摘要:

Contrast figures of unusual form have been observed in bcc metals by transmission electron microscopy. These figures appear to be caused by the anomalous absorption of electrons.

ISSN:0021-8979    

DOI:10.1063/1.1729521

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Theoretical consideration is given to the behavior of the anisotropy field of iron—nickel films ranging in composition from 65% Ni—35% Fe to 90% Ni—10% Fe as a function of applied external stresses and magnetic fields in various directions in the plane of the film. It is postulated that internal stresses in the substrate film system may account for observed discrepancies. An expression is derived which relates the magnetoelastic parameter (&eegr;) to the magnetostriction (&lgr;s) of the film. This parameter is measured as a function of composition and the predicted value of &lgr;sagrees within the limits of precision to that observed for bulk material. Assuming the films to be isotropic in the plane of the substrate, a relation between applied stress and change in the anisotropy field is developed and within limits experimentally verified. It is postulated that observed discrepancies are due to nonlinear anisotropic internal stresses and dispersion in the direction of the easy axis of the film.

ISSN:0021-8979    

DOI:10.1063/1.1729522

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The simplified cylindrical distribution function has been applied to the determination of the degree of orientation in a moderately oriented linear polyethylene fiber. The function has been calculated using the first two and ten lines of the scattering pattern and, though poorly resolved, yields useful orientation information. It is concluded that the greater the knowledge of the molecular structure of the material under investigation the less the amount of intensity data required to produce a useable function. Although the technique is applicable to both crystalline and noncrystalline materials, the standard methods, applicable only to crystalline materials, are simpler. Therefore, the method can be considered to apply mainly to moderately oriented noncrystalline fibers.

ISSN:0021-8979    

DOI:10.1063/1.1729523

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Piezoresistive characteristics of a diffused layer on the surface of a semiconductor having a cubic crystallographic structure are analyzed. The surface is assumed free of external forces, and the current component normal to the surface within the layer is assumed zero. The equations derived are useful in the design of diffused piezoresistive electromechanical transducers. The electric fields in the layer are related to the sheet current densities and the stresses by diffused piezoresistive coefficients, which are defined in integral form. These coefficients are functions of the fundamental piezoresistive coefficients, the crystal orientation, and the unstressed conductivity profile function in the layer, but are independent of the layer thickness. The coefficient of major interest is numerically evaluated as a function of surface impurity concentration forp‐type silicon andn‐type germanium‐diffused layers with Gaussian and complementary error function impurity distributions. Measurements on diffused samples are in agreement with the analysis. The magnitude of a nonlinearity in layer piezoresistance arising from the variations of the bulk coefficients with doping is estimated.

ISSN:0021-8979    

DOI:10.1063/1.1729524

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

High‐field electron emission currents were drawn from a point cathode made from a single crystal ofn‐type gallium arsenide. Stable currents were observed for several cathodes over a wide range of voltage with an upper limit on the currents which could be drawn from the material.

ISSN:0021-8979    

DOI:10.1063/1.1729525

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

When a constant electric field is applied to a dielectric, the current density per unit field decreases with time from an ``initial conductivity'' to a ``final (or steady‐state) conductivity.'' A study is made of this time‐dependent polarization effect for ``pure'' NaCl crystals in the range from 50° to 200°C. The validity of Ohm's law and the superposition principle is demonstrated for these crystals; this establishes the linearity of the formal equation which relates polarization, electric field, and their time derivatives. Also studied are the effect of prolonged current flow, the effect of deliberate introduction of an air gap between the crystal and one of its electrodes, and the effects of impurities, deformation, x‐ray irradiation, and annealing. It is concluded that the results are not consistent with the well‐known space‐charge polarization theory of Joffe´, according to which the buildup of space charge occurs because of blocking of the current carriers at one or both electrodes. Rather, it is necessary to regard the time‐dependent polarization as a dielectric relaxation phenomenon. According to this viewpoint, the final conductivity, and not the initial value, represents the true ionic conductivity. Possible relaxation mechanisms are discussed in terms of defect clusters and charged jogs on dislocations.

ISSN:0021-8979    

DOI:10.1063/1.1729526

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The well‐known practice of using the mirror‐image, in theP, uplane, of the shock Hugoniot curve about a vertical line through the shocked statePH, uHis shown to give a complete thermodynamic description of metals when theU(shock velocity) vsuHrelationship and &agr;≡V‐1(&dgr;V/&dgr;T)P≈0are known. Use of the experimental relationshipU=c0+auH(aandc0constants) and &agr; = constant, leads to a thermodynamic description which results in the metal appearing less compressible than if described by the Mie—Gru¨neisen equation of state. Furthermore, the existance of an anomalous behavior ofcpin the low pressure neighborhood (<10 to <50 kbar depending on the metal) of the initial state rules out thesimultaneousexistence of a Hugoniot satisfying the linearUvsuHrelationship, of isentropes satisfying the mirror‐image assumption, and of a constant value of &agr; in this neighborhood. Thermodynamic functions for 16 metals are calculated up to 2 Mbars and compared with the results obtained from the Mie—Gru¨neisen equation of state.

ISSN:0021-8979    

DOI:10.1063/1.1729527

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

This paper develops the equations needed to determine the surface diffusion coefficient (Ds) when a point source is used and solute is drained off from the high diffusivity surface layer into the bulk. The assumptions used are essentially those used by Fisher for his analysis of grain boundary enhanced diffusion, and the results are equally simple to use. The conditions under whichDscan be most easily and accurately determined are discussed.

ISSN:0021-8979    

DOI:10.1063/1.1729528

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

It is found that Ge can be plastically deformed by indentation at temperatures down to 78°K without introducing cracks. Photomicrographs are presented which show the characteristic etch‐pit pattern of dislocation half‐loops resulting from annealing and etching of indented (111) surfaces.

ISSN:0021-8979    

DOI:10.1063/1.1729529

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Superposition of a radially symmetric magnetic quadrupole field onto an abnormal glow discharge operating atE/Pof 105produces an additional ionization region in the negative glow which is not observed in the absence of a magnetic field and which increases the ion current density at the cathode by more than an order of magnitude. Preliminary Langmuir probe measurements show the electric field gradient in this region to be small and an average electron energy of only 0.8 eV. Data are given to show how sputtering ratio measurements in such a system can be correlated to secondary electron emission at the cathode and charge transfer in the Crooks dark space. Ion current density profile measurements across the cathode as well as corresponding cathode erosion and anode deposition profiles are given.

ISSN:0021-8979    

DOI:10.1063/1.1729530

出版商:AIP    

年代:1963

数据来源: AIP