Materials Literature
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We report on the optical properties of undoped single crystal ${\mathrm{LaMnO}}_{3},$ the parent compound of the colossal magnetoresistive manganites. Near-normal-incidence-reflectance measurements are reported in the frequency range of $20\ensuremath{-}50000 {\mathrm{cm}}^{\ensuremath{-}1}$ and in the temperature ran…
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Reversible generation and dissolution of 3 nm silver particles in a glass containing only silver ions are repeatedly achieved through a combination of x-ray radiation and heat treatment. X-ray irradiation and 400 °C heat treatment induce a yellow color, whereas heating at 500 °C can change the glass to colorless again…
A rough and thick film of doped praseodymium nickel oxide (Pr2NiO4+δ) has been obtained by combining the spray pyrolysis deposition technique with rapid thermal annealing process. The precursors are nitrate solutions. Spectral emissivity measurements from the far infrared up to the midinfrared region at T=1000 K show…
The surfaces of polystyrene (PS) films decorated with gold nanoclusters were investigated by x-ray reflectivity measurements. The thicknesses of the films are much larger than the radii of gyration of the different PS samples. By annealing the films above the glass transition temperature T(g) an embedding process of t…
Rare-earth and lead ions (Eu3+, Tb3+, Dy3+, Pb2+) doped Ca2Y8(SiO4)6O2 and Ca2Gd8(SiO4)6O2 thin films have been dip-coated on silicon and quartz glass substrates through the sol–gel route. X-Ray diffraction (XRD), TG–DTA, scanning electron microscopy (SEM), atomic force microscopy (AFM), FT-IR and luminescence excitat…
The physical principles, the experimental realization, the methodology and the application of synchrotron radiation-induced non-scanning photoemission electron microscopy (XPEEM) are discussed, including the combination with low-energy electron microscopy and the corresponding diffraction and spectroscopy techniques.…
We report on the preparation and characterization of the double-perovskite compound Sr2CrWO6 with a Curie temperature of 390 K. We have fabricated both Sr2CrWO6 bulk sintered polycrystalline bars and high-quality epitaxial thin films on SrTiO3 substrates by pulsed-laser deposition. The samples were characterized by th…
A type of carbon nanotube transistors, which would be suitable for large-scale integration, has been fabricated from vertically aligned carbon nanotubes. We fabricated highly ordered carbon nanotubes, which are selectively grown on the patterned aluminum oxide nanotemplates. Each device element is formed on a vertical…
Direct hysteresis measurements on single submicron structure sizes were performed on epitaxial ferroelectric Pb(Zr,Ti)O3 thin films grown on SrTiO3 with La0.5Sr0.5CoO3 (LSCO) electrodes. The samples were fabricated by focused-ion-beam milling resulting in pad sizes down to 200 nm×200 nm. The influence of parasitic cap…
Nanocrystalline Er-doped CeO2 phosphors with an average crystallite size of 18, 38, and 70 nm were prepared by glycine–nitrate solution combustion synthesis. The particle size of the resultant powders is tied up with the combustion flame temperature, which can be controlled by adjusting the ratio of glycine to nitrate…
The influence of dc current flow on the resistivity and phase transitions in low-doped ${\mathrm{La}}_{0.82}{\mathrm{Ca}}_{0.18}{\mathrm{MnO}}_{3}$ single crystals has been investigated. At low temperatures, where the resistivity strongly increases with decreasing temperature, dc current depresses resistivity in a way…
Isothermal annealing of two partially metamict zircon from Sri Lanka were carried out at 870 K, 968 K, 1071 K, and 1166 K for 0.5 min up to ∼; 210 hours. Raman spectroscopy was used to monitor the amorphous-to-crystalline transformation. The evolution of the phonon frequency and the linewidth of the v 3 Si-O stretchin…
Evidence has been found for a change in the ordered occupation of the vanadium d orbitals at the 77 K phase transition in YVO3, manifested by a change in the type of Jahn-Teller distortion. The orbital ordering above 77 K is not destroyed at the magnetic ordering temperature of 116 K, but is present as far as a second…
Crystallization processes in different Te alloys, employed in phase change materials for optical data storage, have been investigated by in situ mechanical stress measurements. Upon crystallization a considerable stress buildup is observed, which scales with the volume change upon crystallization. Nevertheless the obs…
A magnetoresistance study of carbon nanotubes demonstrates that, for small diameters, the location of the chemical potential and the orientation of the magnetic field are parameters that enable tuning from positive to negative magnetoresistance, a phenomenon not related with weak localization. For larger diameters (>…
The complex dielectric functions of wurtzite ZnS thin films grown on (0001) Al2O3 have been determined by using spectroscopic ellipsometry over the spectral range of 1.33–4.7 eV. Below the band gap, the refractive index n is found to follow the first-order Sellmeir dispersion relationship n2(λ)=1+2.22λ2/(λ2−0.0382). S…
Experimental measurements of Raman spectra for hcp iron at high pressure show two modes over a considerable pressure range in contrast to the prediction of one doubly degenerate mode for the hcp lattice. We use density functional theory to investigate the influence of magnetic order on the Raman active modes of hcp ir…
We report the discovery of a new class of molecular phases of solid nitrogen at high pressures and temperatures by Raman and infrared spectroscopy and powder x-ray diffraction. Unlike the molecular phases consisting of disk- and sphere-like molecular disorder ($δ$-, $ε$- and $ζ$-N$_2$) and reportedly stable over a wid…
The spin-polarized scanning tunnelling microscope (STM) can in principle resolve not only the electronic, but also the magnetic surface structure. We model recent STM measurements achieving magnetic resolution on the atomic scale by a first-principles method. It is shown that the signature of a specific magnetic or no…