Materials Literature
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Micro-Raman spectroscopy and x-ray diffraction measurements have been used to identify the presence of hexagonal diamond polytypes in chemical vapor deposited diamond films. The presence of additional reflections, in addition to the normal cubic diamond reflections in the diffraction spectra and bands at 1306 and 1193…
Record values of colossal magnetoresistance (CMR) have been achieved in the antiferromagnetic phase of the La1−xCaxMnO3 system. At 125 K, the CMR of the La0.5Ca0.5MnO3 reaches nearly 1 000 000%. It increases exponentially to 100 000 000% at 57 K. While the ground state is primarily an antiferromagnet, application of a…
Rayleigh-Brillouin light-scattering spectroscopy performed on oriented samples of tetragonal SrTi${\mathrm{O}}_{3}$ reveals the presence of a new doublet at low temperatures. This scattering, also seen in KTa${\mathrm{O}}_{3}$, appears in addition to the broad central peak already reported by Lyons and Fleury. The lik…
Using electron paramagnetic resonance (EPR), we show the alignment of defect dipoles along the direction of the spontaneous polarization in polycrystalline BaTiO3 ceramics by subjecting the capacitors to a dc bias at elevated temperatures. The alignment is demonstrated to occur via orientation dependent EPR signals in…
A method is presented to obtain {\it ab initio} upper and lower bounds to surface energies of stress-driven discommensurate surface structures, possibly non-periodic or exhibiting very large unit cells. The instability of the stressed, commensurate parent of the discommensurate structure sets an upper bound to its sur…
We develop a molecular model of non-uniform deformations within the framework of liquid crystal rubber elasticity. We show that, similarly to the uniform case, the theory is not sensitive to the molecular details of polymer liquid crystal involved and the resulting elastic free energy is quite universal. The result of…
A method is presented for evaluating the dislocation mobility from measurements of the amplitudedependent internal friction in a vibrating solid. The formulation is based on an idea that the forward and backward motion of dislocations occurs during each period of a steady-state vibration, which is impeded by friction…
Manganese-zinc ferrite Mn1−xZnxFe2O4 with different values of x is prepared by the usual ceramic technique. X-ray analysis shows that the samples are cubic spinels (single phase). The lattice parameter, the theoretical density, the bulk density, and the porosity are deduced and their variation with Zn2+ additions is s…
The retention and imprint properties of ferroelectric Pb(Zr0. 53Ti0. 47)O3 (PZT) and SrBi2Ta2O9 (SBT) thin films are studied. A simple characterization technique which consists of four measurement pulses is used to differentiate the retention and imprint effects. The high concentration of oxygen vacancies in PZT capac…
Undoped and indium-doped ZnO thin films are deposited by the spray pyrolysis process onto glass substrates. The effects of starting solution composition and indium doping on the structural, electrical, and optical properties are investigated. The surface morphology of the deposited films is a strong function of the so…
New laser data on orthorhombic YAlO3:Er3+ crystals are obtained. Stimulated emission in the 4S3/2 →5I15/2 channel and cascase lasing of the sequential intermanifold 4S3/2 → 4I11/2 → 4I13/2 transitions are excited at ≈︁ 110 K with Xe-flashlamp pumping. Intensity absorption and luminescence characteristics of Er3+ ions…
Electric resistance degraded by electromigration at low temperatures is investigated by sweeping temperatures up to 400 K at a constant rate. Recovery (decrease) of the resistance is found and a first-order reaction model is applied to evaluate the activation energy spectra for this recovery. The energy spectra are fo…
Abstract Transmission electron microscopy has been used to investigate the microdeformation behavior of thermally imidized thermoplastic pyromellitic dianhydride/1,1‐bis(4‐amino‐phenyl)‐1‐phenyl‐2,2,2 trifluoroethylene (3FDA/PMDA) polyimide films with a T g of ∼ 440°C, prepared by solution casting of a polyamic ester…
Abstract Copolycondensation of isophthaloyl chloride, bisphenol A, and aliphatic diols with additional reactive groups were performed in the presence of triethylamine by a trimethyl phosphate/cyclohexane organic/organic interfacial method. The composition of idol and bisphenol A residues in the resulting copolyesters…
We have measured the stress-strain (\ensuremath{\sigma}-\ensuremath{\epsilon}) relations in o-${\mathrm{TaS}}_{3}$ below the charge-density-wave (CDW) transition temperature. We find a large peak in d\ensuremath{\epsilon}/d\ensuremath{\sigma} at a critical stress ${\mathrm{\ensuremath{\sigma}}}_{\mathit{c}}$\ensuremat…
Diffractive optical elements (DOEs) have found their acceptance in lens design as an additional tool to refractive and reflective elements. They are especially powerful for applications in the infrared spectrum, because many of the materials, suitable for transmission in this region, lend themselves exceptionally well…
Abstract The influence of hydrogenated olio(cyclopentadiene) (HOCP) on tensile mechanical properties of its blends with high density polyethylene (HDPE) has been studied at 20, 80, and 100°C. The nominal stress‐strain curves performed at 20°C indicate an increase of the modulus and a conspicuous decrease of the ultima…
Abstract The performance of finite elements is scrutinized in isochoric and dilatant/contractant plastic flow. Standard displacement based elements, uniformly and selectively integrated elements, and elements with augmented strain rate fields are considered in plane‐strain, axisymmetric and three‐dimensional configura…
There has been a controversy over the photoexcited electron state in Eu chalcogenides. This paper examines whether the photoexcited electron in Eu chalcogenides, especially in EuTe, is the self-trapped magnetic polaron (STMP) or the photoinduced localized magnetic polaron (PILMP) bound by the 4f hole produced in the p…
We attempt to establish a dielectric tensor database for magneto-optical (MO) thin film materials with potential application for blue recording. For this purpose a method is developed for measuring the dielectric tensor of the MO layer within a multilayered stack. It uses a combination of ellipsometric, reflection/tra…