Materials Literature
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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…
In this article, we show how the substituting different peripheral substituents around the cobalt phthalocyanine core correlate with nonlinear optical properties. We present the results on nonlinear optical properties of solution of cobalt phthalocyanine (CoPc), cobalt phthalocyanine with DNA-CTMA surfactant complex (…
We have studied optical losses as a function of the wavelength for planar waveguides formed from porous silicon or oxidized porous silicon. Scattered light from the surface of samples was also observed. This observation reveals the influence of porous silicon dissolution front fluctuations called waviness on propagati…
Relatively fast kinetics of strain-induced crystallization (SIC) of cross-linked samples with various network-chain densities (ν) of natural rubber and its synthetic analog was examined by the fast time-resolved wide angle x-ray diffraction and simultaneous tensile measurements. The lateral crystallite size was almost…
Fully epitaxial magnetic tunnel junctions (MTJs) were fabricated with a full-Heusler alloy Co2Cr0.6Fe0.4Al (CCFA) thin film and a MgO tunnel barrier. Pseudo-spin-valve-type, fully epitaxial CCFA∕MgO∕Co50Fe50 MTJs with a CCFA film composition close to the stoichiometric one demonstrated high tunnel magnetoresistance (T…
The wettability analysis is often used to characterize a surface in micro and nanometer scale. At these small scales, effects of the contact line tension are also expected to play a significant role. Wettability effect is studied using environmental scanning electron microscopy on silicon dioxide surface modified by a…
The optical and other physical properties of semiconducting xV2O5−(1−x)CdO glasses have been reported in this article. The changes in both density and molar volume indicate structural modification of crystalline V2O5 due to addition of CdO. The glass transition temperatures are observed to decrease with an increase in…
A combined photoconductivity, absorption, and thermoluminescence study was performed to understand the absence of luminescence from Ce3+ in LaAlO3:Ce3+. It is demonstrated that the absence of luminescence is the result of Ce3+ ionization from the 5d excited states, which are all located in the conduction band. Ce3+ io…
Broadband microwave spectroscopy is commonly employed in the determination of the wave transport properties in mesostructured polymers with embedded carbon black particles. However, very little is known on how uniaxial stress affects the effective permittivity of these percolative materials. In this work we carry out…
The dependence of yield strength, uniform elongation, and toughness on grain size in metallic structural materials was discussed. The toughness is defined as the product of yield strength and uniform elongation. The yield strength versus grain size can be well described by the Hall-Petch relation; however, the uniform…
The three omega method has proven to provide accurate and reliable measurements of thermal conductivity of thin films and other materials. However, if the films are soft and conductive, conventional methodologies to prepare samples for the measurement technique are challenging and often unachievable. Various modificat…
V 2 O 5 nanotubes synthesized via the sol-gel route has been studied by electron energy loss spectroscopy (EELS), x-ray absorption spectroscopy (XAS), and energy dispersive x-ray analysis, in order to understand the local structure of vanadium in the nanotubes. Contrary to our expectation, all the features of the XAS…
The mechanical responses of several different carbon nanotube systems to applied torsional loading at various temperatures are examined using classical molecular dynamics simulations, and the results are interpreted and compared to the predictions of continuum mechanics theory. The specific materials considered includ…