Materials Literature
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We propose a mechanism for creating lateral order in thin films of a homopolymer mixture via spinodal decomposition in the presence of a laterally structured substrate surface. The system under consideration is a mixture of deuterated polystyrene and partially brominated polystyrene (PBrxS, x=0.5) spuncast onto differ…
Abstract Three conventional polyurethane (PU) elastomers were blended physically with various ratios of high molecular weight of poly(4,4′‐diphenylsulfone terephthalamide) (PSA) to form 12 PU/PSA polyblends in order to modify their physical properties. Also three new polyurethanes were synthesized with a low‐molecular…
Abstract Polyurethanes were synthesized from polyester polyols, derived from PET Waste. The PET waste was first depolymerized by glycolysis. The glycolysized products were reacted with adipic acid to yield polyester polyols, and the polyester polyols were then reacted with either MDI or TDI to obtain polyurethanes. In…
Deep level transient spectroscopy (DLTS) has been used to investigate trap levels in sol-gel derived polycrystalline Pb(Zr0.54,Ti0.46)O3 thin films. Metal-ferroelectric-metal capacitor structures 2400 and 3000 Å in thickness were fabricated and characterized using a constant voltage DLTS system. Prominent peaks associ…
Transparent conducting cadmium oxide films are prepared by the spray pyrolytic technique. The dependence of structural, optical, and electrical properties on the film thickness is investigated. X-ray diffraction studies confirm the polycrystallinity of the films and the films show preferential orientation along the (2…
A diamond field emitter array has been fabricated. by Chemical vapor deposition. Diamond was grown on an inverted pyramidal-shape Si substrate followed by removal of the substrate. The fabricated array was placed in a high vacuum pumping system with the pressure of ∼10−7 Torr and the emission current as a function of…
Pulsed laser ablation-deposition is used to produce fatigue-free La0.5Sr0.5CoO3(LSC)/ PbZr0.53Ti0.47O3 (PZT)/LSC ferroelectric capacitors on oxidized (100) Si substrates coated with a bilayer of Pt/Ti. These capacitors utilize a unique bottom electrode combination of LSC on Pt, where the LSC (a conducting oxide) acts…
Structural phase transitions are considered in which the effective ordering interaction J(R ij ) arises from local stresses induced by the ordering in cell i and propagated elastically to a distant cell j. The generalized Landau free energy functional is set up and four applications made. Firstly the origin of metasta…
The low-temperature, high magnetic field heat capacity (1.5 to 70 K and 0 to 9.85 T), dc and ac magnetic behaviors of the compound (Gd0.54Er0.46)AlNi show that field-induced magnetic entropy change is significant and almost constant over the temperature region of ∼15 to ∼45 K. The resulting temperature dependence of t…
We have fabricated high quality, dielectric Ga2O3 thin films. The films with thicknesses between 40 and 4000 Å were deposited by electron-beam evaporation using a single-crystal high purity Gd3Ga5O12 source. Metal-insulator-semiconductor (MIS) and metal-insulator-metal structures (MIM) were fabricated in order to dete…
Magnetostriction of polycrystalline Co100−xPdx alloys was measured by the strain gauge method from 4 to 300 K. The saturation magnetostriction λs=(2/3)[(ΔL/L)s∥−(ΔL/L)s⊥], where (ΔL/L)s∥ and (ΔL/L)s⊥ are the saturated values (when HE≳5 kG) of ΔL/L in fields parallel and perpendicular to sample’s length (L). λs at 4 K…
Mechanical strength and properties of thin plates were investigated for hot-rolled Pr-Fe-B-Cu magnets. Tensile strengths of the hot-rolled magnets were more than 23.7 kg f/mm2. Bending tests were also applied and the strength of 37.7 kg f/mm2 was obtained. The strengths obtained are definitely higher than that of comm…
A phenomenological inherently vector hysteresis model employing simple differentials as a means of keeping track of the past history of the magnetic field is proposed. This results in a simple and computationally fairly efficient formulation for vector hysteresis of any dimension. An expression for determining model p…
The crystalline structures of various amorphous carbon grains and of graphite have been studied by means of transmission electron microscopy. It is found that differences amongst the specimens in the absolute value of absorption and in the spectral index depend on differences in the crystallite size of the amorphous g…
Magnetoacoustic emission (MAE) has been measured from a Ni bar and a mild steel bar. The magnetizing field was produced by a c-core electromagnet, which was separated from the specimen surface by a nonmagnetic spacer layer (thickness la). In Ni, the MAE profile contains a single peak when la is small. As la increases,…
The observation of a magnetization reversal and a superparamagnetic behavior are reported for films of copper ferrite sputtered in an oxygen atmosphere. X-ray diffraction studies indicate the presence of 14-nm nanoscale crystals of CuFe2O4 in the films. Data on the temperature dependence of the film magnetization M fo…
The mixed series CoxFe1−xCr2S4 has been studied by x-ray, Mössbauer spectroscopy, and superconducting quantum-interference device (SQUID) magnetometry. The crystal structure is found to be a cubic spinel, and the lattice constant a0 decreases linearly with increasing cobalt concentration. Mössbauer spectra of CoxFe1−x…
In nuclear power plants, neutron embrittlement of pressure vessel steels has been one of the main concerns. The use of micromagnetic Barkhausen emissions is a promising method to monitor the variations in microstructural and subsurface stress states due to their influence on these emissions. Measurements of these emis…
Hysteresis loops in some magnetic systems are composed of small avalanches (manifesting themselves as Barkhausen pulses). Hysteresis loops in other first-order phase transitions (including some magnetic systems) often occur via one large avalanche. The transition between these two limiting cases is studied, by varying…
Heavily terbium-doped boron-silicate glasses (Tb3+10.4 at. %) with a Verdet constant (632.8 nm, room temperature) as large as −0.338 min/Oe cm, 38% larger than that of the famous FR-5 glasses, have been made. The wavelength and temperature dependencies of the Verdet constants of samples have been investigated in the r…