Materials Literature
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Mechanisms of failure in a unidirectional Sic‐fibe/glass‐ceramic composite are investigated using in situ observations during tensile and flexural loading. These experiments show that failure in tension occurs in several stages (similar to certain other brittle fiber composites): multiple matrix cracking, followed by…
The ultraviolet (UV)/ozone surface cleaning method is reviewed. The UV/ozone cleaning procedure is an effective method of removing a variety of contaminants from surfaces. It is a simple-to-use dry process which is inexpensive to set up and operate. It can rapidly produce clean surfaces, in air or in a vacuum system,…
Electroactive polyaniline coatings have been deposited on ferritic stainless steels. The coatings appear to be deposited over the passive metal oxide film but can undergo electron transfer with the metal. Polyaniline immobilized on the alloys imparts a form of anodic protection which stabilizes the materials in minera…
The results of structural and theoretical studies on cluster compounds with a framework in the form of a triangle made up of metal atoms are examined, a systematic account is given of the types of three-membered metallocycles in which the number of electrons is different from the magic number, and the causes of their…
Raman spectra are reported for single Se and Te chains stabilised in the regular system of parallel channels of a mordenite dielectric matrix. The symmetric bond-stretching mode frequency is determined for Se chains (260 cm -1 ) and for Te chains (164 cm -1 ). The distinct bond-bending mode bands associated with ring-…
We develop a model for the recrystallization of Si films that are traversed by a molten zone. The model simulates the branching behavior of low-angle grain-boundary defects in these films to a remarkable degree. The simulated subboundary patterns scale approximately as the square root of the scan velocity, in excellen…
A well-resolved core exciton at the bulk diamond C-$1s$ absorption edge has been observed using high-resolution partial-yield spectroscopy with synchrotron radiation. The obtained excitonic binding energy, 0.19\ifmmode\pm\else\textpm\fi{}0.015 eV, agrees well with a first-principles effective-mass approximation (EMA).…
The optical modulation technique is used for direct determination of energy levels and the effective correlation energy ${U}_{\mathrm{eff}}$ of dangling-bond defects. With an accuracy of 0.1 eV we found for the dangling-bond defect in $a$-Si: H, ${U}_{\mathrm{eff}}=0.5$ eV; in $a$-${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$…
Resistivity measurements on epitaxial, single-crystal films of Co${\mathrm{Si}}_{2}$ grown on Si show little dependence on film thickness down to \ensuremath{\sim}60 \AA{}. This dimension is much less than the bulk transport scattering length of \ensuremath{\sim} 1000 \AA{} as determined from magnetoresistance measure…
The electronic and vibrational properties of group IVB transition-metal dichalcogenides are investigated by near-normal-incidence reflectivity measurements. The experimental spectra are discussed in terms of a dielectric function expressed as epsilon ( omega )=1+ chi VE + chi PH + chi FC , where chi VE represents the…
Five absorption bands of the allowed 5d←4f transitions of Ce3+ were detected in the ultraviolet region between 37 and 51 × 103 cm-1 by σ- and π-polarized absorption, luminescence excitation, and MCD spectra with the single crystals of Ce3+ doped lanthanum ethylsulphate enneahydrate. In the crystal, Ce3+ is in a D 3h l…
A general theoretical treatment is developed for NMR spin-lattice (T 1 and T 1 rho ) and spin-spin (T 2 ) times for relaxation due to modulation for dipolar interactions by diffusion of atoms on inequivalent lattice sites. This extends previous calculations of T 2 to the other relaxation parameters and gives rate equa…
A model of the superionic conductor Ag 2 S is proposed and studies by the molecular dynamics technique using effective pair potentials. The self-diffusion for silver, D Ag (T), is in good agreement with experiment. The Ag density map and its temperature dependence is calculated. The authors also calculate the X-ray an…
The Raman spectra of the symmetric stretching v 1(A′1) mode of NO3 - ions have been measured in a series of molten nitrates, LiNO3, NaNO3, KNO3, RbNO3, CsNO3, AgNO3, TlNO3, at a temperature 10–20 K above each melting point. Temperature dependence of the Raman spectrum was also measured in molten NaNO3. Reorientation o…
The phase transformations and magnetic properties of single crystals of a MnAlC alloy are investigated. Using optical microscopy and X-ray diffraction method it is found that the morphology and the number of orientations of the τ-phases formed at 500 and 600 °C are different. This leads to a considerable difference i…
On the basis that metal films possess the properties of high reflection for infrared and induced transmission for visible bands, the authors have designed a broadband dichroic filter capable of transmitting visible and reflecting infrared bands through stacking to form a combined dielectric–metal–dielectric thin-film…
The hysteresis loops of three commercial magnets with room temperature energy products greater than 25 MGOe were obtained over the temperature range 4.2–700 K in applied magnetic fields extending to ±90 kOe. Two of the samples are of the Sm2Co17 type and the other of Nd2Fe14B. The magnetic parameters extracted from th…
Fe-Cr-Co ductile alloys produce magnetic properties comparable to those of Alnico permanent magnets family, up to (BH)max=91.2 kJ/m3(11.4 MGOe). It is technologically known that the addition of Ti to the Fe-Cr-Co alloys extends the α-phase region of system and improves the magnetic properties. The purpose of this work…
Magnetization and Mössbauer studies have been carried out on GdCo3B2 and DyCo3B2. These compounds are magnetically ordered with Curie temperatures of 56 and 21 K, respectively. The Co atoms are either nonmagnetic or carry a small moment in these compounds. The saturation moment of DyCo3B2 at 5 K is smaller than the Dy…
A setup is described to determine the flow alignment angle θ0 in nematic liquid crystals. Results for compounds with and without a strongly polar terminal cyano group indicate that the antiparallel dipole correlation associated with cyano groups has no influence on θ0. The influence of the occurence of a smectic-A pha…