摘要:

It is convenient to measure foil weight and area and use known values of density to calculate an average thickness. It is also possible to measure the transmission of monochromatic x rays through the foil and use accepted values of the absorption coefficient to determine foil thickness. If this x‐ray transmission measurement is performed over a large area of an irregular foil, the resulting calculation of average foil thickness will not be in agreement with the weight‐area method. The purpose of this paper is to indicate the error introduced in the average thickness measurement by examining the disparity in transmission between a uniform foil and several nonuniform foils having the same average thickness.

ISSN:0021-8979    

DOI:10.1063/1.1662840

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

This paper shows that, contrary to some previously published work, large perfect dislocation loops donotalter the lattice parameter of a crystal. This conclusion has been verified by optical diffraction experiments using an elastic model of a dislocation loop.

ISSN:0021-8979    

DOI:10.1063/1.1662841

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Contrary to the conclusion in the preceding communication, elasticity theory predicts a lattice parameter change due to the presence of a uniform distribution of prismatic dislocation loops. This result, previously derived by us on the basis of isotropic elasticity theory, has been shown by others to be valid for an anisotropic medium as well. That is, a random distribution of prismatic dislocation loops all with Burgers vectorbproduces a mean strain and lattice dilatation in the directionb. In this communication we review the steps leading to this result.

ISSN:0021-8979    

DOI:10.1063/1.1662842

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Macdonald analyzes the results and interpretations of an earlier experimental work by Mitoff and Charles, in which it was concluded that observed capacitances were too large to be explained by space‐charge polarization due to blocking of a single mobile ion. These comments indicate the difficulties and uncertainties that arise in attempts to apply to this case two mobile ion models, in which the possibility of allowing the mobility of one of the ions to become zero is not explicitly accounted for.

ISSN:0021-8979    

DOI:10.1063/1.1662843

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Estimates of the spectral densities of a model thought to be appropriate to 1/fcurrent noise are found using a Monte Carlo method. The results are compared with theory. It is concluded that the model should be useful in the explanation of the occurrence of this type of noise in many materials.

ISSN:0021-8979    

DOI:10.1063/1.1662844

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A uniqueness theorem for a static electric or magnetic field in an isotropic but saturable medium is presented. We show that if, in a given region,BandHare appropriately related and Maxwell's equations are satisfied, and if over the boundary of that region either normalBor tangentialHis prescribed, then bothBandHare unique in that region. A similar statement can be made aboutDandEin an electric field calculation if, in addition, we assume that the region is free of electric charge.

ISSN:0021-8979    

DOI:10.1063/1.1662845

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Results of Diamond and Wert on the kinetics of the reorientation of carbon pairs in nickel are used to demonstrate that the low activation energy reported by Massaro and Petersen for diffusion of carbon in nickel at 350–‐700°C cannot be explained by a change in the mechanism for the lattice migration of carbon. Boundary diffusion also appears incapable of explaining the results, and it is concluded that there may be unsuspected difficulties with the particular method of measurement employed for the diffusion measurements.

ISSN:0021-8979    

DOI:10.1063/1.1662846

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

In attempting to calculate the anomalous transistor profiles published by Ziegler, Cole, and Baglin, it was necessary to assume the shape of the initial B profile. A complementary error function distribution was used, based upon their published junction depth and sheet resistance measurements. However, subsequent measurements of the initial B profile (unpublished results provided by Ziegler) showed that it did not have a complementary error function shape. In this paper, the calculations are repeated using the corrected initial B profile.

ISSN:0021-8979    

DOI:10.1063/1.1662847

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A systematic study was made of some of the oscillatory phenomena which are found to occur in bounded dc discharge plasmas. The nature of the oscillator patterns was explored over a pressure interval (0.01≤P≤1.5 Torr), a current interval (0.5≤I≤10 mA), and a discharge‐voltage interval (0.8≤V≤3.5 kV) in order to establish the conditions for onset of oscillatory modes within the plasma. An rf pickup coil, to detect the oscillations, was placed such that it contained the plasma filament coaxially. Signals having a frequency range of 20–200 kHz were observed to be coming from the plasma. These frequencies were found to be sensitive to pressure, current, and discharge voltages for a given geometry tube. The gases considered in this investigation were N2, O2, CO2, air (atmospheric), H2, D2, He, and argon. Electron densities calculated from the ``resonant'' conditions for the ions are presented.

ISSN:0021-8979    

DOI:10.1063/1.1662848

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

From thermoluminescence (TL), thermally stimulated currect (TSC), and photoluminescence and photoconductivity kinetic response measurements, the excitation mechanism of the Cr3+luminescence center in SrTiO3is explored. Based primarily on the strong correlation between TSC and TL, it is concluded that the dominant excitation mechanism is a charge‐transfer process, although a contribution from a resonance‐transfer process cannot be completely ruled out. The superficial differences which exist between photoluminescence and photoconductivity kinetics can be accounted for completely within the framework of a charge‐transfer model by recognizing that the photocurrent is controlled primarily by the electron traffic through the conduction band, while the photoluminescence is controlled primarily by the hole traffic through the luminescence center.

ISSN:0021-8979    

DOI:10.1063/1.1662849

出版商:AIP    

年代:1973

数据来源: AIP