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- Cation ordering (3)
- Octahedral tilting (3)
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- 1-12-Diferrocenyldodecane (1)
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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
The Effects Of Small Metal Additions (Co,Cu,Ga,Mn,Al,Bi,Sn) On The Magnetocaloric Properties Of The Gd5ge2si2 Alloy, R D. Shull, V Provenzano, A J. Shapiro, A Fu, Michael W. Lufaso, J Karapetrova, G Kletetschka, V Mikula
The Effects Of Small Metal Additions (Co,Cu,Ga,Mn,Al,Bi,Sn) On The Magnetocaloric Properties Of The Gd5ge2si2 Alloy, R D. Shull, V Provenzano, A J. Shapiro, A Fu, Michael W. Lufaso, J Karapetrova, G Kletetschka, V Mikula
Michael W. Lufaso
The structural and magnetic properties of arc-melted and homogenized (1300 °C, 1 h) alloys of Gd5Ge1.9Si2X0.1 (X = Cu, Co, Ga, Mn, Al, Bi, or Sn) were investigated by powder x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and magnetometry. The addition of Cu, Ga, Mn, and Al completely eliminated the large hysteresis losses present in the undoped Gd5Ge2Si2 alloy between 270 and 330 K, broadened the magnetic entropy change ΔSm peak, and shifted its peak value from 275 to 305 K similar to that observed earlier for Gd5Ge1.9Si2Fe0.1. The addition of Bi or Sn had a negligible effect on …
Pressure Induced Octahedral Tilting Distortion In Ba2ytao6, Michael W. Lufaso, René B. Macquart, Yongjae Lee, Thomas Vogt, Hans-Conrad Zur Loye
Pressure Induced Octahedral Tilting Distortion In Ba2ytao6, Michael W. Lufaso, René B. Macquart, Yongjae Lee, Thomas Vogt, Hans-Conrad Zur Loye
Michael W. Lufaso
Herein we communicate the first example of a pressure induced octahedral tilting distortion in a double perovskite phase, which was observed during the structural characterization of Ba2YTaO6 using high-pressure synchrotron X-ray powder diffraction.
Reactions Of Oxygen Atoms With Van Der Waals Complexes: The Effect Of Complex Formation On The Internal Energy Distribution In The Products, A B. Mccoy, Michael W. Lufaso, M Veneziani, S Atrill, R Naaman
Reactions Of Oxygen Atoms With Van Der Waals Complexes: The Effect Of Complex Formation On The Internal Energy Distribution In The Products, A B. Mccoy, Michael W. Lufaso, M Veneziani, S Atrill, R Naaman
Michael W. Lufaso
Reactions of atomic oxygen with complexes containing HCl are investigated and the OH product state distributions are compared to those observed for the corresponding reactions of HCl monomers. In previous studies of reactions of O(3P) with HCl and hydrocarbon complexes, rotationally colder OH product state distributions were observed, when compared to the corresponding reactions of monomers. In contrast, we find that reactions of O(1D) with HCl clusters yield OH rotational distributions that are unaffected by the incorporation of HCl into a van der Waals complex. Quasiclassical trajectories are run on collisions of oxygen with HCl and Ar⋯HCl at 1 eV …
Relaxations In Ba2bisbo6 Double Complex Perovskite Ceramics, Manoel Carvalho Castro Jr., Carlos William De Araujo Paschoal, Frank C. Snyder, Michael W. Lufaso
Relaxations In Ba2bisbo6 Double Complex Perovskite Ceramics, Manoel Carvalho Castro Jr., Carlos William De Araujo Paschoal, Frank C. Snyder, Michael W. Lufaso
Michael W. Lufaso
The electric properties of the complex double perovskite Ba2BiSbO6 have been investigated using impedance spectroscopy in the frequency range from 1 Hz up to 1 MHz and in the temperature range from room temperature up to 560 K. There are two contributions to the electrical properties due to the grain and grain boundary. The oxygen vacancies play an important role in the conductivity and strongly increase the dielectric constant at high temperatures. The analysis of the frequency dependence of the conductivity clearly shows the structural phase transition of this compound near 515 K.
1,12-Diferrocenyldodecane At 100 K, Danielle M. Bequeath, Richard L. Porter, Michael W. Lufaso, Timothy R. Wagner, Rachel L. Kusnic, Matthias Zeller, Larry S. Curtin
1,12-Diferrocenyldodecane At 100 K, Danielle M. Bequeath, Richard L. Porter, Michael W. Lufaso, Timothy R. Wagner, Rachel L. Kusnic, Matthias Zeller, Larry S. Curtin
Michael W. Lufaso
1,12-Diferrocenyldodecane, [Fe2(C5H5)2(C22H32)], was synthesized from ferrocene and 1,12-dodecanedioyl chloride, followed by Clemmensen reduction. The single-crystal structure was determined at 100 K by X-ray diffraction and the spectroscopic and cyclic voltammetric data of 1,12-diferrocenyldodecane and its precursor are reported.
Jahn-Teller Distortions, Cation Ordering And Octahedral Tilting In Perovskites, Michael W. Lufaso, Patrick M. Woodward
Jahn-Teller Distortions, Cation Ordering And Octahedral Tilting In Perovskites, Michael W. Lufaso, Patrick M. Woodward
Michael W. Lufaso
In transition metal oxides, preferential occupation of specific d orbitals on the transition metal ion can lead to the development of a long-range ordered pattern of occupied orbitals. This phenomenon, referred to as orbital ordering, is usually observed indirectly from the cooperative Jahn-Teller distortions (CJTDs) that result as a consequence of the orbital ordering. This paper examines the interplay between orbital ordering, octahedral tilting and cation ordering in perovskites. Both ternary AMX3 perovskites containing an active Jahn-Teller (J-T) ion on the octahedral site and quaternary A2MM'X6 perovskites containing a J-T ion on one-half of the octahedral sites have been examined. …
Structure Determination Of A2m3+Tao6 And A2m3+Nbo6 Ordered Perovskites: Octahedral Tilting And Pseudosymmetry, Paris W. Barnes, Michael W. Lufaso, Patrick M. Woodward
Structure Determination Of A2m3+Tao6 And A2m3+Nbo6 Ordered Perovskites: Octahedral Tilting And Pseudosymmetry, Paris W. Barnes, Michael W. Lufaso, Patrick M. Woodward
Michael W. Lufaso
The room-temperature crystal structures of six A2M3+M5+O6 ordered perovskites have been determined from neutron and X-ray powder diffraction data. Ba2YNbO6 adopts the aristotype high-symmetry cubic structure (space group Fm3̄m, Z = 4). The symmetries of the remaining five compounds were lowered by octahedral tilting distortions. Out-of-phase rotations of the octahedra about the c axis were observed in Sr2CrTaO6 and Sr2GaTaO6, which lowers the symmetry to tetragonal (space group = I4/m, Z = 2, Glazer tilt system = a0a0c-). Octahedral tilting analogous to that seen in GdFeO3 occurs in Sr2ScNbO6, Ca2AlNbO6 and Ca2CrTaO6, which lowers the symmetry to monoclinic (space group …
Prediction Of The Crystal Structures Of Perovskites Using The Software Program Spuds, Michael W. Lufaso, Patrick M. Woodward
Prediction Of The Crystal Structures Of Perovskites Using The Software Program Spuds, Michael W. Lufaso, Patrick M. Woodward
Michael W. Lufaso
The software program SPuDS has been developed to predict the crystal structures of perovskites, including those distorted by tilting of the octahedra. The user inputs the composition and SPuDS calculates the optimal structure in ten different Glazer tilt systems. This is performed by distorting the structure to minimize the global instability index, while maintaining rigid octahedra. The location of the A-site cation is chosen so as to maximize the symmetry of its coordination environment. In its current form SPuDS can handle up to four different A-site cations in the same structure, but only one octahedral ion. Structures predicted by SPuDS …
Structure Prediction Of Ordered And Disordered Multiple Octahedral Cation Perovskites Using Spuds, Michael W. Lufaso, Paris W. Barnes, Patrick M. Woodward
Structure Prediction Of Ordered And Disordered Multiple Octahedral Cation Perovskites Using Spuds, Michael W. Lufaso, Paris W. Barnes, Patrick M. Woodward
Michael W. Lufaso
The software package SPuDS has previously been shown to accurately predict crystal structures of AMX3 and A1 - xA'xMX3 perovskites that have undergone octahedral tilting distortions. This paper describes the extension of this technique and its accuracy for A2MM'X6 ordered double perovskites with the aristotype Fm3̄m cubic structure, as well as those that have undergone octahedral tilting distortions. A survey of the literature shows that roughly 70% of all ordered double perovskites undergo octahedral tilting distortions. Of the 11 distinct types of octahedral tilting that can occur in ordered perovskites, five tilt systems account for ~97% of the reported structures. …