Materials Literature
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One of the intrinsic instabilities of permanent magnets is magnetic aftereffect. The magnetic field and temperature dependences of the magnetic aftereffect constant, S v , were measured for a Sm 2 Co 17 sintered magnet under the effective magnetic field, H eff , ranging from -230 to -700 kA/m and at a temperature rang…
New data concerning the refractive-index profiles in Ag/Na ion-exchanged waveguides are obtained using a parabolic-segment reconstruction method. The profiles can be described as second-order polynomials, but with a mean curvature b = 2·8 which is significantly greater than the originally suggested value 0·64. The pro…
Some of the spectroscopic properties of the promethium ion (Pm/sup 3+/) were investigated in order to assess its feasibility for laser action. The fluorescence spectra and decays from the /sup 5/F/sub 1.2/ manifolds were measured in 11 dielectric materials. The calculated peak emission cross sections are comparable to…
A logarithmic increase of resistance with decreasing temperature and a negative magnetoresistance have been observed on low stage acceptor graphite fiber intercalation compounds (GACs) at low temperature. These results may be explained within the framework of the recent theories of weak localization and electron-elect…
Abstract Electrical resistivities ϱ and lattice parameters of quasi‐two‐dimensional crystals of monoclinic η‐Mo 4 O 11 and orthorhombic γ‐Mo 4 O 11 are measured under hydrostatic pressure up to 1.2 GPa at room temperature. Both crystals have negative pressure coefficients of ϱ, which can be qualitatively explained by…
Les cristaux de scolecite sont constitues de secteurs de croissance {110}, {010} et {111} de symetrie triclinique alors que l'analyse par diffraction RX indique une symetrie monoclinique. Existence de deux types de maclages: l'un du a un arrangement asymetrique des ions calcium et des molecules d'eau, et l'autre du a…
Abstract A quasi‐steady state model, based on two parallel modes of diffusion and a polycondensation reaction at the inside surface of a microcapsule, is formulated to compute the time of this microencapsulation process. The predicted times of encapsulation are in agreement with observed values reported in patents. It…
Resistivity measurements on Cu/Mo multilayered films have been performed and the in-plane resistivities interpreted with a model based on the Boltzmann kinetic theory as derived by Dimmich (1985). Theoretical calculations are in excellent agreement with the experimental data at two different temperatures. On the basis…
Abstract A quantitative simultaneous determination method by X-ray powder diffractometry is described for calcium sulfate and calcium carbonate in airborne dusts. In order to eliminate the mutual interference among diffraction peaks, and to avoid the presence of the hydration isomers of calcium sulfate, dust samples w…
An empirical core model construction procedure for pressurized water reactor (PWR) in-core fuel management problems is presented that (a) incorporates the effect of composition changes in all the control zones in the core on a given fuel assembly, (b) is valid at all times during the cycle for a given range of control…
Morphological and chemical properties of brown forest soils and podzolic soils developed on paleozoic shale under beech and/or cryptomeria have been studied with special reference to the eluviation-illuviation characteristics of Fe and Al. Mobilization of Al was observed even in brown forest soils and its pattern was…
Cristallisation dans P4 2 /n. Confirmation de la structure decrite par Strunz: alternance d'octaedres Fe(OH) 6 et Ge(OH) 6 relies par un sommet, dans un reseau tridimensionnel. La baisse de symetrie par rapport a un systeme cubique est accomplie par rotation rigide de ces polyedres. Les longueurs de liaison Fe−O et Ge…
Abstract Bright apple green millimeter-sized crystals of tavorite from the Tip Top pegmatite, near Custer, South Dakota are triclinic, space group , with refined unit-cell parameters a = 5.340(2), b = 7.283(2), c = 5.110(2)Å, α = 109.29(2)°, β = 97.86(3)°, γ = 106.32(3)°, V = 174.1(3)Å 3 , a:b:c = 0.7332:1:0.7016, Z =…
The structure of rhombohedral PbZr0.75Ti0.25O3 has been refined at liquid nitrogen and room temperatures (low temperature form) and at 105°C (high temperature form) using neutron diffraction data. Rotations of oxygen octahedra, characteristic for the low temperature phase, amount to ±5.3 and ±3.2 degrees for the forme…
In relation to the temperature effect in cavitation damage, the collapse of a single bubble in water over a wide range of temperatures was experimentally studied. A spark-induced bubble was observed by using a high speed camera and the impulsive pressure caused by the bubble collapse was measured by means of a pressur…
The rhombohedral R -phase appearance in NiTi alloys can be induced by thermal cycling between martensite ( M ) and parent phase ( P ). This procedure has here been followed to separate P-R and R-M transformations. Differential Scanning Calorimetry has been used to detect transformation temperature onset and the enthal…
The model of a KDP-type ferroelectric, in which heterophase fluctuations can occur, is considered. Stability conditions of such states are found. The influence of heterophase fluctuations on thermodynamic characteristics, especially in the critical region, is investigated. It is shown that for some correlation between…
The static Debye-Waller factor and its dependence on the crystal perfection have been obtained through the detailed analysis of the intensity distribution in X-ray diffraction topograph for heat-treated Cz-silicon crystals. The size and density of oxygen precipitates have been determined using the experimental and cal…
Patterned aluminum films are used as conductors for integrated circuits. Unless encapsulated in plastic for protection, these films are easily corroded by moisture, which can result in device failure. In humid environments, this may not fully protect the aluminum, and a means to provide, at low cost, additional protec…
A robotic work station has been constructed for automatically initiating and monitoring microscale chemical reactions. The work station consists of a robot with a general-purpose arm and interchangeable special-purpose hands, a carousel of seven reaction vessels, a series of stations for performing quantitative automa…