Materials Literature
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The magnetic behavior of nickel ferrite nanoparticles of different sizes was studied by annealing nickel ferrite powders at temperatures ranging from 300 to 900 °C. Transmission electron microscopy studies show that the average particle sizes change from ∼8 to ∼120 nm with increasing annealing temperatures. The x-ray…
The problem of the physical mechanisms of collective magnetic behavior, both static and dynamic, of an assembly of ferromagnetic particles comprising a nanocomposite material has been addressed. Detailed measurements of magnetization curves and microwave absorption spectra of films prepared from chemically synthesized…
Thin films of Pr1−xCaxMnO3 (x=0.5,0.6) deposited on LaAlO3 and SrTiO3 substrates have been studied by Raman spectroscopy at low temperatures in order to investigate the effect of strains from the Ca doping or the substrate. A detailed assignment of the observed bands is suggested based on the present observations and…
The quasi-LO phonon mode is related to the specific defects that strongly affect the photonic properties of materials such as zinc oxide (ZnO). The line shapes of the quasi-LO phonon of ZnO annealed in different environments have been investigated. The experimental results show that this mode has the greatest Raman sh…
Based on theoretical calculations, we find that the crystal structure of InGaO3(ZnO)m consists of an alternating stack of a wurtzite (Ga∕Zn)–O block and an In–O octahedral layer. In the (Ga∕Zn)–O block, the Ga atoms favor a modulated boundary structure against a flat boundary structure. The band spectrum shows that ho…
Highly aligned, 2-3 wall carbon nanotube (CNT) arrays were used to examine the kinetics of CNT growth. A growth interruption method was used to determine the in situ growth rate. The growth interruption method with a water vapor treatment or acetylene treatment during the interruption enabled the production of CNT sta…
Deep level transient spectroscopy, current-voltage, and capacitance-voltage measurements are used to study interface traps in metal-on-bulk-ZnO Schottky barrier diodes (SBDs). c-axis-oriented ZnO samples were cut from two different vapor-phase-grown crystals, and Au- and Pd-SBDs were formed on their (0001) surfaces af…
LaNiO 3 films with various thicknesses were deposited on Si substrates by sputtering. The film thickness dependent strain state, microstructure and electrical properties were investigated. X-ray diffraction analysis shows that the films are generally strained with larger lattice constants than the value for bulk LaNiO…
A comparative study of the gas sensing properties of n- and p-type ZnO films was performed. The carrier type and concentration tailored by varying the sputtering Ar/O2 mixture were examined by Hall effect measurements. The gas sensing properties were studied by monitoring changes in the dc resistance upon exposure to…
A complete two-layer Hall-effect model, allowing arbitrary donor and acceptor profiles, is presented and applied to the problem of conductive surface layers in ZnO. Temperature-dependent mobility and carrier concentration data in the temperature range of 20–320 K are fitted with an efficient algorithm easily implement…
Plasma chemical technology is experimentally applied to the fabrication of a Bi-activated alumosilicate-core pure-silica-cladding fiber preform. To the best of our knowledge, this is the first time this technology has been applied in this way. We measure gain efficiency at pumping by a 1058 nm wavelength Yb fiber lase…
Glasses from xFe 2 O 3 (100-x)[3B 2 O 3 0.7PbO0.3Ag 2 O] system, with 0 x 20 mol.%, were prepared and investigated by means of two complementary spectroscopic methods, FT-IR absorption and Raman scattering in order to obtain information concerning the network structure. Both FT-IR and Raman spectroscopic techniques ha…
Abstract The recovery prediction of chloroprene rubber (CR) composite from deformation was studied using the conventional compression set test and the circular deformation method to change a linear specimen into a circular shape. The CR composite was thermally aged at 60, 70, 80, 90, and 100°C for 1, 6, 15, and 30 day…
Aging phenomena in soft viscoelastic materials have been used as an important tool to investigate the physics of complexity for both scientific and practical purposes. At ambient conditions, microwave frequency-domain spectroscopy (gigahertz-FDS) is employed to investigate the electromagnetic properties at continuum l…
Abstract The chemical oxidation of aniline to form polyaniline (PANI) films and powder samples was made using Fenton reagent as an oxidizing agent in aqueous sulfuric acid medium. The PANI films were monitored by using the quartz crystal microbalance and the electronic absorption techniques. The optimum concentration…
With reference to our recent reports [Appl. Phys. Lett. 90, 192107 (2007); Appl. Phys. Lett. 91, 202102 (2007)] about the electronic structure of chlorine treated and oxygen-plasma treated nitrogenated carbon nanotubes (N-CNTs), here we studied the electron field emission effects on chlorination (N-CNT:Cl) and oxidati…
It was observed that mixed ZnO nanorods and twisted nematic liquid crystals (LCs) show highly ordered molecular system. The observed molecular relaxation arose due to a reorientation of long molecular axis of the order of 400 kHz for pure ZLI-1636, while such relaxation was shifted to a lower frequency for mixture. By…
Low-temperature scanning tunneling microscopy on alkyl-surface-functionalized graphene oxide nanosheets reveals the formation of low-dimensional graphenite nanostructures with extended pi-conjugation at deoxidation temperatures above 150 degrees C. The elimination of these alkyl chains from the surface of the nanoshee…
Epitaxial (100)/(001)-oriented PbTiO3 films with thickness of 2.8 μm were grown on Nb-doped (100) SrTiO3 substrates by pulsed metal organic chemical vapor deposition. Complex domain structures consisting of c-domains (c1) and three types of a-domains (a1, a2, and a3) were observed by piezoresponse force microscopy in…
Transmission electron microscopy is used to reveal threading defects in single crystal c-oriented GaN nanorods grown on (0001)sapphire by molecular beam epitaxy. The defects are shown to be planar faults lying on {101¯0} planes and bounded by opposite partial screw dislocations with Burgers vectors of 1/2⟨0001⟩. The f…