摘要:

The rate of thermal formation of colloids in additively colored KCl has been studied in an attempt to understand the mechanism of precipitation of the excess potassium. It is found that the process is best described as a dislocation induced precipitation, the end product being an equilibrium between the remainingFcenters and the precipitated potassium. Analysis of the rate data leads to a diffusion constant of the diffusing entity of the order of 10−9cm2sec−1to 10−13cm2sec−1. The model postulated for the formation of the colloids is the diffusing ofFcenters to a nucleation site where they combine with lattice potassium ions to form atomic potassium.

ISSN:0021-8979    

DOI:10.1063/1.1702569

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A recent conclusion that the vibrating string model of dislocation motion cannot account for the magnitude of the observed amplitude‐independent damping at kilocycle per second frequencies is shown to be not generally valid. In fact, it is shown that there are specimens for which the extrapolated values of the decrement from megacycle frequencies to 15 kc are higher than any previously measured values at 15 kc. This result shows that the model can easily account for the magnitudes observed in the kilocycle region, and contributes a substantial fraction, if not all, of the component of the damping at 15 kc, which can be removed by irradiation. Since it has been demonstrated for the megacycle measurements that the source of the damping is the dislocation‐phonon interaction, the evidence is strong that the same mechanism contributes to the damping observed at 15 kc. The argument given does not depend on assumed values for dislocation parameters, but only on experimentally established relations. A critical experiment would now be a measurement of the frequency dependence in the kilocycle range of the component of the damping which can be removed by irradiation. Such a measurement, if feasible, should show whether or not other as yet unknown mechanisms also contribute to the damping at 15 kc.

ISSN:0021-8979    

DOI:10.1063/1.1702570

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A new equation for gas flow through capillaries in low and intermediate pressure ranges is derived without attempting to distinguish between Poiseuille flow with slip and Knudsen flow. It is assumed here simply that the total flow has two components, one characterized by an effective mean free path and the other by an effective viscosity, both of which depend on the ratio of the average pressure in the capillary to a characteristic pressurep1and, in addition, on the mean hydraulic radius of the capillary and properties of the gas. At low pressure, the usual expression for Knudsen flow is obtained, but in a form which separates out a term, due to a viscous effect, that is related to the ``free‐molecule viscosity.'' At high pressure, Poiseuille flow with slip is obtained, but the slip term is cast in a new form in terms of the characteristic pressurep1. Also, our equation has a minimum in the relationship between the permeability and the pressure, which is not given by most permeability formulas but which is observed experimentally under some conditions. At this minimum, diffusion flow and viscous flow are equal in magnitude. At pressures below that corresponding to minimum flow, the phenomenon becomes more ``diffusionlike'' and at higher pressures more ``viscouslike.''Original data of Knudsen and Klose on the flow rates of various gases through capillaries are well fitted by this new equation at low pressure as well as in the ``transition region'' between Knudsen flow and Poiseuille flow. This fit is obtained by setting the adjustable constant &agr;, which definesp1, equal to unity. Elementary theory of the slip‐flow correction also indicates that &agr; should be about unity. Results obtained with this equation are compared with those obtained with Knudsen's four‐constant formula.

ISSN:0021-8979    

DOI:10.1063/1.1702571

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The recent measurements of the elastic constants of calcite by Reddy and Subrahmanyam (1960) disagree with the values obtained independently by Voigt (1910) and Bhimasenachar (1945). The present authors, using an ultrasonic pulse technique at 3 Mc and 25°C, determined the elastic constants of calcite using the exact equations governing the wave velocities in the single crystal. The results areC11=13.7,C33=8.11,C44=3.50,C12=4.82,C13=5.68, andC14=−2.00, in units of 1011dyn/cm2. Independent checks of several of the elastic constants were made employing other directions and polarizations of the wave velocities. With the exception ofC13, these values substantially agree with the data of Voigt and Bhimasenachar.

ISSN:0021-8979    

DOI:10.1063/1.1702572

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

In solid metal samples which have a strong texture, certain planes will favor the diffraction of the vertically divergent rays of the x‐ray beam more than the parallel rays. In extreme cases this will produce a diffraction peak shift. The direction and magnitude of the shift obtained from a specimen with a prominent ⟨001⟩ wire texture is in good agreement with the theoretical calculations of Pike (1957).

ISSN:0021-8979    

DOI:10.1063/1.1702573

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

p‐i‐njunctions were fabricated by ion‐drift techniques using lithium inp‐type silicon. Highly compensated intrinsic regions from 0.1 to 5.0 mm were obtained. At temperatures between 120° and 200°C, the space charge of thermally generated carriers in the intrinsic region distorted the lithium ion distribution, producing linear graded junctions whose gradients were between 1011and 1014atoms/cm3/cm. Room‐temperature capacitance measurements were used to determine the impurity distribution. Agreement was found between calculated and measured values of the impurity gradient. Precipitation of lithium ions in the intrinsic region was not observed.The increase of the direct current under reverse junction potential as a function of the increased width of the depletion region permitted measurement of the diffusion and depletion‐region‐generated current components. The value of the diffusion current component at any temperature was proportional to the resistivity of thep‐type silicon. The depletion‐region‐generated component was proportional to the width of the depletion region.

ISSN:0021-8979    

DOI:10.1063/1.1702574

出版商:AIP    

年代:1962

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1702576

出版商:AIP    

年代:1962

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1702577

出版商:AIP    

年代:1962

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1702579

出版商:AIP    

年代:1962

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1702580

出版商:AIP    

年代:1962

数据来源: AIP