Materials Literature
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We report the observation of both metallic and semiconducting behavior in epitaxial thin films of the metallic oxide CaRuO3 deposited under identical conditions. X-ray diffraction studies showed that while semiconducting films with enlarged unit cells were obtained on single-crystal (100) SrTiO3 substrates, metallic f…
In low temperature studies of ultrapure erbium (and dysprosium) we have discovered unusual thermal effects at the first order magnetic transformation of erbium $(\ensuremath{\cong}19\mathrm{K})$. These include (1) superheating (i.e., the metal is colder after heat has been added to it than before the heat pulse), (2)…
The classic Peierls theory of dislocations is critically examined and shown to contain a number of inconsistencies. For narrow core dislocations, as in Si, the classic theory leads to gross overestimation of the barrier to dislocation motion. We present a new, semidiscrete theory which corrects the inconsistencies of…
We present an effective medium theory in order to analyze the reported optical properties of aligned carbon nanotube films [W. A. de Heer et al., Science 268, 845 (1995)]. This methodology is based on photonic band structure calculations and allows treatment of complex media consisting of particles that interact stron…
We studied three distorted perovskite manganites, ${\mathrm{Pr}}_{1/2}{\mathrm{Sr}}_{1/2}{\mathrm{MnO}}_{3}$ and ${\mathrm{Nd}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ with $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1/2$ and 0.55 by the neutron diffraction technique. Two samples with $x\phanto…
We have observed an insulator-to-metal (I-M) transition triggered by the photocarrier injection into the charge-ordered (CO) state of a perovskite manganite crystal, ${\mathrm{Pr}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_{3}$. The photocurrent is a highly nonlinear function of applied electric field and of light intens…
In this Letter we present a coherent description of the optical properties of a unique type of nanoparticle, metal-coated dielectric nanoparticles. These structures occur naturally in the form of Au-coated ${\mathrm{Au}}_{2}\mathrm{S}$ nanoparticles. During the course of nanoparticle growth, the plasmon-related absorp…
The thermal conductivity of Si–Ge superlattices with superlattice periods 30<L<300 Å, and a Si0.85Ge0.15 thin film alloy is measured using the 3ω method. The alloy film shows a conductivity comparable to bulk SiGe alloys while the superlattice samples have a thermal conductivity that is smaller than the…
Abstract— ZnS films were grown on (100) Si substrates by atomic layer epitaxy (ALE) using a metal‐organic chemical vapor deposition system. We studied the growth rate as a function of the substrate temperature and the flow rates of DMZn and H 2 S. The growth rate was kept constant at 0.7 monolayers per cycle and was i…
The Raman and IR spectra of LnTPPTS·10H2O [Ln=La,Sm, TPPTS=P(m-C6H4SO3) 3 3− ] complexes are reported. Based on the observed Raman and IR characteristic frequencies, a vibrational assignments has been made for these complexes. Coordination induces a lengthening of the S−O bonds and a shortening of the C−S bond. The C−…
Abstract Malanite was first found in veinlets of disseminated copper–nickel ores in Zunhua County, Hebei Province, and then in platinum–bearing chromite ores in Shuangfeng Village, Yanshan. In the former case, malanite appears as octahedrons or dodecahedrons associated with pyrrhotite, pentlandite, sperrylite and coop…
Failure modes of constrained metal foils between two elastic solids are rather different from those in the unconstrained condition. If the interface adhesion is strong between materials, a lower strength thin metal (plastic) foil between two much higher strength metals (elastic) can undergo substantial plastic deforma…
A systematic investigation of structure and magnetic properties of the new R3Fe29-xCrx compounds (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy) has been performed. The Curie temperature of R3Fe29-xCrx increased with increasing atomic number from R = Ce to Gd and decreased from Gd to Dy. The saturation magnetization of R3Fe29-xCr…
The electrical power industries are experiencing a considerable energy loss in transformers and motors because of inefficiencies caused by core loss. The objective of our research is to investigate any effect of laser scribing on the reduction of the core loss in the low cost, non-oriented steels used in numerous util…
The Cu and Ni derivatives of -amino-5,10,15,20-tetraphenylporphyrin react with sodium nitrite in THF by formation of 2-diazo-3-oxo-5,10,15,20-tetraphenylchlorins. The spectroscopic properties and some electrochemical properties of the synthesised compounds were investigated.
The PbTiO3, BaTiO3 ultrafine powders with nanometer crystallites are prepared through sol-gel and thermal decomposition of chelate respectively. Particle size is 300 run in volume. XRD analysis indicates the average crystallite size is 51.2 nm, and c/a ratio is 1.061. TEM observation demonstrates crystalline BaTiO3 pa…
Photoluminescence (PL) of chromium-doped spinel-type semiconductor α-ZnAl2S4 has been studied in the temperature range 2–540 K. The transitions between ground state 4A2g and 2Eg, 2T1g, 2T2g, 4T2g, 4T1g excited levels of Cr3+ ions in absorption and emission spectra have been observed. A fit of the measured temperature…
Abstract Irradiations of Ni/TiO 2 catalyst by UV in hydrogen at 77 K produced not only Ni + ions on the catalyst surface, but also Ni 3+ and Ti 3+ species in bulk or near the interface between nickel and titania. These photo‐generated species were detected and characterized by low temperature electron paramagnetic res…
This paper presents a review of the state of the art developments in the pitting corrosion fatigue of aircraft structural materials. Mechanisms that govern the nucleation and growth of pitting and corrosion fatigue (CF) are briefly addressed. Some of the developments made in the author's laboratories in proposing the…
Abstract A transparent LiAl5O8 : Co2+ film was prepared by the sol–gel method using LiNO3, Al(i-OC3H7)3, and Co(NO3)2·6H2O. The microstructure and optical properties of the film were examined using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), optical absorption,…