Materials Literature
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Using the vapor-liquid-solid (VLS) technique, we have grown well-aligned nanopillars on [112¯0]-sapphire (a-plane) substrates at atmospheric pressure in a horizontal tube furnace employing gold catalyst seeds of different sizes and densities. It was the aim of the present work to find experimental conditions (source a…
Abstract Conducting polypyrrole (PPy) films doped with p-toluenesulfonate (TOS−), ClO4−, and Cl− were electrochemically prepared, respectively. The electrochemical capacitance properties of the PPy films were investigated with cyclic voltammetry (CV), galvanostatical charge/discharge, and electrochemical impedance spe…
We construct a synthetic left-handed transmission line with cascaded varactors and shunt inductors. By modulating dc bias, the capacitance of the varactors can be changed and modulation of the output phase state is possible. For frequencies from 4.7 to 6.4 GHz, a very linear phase variation versus voltages of over 200…
For many wood machining processes, the interest of tool steels remains very important because of their good tool edge accuracy and easy grinding. The main problem is their low resistance to wearing and moderately toughness. To increase their performance, a laser treatment applied on the tool edges was presented in thi…
Poor corrosion resistance is a major obstacle in widespread application of Mg alloys. In the present study, cast Mg alloys, AZ61 and AZ91 were subjected to laser treatments with a view to modifying surface/subsurface microstructure and improving the microstructure assisted localised corrosion resistance of the alloys.…
The composite of carboxyl‐modified multi‐walled carbon nanotubes (MWNT‐COOHs) and TiO2 nanoparticles was prepared by improved solvothermal process. X‐ray diffraction (XRD), transmission electron microscope (TEM) and UV‐Vis spectra were used to characterize the products. The results show that MWNT‐COOHs were “welded” b…
In the paraphase of a number of La1−x BaxMnO3 single crystals with 0.1 ≤ x ≤ 0.2 below 340 K, signals of the ferromagnetic resonance are observed, which indicates the presence of magnetically ordered nanoscopic objects (ferrons). The region of the existence of ferrons on the Ba density-temperature phase diagram has an…
Abstract A permanganate‐rare earth metal salt (REMS) chemical conversion bath was applied to a sample of AZ91 magnesium alloy in this study, a red‐brown conversion coating formed subsequently on the sample surface. The test results of this coating with a scanning electron microscope (SEM) showed that there existed net…
In this study, a SrCo 0.4 Fe 0.5 Zr 0.1 O 3- δ (SCFZ) dense mixed-conducting membrane was applied to a membrane reactor for the thermal decomposition of carbon dioxide (TDCD) (CO 2 ↔ CO + 1 / 2 O 2 ). The SCFZ membrane broke after the membrane reactor ran for about 36 h, because the eroding gases, such as CO 2 and CO,…
We report on a new electrochemical cell setup, combined with a portable UHV chamber, for in situ x-ray diffraction using synchrotron radiation. In contrast to more traditional electrochemical sample preparation schemes, atomically clean and well-ordered surfaces are routinely prepared by UHV methods, even in the case…
The industrial production of poly(N‐vinylformamide), PNVF, was started a few years ago, making the desired polyvinylamine, PVAm, accessible on a large scale via hydrolysis of PNVF. According to the literature, the key to achieving a 100% conversion of PNVF into PVAm is to employ basic hydrolysis conditions. However, r…
Metal carbides are good candidates to contact carbon-based semiconductors (SiC, diamond, and carbon nanotubes). Here, we report on an in situ study of carbide formation during the solid-state reaction between thin films. The solid-state reaction was examined between 11 transition metals (W, Mo, Fe, Cr, V, Nb, Mn, Ti,…
In the present work, skutterudite CoSb3 were fabricated by hot pressing at different sintering temperatures under vacuum and argon. For the prepared compacts, the phase, the microstructure, and the temperature dependent thermoelectric properties were characterized. The correlation of the materials factors: density, gr…
Bi 3.15 Pr 0.85 Ti 3 O 12 (BPT) thin films with (100) (α(100)=89.1%), (117) (α(117)=83.2%), and (001) (α(001)=99.7%) orientations and a c-axis-oriented (α(001)=99.9%) Bi4Ti3O12 (BT) film were deposited on Pt(100)∕TiO2∕SiO2∕Si substrates using a metal organic decomposition process. Both the values of the remanent polar…
This technical note explores the concepts and applications of recovering and reusing two common disposable materials (crushed glass and dredged spoil) for beneficial engineering purposes. Dewatered fine-grained dredged material (DM) amended with glass cullet may prove to be a marketable combination especially useful a…
Biodegradable and biocompatible poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a copolymer of microbial polyester, was fabricated as a nanofibrous mat by electrospinning. The specific surface area and the porosity of electrospun PHBV nanofibrous mat were determined. When the mechanical properties of flat film an…
Pure, Nb-doped and Ag-doped titania nanoparticles were synthesized by sol-gel technique with dopant concentrations ranging from 0.5 to 1.5 atomic percent Nb or Ag. The annealing temperatures ranged from 250 to 900 °C. Changes in phase transformation of the doped samples with reference to pure titania were studied. It…
The four optical spectrum bands (or d-d transitions) and six spin Hamiltonian parameters (g factors gx, gy, gz and hyperfine structure constants Ax, Ay, Az) of the rhombic Zr3+ (4d1) center in Y3Al5O12 crystal are calculated from the complete diagonalization (of energy matrix) method and the perturbation theory method…
For more than 200 years, the beautiful “molybdenum blue solutions†have been a puzzle for chemists because they could not determine the molecular structures of the solutes while experiments showing the Tyndall effect proved the presence of “giant speciesâ€. This problem was finally solved in Bielefeld. As a resul…
For a thermoelectric module (TEM) operating in refrigeration mode, the cooling flux provided by it, its coefficient of performance and its operating voltage per unit footprint are key parameters. They are provided here as a function of the temperatures on both sides of a TEM, current flow through it, electrical contac…