Materials Literature
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Interface phenomena play a vital role in thermoelectric (TE) microrefrigerators. The present study employs a phenomenological model to examine the behavior of TE refrigerators as a function of thermal and electrical contact resistance, boundary Seebeck coefficient, and heat sink conductance. We modify the conventional…
Rutherford backscattering (RBS) is a nondestructive, fully quantitative technique for accurately determining the compositional depth profile of thin films. The inverse RBS problem, which is to determine from the data the corresponding sample structure, is, however, in general ill posed. Skilled analysts use their know…
The stress corrosion cracking (SCC) of structural materials used in boiling water reactors has been studied at relatively low hydrogen peroxide (H2O2) concentrations, around lOppb, which was assumed to be representative of the corrosion environment formed in hydrogen water chemistry (HWC). The 1/4T compact tension spe…
We present systematic studies of polycrystalline ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ where x is varied from 0.46 to 0.53 at 0.01 intervals. We have measured the magnetic resonance, ac susceptibility, dc magnetization, x-ray diffraction, four-probe resistivity, and optical reflectivity…
Static force−distance relations as well as linear and nonlinear viscoelastic responses to oscillatory shear were studied in 4‘- n -pentyl-4-cyanobiphenyl (5CB) confined between two muscovite mica surfaces at 25 °C. The orientation of the crystallographic axes of the mica sheets was varied from close to perfect alignme…
A thermal analysis has been performed for a package design pertinent to power electronics. The objective has been the derivation of straightforward expressions that relate the materials used and their physical dimensions to the power input and the junction temperature. This has been done for both steady-state operatin…
Small amounts of niobium (donor) doping in barium titanate (BaTiO 3 ) cause semiconductivity in this material. When the amount of niobium is increased slightly, the BaTiO 3 is converted back to an insulator. This phenomenon is attributed to donor segregation. Such an insulating material can recover its semiconductivit…
Small alterations in chemical composition, even within the boundaries of the international standards, can drastically alter the formation kinetics of intermetallic phases in a stainless steel. Therefore, by means of isothermal annealing experiments, the time-temperature-precipitation (TTP) diagram was constructed for…
Variable temperature X-ray diffraction (XRD) and real time Fourier transform infrared spectroscopy (FT-IR) were used to study the Brill transition of well crystallized Nylon 10 12 samples. The experimental data demonstrate that Nylon 10 12 undergoes Brill transition at about 120°C. IR spectra also show that a sequence…
Microstructural changes occurring during oxidation of the reduced form of donor‐doped BaTiO 3 (Ba 1− X D X . Ti 1− X 4+ Ti X 3+ O 3 ) and during reduction of the oxidized form of donor‐doped BaTiO 3 (Ba 1− X D X . Ti 1− X /4 4+ ( V Ti ) X /4 O 3 ) were studied using TEM. Samples of both types of solid solutions, con…
Using a broad-range pH indicator, the corrosion of Al and Al alloys in chloride-containing agar gels was studied. Distinct changes in pH were observed at low-pH anodic sites and at high-pH cathodes. There was a definite edge effect that occurred when gels were placed directly on the metal, which dominated the pattern…
Opalescent films, which own their color to Bragg reflection of light, can be prepared from cholesteric cellulose derivatives. Both lyotropic and thermotropic systems can be realised. Here we describe the manipulation of the wavelength of selective reflection by (a) mechanical compression, (b) photoisomerization of pen…
Abstract The 4‐environment generalized micromixing (4‐EGM) model is applied to describe turbulent mixing and precipitation of barium sulfate in a tubular reactor. The model is implemented in the commercial computational fluid dynamics (CFD) software Fluent. The CFD code is first used to solve for the hydrodynamic fiel…
We present a Stokesian dynamics (SD) computer simulation study of the static and dynamical properties of a monolayer of spherical colloidal particles restricted to diffuse in the midplane between two parallel walls. SD simulations account for hydrodynamic interactions (HI's) among the particles, and between particles…
The segmental ligand 2-(6-(N,N-diethylcarbamoyl)pyridin-2-yl)-1,1'-dimethyl-2'-(5-(N,N-diethylsulfonamido)-pyridin-2-yl)-5,5'-methylenebis[1H-benzimidazole] (L3) is synthesized via a multistep strategy that allows the selective introduction of an electron-withdrawing sulfonamide group into the ligand backbone and its…
Abstract A combinatorial library approach enables us to find new low molecular-weight organogelators composed of a bile acid–alkylamine salt; the gel phenomena are investigated by FT-IR spectroscopy, SEM, and X-ray crystallography.
Poly[3-(3‘,5‘-di- tert -butyl-4‘-acetoxyphenyl)thiophene] ( 1a ) was regioselectively synthesized via simple oxidative polymerization of 3-(3‘,5‘-di- tert -butyl-4‘-acetoxyphenyl)thiophene ( 2a ) with ferric chloride. Head-to-tail content of 1a with a molecular weight of >10 4 reached 96% by modulating both the polyme…
Bi-layered Aurivillius compounds prove to be efficient candidates of nonvolatile memories. SrBi2Nb2O9 thin films were deposited by excimer laser ablation at low substrate temperature (400 °C) followed by an ex situ annealing at 750 °C. The polarization hysteresis behavior was confirmed by variation of polarization wit…
The metastable state of an undercooled melt can provide access to the formation of metastable phases whose crystallographic structures differ from their stable counterparts. The electromagnetic levitation technique is used here to undercool bulk melts without containers. This technique, combined with energy dispersive…
Cubic BaTiO 3 powders have been synthesized from gel powders after thermal treatment in an alcohol solution and characterized using X‐ray diffractometry, transmission electron microscopy, and other techniques in detail. The borderline reaction conditions, such as the reaction temperature and time, for the synthesis of…