Thermodynamics of(001)epitaxial ferroelectric films completely relaxed due to the formation of elastic domains with a three-domain architecture is *** polydomain structure and electromechanical response of such films ...
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Thermodynamics of(001)epitaxial ferroelectric films completely relaxed due to the formation of elastic domains with a three-domain architecture is *** polydomain structure and electromechanical response of such films are analyzed for two cases corresponding to immobile and mobile elastic domain *** is shown that immobile elastic domains provide additional constraint which increases the mechanical and electrical clamping,thereby significantly reducing the piezoelectric and dielectric *** the other hand,a polydomain ferroelectric film adapts to the variations in the applied electric field by reversible domain wall displacements in the case of mobile domain *** comparison of the theory with experiments shows that the elastic domain walls are mobile in the fully relaxed films of~1μm *** addition,if the substrate constraint is reduced via decreasing lateral size of a polydomain ferroelectric film,its piezoresponse will increase dramatically,as is experimentally verified on small islands of polydomain ferroelectric *** general conclusions can be readily applied to other constrained polydomain films.
We study the spin Hall magnetoresistance (SMR) in noncollinear antiferromagnet Mn3Sn/heavy metal stacks. The measured SMR exhibits peculiar magnetic field angle and magnitude dependence that sharply deviates from the ...
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We study the spin Hall magnetoresistance (SMR) in noncollinear antiferromagnet Mn3Sn/heavy metal stacks. The measured SMR exhibits peculiar magnetic field angle and magnitude dependence that sharply deviates from the conventional SMR theory based on the dampinglike spin-transfer torque. An alternative model based on a coherent fieldlike torque reproduces the observations well. Our work reveals a previously unrecognized mechanism of interfacial exchange that indicates a precession of the conduction-electron spins in the collective local exchange fields of the noncollinear antiferromagnetic order. The unraveled physics is essential to understanding and controlling spin transport in unconventional magnetic materials.
Compounds containing oxygen functional groups, especially phenols, are undesirable components of coal-derived liquids. Removal of these compounds from the products of coal liquefaction is required. A beneficial altern...
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Compounds containing oxygen functional groups, especially phenols, are undesirable components of coal-derived liquids. Removal of these compounds from the products of coal liquefaction is required. A beneficial alternative would be the removal of these compounds, or the prevention of their formation, during the liquefaction reaction itself, rather than as a separate processing step. A novel organometallic catalyst precursor containing-Co and Mo has been studied as a potential hydrogenation catalyst for coal liquefaction. To ascertain the hydrodeoxygenation activity of this catalyst under liquefaction conditions, model compounds were investigated. Anthrone, 2,6-di-r-butyl-4-methyl-phenol, dinaphthyl ether, and xanthene were reacted in the presence of the Go-Mo catalyst precursor and a precursor containing only Mo over a range of temperatures, providing a comparison of conversions to deoxygenated products. These conversions give an indication of the hydrodeoxygenating abilities of organometallic catalyst precursors within a coal liquefaction system. For example, at 400 degrees C dinaphthyl ether was converted 100% (4.5% O-containing products) In the presence of the Go-Mo organometallic precursor, compared to 76.5% conversion (7.4% O-products) in the presence of the Mo catalyst.
Acoustic emission analysis showed that the failure of some low density aluminous cement bonded perlite composites cannot be explained adequately using the classical Griffith type approach in which it is assumed that f...
Acoustic emission analysis showed that the failure of some low density aluminous cement bonded perlite composites cannot be explained adequately using the classical Griffith type approach in which it is assumed that failure is caused by the catastrophic propagation of the most severe flaw. It was found that the general concept of cumulative weakening could be applied to the failure of these composites. A change in failure mode from that of cumulative weakening to Griffith type fracture occurred when the bulk density of the composite was greater than about 1.6 lb/bd ft and/or the cement content of the material was greater than approximately 30%. In addition, microscopic examination showed a change in fracture surface morphology from primarily interparticle failure at low density or low cement contents to primarily transparticle failure at high density or high cement content. L'analyse d'émission acoustique montre qu'on ne peut pas suffisamment expliquer la fracture de certains composites en perlite, liés par du ciment alumineux de densité basse, en utilisant une approche de type traditionnel comme celle de Griffith; celle-ci affirme que la fracture est causée par la propagation destructive de la plus sévère craquelure. On a prouvé qu'on peut appliquer le concept de l'affaiblissement cumulatif à la fracture de ces composites. La fracture type “affaiblissement cumulatif” est remplacé par fracture type Griffith lorsque la masse volumique est plus grande que 1.6 lb/bd ft et/ou le contenu en ciment des matériaux est approximativement plus grande que 30%. En outre, un changement apparait dans la morphologie de la fracture en surface selon la densité et le contenu en ciment: Fracture surtout intraparticulaire pour un ciment de basse densité et en faible quantité et plutôt transparticulaire pour un ciment de haute densité et en grande quantité.
This paper demonstrates the generation of DSC thermograms from TREF chromatograms. The reverse is clearly possible, and shows that compositional distribution information is obtainable from DSC using solution crystalli...
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This paper demonstrates the generation of DSC thermograms from TREF chromatograms. The reverse is clearly possible, and shows that compositional distribution information is obtainable from DSC using solution crystallized material. However, TREF is essential, at least initially, in providing fractions for calibration curves.
A delicate interplay between lattice and charge provides a unique strategy to control the strain-driven stability of the electronic phase in quantum materials featuring metal–insulator transition (MIT). The strain-in...
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A commercial Co-Mo/Al 2 O 3 HDS catalyst displayed catalytic activity towards the coking of anthracene. This is related to its hydrogenation/dehy As with the Al 2 O 3 support, little or no coking activity was displaye...
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A commercial Co-Mo/Al 2 O 3 HDS catalyst displayed catalytic activity towards the coking of anthracene. This is related to its hydrogenation/dehy As with the Al 2 O 3 support, little or no coking activity was displayed by a carbon black composite. Following the addition of Co and Mo to the c
A method for systematic evaluation of the Lennard-Jones parameters for polycyclic aromatic hydrocarbon (PAH) compounds is presented, in which correlations for these parameters are derived using a group contribution te...
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A method for systematic evaluation of the Lennard-Jones parameters for polycyclic aromatic hydrocarbon (PAH) compounds is presented, in which correlations for these parameters are derived using a group contribution technique for critical temperatures and pressures and the Tee-Gotoh-Stewart correlations of corresponding states. The Lennard-Jones self-collision diameters and well depths of 29 PAHs were estimated using this approach and are shown to correlate with the molecular weights of aromatics. The gaseous binary diffusion coefficients of aromatics in common gases were calculated with Chapman-Enskog equation using the estimated Lennard-Jones parameters and were found to compare well with the available experimental data and the predictions of one of the most reliable empirical approximations. The effect of ordinary diffusion of PAH species on their predicted concentration profiles in a 20-torr laminar premixed acetylene flame is demonstrated computationally.
This paper reports on the application of solid-state CPMAS C-13 NMR and flash pyrolysis-GC-MS for characterization of the macromolecular network of a Montana subbituminous coal and its residues from temperature-progra...
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This paper reports on the application of solid-state CPMAS C-13 NMR and flash pyrolysis-GC-MS for characterization of the macromolecular network of a Montana subbituminous coal and its residues from temperature-programmed and non-programmed liquefaction (TPL and N-PL) at final temperatures ranging from 300 to 425-degrees-C in H-donor and non-donor solvents. The combined use of C-13 NMR and Py-GC-MS revealed that this coal contains significant quantities of oxygen-bearing structures, corresponding to about 18 O-bound C per 100 C atoms and one 0-bound C per every five to six aromatic C's. The oxygen-bearing components in the coal include catechol-like structures, which seem to disappear from the liquefaction residues above 300-degrees-C;carboxyl groups, which almost disappear after 350-degrees-C;and phenolic structures, which are most important in the original coal but diminish in concentration with increasing temperature. These results point to the progressive loss of oxygen functional groups and aliphatic-rich species from the macromolecular network of the coal during programmed heat-up under TPL conditions. The higher conversions in TPL runs in H-donor tetralin (relative to the conventional N-PL runs) suggest that the removal of carboxylic and catechol groups from the coal and the capping of the reactive sites by H-transfer from H-donors at low temperatures (less-than-or-equal-to 350-degrees-C) have contributed to minimizing the retrogressive crosslinking at higher temperatures. Quantitative calculation of NMR data and mathematical correlation were also attempted in this work. For 24 liquefaction residues derived under significantly different conditions, linear correlations between C-distribution and reaction temperature (greater-than-or-equal-to 300-degrees-C) have been found, which can be expressed by a simple equation, C(i) = alphaf(i) + betaT, where f(i) and C(i) represent content of aromatic, aliphatic, or oxygen-bound carbons in the original coal and residue,
Silicon-oxynitride glasses were prepared in the NaSiON, NaSiON, and the NaBSiON systems by conventional melting techniques. Increasing amounts of nitrogen were substituted for oxygen to a two weigh...
Silicon-oxynitride glasses were prepared in the NaSiON, NaSiON, and the NaBSiON systems by conventional melting techniques. Increasing amounts of nitrogen were substituted for oxygen to a two weight percent level of nitrogen. The Young's elastic moduli, Vicker's microhardnesses, and the fracture toughnesses were measured and observed to increase linearly with nitrogen content in each of these systems. These results are consistent with the incorporation of nitrogen into the glass structure in three-fold coordination with silicon.
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