摘要:

At atmospheric pressure, alloys of high‐pressure InSbIIand &bgr; Sn are retained indefinitely as metastable phases at 77°K but are transformed into stable two‐phase mixtures of low‐pressure InSbIand Sn at sufficiently high temperatures. The resistivity of these alloys at 77°K has been measured as a function of composition, and the temperature and time dependence of resistivity up to 300°K has been determined for samples containing up to 60 at.% Sn. The data show that at any temperature the rate of transformation decreases monotonically with increasing Sn content, and, therefore, that solid solutions of InSbIIand Sn are formed up to at least 60 at.% Sn. The data are thus consistent with complete solid solution in the InSbII&sngbnd;Sn system, as previously concluded on the basis of superconductivity data.

ISSN:0021-8979    

DOI:10.1063/1.1714446

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The velocities of ultrasonic shear and compressional waves in polycrystalline tungsten (99.4% dense) have been measured by a pulse‐echo technique from 24° to 1800°C. Adiabatic elastic constants have been calculated from these velocities with accuracies of ±0.25% to ±0.65%, and corrections have been applied to obtain the following equations for the elastic constants of fully dense tungsten vs temperature (°C):G=1.5893×1012−1.4733×108T−2.448×104T2 dyn−cm−2,L=5.2415×1012−3.7399×108T−4.598×104T2 dyn−cm−2,K=3.1224×1012−1.7755×108T−1.333×104T2 dyn−cm−2,E=4.0761×1012−3.5521×108T−5.871×104T2 dyn−cm−2,v=0.28247+6.1902×10−6T+3.162×10−9T2.

ISSN:0021-8979    

DOI:10.1063/1.1714447

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A theory is developed for the voltage arising from a gradient in a high electric field, i.e., a field sufficient to change the average energy of the carriers, and applied to calculations for the warm‐carrier region in a semiconductor. For a situation in which there is a region of constant fieldEnext to a region, consisting of the same material, in which the field decreases to zero, it is found that, forEin the warm‐electron range, the field‐gradient voltage is proportional toE2. This dependence is found experimentally for bothnandpgermanium at room temperature. Because a region of inhomogeneous material at a contact also makes some contribution to the measured voltage, it is not possible to make a quantitative comparison between experiment and theory. The contribution of the contact is found to depend on the nature of the transition region between semiconductor and metal and, in the hot‐electron region, upon the magnitude of the electric field.

ISSN:0021-8979    

DOI:10.1063/1.1714448

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The lifetimes of excess carriers in phosphorus‐doped, float‐zoned silicon were measured before and after irradiation by cobalt‐60 gamma rays. Recombination in the samples prior to irradiation was dominated by a donor‐like recombination center located 0.13 eV above the valence band. After irradiation, two recombination centers were found in the samples: one located atEc‐0.17 eV and the other atEc‐0.40 eV. The center atEc‐0.17 eV can be identified with the oxygen‐vacancy defect (Si‐Acenter), but no positive identification of theEc‐0.40 eV center can be made. By assuming that theEc‐0.40 eV center is the phosphorus‐vacancy complex, the hole capture cross section of the center was estimated as 9 × 10−14cm2.

ISSN:0021-8979    

DOI:10.1063/1.1714449

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Turbulent free convection of the melt during growth of calcium fluoride crystals by the Czochralski technique has been observed visually and by thermocouple measurement of the attendant temperature fluctuations. Such fluctuations, on the order of 30°C, were shown to cause growth rate fluctuations, and explain the origin of some of the striations previously observed in Czochralski‐grown semiconductor crystals. Effects of operating variables on the turbulence were measured. The best method for reducing or eliminating the turbulence was shown to be reduction of the vertical temperature gradient by use of reflectors or after‐heaters around the crystal.

ISSN:0021-8979    

DOI:10.1063/1.1714450

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Equations are derived for the surface activity of a diffusion specimen for two cases: In the thin plate case (plane source at the origin of a semi‐infinite slab), an analytical solution is obtained for a statically annealed sample and for a sample annealed during simultaneous deformation (either compression or tension normal to the free surface). In the thick plate case, solutions for similar situations are obtained (under proper experimental conditions) in the form of a definite integral convenient for evaluation on an automatic digital computer. Specific cases are shown (using nickel) to illustrate the range in which the thin‐ and thick‐plate solutions are valid. When surface intensity methods are used with a plate sufficiently thick that considerable absorption takes place before diffusion, it is necessary to know precisely the initial plate thickness. This is true regardless of the diffusion time; this is not necessary when the sectioning method is used (with sufficiently long diffusion times). A discussion of a surface intensity experiment by Wazzan is given to illustrate this point.

ISSN:0021-8979    

DOI:10.1063/1.1714451

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Thermal conductivity (&lgr;) of a high‐purity iron (99.998+% Fe) has been studied as a function of temperature (T) between 7° and 200°K. The &lgr; vsTcurve reaches a maximum of about 15 W‐cm−1°K−1at 21°K. This value is considerably larger than that of 4.5 W‐cm−1°K−1observed before by Kempet al.in 1959. Our measurements are in qualitative agreement with the theoretical expectations for a high‐purity iron. The problem, associated with accurate determination of the Lorenz number and the thermal resistivity due to electron‐phonon scattering at low temperatures in iron, is briefly discussed.

ISSN:0021-8979    

DOI:10.1063/1.1714452

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A series of maxima in the internal friction of aluminum at temperatures between 4.2° and 270°K are reported and analyzed. These maxima follow cold work and fast cooling of the specimen and occur on warm‐up. The maxima are related to a mechanism of vacancy pinning of dislocations. Vacancies are indicated by the annealing characteristics of the phenomena. The vacancies in the model are supposedly produced by the cold work and are associated in strings or clusters. Extended dislocations move over saddle interaction energies and produce the relaxation maxima found at kilocycle frequencies. The megacycle attenuation measurements indicate the temperature at which the dislocation breaks from the pinned configuration.

ISSN:0021-8979    

DOI:10.1063/1.1714453

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The free‐radical density produced in polymethylmethacrylate under x‐ray and &ggr;‐ray irradiation has been measured as a function of the amount and kind of organic additive substances present in the polymer. The ratio of radical density produced in the pure polymer by a given radiation dose to that produced in polymers containing additives exhibits a strong dependence upon radiation dose, unlike the similarly defined ratio for the protection against radiation damage by polymer chain scission. The time rate of decay of free‐radical density was also found to depend upon the additives present. The existence of a radiation‐dependent free‐radical annihilation process is postulated.

ISSN:0021-8979    

DOI:10.1063/1.1714454

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Using the Borrmann diffracted beams for AgK&agr;radiation, x‐ray topographs have been made of copper crystal plates 1 × 1 ×Zcm,Z≦ 0.1, with (111) faces. Dislocation lines were generally recorded as lines of less intensity on the x‐ray plate. Both annealed and neutron irradiated crystals were investigated. In the latter the dislocations were pinned and were not moved by the small stresses accidently imposed while making the topographs; and dislocation arrangements in the bulk crystal were determined. The Burgers vectors were deduced from {111} topographs, employing the condition that for no contrastg· b= 0. For edge dislocations, the additional conditiong × n= 0 was necessary for no contrast, and it was demonstrated that this type of contrast was more pronounced for dislocations grouped in a slip trace. It was found that dislocations could be seen all the way through crystals forZ= 0.06 cm. A semiquantitative correlation has been established between etch pits formed at dislocation sites on the (111) surfaces and the dislocations revealed by the x‐ray topography. It has been possible to obtain complete sets of topographs on only a few annealed crystals; for these, an analysis of the dislocations produced by accidental microstrains has been possible.

ISSN:0021-8979    

DOI:10.1063/1.1714455

出版商:AIP    

年代:1965

数据来源: AIP