brown, L. Civale, J. D. Thompson, F. Ronning, E. D. Bauer
The synthesis, crystal structure and physical properties by means of single crystal x-ray diffraction, neutron powder diffraction, magnetic, thermal and transport measurements of the new heavy fermion compounds Ce 2M Al 7Ge 4(M = Co, Ir, Ni, Pd) are

Hydration-Induced Spin-Glass State in a Frustrated Na-Mn-O Triangular Lattice

May 18, 2016
Author(s)
Ioanna Bakaimi, Rosaria Brescia, Craig Brown, Alexander A. Tsirlin, Mark A. Green, Alexandros Lappas
Birnessite compounds are stable across a wide range of compositions that produces a remarkable diversity in their physical, electrochemical and functional properties. These are hydrated analogues of the magnetic frustrated, mixed-valent manganese oxide

High Thermopower with Metallic Conductivity in p-Type Li-Substituted PbPdO 2

May 9, 2016
Author(s)
Leo K. Lamontagne, Geneva Laurita, Michael W. Gaultois, Michael Knight, Leila Ghadbeigi, Taylor D. Sparks, Markus E. Gruner, Rossitza Pentcheva, Craig Brown, Ram Seshadri
PbPdO 2 is a band semiconductor with a band gap arising from the filled d 8 nature of square-planar Pd 2+. We establish that hole doping through Li substitution for Pd in PbPdO 2 results in a p-type metallic oxide with a positive temperature coefficient of

High Thermopower with Metallic Conductivity in p/p}-Type Li-Substituted PbPdO 2

May 9, 2016
Author(s)
Leo K. Lamontagne, Geneva Laurita, Michael W. Gaultois, Michael Knight, Leila Ghadbeigi, Taylor D. Sparks, Markus E. Gruner, Craig Brown, Ram Seshadri
Early age hydration kinetics of Portland cement with pozzolanic volcanic ash was examined using quasi-elastic neutron scattering. Volcanic ash consisting of two different particle sizes was used to prepare cement pastes by combinations of Portland cement

Topochemical Nitridation with Anion Vacancy-Assisted N 3- /O 2- Exchange

March 9, 2016
Author(s)
Riho Mikita, Tomoko Aharen, Takafumi Yamamoto, Fumitaka Takeiri, Tang Ya, Wataru Yoshimune, Koji Fujita, Suguru Yoshida, Katsuhisa Tanaka, Dmitry Batuk, Artem M. Abakumov, Craig Brown, Yoji Kobayashi, Hiroshi Kageyama
We present how the introduction of anion vacancies in oxyhydrides enables a route to access new oxynitrides, by conducting ammonolysis of perovskite oxyhydride EuTiO 3-xH x (x0.18). At 400 °C, similar to our studies on BaTiO 3-xH x, hydride lability

Outlook and Challenges for Hydrogen Storage in Nanoporous Materials

March 1, 2016
Author(s)
D. P. Broom, C. J. Webb, K. E. Hurst, P. A. Parilla, T. Gennett, Craig Brown, R. Zacharia, E. Tylianakis, E. Klontzas, G. E. Froudakis, Th. A. Steriotis, P. N. Trikalitis, D. L. Anton, B. Hardy, D. Tamburello, C. Corgnale, B. A. van Hassel, D. Cossement, R. Chahine, M. Hirscher
Considerable progress has been made recently in the use of Nanoporous materials for hydrogen storage. In this article, the current status of the field and future challenges are discussed, ranging from important open fundamental questions, such as the

The Magnetic Transitions and Dynamics in the Multiferroic Lu 0.5 Sc 0.5 FeO 3

February 26, 2016
Author(s)
Junjie Yang, Chunruo Duan, John R. Copley, Craig Brown, Despina Louca
In spite of its frustrated lattice, the multiferroic Lu 0.5Sc 0.5FeO 3 exhibits two consecutive magnetic transitions at T% N1approximately equal to}175 K and T N2 approximately equal to}70 K determined from neutron diffraction. In the ordered state

Improved Catalytic Activity and Stability of Palladium Pincer Complex by Incorporation into a Metal-Organic Framework

February 17, 2016
Author(s)
Samantha A. Burgess, Abebu Kassie, Sarah A. Baranowski, Keith J. Fritzsching, Klaus Schmidt-Rohr, Craig Brown, Casey R. Wade
A porous metal-organic framework Zr 6O 4(OH) 4(L-PdX) 3 (1-x) has been constructed from Pd diphosphinite pincer complexes ([L-PdX} 4 = [1,3-(OPAr 2) 2C 6H 3)PdX] 4-, Ar = p-C 6H 4CO 2, X = Cl, I). Reaction of 1-X with Phi(O 2CCF 3) 2 generates 1-TFA, which

Rotational Dynamics of Organic Cations in the CH 3 NH 3 Pbl 3 Perovskite

December 14, 2015
Author(s)
Tianran Chen, Benjamin J. Foley, Bahar NMN Ipek, Madhu Sudan Tyagi, John R. Copley, Craig Brown, Joshua J. Choi, Seunghun Lee Lee
All semiconductors can generate free charges by absorbing light. However, not all semiconductors are high performance photovoltaic materials, because the charge carriers with opposite signs, electrons and holes, quickly annihilate each other. High

Magnetic Structure and Exchange Interactions in Quasi-One-Dimensional MnCl 2 (urea) 2

December 11, 2015
Author(s)
Jamie L. Manson, Qingzhen Huang, Craig Brown, Jeffrey W. Lynn, Matthew B. Stone, John Singleton, Fan Xiao
MnCl 2(urea) 2 is a new linear chain coordination polymer that exhibits slightly counter-rotated MnCl 4 rhomboids along the chain-axis. The material crystallizes in the non-centrosymmetric orthorhombic space group Iba 2, with each Mn(II) ion equatorially

A Labile Hydride Strategy for the Synthesis of Heavily Nitridized BaTiO 3

December 1, 2015
Author(s)
Takeshi Yajima, Fumitaka Takeiri, Kohei Aidzu, Hirofumi Akamatsu, Koji Fujita, Wataru Yoshimune, Masatoshi Ohkura, Shiming Lei, Venkatraman Gopalan, Katsuhisa Tanaka, Craig Brown, Mark Green, Takafumi Yamamoto, Yoji Kobayashi, Hiroshi Kageyama
Oxynitrides, which have been explored extensively in the last decade, exhibit various novel properties beyond oxides, including visible light absorption, photocatalytic activity and high dielectric constants. The synthesis of these oxynitrides generally

Observation of the reduction of thermal conductivity in a p-type nanostructured half-Heusler using neutron inelastic scattering

November 24, 2015
Author(s)
Winnie K. Wong-Ng, Jeffrey W. Lynn, Qingzhen Huang, Craig Brown, James A. Kaduk, Giri Joshi
To understand the role of the nanophase in reducing the lattice contribution of the thermal conductivity of thermoelectrics, the structure and phonon density of a p-type half-Heusler thermoelectric ingot (ingot-HH, nominal composition of (Hf0.5Zr0.5)Co(Sb0

Understanding Small-Molecule Interactions in Metal-Organic Frameworks: Coupling Experiment with Theory

October 14, 2015
Author(s)
Jason S. Lee, Bess Vlaisavljevich, David K. Britt, Craig Brown, Maciej Haranczyk, Jeffrey B. Neaton, Berend Smit, Jeffrey R. Long, W. L. Queen
Metal-organic frameworks (MOFs) have gained much attention as next generation porous media for various applications, especially gas separations/storage and catalysis. New MOFs are regularly reported; however, to develop better materials in a timely manner

Stabilization of Cubic Sr 2 FeMoO 6 through Topochemical Reduction

August 7, 2015
Author(s)
Daniel D. Taylor, Nathaniel J. Schreiber, Craig Brown, Angel M. Arevalo-Lopez, Efrain E. Rodriguez
Sr 2FeMoO 6 has been extensively studied for application in spintronic devices. Through the topochemical deintercalation of the oxygen anions, the high temperature cubic phase can be stabilized at room temperature while leaving the magnetic ordering intact

Flexible metal-organic framework compounds: In situ studies for selective CO2 capture

June 19, 2015
Author(s)
Andrew J. Allen, Laura Espinal, Winnie K. Wong-Ng, Wendy Queen, Craig Brown, Steven R. Kline, Kristi L. Kauffman, Jeffrey T. Culp
Results from in situ experiments are presented to correlate carbon capture with dynamic structural changes in two flexible metal-organic framework (MOF) materials: porous coordination polymers (PCPs) exhibiting promising carbon dioxide adsorption

Gradual Release of Strongly-Bound Nitric Oxide from Fe 2 (NO) 2 (dobdc)

February 24, 2015
Author(s)
Eric D. Bloch, Wendy L. Queen, Sachin Chavan, Paul S. Wheatley, Joseph M. Zadrozny, Russell E. Morris, Craig Brown, Carlo Lamberti, Silvia Bordiga, Jeffrey R. Long
An iron-based metal-organic framework featuring coordinatively-unsaturated redox-active metal cation sites, Fe 2(dobdc) (dobdc 4- = 1,4-dioxido-2,5-benzenedicarboxylate), is shown to strongly bond nitric oxide at 298 K. Adsorption isotherms indicate an

Inducing Ferrimagnetism in Insulating Hollandite Ba 1.2 Mn 8 O 16

January 27, 2015
Author(s)
Amber M. Larson, Pouya Moetakef, Karen Gaskell, Craig Brown, Graham King, Efrain E. Rodriguez
Folded triangular lattices connecting magnetic metal centers can be realized in the so-called hollandite type structure, providing a new platform for multifunctional behavior in transition metal oxides. The microporous oxide BaMn 8O 16 has been tuned from

Molecular Basis for the High CO 2 Adsorption Capacity in Chabazite Zeolites

November 7, 2014
Author(s)
Trong D. Pham, Matthew Ross Hudson, Craig Brown, Raul F. Lobo
The structure-property relationship for CO 2 adsorption in Li-, Na-, K-CHA (Si/Al = 5 and = 12), and pure silica chabazite (Si-CHA) zeolites was investigated by X-ray and neutron powder diffraction measurements. Two adsorption sites for CO 2 were found in