Materials Literature
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An X-ray scattering experiment using synchrotron radiation has been performed on rutile-type β-MnO 2 single crystal. Below T N , satellites due to magnetic scattering appear, which provides direct evidence of a helical magnetic structure. The wave number of the magnetic helix is approximately 0.297 c * , incommensurat…
Presently, the best epitaxial thin films of CrO2 are made by chemical-vapor deposition (CVD) in a two-zone furnace with oxygen flow from a CrO3 precursor. The growth mode has previously been described as CrO3 vaporizing in the first zone, and thermally decomposing at higher temperature in the second zone onto a substr…
The electrical and optical properties of carbon-nitride CNx films (0⩽x⩽0.25) deposited by unbalanced reactive magnetron sputtering from a graphite target in mixed Ar/N2 discharges at a substrate temperature of 350 °C have been investigated. Pure C films exhibit a dark conductivity at room temperature of 25 Ω−1 cm−1, w…
Microwave plasma enhanced chemical vapor deposition has been used to grow diamond films at substrate temperatures down to 435 °C using CO2/CH4 gas mixtures. An Arrhenius plot of growth rate as a function of substrate temperature yields a value for the activation energy for the growth step of 28 kJ mol−1. This is lower…
The stability of anionic aluminum–nitrogen clusters has been examined and Al2N−, Al3N2−, Al5N2−, Al6N3−, Al8N3−, and Al9N2− are found to be particularly stable. Theoretical density functional calculations on neutral and anionic AlnN (n=1–8) clusters were performed and the stability and reaction energetics with oxygen…
We study annealing of Si/SiO2 superlattices on fused quartz and crystalline Si substrates. Under annealing at 1200 °C, the superlattices on Si undergo partial crystallization involving clusterization of Si layers through ultrathin (1 nm) oxide, and visible photoluminescence (∼2.1 eV) strongly increases for the samples…
Tm 3+ ion doped transparent oxyfluoride glass ceramics containing PbF2 nanocrystals were prepared and infrared fluorescence properties of Tm3+ ions were investigated. From luminescence decay measurement, it is revealed that part of the Tm3+ ions were incorporated into fluoride crystals by annealing as-made glass above…
Pyrochlore free Pb(Mg1/3Nb2/3)O3 (PMN) thin films were prepared from alkoxide-based solution precursors. The influence of different seeding layers and chemical solution on the microstructures is shown. Dielectric, electrostrictive, and piezoelectric properties of the films were characterized in detail. Films show rela…
Ferromagnetic shape memory alloys have demonstrated strains up to 5% resulting from the rearrangement of crystallographic variants by twin boundary motion under an applied field. A model is proposed that describes twin boundaries moving abruptly in order to accommodate either the mechanical energy of an applied stress…
The electronic structure of networked nano-graphites is investigated in relation to the effects of fluorine-introduced s p 3 -defects on the nano-sized π-electron system. In the low fluorine concentration region, the shrinkage of the π-conjugated system due to introduced s p 3 -defects reduces the orbital diamagnetism…
Undoped and Ta-doped SnO2 (Sn1−xTaxO2) thin films were prepared on Corning 7059 glass substrates by the metal–organic chemical-vapor deposition method. The relative amount of Ta, CTa=XTa/(XTa+XSn), varied from 0 to 7.13 at. %. For the five compositions studied, the lowest resistivity at room temperature was 2.01×10−4…
Spherical and uniform CdS nanoclusters were synthesized by hydrothermal microemulsion. The reaction of Cd2+ ions with S2− ions generated from the decomposition of thioacetamide proceeded in water microdroplets. The mean diameter of the CdS nanoclusters can be varied from 20 to 80 nm by increasing the reaction temperat…
Acetate kinase, an enzyme widely distributed in the Bacteria and Archaea domains, catalyzes the phosphorylation of acetate. We have determined the three-dimensional structure of Methanosarcina thermophila acetate kinase bound to ADP through crystallography. As we previously predicted, acetate kinase contains a core fo…
In this letter, we report the improved magnetotransport properties of La0.7Sr0.3MnO3-borosilicate glass composite with different weight percents of glass. All the composites showed ferromagnetic nature at room temperature. The microstructure of these composites was seen using a scanning electron microscope. The micros…
The nuclear quadrupole moment of the I=3/2- excited nuclear state of 57Fe at 14.41 keV, important in Mössbauer spectroscopy, is determined from the large-scale nuclear shell-model calculations for 57Fe and also from the electronic ab initio and density functional theory calculations including solid state and electron…
The Mn2+ emission wavelengths are at 591, 588, 581 and 570 nm, respectively, for the ∼10, ∼4.5, ∼3.5 nm sized nanoparticles and the ZnS:Mn nanoparticles formed in an ultrastable zeolite-Y. To reveal the cause for the shift, the crystal field and phonon coupling were investigated. The results show that the predominant…
The contrast mechanisms of domain imaging experiments assisted by atomic force microscope (AFM) have been investigated by model experiments on nonpiezoelectric (silicon oxide) and piezoelectric [Pb(Zr,Ti)O3] thin films. The first step was to identify the electrostatic charge effects between the tip, the cantilever, an…
In this article, domain wall motion and the extrinsic contributions to the dielectric and piezoelectric responses in sol–gel derived lead zirconate titanate (PZT) films with compositions near the morphotropic phase boundary were investigated. It was found that although the films had different thicknesses, grain sizes,…
We describe the electrically enhanced growth of needle crystals from the vapor phase, for which there exists a morphological instability above a threshold applied potential. Our improved theoretical treatment of this phenomenon shows that the instability is present in both polar and non-polar systems, and we provide a…
XPS, ATR-FTIR, 19 F MAS solid-state NMR, and imaging TOF−SIMS have been used to compare the depth and extent of chemical modification achieved during nonisothermal CF 4 plasma fluorination of nonporous, mesoporous, and microporous polystyrene spheres. It is shown that different depths of functionalization can be achie…