摘要:

Oxygen has been diffused into silicon at temperatures above 1250°C. The diffused layers have been detected by subjecting the samples to a second heat treatment at 450°C. The donors, which then form from the oxygen, cause the layer to convert tontype. The relationship between donor and oxygen concentrations was established by studying donor formation in crystals of known oxygen concentration. From these results and the electrical properties of the layers, the diffusivity and solubility of oxygen in silicon has been measured. For silicon, in contact with SiO2(glass), the heat of solution is (2.3±0.3) ev and the diffusivity is given byD=135exp(−3.5 ev/kT).

ISSN:0021-8979    

DOI:10.1063/1.1735025

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

Permanent and elastic strains in silicon crystals grown by the Czochralski technique have been studied by observing the crystal birefringence. These studies reveal that the presence of birefringence is related to (a) plastic deformation caused by severe thermal gradients which produce forces exceeding the crystal yield force and (b) work damage or externally applied forces. The first source of birefringence has been termed permanent strain since this appears in the crystal as grown and the birefringence pattern cannot be altered by changes in sample geometry. This characteristic is typical of a ``frozen‐in'' strain. A strain‐free sample may also be made birefringent, however, by a work damage such as surface abrasion or sand blasting. Such a birefringent pattern can be altered if the sample geometry is changed. This characteristic, of course, is typical of elastic strain.Studies made of samples both parallel and perpendicular to the direction of crystal growth revealed birefringence patterns similar to those of naturally anisotropic crystals such as calcite. The patterns indicate the formation of a pseudo‐optic axis in silicon coincident with the growth direction and is caused by the uneven temperature distribution which results in perdominantly uniaxial stress.Regions of tension and compression have been discovered and their respective magnitudes determined. The calculation of the ``frozen‐in'' tension and compression stresses are based upon experimental determination of the stress‐optic coefficient of silicon. Satisfactory agreement was obtained between frozen‐in stress calculations and measurements of yield stress at elevated temperatures.

ISSN:0021-8979    

DOI:10.1063/1.1735026

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

Aluminum was strained in tension under a Geiger‐Mu¨ller counter. Both the electron emission associated with plastic deformation and the subsequent delayed emission were observed. An attempt was made to correlate quantitatively the emission rates with the mechanical variables, i.e., strain and rate of deformation. The model used for this correlation links point imperfections formed during deformation with the emission from the oxide surface film.

ISSN:0021-8979    

DOI:10.1063/1.1735027

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

Dynamic pyroelectric techniques have been used to study single crystal triglycine sulfate hysteresis loops at room temperature. An apparent polarization bias is observed and is similar to that reported earlier for BaTiO3. The apparent polarization bias can be shifted with the application of a dc electric field. When precautions are taken to eliminate electrode‐edge effects, the pyroelectric hysteresis loops are always symmetric. The apparent polarization bias is ascribed to electrode‐edge effects as in the case of BaTiO3.

ISSN:0021-8979    

DOI:10.1063/1.1735028

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The influence of plastic deformation upon the linear magnetostriction of hard‐worked nickel has been determined by use of direct measurements of strain in three normal directions and then by measurement of magnetostriction in the same three directions using the method of rotating the specimen 90° for each measurement. This combination of measurements appears to have advantages for the interpretation of magnetostriction in nonisotropic bodies.The value of magnetostriction at saturation for gradeAnickel plastically deformed with an 84% reduction of cross‐sectional area was found to be −33.5±1×10−6. This compares with −35±1×10−6for annealed nickel of the same quality. The hard‐worked nickel was free of volume magnetostriction of determinable magnitude. It showed inappreciable preferred domain orientation. It did appear to have a small amount of preferred crystalline orientation.

ISSN:0021-8979    

DOI:10.1063/1.1735029

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A statistical approach is used to determine the effect of porosity in ceramic materials on their dielectric breakdown strength. The calculated drop in dielectric strength is in good agreement with the experimental data for lead zirconate titanate ceramics. The theory shows that the measured dielectric strength in porous materials is a function of the porosity, the void size, and of the dimensions of the test sample.

ISSN:0021-8979    

DOI:10.1063/1.1735030

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

Two x‐ray methods have been developed for determining the crystallinity of cellulose using a Geiger counter spectrometer. The two methods were applied to six native cotton varieties, to a cross‐bred variety, and to two cottons chemically modified with ethylamine. The x‐ray scattering curves for each of the nine samples were compared with those from a highly crystalline sample, a cotton hydrolyzed in HCl, and an amorphous cotton sample to provide a relative measure of crystallinity, or crystalline index.With fully corrected data the average crystalline index of the six cotton varieties was found to be 68.3 and 78.7% by the correlation and by integral methods, respectively. The crystalline indices of the remaining samples determined by the correlation and by the integral methods are, respectively, cross‐bred cotton (S×P), 54.3 and 77.2%; cotton treated with anhydrous ethylamine, 29.7 and 50.9%; and cotton treated with 75% aqueous ethylamine, 28.3 and 50.3%.

ISSN:0021-8979    

DOI:10.1063/1.1735031

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The dependence of switching rate on the crystal thickness has been measured by Merz and explained by him in terms of a surface layer which has a low dielectric constant, and is about 10−4cm thick. While not explicitly stated in Merz' original arguments, the layer must have a reversible polarization. If a layer without a reversible polarization is assumed, instead, and the discontinuity of the normal component of polarization at the interface between the layer and the bulk is taken into account, then a much thinner layer (∼1 atomic thickness) will explain the thickness dependence. This layer can be taken to be very lossy, so that it has a relaxation time (for the disappearance of electric fields) short compared to the switching time, and yet the layer will still be completely effective in slowing down domain wall motion.

ISSN:0021-8979    

DOI:10.1063/1.1735032

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

When a cloud of highly ionized gas flows across a magnetic field, an emf is produced in the gas which is proportional to the speed of flow. Oscillographic probe measurements have been carried out giving the flow speed as a function of position. By drawing currents from the probes the plasma resistance can be found at various distances from the plasma generator. The resistance is shown to be due to the motion of positive ions.

ISSN:0021-8979    

DOI:10.1063/1.1735033

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

With the aid of a mass spectrometer a study has been made of the gaseous contaminants present when oxygen is exposed to different incandescent filaments. In agreement with others CO and CO2were the most abundant contaminants found. The amounts of CO and CO2found, at a given filament temperature and oxygen pressure, were greater for Mo 0.031% C, W 0.012% C, and Re 0.010% C than for Ta 0.001% C. Also at the same oxygen pressure and filament temperature the quantity of CO found was much greater for a carbonized W filament than for any of the other filaments investigated. These results are consistent with the hypothesis that CO and CO2are produced by the interaction of oxygen with the carbon present in the hot filaments. No evidence was found to indicate that the glass walls contribute to the formation of CO and CO2.

ISSN:0021-8979    

DOI:10.1063/1.1735034

出版商:AIP    

年代:1959

数据来源: AIP