Materials Literature
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The lifetime of excitons in ${\mathrm{Cu}}_{2}\mathrm{O}$ decreases significantly at high gas densities. This effect has been attributed to an Auger recombination process between two excitons, resulting in a loss rate given by ${\ensuremath{\tau}}^{\ensuremath{-}1}=An$, where $A$ is the Auger constant and $n$ is the e…
Amorphous CrxTi1−xO2 films with different Cr concentrations of 0⩽x⩽0.16 were prepared by cosputtering method at room temperature. All as-deposited samples show hysteresis behavior from 2to340K and the Curie temperatures are well above 390K. The saturation magnetization is about 3.21×10−1μB∕Cr for x=0.05 at 340K and de…
Fivefold deformation twins were reported recently to be observed in the experiment of the nanocrystalline face-centered-cubic metals and alloys. However, they were not predicted previously based on the molecular dynamics (MD) simulations and the reason was thought to be a uniaxial tension considered in the simulations…
With femtosecond pulse excitation at the wavelength near 800nm, we observed three upconverted emission peaks from ZnO nanowires. The ultraviolet peak at about 385nm and the green emission band centered at about 515nm were attributed to the near band edge emission and defect level emission, respectively, while the inte…
Natural rubber (NR) composites were prepared by incorporating short oil palm fibers of different lengths (viz., 2, 6, 10, and 14 mm) into natural rubber matrix in a mixing mill according to a base formulation. The curing characteristics of the mixes were studied and the samples were vulcanized at 150°C. The vulcanizat…
A large increase of diagonal piezo-optic coefficient (up to 3.7×10−13m2∕N at λ=633nm) was observed in Er doped ZnO films under photoinduced treatment by two laser beams with frequencies of 1,060 and 530nm originating from the same Nd:YAG pulsed laser. It was demonstrated that piezo-optic effect is enhanced with increa…
The authors found high Curie temperatures of up to 90K in annealed (In,Mn)As epilayers grown by molecular beam epitaxy using a relatively high V/III beam flux ratio. Magnetization data suggest that increasing the As beam flux results in an increase in the effective Mn content, and the carrier transport data indicate a…
A variety of one-dimensional (1D) micro- and nanostructures of zinc oxide (ZnO) were self-assembled on amorphous carbons using thermal chemical vapor transport and condensation without any metal catalysts. The low turn-on electronic field and the higher current density were achieved on these 1D ZnO micro- and nanostru…
Abstract Summary: In the present study, it has been unexpectedly found that solid‐state polycondensation (SSP) can act as a facile method to prepare poly(ethylene terephthalate)/silica (PET/SiO 2 ) nanocomposites with high molecular weight and an adjustable degree of branching or crosslinking. Fumed silica, with its s…
We investigate photoluminescence from reproducible Li-doped p-type ZnO thin films prepared by dc reactive magnetron sputtering. The LiZn acceptor state, with an energy level located at 150meV above the valence band maximum, is identified from free-to-neutral-acceptor transitions. Another deeper acceptor state located…
A model for the straight antiphase domain boundary of the ultrathin aluminum oxide film on the NiAl(110) substrate is derived from scanning tunneling microscopy measurements and density-functional theory calculations. Although the local bonding environment of the perfect film is maintained, the structure is oxygen def…
A hierarchical micro-/nanoscale domain structure is revealed in MC phase of (1−x)Pb(Mg1∕3Nb2∕3)O3–xPbTiO3 single crystal near the morphotropic phase boundary by combination of analytical electron microscopy and polarized light microscopy. The hierarchical domain structure is a self-assembling of nanodomains with tetra…
In this paper we show spin dependent transport experiments in nanoconstrictions ranging from 30 to 200nm. These nanoconstrictions were fabricated combining electron beam lithography and thin film deposition techniques. Two types of geometries have been fabricated and investigated. We compare the experimental results w…
Structural and magnetization studies were carried out on Dy1-xYxCo5 [x = 0, 0.2, 0.4, 0.6, 0.8, 1] compounds which crystallize in the hexagonal CaCu5-type structure. Lattice parameters and unit-cell volume increase with Y concentration. Large thermomagnetic irreversibility between the field-cooled and the zero-field c…
Heusler alloys containing Co and Mn are amongst the most heavily studied half metallic ferromagnets for future applications in spintronics. Using state-of-the-art electronic structure calculations, we investigate the effect of doping and disorder on their electronic and magnetic properties. Small degrees of doping by…
The equilibrium domain structure and its evolution under an electric field in ferroelectric bilayers and graded multilayers are considered. The equilibrium bilayer is self-poled and contains single-domain and polydomain (with 180° domains) layers. The polarization of a graded multilayer proceeds by movement of wedge-l…
Recent experimental results for covalent glasses suggest the existence of an intermediate phase attributed to the self-organization of the glass network resulting from the tendency to minimize its internal stress. However, the exact nature of this experimentally measured phase remains unclear. We modified a previously…
We derive sum rules for the phonon self-energy and the electron-phonon contribution to the electron self-energy of the Holstein-Hubbard model in the limit of large Coulomb interaction U. Their relevance for finite U is investigated using exact diagonalization and dynamical mean-field theory. Based on these sum rules,…
We present an experimental and theoretical study of the fatigue failure of asphalt under cyclic compression. Varying the load amplitude, experiments reveal a finite fatigue limit below which the specimen does not break, while approaching the tensile strength of the material a rapid failure occurs. In the intermediate…
We present a detailed study of the magnetic properties of low-temperature-molecular-beam-epitaxy grown Ge:Mn dilute magnetic semiconductor films. We find strong indications for a frozen state of Ge_{1-x}Mn_{x}, with freezing temperatures of T_f=12K and T_f=15K for samples with x=0.04 and x=0.2, respectively, determine…