Materials Literature
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We report the clearly observed tunneling magnetoresistance at 5 K in magnetic tunnel junctions with Co-doped ZnO as a bottom ferromagnetic electrode and Co as a top ferromagnetic electrode prepared by pulsed laser deposition. Spin-polarized electrons were injected from Co-doped ZnO to the crystallized Al2O3 and tunnel…
The physics of deep defect states associated with group-III (Ga, In, Tl) impurities in PbTe has been of great interest over the last several decades. Three different models have been proposed to understand interesting and unusual properties exhibited by these impurities. These are ``impurity level'' model, ``mixed-val…
Understanding the loss of ferroelectricity in submicron- and nano-sized perovskites is an issue that has been debated for decades. Here we report results from a high-energy x-ray diffraction (XRD) study on a prime example of the perovskite's family, ${\text{BaTiO}}_{3}$ ceramics with a grain size ranging from 1200 to…
We derive and analyze the $f$-sum rule for a two-dimensional system of interacting electrons whose behavior is described by the Dirac equation. We apply the sum rule to analyze the spectral weight transfer in graphene within different approximations discussed in the literature. We find that the sum rule is generically…
In recent works, we have suggested that plasmonic covers may provide an interesting cloaking effect, dramatically reducing the overall visibility and scattering of a given object. While materials with the required properties may be directly available in nature at some specific infrared or optical frequencies, this is…
Carbon nanotubes (CNTs) used to reinforce polymer matrix composites are functionalized to form covalent bonds with the polymer in order to enhance the CNT/polymer interfaces. These bonds destroy the perfect atomic structures of a CNT and degrade its mechanical properties. We use atomistic simulations to study the effe…
By using an alternative wet-etch procedure, we have obtained high-quality atomically flat TiO2 terminated surfaces of SrTiO3 single crystals with the morphology equivalent to that of the conventional wet-etch methods. By applying a combined power of photoluminescence (PL) spectroscopy, reflection high-energy electron…
In this work, the chemical changes in calf thymus DNA samples were analyzed by X-ray photoelectron spectroscopy (XPS). The DNA samples were irradiated for over 5 h and spectra were taken repeatedly every 30 min. In this approach the X-ray beam both damages and probes the samples. In most cases, XPS spectra have comple…
Since the mechanical properties and the integrity of the weld metal depend on the solidification behaviour and the resulting microstructural characteristics, understanding weld pool solidification is of importance to engineers and scientists. Thermal and fluid flow conditions affect the weld pool geometry and solidifi…
Molecular materials may overcome some of the difficulties for making an intermediate band solar cell by storing energy in long-lived triplet states. Both the problems of fast nonradiative interband relaxation and selective photon absorption can be solved by this approach. A practical implementation of the molecular in…
Abstract The synthesis of ( L )‐lactide oligomers from dimer to 64mer via an exponential growth strategy is described. By careful selection of orthogonal protective groups, the synthesis were conducted using a t ‐butyldimethylsilyl (TBDMS) ether as the protective group of the hydroxyl group and benzyl (Bn) ester as th…
Magnetic behaviors of pure CeO2 nanoparticles and nanocubes have been investigated both experimentally and theoretically. It is found that monodisperse CeO2 nanocubes with an average size of 5.3 nm do show ferromagnetic behavior at ambient temperature with a saturation magnetization of about 5.7 memu/g and coercive fo…
Abstract ZnO nanorods and nanowires are promising candidates as new types of high‐sensitivity ultraviolet (UV) photodetectors due to their wide bandgap and large aspect ratio. In this study, single‐crystalline ZnO nanorods were grown on glass substrates by a hydrothermal method. Specific structural, morphological, ele…
Dislocations in a material will, when present in enough numbers, change the speed of propagation of elastic waves. Consequently, two material samples, differing only in dislocation density, will have different elastic constants, a quantity that can be measured using Resonant Ultrasound Spectroscopy. Measurements of th…
Abstract A novel microbubble inflation method has been used to determine the creep compliance of poly(vinyl acetate) and polystyrene ultra‐thin films (13–300 nm thick) at temperatures from below to above the glass temperature. We present results that suggest that time‐temperature and time‐thickness superposition hold…
Abstract Superoleophobic surfaces possessing static contact angles greater than 140° with organic liquids are extremely rare. A simple approach has been developed to fabricate an extremely superamphiphobic coating material based on fluorinated silica nanoparticles resulting contact angles of water and diiodomethane at…
Lanthanum doping of the high-temperature p-type thermoelectric material Yb14MnSb11 enhances the figure of merit (zT) through carrier concentration tuning. This is achieved by substituting La3+ on the Yb2+ site to reduce the free hole concentration as expected from the change in valence. The high-temperature transport…
The electron field emission characteristics of individual multiwalled carbon nanotubes were investigated by a piezoelectric nanomanipulation system operating inside a scanning electron microscopy chamber. The experimental set-up ensures a precise evaluation of the geometric parameters (multiwalled carbon nanotube leng…
We present low-temperature anelastic and dielectric spectroscopy measurements on the perovskite ionic conductor ${\text{BaCe}}_{1\ensuremath{-}x}{\text{Y}}_{x}{\text{O}}_{3\ensuremath{-}x/2}$ in the protonated, deuterated, and outgassed states. Three main relaxation processes are ascribed to proton migration, reorient…
We report results of a systematic study of structural, vibrational and thermodynamical properties of 34-atom bimetallic nanoparticles from the AgnCu34-n family using model interaction potentials as derived from the embedded atom method and in the harmonic approximation of lattice dynamics. Systematic trends in the bon…