Materials Literature
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We present an analysis of the effect of finite temperatures on the deuteron nuclear quadrupole coupling constants in a strongly hydrogen-bonded molecular crystal by means of first-principles Car-Parrinello molecular-dynamics simulations. Our findings agree well with experiments and provide a microscopic explanation of…
The solute-drag-dependent growth kinetics of core-shell-structured grains in rare-earth-doped BaTiO3 ceramics was studied based on an analytical description of the diffusion of rare-earth atoms doped. Dependence of the sizes of grain core and shell on the sintering conditions, dopant content, and starting powder size…
We report on broadband microwave-frequency measurements of epitaxial ferroelectric Ba0.3Sr0.7TiO3 thin films that reveal systematic increases in the loss and dispersion as the frequency increases toward 40 GHz. Our analysis provides evidence that the origin of this increased loss and dispersion is the direct coupling…
The results of a parametric study on the growth of vertically aligned carbon nanofibers (CNFs) by high-density inductively coupled plasma (ICP) chemical-vapor deposition are reported. We investigated the mechanisms that cause the detachment of CNFs during the growth process by high-density plasma-enhanced chemical-vap…
The effects of phase distribution and grain size on the effective anisotropy and coercivity of the exchange-coupled nanocomposite permanent materials have been investigated in this paper. The effective anisotropy of nanocomposite permanent materials is supposed to be equal to the statistical average value of the aniso…
Coexistence between the isotropic and the nematic phase in suspensions of rods is studied using grand canonical Monte Carlo simulations with a bias on the nematic order parameter. The biasing scheme makes it possible to estimate the interfacial tension gamma(IN) in systems of hard and soft rods. For hard rods with LD=…
The binding energy of a biexciton confined in InAs nanorods is calculated using the potential morphing method. Once the system under investigation is in a crossover state, the spectral shapes of the exciton and biexciton photoluminescence were predicted. Our results indicate that for the decreasing length of the nanor…
We studied the crystal and magnetic structure of the ${\mathrm{La}}_{1∕4}{\mathrm{Ca}}_{3∕4}\mathrm{Mn}{\mathrm{O}}_{3}$ compound using ultrahigh resolution synchrotron x-ray and neutron-diffraction techniques. The experimental results revealed that the particular compound undergoes a structural transition at ${T}_{\m…
ABSTRACT The present study focuses on the effect of microstructural gradients on the fatigue crack growth resistance of Ti‐6Al‐4V and Ti‐6242 titanium alloys. Sharp microstructural gradients from fine‐grained bimodal to coarse‐grained lamellar microstructures were obtained by heat treating only a portion of fine‐grain…
A phase-field model for investigating the surface morphological evolution of a film is developed, taking into account the surface energies of film and substrate, the interfacial energy between the film and substrate, and the elastic energy associated with the lattice mismatch between the film and substrate. Using the…
Elastic constants and the Poisson ratio of the fcc hard-sphere crystalline phases, free of defects and with vacancies, are determined by two Monte Carlo methods: (i) the analysis of the box fluctuations in the constant pressure ensemble with variable box shape (N-P-T) and (ii) by the free-energy differentiation with r…
We report colossal magnetoresistance at room temperature by introducing disorder to the A-site ordered manganites, SmBaMn2O6. SmBaMn2O6 shows the metal to CE-type charge/orbital ordered insulator transition at 375K above room temperature. We have achieved a magnetoresistance effect of 340% at room temperature and 300%…
Alkyl-modified silicon nanocrystallites are efficient fluorophores which are of interest for fundamental spectroscopic studies and as luminescent probes in biology because of their stability in aqueous media. In this work we have investigated these particles using scanning tunneling microscopy, synchrotron-radiation e…
Room-temperature ferromagnetic In1−xCrxN films with x ranging from 0.0005 to 0.04 and antiferromagnetic CrN films have been grown by plasma-assisted molecular-beam epitaxy. Electron and x-ray-diffraction techniques could find no evidence for precipitates or phase segregation within the films. Ferromagnetism was observ…
While the swelling behavior of laboratory-prepared homoionic montmorillonites has been studied extensively in numerous experimental and simulation works, far less attention has been given to much more abundant natural montmorillonites, containing a mix of monovalent and/or bivalent cations in interlayer spaces. We car…
We observed a significant enhancement of electric resistivity excited by a dc current in ${\mathrm{La}}_{0.8}{\mathrm{Ca}}_{0.2}{\mathrm{MnO}}_{3}$ epitaxial thin films. Such an enhanced resistance can be achieved when the applied dc current exceeds a threshold value. It also strongly depends on the duration of the dc…
We have measured the temperature-dependent thermal conductivity κ(T) of boron-carbon-nitride (B-C-N) and boron nitride (BN) nanotube mats. The thermal conductivity of B-C-N nanotubes is phonon dominated and reflects dimensional effect below 70 K. We employ a new analysis method to estimate the intrinsic κ(T) of BN nan…
The effect of TiO2 doping on the structure and magnetic and magnetotransport properties of La0.75Sr0.25MnO3 (LSMO)∕xTiO2 has been investigated. These studies show that at low doping level (x⩽2) TiO2 mainly goes into the grain-boundary region, but at high doping level (x⩾3), some part of the TiO2 goes into the perovski…
Miniaturized planar solid-oxide fuel cells (SOFCs) and stacks can be fabricated by thin film deposition and micromachining. Serious thermal stresses, originating in fabrication and during operation, cause thermal–mechanical instability of the constituent thin films. In this paper, the effect of thin film geometry on t…
The Ni2MnGa-based Heusler alloys with high magnetocaloric effect have attracted considerable attention as a promising magnetic refrigerant. The phase-transition processes and magnetic entropy changes in the NiMnGa alloys with the concurrence of magnetic and structural phase transitions were studied. The ac magnetic su…