Materials Literature
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The topology and the trace of ferroelastic domains, namely W walls, of Ca-doped lead orthophosphate (Pb 1− x , Ca x ) 3 (PO 4 ) 2 with a Ca content of 2.7% mol were studied on the monoclinic cleavage plane (100) using contact mode atomic force microscopy. Furthermore, conducting atomic force microscopy was applied usi…
In the cubic C-type rare-earth (R) sesquioxides, C-R 2 O 3 , the trivalent R ions (R 3+ ) occupy two different crystallographic sites with S 6 and C 2 symmetries. The R ions in the C 2 lattice site have been studied intensively whereas the properties of the R 3+ ions in the S 6 site are largely unknown or the data are…
γ-Ga2O3 and α-Ga2O3 samples were prepared as single-phase materials having a high surface area. 71Ga NMR showed the simultaneous presence of tetracoordinated (GaIV) and hexacoordinated (GaVI) in γ-Ga2O3, whereas in α-Ga2O3 most of the gallium present was found to be as GaVI. However, the apparent rate of methanol conv…
The single-crystal X-ray structure of 2,3,6,7,10,11-hexaethoxy-1-nitrotriphenylene confirms earlier calculations of the molecular geometry and shows that the α-nitro substituent imparts a helical twist to the triphenylene nucleus. Within the crystal, the molecules are arranged in tilted columns on an oblique lattice,…
The layered oxides LiNi1−xMnxO2 (x = 0.1–0.5) were synthesized and characterized using synchrotron X-ray diffraction, TOF neutron diffraction, SQUID magnetometry, ICP spectroscopy, XAFS, and electrochemical measurements. All the samples were single-phase and adopted the α-NaFeO2 structure; LiNi1−xMnxO2 can be represen…
Axially chiral bis(azo) derivative 1 undergoes photochemical isomerisation, which can be seen with circular dichroism and pitch measurements of the induced cholesteric phases.
We present a theoretical analysis of low-temperature quenching of one-dimensional Frenkel excitons that are localised by moderate on-site (diagonal) uncorrelated disorder. Exciton diffusion is considered as an incoherent hopping over localization segments and is probed by the exciton fluorescence quenching at point tr…
The high resistivity of many bulk and film samples of MgB2 is most readily explained by the suggestion that only a fraction of the cross-sectional area of the samples is effectively carrying current. Hence the supercurrent (Jc) in such samples will be limited by the same area factor, arising for example from porosity…
The bonding and stability of MgSi and AlMgSi compounds relevant to AlMgSi alloys is investigated with the use of (L)APW+(lo) DFT calculations. We show that the $β$ and $β''$ phases found in the precipitation sequence are characterised by the presence of covalent bonds between Si-Si nearest neighbour pairs and covalent…
Electrical and magnetic properties of four series of manganates LnxCa1-xMnO3 (Ln=La, Nd, Gd and Y) have been studied in the electron doped regime (x=0.02-0.25) in order to investigate the various inter-dependent phenomena such as ferromagnetism, phase separation and charge ordering. The general behavior of all the fou…
We investigate the structure of magnetic domain walls in a classical double exchange ferromagnet, evaluating domain wall energies and charges. Three different cases are studied: (i) a conventional smooth Bloch wall, (ii) an abrupt Ising-type wall, which is shown to have lower energy at small values of carrier concentr…
We investigate the resonance steps, spatiotemporal dynamics, and dynamical phase diagrams of the dc-driven diatomic Frenkel-Kontorova model. The complete resonance velocity spectrum is given. The diatomic effects result in each resonant state being characterized by two integer pairs, $(k_1,k_2)$ and $(k_1,k_2^{\prime}…
Structural and kinetic aspects of 2-D irreversible metal deposition under potentiostatic conditions are analyzed by means of dynamic Monte Carlo simulations employing embedded atom potentials for a model system. Three limiting models, all considering adatom diffusion, were employed to describe adatom deposition.The fi…
The magnetic flux trapping in type-II superconductor containing fractal clusters of a normal phase, which act as pinning centers, is considered. The critical current distribution for an arbitrary fractal dimension of the boundaries of the normal phase clusters is obtained. It is revealed that the fractality of the clu…
We have investigated the lattice dynamics of LiBC. Experimental Raman and inelastic neutron scattering results are confronted with density functional calculations. The excellent agreement between experiment and theory indicates that we have attained a high level of understanding for LiBC, which by its structure is clo…
We present a detailed investigation of the temperature and frequency dependence of the anomalous EPR transitions first observed in Mn12-acetate by Hill et al. [Phys. Rev. Lett. 80, 2453 (1998)]. The most dominant of these transitions manifest themselves as an extra series of EPR absorption peaks for spectra obtained w…
Unusual emission of visible light is observed in scanning tunneling microscopy of the quantum well system Na on Cu(111). Photons are emitted at energies exceeding the energy of the tunneling electrons. Model calculations of two-electron processes which lead to quantum well transitions reproduce the experimental fluore…
The oxidation of polystyrene, polyethylene, polypropylene and poly(vinylidene fluoride) is retarded by carbon nanotubes. Incorporation of boron into the nanotubes enhances the electron affinity of the tubes and leads to a small increase in antioxidant efficiency.
The propagation of light in nonperiodic quasicrystals is studied by ultrashort pulse interferometry. Samples consist of multilayer dielectric structures of the Fibonacci type and are realized from porous silicon. We observe mode beating and strong pulse stretching in the light transport through these systems, and a st…
The optical response of ring-shaped gold nanoparticles prepared by colloidal lithography is investigated. Compared to solid gold particles of similar size, nanorings exhibit a redshifted localized surface plasmon that can be tuned over an extended wavelength range by varying the ratio of the ring thickness to its radi…