Resistivity anisotropic

Ion bombardment can be used to enhance resist etch rates and thus achieve anisotropic resist profiles. Reactive sites produced by bombardment permit more rapid attack by oxygen species in the plasma. Multilevel processing (181,182), in which an etch-resistant layer serves as a mask to pattern... 

Fig. 74. Anisotropic resistivity in nonstoichiometric rutile Ti02 x, where p and pc are a- and c-axis resistivities, respectively, (a) Anisotropy ratio p /ptf at —60°C vs. pat where p and Rtt decrease with increasing oxygen deficiency X. Rtt(c axis) < Rc(Ti) for pa < approx. 10 ohm-cm. The sharpness of the breakdown in pa with Rtt(a axis) is not apparent from this type of plot, (b) The o-axis and c-axis resistivities vs. temperature for composition G, a nonstoichiometric rutile. (Adaoted from Hollander and Castro (278).)...

In order to develop eddy current measurement techniques for CFRP it is necessary to understand the effect of the anisotropic resistance on the eddy currents. A method was developed which enables the visualisation of eddy currents in CFRP. In this method the z-component of the magnetic field was measured using a receiver coil. From the two-dimensional magnetic field distribution the current distribution can be calculated. 

Kawamoto (2) developed a two-dimensional model that is based on a double iterative boundary element method. The numerical method calculates the secondary current distribution and the current distribution within anisotropic resistive electrodes. However, the model assumes only the initial current distribution and does not take into account the effect of the growing deposit. Matlosz et al. (3) developed a theoretical model that predicts the current distribution in the presence of Butler-Volmer kinetics, the current distribution within a resistive electrode and the effect of the growing metal. Vallotton et al. (4) compared their numerical simulations with experimental data taken during lead electrodeposition on a Ni-P substrate and found limitations to the applicability of the model that were attributed to mass transfer effects. 

The anisotropic continuum approach to losses in multifilament conductors was first conceived by Carr, who developed the model assuming that the inductor is a continuum material with anisotropic resistivity. He applied this approach to the special case of losses in cylindrical conductors for applied transverse sinusoidal fields in the absence of transport current [ ]. Those losses resulting from pJ in the conductor are classified as eddy current or saturation hysteresis losses, depending upon the level of /. Eddy current losses result from J below Jc, with the implicit assumption of rapidly rising resistivity in the flux-flow regime with currents saturated at Jc. The magnetization loss for the continuum is essentially the magnetic hysteresis loss for the filaments times the fraction of the composite occupied by the filaments. 

Fig. 4.2-33 Anisotropic resistivity of YBCO for a twin-free single crystal along the orthorhombic axes [2 41]...

Boarino L, Borini S, Amato G (2009) Electrical properties of mesoporous silicon from a surface effect to coulomb blockade and more. J Electrochem Soc 156 K223 Borini S, Boarino L, Amato G (2006) Anisotropic resistivity of (lOO)-oriented mesoporous silicon. Appl Phys Lett 89 132111... 

Hagiwara, T., 1994. Response of 2 MHz resistivity devices in thinly laminated formations (anisotropic resistivity and EM log interpretation). In Presented at SPE 69th Annual Technical Conference, pp. 667-675. Paper 28426. 

In packed beds of particles possessing small pores, dilute aqueous solutions of hydroly2ed polyacrylamide will sometimes exhibit dilatant behavior iastead of the usual shear thinning behavior seen ia simple shear or Couette flow. In elongational flow, such as flow through porous sandstone, flow resistance can iacrease with flow rate due to iacreases ia elongational viscosity and normal stress differences. The iacrease ia normal stress differences with shear rate is typical of isotropic polymer solutions. Normal stress differences of anisotropic polymers, such as xanthan ia water, are shear rate iadependent (25,26). 

The specific resistance of natural graphite crystals is ca Hem (room temperature) along the a axis parallel to the network basal plane. The resistance along the c axis (perpendicular to the basal plane) is ca 1 Q. The cja axis anisotropy ratio is, therefore, ca 10 . Screw dislocations within the crystal may short-circuit the current path parallel to the c axis and cause lower anisotropic ratios separation of planes may cause higher anisotropic ratios. 

The measurement of mechanical properties is a major part of the domain of characterisation. The tensile test is the key procedure, and this in turn is linked with the various tests to measure fracture toughness... crudely speaking, the capacity to withstand the weakening effects of defects. Elaborate test procedures have been developed to examine resistance to high-speed impact of projectiles, a property of civil (birdstrike on aircraft) as well as military importance. Another kind of lest is needed to measure the elastic moduli in different directions of an anisotropic crystal this is, for instance, vital for the proper exploitation of quartz crystal slices in quartz watches. 

In addition to specific properties of interest for a particular application of a material, its elasticity, compressive and tensile strength, deformability, hardness, wear-resistance, brittleness and cleavability also determine whether an application is possible. No matter how good the electric, magnetic, chemical or other properties are, a material is of no use if it does not fulfill mechanical requirements. These depend to a large extent on the structure and on the kind of chemical bonding. Mechanical properties usually are anisotropic, i.e. they depend on the direction of the applied force. 

The idea of electronic conductivity in the crystals of this cluster is stimulated by the metallic reflectance of the crystals. A potential conductivity is expected to be anisotropic because of the anisotropic order of the clusters inside the crystal. As a consequence, the electric resistance is expected to be smaller in the direction of the tubes than in the vertical direction where there is no graphite-like bridging between the clusters. 

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