Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
We suceeded in the preparation of polycrystalline Ca_2FeReO_6 which has a Curie temperature of 540 K, the highest value of all magnetic perovskites investigated up to now. This material has been characterised by X-ray and neutron powder diffraction. We found at 548 K a monoclinic unit cell (space group P2_1/n) with a=…
The elaboration of solids from the molecular scale by a kinetically controlled methodology is one of the main challenges of molecular chemistry. In the long term, this should permit the design of solids with desired properties. Here, some examples are given which show a few methods that have been used for the preparat…
Monodisperse, rodlike molecules 1 composed of repeating individual chromophores that have substantial electronic interactions in the ground state have been synthesized by the meso – meso coupling of porphyrins. The 128-mer (n=63) at about 106 nm long is the longest such system known. The S1 states are delocalized over…
We report that calculating the Gibbs free energy of the alpha-Al2O3 (0001) surfaces in equilibrium with a realistic environment containing both oxygen and hydrogen species is essential for obtaining theoretical predictions consistent with experimental observations. Using density-functional theory we find that even und…
We construct the 1/S spin-wave expansion for double exchange ferromagnets at T=0. It is assumed that the value of Hund's rule coupling, J_H, is sufficiently large, resulting in a fully saturated, ferromagnetic half-metallic ground state. We evaluate corrections to the magnon dispersion law, and we also find that, in c…
Using Brownian molecular dynamics simulation, we study the surface dynamics near the reconstruction transition of W(100) via a model Hamiltonian. Results for the softening and broadening of the surface phonon spectrum near the transition are compared with previous calculations and with He atom scattering data. From th…
We have measured the 161 Dy Mössbauer effects on the cubic ferroquadrupolar ordering compound DyB 6 . In the antiferromagnetic phase, the Mössbauer spectra are interpreted well by a single set of hyperfine parameters which gives the Dy magnetic moment of 9.8 µ B . The nuclear quadrupole splitting implies that the crys…
Aliphatic polypyromellitimides having high crystallinity were synthesized by the high-pressure thermal polycondensation of the nylon-salt-type monomers XPME composed of aliphatic diamines and pyromellitic acid p-diethyl esters. The polymer-forming reactivity of the salt monomers XPME was comparable to that of the pare…
The microscopic a parameter, which alone is needed to describe the surface sensitive dependence of second-harmonic generation from jellium metals, is calculated within a time-dependent local-density-functional approximation for frequencies between zero and twice the bulk plasmon. The calculations incorporate an extrin…
New types of second-order nonlinear optical properties of hexagonal ${\mathrm{YMnO}}_{3}$ have been studied, caused by the coexistence of the noncentrosymmetric ferroelectric ordering of charges and the centrosymmetric spin ordering below its Neel temperature ${T}_{N}.$ Using time-dependent perturbation theory and the…
Compositionally modulated structures consisting of La2/3Ca1/3MnO3 ferromagnetic (FM) layers and La1/3Ca2/3MnO3 antiferromagnetic (AF) layers, with layer thickness 1.5 nm ⩽tFM,tAF⩽6 nm, were grown on (100)LaAlO3 by pulsed laser deposition. Thermomagnetic and isothermal magnetic measurements reveal an exchange-biasing m…
The surface shape and the spatial distribution of strain in GaInAs/InP multilayer gratings is experimentally determined by combining high-resolution x-ray diffraction and grazing-incidence diffraction. Dramatic deformations of the diffraction patterns in the measured reciprocal space maps of such gratings indicate a s…
Electrical resistivity (ρ), magnetoresistance (MR) and magnetization (σ) for Heusler type alloys Fe 2+ x V 1- x Al with -0.10≦ x ≦0.20 were measured. A giant magnetoresistance (GMR) of about 40% was observed for the weakly inhomogeneous ferromagnet Fe 2.1 V 0.9 Al at 4.2 K in 130 kOe. In the ferromagnetic alloys ( x ≧…
Time-resolved light scattering experiments have been performed on the two-step phase separation process for a binary mixture of deuterated polybutadiene and protonated polyisoprene with the critical composition. The first-step phase separation was induced by quenching the system from a temperature T0 in a single-phase…
The dynamic structure factor, S ( Q , E ), of liquid lithium ( T = 475 K) has been remeasured by inelastic X-ray scattering (IXS) in an extended momentum transfer region ( Q = 1.4–110 nm −1 ) and with improved energy resolution (down to 1.5 meV). These new data on such prototypical simple liquid allow to observe the f…
Nonlinear time evolution of phase-separating structures in the two-step phase separation process was investigated for a deuterated polybutadiene–polyisoprene mixture by using a time-resolved light scattering technique. The mixture studied has a lower critical solution temperature type phase diagram with a spinodal tem…
ε-Caprolactone (ε-CL) has been mixed with ZnCl2 at different mol ratios. The resulting complex was characterized through 1H and 13C NMR spectroscopy in bulk and in solutions, differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and optical microscopy. Ring-opening polymerization of ε-caprolact…
A poly(isoprene-b-ethyleneoxide) diblock undergoes multiple ordered state transitions: from a crystalline lamellar (L c ), to a hexagonal (Hex) mesophase, to a bicontinuous cubic phase (Gyroid) before disordering (Dis). We have studied the kinetics of the Hex-to-Gyroid, Hex-to-L c and L c -to-Gyroid transitions using…
The growth of narrow single-wall carbon nanotubes through adduction of small carbon clusters is studied using a molecular-dynamics simulation method. Statistical behavior of the growth and defect formation process is analyzed. For ${C}_{2}$ dimer colliding onto the side-wall of narrow single-wall nanotubes, it is very…
Boron carbonitride (BCN) films with various compositions have been prepared by bias-assisted hot filament chemical vapor deposition. The three elements of B, C, and N are chemically bonded with each other and an atomic-level BCN hybrid has been formed in the films. The deposited films are composed of turbostratic stru…