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61.
P. Svoboda J. Vejpravová M. Hofmann R. Schneider M. Rotter M. Doerr M. Loewenhaupt 《Czechoslovak Journal of Physics》2002,52(2):267-270
Intermetallic compound TmCu2 crystalizes in the orthorhombic structure, orders antiferromagnetically (AF) and exhibits four different AF phases below T
N = 6.5 K. In all these phases the Tm magnetic moment is parallel to the b-axis. The ground-state AF1 (T < 3.4 K) corresponds to the squared-up AF structure with propagation vector
01 = (5/8, 0, 0) and magnetic unit cell 8a × b × c. Narrow phases AF2 and AF3 (3.3 K < T < 3.7 K and 3.6 K < T < 4.6 K) are 'spin-slip'-derivatives from the AF1 structure, yielding propagation vectors
02 = (0.633, 0, 0.02) and
03 = (0.618, 0, 0), respectively. The phase AF4 (4.4 K < T < T
N) is then incommensurate transversal spin-wave with the propagation
04 = (0.64, 0, 0). The co-existence of AF phases indicates the first-order transitions between them. 相似文献
62.
Koichi KikuchiHiroyuki Nishikawa Isao IkemotoTakashi Toita Hiroki AkutsuShin'ichi Nakatsuji Jun-ichi Yamada 《Journal of solid state chemistry》2002,168(2):503-508
Three FeCl4 salts based on non-tetrathiafulvalene (TTF) donors, 2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene (BDH-TTP) and 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene (BDA-TTP), have been prepared and characterized as κ-(BDH-TTP)2FeCl4, β-(BDA-TTP)2FeCl4, and (BDA-TTP)3FeCl4 · PhCl. The κ-(BDH-TTP)2FeCl4 salt, with a room-temperature conductivity (σrt) of 39 S cm−1, is metallic down to 1.5 K, and its magnetic susceptibility obeys the Curie-Weiss law with a Curie constant (C) of 4.25 emu K mol−1 and a Weiss constant (θ) of 0.041 K. β-(BDA-TTP)2FeCl4 exhibits metallic behavior (σrt=9.4 S cm−1) with a sharp metal-to-insulator (MI) transition (TMI=113 K) and antiferromagnetic ordering with the Néel temperature of near 8.5 K, whereas the solvated (BDA-TTP)3FeCl4 · PhCl salt is a semiconductor with a thermal activation energy of 0.11 eV (σrt=2.0× 10−2 S cm−1) and exhibits Curie-Weiss behavior (C=4.42 emu K mol−1, θ=−0.35 K). 相似文献
63.
Ch. F. D. McCoy 《Algebra and Logic》2002,41(5):295-305
The notion of
3
0
-categoricity in linear orderings and Boolean algebras is examined. We provide a proof for the fact that there are uncountably many relatively
3
0
-categorical linear orderings, and furnish a proof of another fact which suggests that the (unrelatively)
3
0
-categorical linear orderings may be very difficult to classify. In stark contrast to these results for linear orderings, a complete classification of the relatively
3
0
-categorical Boolean algebras is given. 相似文献
64.
The substrate is shown to induce substantial ordering in diblock copolymer thin films above the bulk order-disorder transition
(ODT) where, thermodynamically, a phase mixed state is favored. Initially, uniform films reorganize to form a hierarchy of
transient surface patterns and stable film thicknesses that depend on the initial film thickness and on the substrate. Self-consistent
field calculations of the free energy of the system for different situations, depending on the relative tendency for the different
block components to be attracted to the substrate and/or free surface, provide an explanation of the formation of the stable
film thicknesses. A continuum picture proposed earlier by Brochard et al.rovides an explanation of the wetting characteristics of this system. In some cases the ordering destabilizes the film so
that dewetting occurs (wetting autophobicity), whereas in other cases the surface ordering results in a kinetic stabilization
of a film that would otherwise dewet.
Received 3 August 2001 and Received in final form 1 November 2001 相似文献
65.
C. Favazza J. Trice A. K. Gangopadhyay H. Garcia R. Sureshkumar Ramki Kalyanaraman 《Journal of Electronic Materials》2006,35(8):1618-1620
Most metals on SiO2 have a finite contact angle and are therefore subject to dewetting during thermal processing. The resulting dewetting morphology
is determined primarily by nucleation and growth or instabilities. The dewetting mechanism implies a disordered spatial arrangement
for homogeneous nucleation, but an ordered one for instabilities such as spinodal decomposition. Here, we show that the morphology
of laser-melted ultrathin Co film (4-nm thick) can be attributed to dewetting via an instability. Dewetting leads to breakup
of the continuous Co film into nanoparticles with a monomodal size distribution with an average particle diameter of 75 nm±23
nm. These nanoparticles have short-range order (SRO) of 130 nm in their separation. This result has important implications
for nanomanufacturing with a robust spacing or size selection of nanoparticles in addition to spatial ordering. 相似文献
66.
We report the results of Monte Carlo simulation of the phase diagram and oxygen ordering in YBa2Cu3O6+x
for low intra-sublattice repulsion. At low temperatures, apart from tetragonal (T), orthorhombic (OI) and ‘double cell’ ortho II phases, there is evidence for two additional orthorhombic phases labelled here asOI andOIII. At high temperatures, there was no evidence for the decomposition of theOI phase into theT andOI phases. We find qualitative agreement with experimental observations and cluster-variation method results. 相似文献
67.
C. T. Black K. W. Guarini 《Journal of polymer science. Part A, Polymer chemistry》2004,42(8):1970-1975
We have measured the time evolution of the self‐assembly process in perpendicular‐oriented cylindrical‐phase diblock copolymer thin films using statistical analysis of high‐resolution scanning electron microscope (SEM) images. Within minutes of annealing above the polymer glass‐transition temperature, microphase separation between polymer blocks results in formation of uniform nanometer‐scale domains whose relative position is initially largely uncorrelated. On further annealing, the cylindrical polymer domains organize into a two‐dimensional hexagonal lattice whose characteristic grain size increases slowly with time (~t1/4). © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1970–1975, 2004 相似文献
68.
69.
P.?G.?ChufyrevEmail author N.?V.?Sidorov N.?N.?Mel'nik 《Journal of Applied Spectroscopy》2005,72(5):667-670
Using the Raman scattering spectra, we investigated the ordering of the structural units in the cation sublattice and the
photorefractive properties of lithium niobate single crystals of variable composition, i.e., nominally pure ones with different
Li/Nb ratios and those doped with the nonphotorefractive cations Mg2+, Gd3+, and Y3+. It is shown that at low concentrations of Mg2+, Gd3+, and Y3+ the magnitude of the photorefractive effect is substantially determined by the ordering of the structural units of the cation
sublattice. It has been found for the first time that the intensity of the line corresponding to the bridge valence vibrations
of oxygen atoms in the octahedrons of NbO6 is sensitive to the dipole ordering of the cation sublattice of the crystal.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 5, pp. 611–614, September–October, 2005. 相似文献
70.
P. Blasiak A. Horzela K.A. Penson A.I. Solomon 《Czechoslovak Journal of Physics》2004,54(11):1179-1184
We solve the normal ordering problem for (A
A)
n
where A and A
are one mode deformed ([A,A
] = [N+1] – [N]) bosonic ladder operators. The solution generalizes results known for canonical bosons. It involves combinatorial polynomials in the number operator N for which the generating function and explicit expressions are found. Simple deformations provide examples of the method. 相似文献