Materials Literature
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Single phases of SrBi2−χNdχNb2O9 (χ=0, 0.1, 0.2, and 0.4) ceramics were prepared by the solid-state reaction method and studied by dielectric and Raman spectroscopy. The substitution of Nd3+ for Bi3+ induced a dielectric relaxation behavior for SrBi2−χNdχNb2O9 (χ=0.1, 0.2, and 0.4). When χ=0.4, the dielectric response…
To date the charging mechanism of porous electret materials is not completely understood. The present study is focused on the investigation of light emission during corona poling of individual films of expanded polytetrafluoroethylene (ePTFE) with nominal porosity of 91% and of the same film sandwiched between two sol…
In order to study the intrinsic electrostatic resonances (ERs) of artificial dielectric heterostructures, we develop an efficient effective-medium-based method for modeling the effective permittivity, with careful attention paid to several key factors controlling ERs. Our method relies on finite element modeling and i…
We investigated the surface roughness and the luminescence properties of MgxZn1−xO thin films (0⩽x⩽0.19). The thin films were grown on a-plane sapphire substrates by pulsed laser deposition. The root-mean-square surface roughness depends on the oxygen partial pressure p(O2) applied during deposition and takes a minima…
The effects of Ca substitution for Y on the electrical transport and thermoelectric properties of Y1−xCaxCoO3 (0⩽x⩽0.1), prepared by using the sol-gel process, were investigated in the temperature range from 300to780K. The results indicated that direct current electrical resistivity ρ of Y1−xCaxCoO3 decreased remarkab…
The frequency-dependent conductivity of TiO2-derived nanotubes pressed to a pellet was measured over the temperature range 100 to 390 K. The temperature dependence of the electrical conductivity measured at 100 Hz indicates a three-dimensional variable range hopping mechanism at higher temperatures and fluctuation-ind…
The magnetoelectric (ME) characterization of stickup bilayers Ni0.8Zn0.2Fe2O3-Pb(Zr, Ti)O3 and trilayers of Ni0.8Zn0.2Fe2O3-Pb(Zr, Ti)O3-Ni0.8Zn0.2Fe2O3 are discussed. The ME interactions in the trilayers were found much stronger than that of bilayers prepared with the same technique. The maximum transverse ME voltage…
We report two possible metastable high density BC6N phases originating from the diamond structure. The ground-state properties of the BC6N phases are calculated using first-principles density-functional methods and the Vickers hardness is estimated using a semiempirical microscopic model. The calculated results show t…
Formation of disordered and ordered pore patterns in two dimensions have been reported in pore growth in nanoporous alumina templates. This is explained in terms of instability in the pattern formation. Here, we report our observation of instability in the pattern formation in three dimensions, that is, along the cyli…
Bi 2 Mg 2 ∕ 3 Nb 4 ∕ 3 O 7 (BMN) pyrochlore thin films were deposited at 25 and 100°C on Cu∕Ti∕Si substrates by pulsed laser deposition. Dielectric and leakage current properties of BMN films are investigated as a function of film thickness. The critical thicknesses showing the thickness dependence of dielectric const…
The stress dependence of the Raman spectrum of a relaxor-based polycrystalline ferroelectric lead zirconate titanate–lead nickel niobate–lead zinc niobate (PZT–PNN–PZN) has been investigated using polarized Raman microprobe spectroscopy. Emphasis has been placed on explicitly working out the second harmonic equations…
In this study we used a low-pressure metal organic vapor phase epitaxy method to investigate the growth of GaAs metal gate semiconductor field effect transistor (MESFET) structures on a Si substrate. The buffer layer between the Si substrate and the grown GaAs epitaxial layers was a composite Ge∕Si0.05Ge0.95∕Si0.1Ge0.…
At 191°C the organic semiconductor α-quaterthiophene is demonstrated to undergo a phase transition from the low temperature to the high temperature polymorph. Calorimetry, x-ray diffraction, optical reflectivity, and ellipsometry measurements were employed to analyze this transition and to show that this can be therma…
Ferroelectric and magnetoresistance heterostructure (Ba,Sr)TiO3/(La,Sr)MnO3 (BST/LSMO) heterostructure is deposited epitaxially on SrTiO3 (001) substrate by pulse laser deposition. The phase structures of the BST/LSMO heterostructure are characterized by x-ray diffraction. Cross-sectional transmission electron microsc…
The nature of defects in polycrystalline Bi4−xLaxTi3O12 (BLT) thin films with x=0.00, 0.25, 0.50, and 0.75 was evaluated by x-ray photoemission spectroscopy measurements. The influence of oxygen vacancies and substitution of Bi for La atoms were discussed. In the BLT thin films, it was found that the oxygen ions at th…
The dc electric-field dependence of the dielectric constant ε′(E) in Sr1−xMnxTiO3 (x=0.005−0.02) ceramics is studied in the temperature range from 10 to 125 K, i.e., around the ε′(T) peak temperature Tmax. Results are analyzed using equations derived analytically from the implicit equations of the Landau-Ginzburg-Devo…
The results on laser heating and ablation of graphite tiles of thermonuclear tokamaks are presented. Two pulsed Nd-YAG lasers (20 Hz repetition rate, 5 ns pulse duration and 10 kHz repetition rate, 100 ns pulse duration) were applied for ablation measurements. The ablation thresholds (1.0±0.5 J/cm2 for 5 ns and 2.5±0.…
Interaction of light with metallic nanostructures exhibit resonances specific to eigenmodes of collective electron motion known as plasmon modes. Both these resonances and effects of electromagnetic singularities lead to local field enhancement. Photoemission electron microscopy (PEEM) was recently used to image the e…
The thermoelectric properties and crystallographic features of layered perovskite-type Ca-substituted (Sr1−xCax)3(Ti1−yNby)2O7 (y=0–0.2), Ruddlesden-Popper phases were investigated. The influence of crystal structure and carrier concentration on the carrier effective mass for Ti-based metal oxides based on TiO6 octahe…
An n-type hydrothermally grown ZnO sample becomes semi-insulating (ρ~108 Ω cm) after 1-MeV electron-irradiation. Deep traps produced by the irradiation were studied by thermally stimulated current spectroscopy. The dominant trap in the as-grown sample has an activation energy of 0.24 eV and is possibly related to LiZn…