Materials Literature
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Copper-doped ZnO (ZnO:Cu) films were prepared on silicon substrates by filtered cathodic vacuum arc technique at room temperature using a Zn target containing 5at.% of Cu. Room temperature ferromagnetism was observed in the ZnO:Cu films with saturation magnetization of 0.037μB∕Cu atom. The origin of the ferromagnetism…
Organogels are thermoreversible, viscoelastic (soft) materials consisting of low molecular weight compounds which self-assemble into fibers, often of micrometer lengths and nanometer diameters. The installation of terminal azide and alkyne functional groups on the end of a standard alkylamide-based organogelator was f…
The influence of postgrowth annealing on the structural and optical properties of rf cosputtered Mn doped ZnO thin films deposited on glass substrate at room temperature has been investigated. All as deposited Zn1−xMnxO films are highly textured, with the c axis of the wurtzite structure along the growth direction. Th…
Grain-boundary relaxation in nanocrystalline Fe was studied by high-resolution transmission electron microscopy (HREM), and its effect on plasticity was characterized by nanoindentation. Samples with grain size of 9.8nm were synthesized by mechanical attrition and subsequently annealed at low temperatures (80 and 100°…
Transducers utilizing the Villari effect (inverse-magnetostrictive effect) consist of a coil wound on a core of magnetostrictive material. In this paper, a linear magnetomechanical coupling model is developed to analytically calculate the potential electrical power such transducers can generate when subjected to appli…
We use Monte Carlo simulations to study NiFe2O4 nanoparticles. Finite size and surface effects differentiate them from their bulk counterparts. A continuous version of the Wang-Landau algorithm is used to calculate the joint density of states g(Mz,E) efficiently. From g(Mz,E), we obtain the Bragg-Williams free energy…
Tiny hairlike sensors or cilia play a very important role in detection for many biological species, including humans. This research took inspiration from the packaging and transduction processes of the inner ear’s cochlea and cilia to design acoustic sensors. Specifically, this work uses nanowires of magnetostrictive…
An approximate analytical solution is proposed to estimate the phonon scattering cross section of polydispersed spherical nanoparticles. Using perturbation of the Hamiltonian due to differences in mass and bond stiffness between a host medium and a spherical nanoparticle, an analytical solution is obtained for the sca…
Co 2 Fe Si crystallizes in the ordered L21 structure as proven by x-ray diffraction and Möβbauer spectroscopy. The magnetic moment of Co2FeSi was measured to be about 6μB at 5 K. Magnetic circular dichroism spectra excited by soft x-rays were taken to determine the element-specific magnetic moments of Co and Fe. The C…
The temperature variation of magnetic anisotropy and coercive field of magnetoelastic manganese-substituted cobalt ferrites (CoMnxFe2−xO4 with 0⩽x⩽0.6) was investigated. Major magnetic hysteresis loops were measured for each sample at temperatures over the range 10–400 K, using a superconducting quantum interference d…
We have studied the magnetic behavior of dextran-coated magnetite (Fe3O4) nanoparticles with median particle size ⟨d⟩=8nm. Magnetization curves and in-field Mössbauer spectroscopy measurements showed that the magnetic moment MS of the particles was much smaller than the bulk material. However, we found no evidence of…
Next generation magnetic microwave devices require ferrite films to be thick (>300μm), self-biased (high remanent magnetization), and low loss in the microwave and millimeter wave bands. Here we examine recent advances in the processing of thick Ba-hexaferrite (M-type) films using pulsed laser deposition (PLD),…
Ca Cu 3 Ti 4 O 12 (CCTO) ceramics are prepared by the conventional solid-state reaction method under various sintering temperatures from 1000to1120°C at an interval of 10°C. Microstructures and crystalline structures are examined by scanning electronic microscopy and x-ray diffraction, respectively. Dielectric propert…
We report a Rietveld refinement analysis and X-ray absorption study on a green-color Cl(-)-intercalated alpha-type cobalt hydroxide phase. The refinement clearly demonstrated that one-fifth to one-sixth of the Co(II) at octahedral sites was replaced by pairs of tetrahedrally coordinated Co(II) on each side of the hydr…
Copper−nickel−aluminum oxide solid solutions were reduced in hydrogen to produce alumina-supported copper−nickel alloy catalysts. XRD patterns of reduced oxides showed that the type of active metals which emerged upon reduction were sensitive to the reduction temperature and the copper content. Variations from +0.8 to…
A concept is presented serving to guide in the search for materials with high spin polarization. It is shown that the magnetic moment of half-metallic ferromagnets can be calculated from the generalized Slater-Pauling rule. Furthermore, it was found empirically that the Curie temperature of Co2-based Heusler compounds…
The electrical properties of single-walled carbon nanotubes (SWNTs) embedded in a poly(3-octylthiophene) matrix have been investigated as a function of SWNT concentration. The electrical conductivity and its temperature dependence were measured as a function of the SWNT concentration. As the nanotube concentration inc…
We describe the physical properties of excitons in hybrid complexes composed of semiconductor and metal nanoparticles. The interaction between individual nanoparticles is revealed as an enhancement or suppression of emission. Enhanced emission comes from electric field amplified by the plasmon resonance, whereas emiss…
Dielectric susceptibility measurements in a wide frequency spectrum were used to obtain the distribution of the relaxation times of ${\mathrm{BP}}_{1\ensuremath{-}x}{\mathrm{BPI}}_{x}$ mixed crystals. The dipole freezing results in a broad distribution of the relaxation times. The parameters of the double-well potenti…
The thermostat introduced recently by Stoyanov and Groot (J. Chem. Phys. 2005, 122, 114112) is analyzed for inhomogeneous systems. This thermostat has one global feature, because the mean temperature used to drive the system toward equilibrium is a global average. The consequence is that the thermostat locally conserv…