摘要:

The electrical resistivity of magnesium at room temperature was found to increase by 1.47±0.37 &mgr;&OHgr; cmper atomic percent addition of neodymium. The additional resistivity is strongly temperature dependentbetween 77° and 373°K. In the temperature range 273° to 373°K the temperature dependence of the additionalresistivity can be characterized by a temperature coefficient of the order−2×10−3 deg−1.

ISSN:0021-8979    

DOI:10.1063/1.1931157

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Crystal growth on the basis of phase equilibrium relationships in the Cd-Te system is discussed. Two verydifferent types of approaches were investigated. Growth by slowly cooling melts of near stoichiometriccomposition under constant cadmium pressure resulted in single crystals up to 5 cm in length. Growth fromcadmium rich compositions at constant cadmium pressure by heating the melt produced crystals up to 1 cmin length. The relative merits of the two processes are discussed with regard to CdTe and other similarsystems.

ISSN:0021-8979    

DOI:10.1063/1.1931158

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The present experiment was conducted to investigate whether edge and screw dislocations play differentroles in the surface work-hardening of metals deformed in tension. The sides of the crystals were so orientedthat one pair of sides was parallel to the Burgers vector of the dislocations of the primary slip system. Thecrystals were deformed in tension to 0.5% and then unloaded. Subsequently, some crystals were masked onone pair of sides, and others were masked on the other pair of sides. They were then electropolished to removethe surface layers from the unmasked faces. This operation was repeated at several strains. At small strains,edge and screw dislocations play different roles in the surface work-hardening mechanism. However, atlarger strains, both edge and screw dislocations harden the surface equally, and preferential surface work-hardeningincreases as the stress level increases.

ISSN:0021-8979    

DOI:10.1063/1.1931159

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

New interest in zinc oxide has developed since it has been discovered to be piezoelectric. In line with thisinterest the zero field adiabatic elastic moduli have been measured. A high frequency, 60 to 500 Mc ultrasonicpulse technique was employed. Two crystals with sufficiently high conductivity to effectively shortthe electric field were available for the measurements.A density of5.676 g/cm3was used to calculate the zero-field adiabatic elastic moduli. This density wastaken as exact with reference to the error limits.The moduli in units of1012 dyn/cm2at 25°C are:c11E = 2.097 ±0.1%,c12E = 1.211 ±0.15%,c13E = 1.051 ±0.15%,c33E = 2.109 ±0.1%,c44E = 0.4247 ±0.1%,c66E = 12(c11E−c12E) = 0.4429±0.1%.

ISSN:0021-8979    

DOI:10.1063/1.1931160

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Approximate solutions for the distribution of dislocation arrays under nonuniform stresses are given.Three basic types of stress fields are investigated: The finite power series, the simple exponential and simpletrigonometric functions.A number of quantitative examples are given. It is found that the number of dislocations in a piled-uparray is particularly sensitive to the relative magnitude of the stress near the tail of the array.

ISSN:0021-8979    

DOI:10.1063/1.1931161

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

In collisionless plasma acceleration and sheath problems, where the potential and one of the fluxes areknown, the distribution in energy of flux of the other species can be computed as a solution of Abel's equation.This technique is illustrated, and self-consistent sample solutions are given for ion and electron beamscrossing a potential drop, with a concomitant-trapped electron flux.

ISSN:0021-8979    

DOI:10.1063/1.1931162

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

This paper correlates the appearance of the discharge around a probe with data obtained with a fixedand a movable wall probe. A relatively small probe at the axis of a discharge has much less effect than theinsulating sleeve around the probe lead. Since ion depletion is the controlling factor, the disturbing effectincreases a little as the probe is made more negative. The presence of the insulating sleeve enhances theelectric field on the anode side of it, increasing ion production, and displaces the region of maximum ionproduction toward the part of the tube beyond the end of the probe. Corresponding increases in ion flow tothe wall beyond the end of the probe and to either side of it are observed. In noble gas discharges (tube 34mm i.d., filling pressure 1.0–7.0 mm Hg, are current 1.0–1.4 A) increases in wall current beyond the end of aprobe at the axis of the discharge, with an insulator 0.15 mm in diameter around its lead, ranged from12 to 29%.

ISSN:0021-8979    

DOI:10.1063/1.1931163

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The properties of a pressure transducer consisting of a single-crystal silicon diaphragm having stress-sensitivepiezoresistive regions formed by the localized diffusion of impurities have been theoretically andexperimentally investigated. The longitudinal and transverse piezoresistance effects are discussed and theresults are applied to the stress pattern of a deformed diaphragm. The conditions under which the stress inthe diaphragm varies linearly with applied pressure are discussed and good agreement between the predictedand measured sensitivity is found in both the linear and nonlinear cases.

ISSN:0021-8979    

DOI:10.1063/1.1931164

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

An examination of the theory of the thermionic hollow cathode shows that several distinct modes of zero-fieldemission are possible. The mode that exists in any given case depends on the relationship between acertain parameterd, which characterizes the nature of the electron cloud within the cavity, and the size ofthe effusion hole and the cavity dimensions. A quantitative expression is given for the conditions underwhich the hollow cathode can be used for a precise determination of the thermionic constants by the methodof Jain and Krishnan. Under other conditions a quasi-hollow beam is obtained and a theoretical predictionof the total zero-field current from the hole was found to be in order of magnitude agreement with experimentalobservations. An explanation of the similarity of emissions between ‘L’ cathodes of different porosityis also given.

ISSN:0021-8979    

DOI:10.1063/1.1931165

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A discussion is given concerning the properties of superconductors considered as permanent magnets.Experiments on solid and hollow cylinders of lead are reported and compared to theoretical predictions. Amacroscopic theory is developed of the filamentary mesh high-field superconductor in the form of an infiniteplate. An experiment on a sample ofNb3Snshows maximum energy product greater than 25 MG-Oe at4.2°K. The phenomenon of discontinuous flux jumping is demonstrated and discussed briefly.

ISSN:0021-8979    

DOI:10.1063/1.1931166

出版商:AIP    

年代:1962

数据来源: AIP