摘要:

Dislocation arrays have been observed in deformed germanium using a technique based on the selective etching of lithium precipitates which prefer to nucleate on or near dislocations. Evidence is presented which indicates that both internal Frank‐Read sources and surface dislocation sources are of importance in the deformation of germanium.

ISSN:0021-8979    

DOI:10.1063/1.1722622

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The theory of ferromagnetic microwave amplification is presented in detail. All three possible types of operation using, respectively, two electromagnetic cavity modes, two sample modes, and one sample and one cavity mode, are discussed. One especially simple case, that of a sphere in the first type of operation is treated separately. Thereafter all three cases are discussed in terms of scaler and vector potentials. An appendix deals with the gain‐band‐width problem and gives an expression for the equivalent ``negativeQ'' of the sample.

ISSN:0021-8979    

DOI:10.1063/1.1722623

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

Symmetric faceted etch hillocks have been observed on certain germanium surface orientations exposed to an H2O2&sngbnd;HF (Superoxol) etchant. Considerations of surface curvature and etch rate lead to the conclusion that the faces bounding the hillocks must be at saddle points on an etch ratevsorientation surface. A measurement of etch rate throughout the stereographic triangle has supported this conclusion. The formation of dislocation pits and hillocks is discussed in terms of the variation of surface etch rate with orientation.

ISSN:0021-8979    

DOI:10.1063/1.1722624

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

Two methods have been developed for the preparation of large‐areap‐njunctions in monocrystalline silicon by surface melting and overdoping of the molten material. In one method, direct rf power coupling is used to form a cylindricalp‐njunction in a rod of silicon. Also, radiation heating has been used to melt the surface of thin disks of silicon. The junctions can sustain a peak inverse voltage (PIV) given approximately by PIV=40&rgr;nor PIV=10&rgr;pdepending on the polarity of the base material, of resistivity &rgr;nor &rgr;p. Low‐resistivityn‐type base material overdoped with aluminium forms junctions exhibiting very sharp breakdown characteristics, and PIV=40&rgr;nholds for material at least up to 15 ohm cm. Some results obtained by using a gas doping technique are also given.

ISSN:0021-8979    

DOI:10.1063/1.1722625

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

In treating problems of sputtering and radiation damage of solids, a billiard ball model is frequently assumed. An attempt is made to indicate to what extent such a model is justified. Using this model it is noted that the lattice structure of a crystal implies a correlation between successive collisions in a damage process which can lead to the propagation of an energy pulse, or a sequence of collisions, along a close‐packed line of atoms. The rate of attenuation of these pulses is estimated for a particular case and certain implications of the effect are discussed.

ISSN:0021-8979    

DOI:10.1063/1.1722626

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The efficiency of a class of electron‐multiplication processes previously considered to be possible initiators of high‐voltage vacuum arcs has been studied as a function of applied voltage in the voltage range below about one hundred fifty kilovolts. This efficiency is found to be typically less than one part in ten thousand, in contrast to the unity or greater required for arc initiation by such processes. The variation of the efficiency with field is noted. The conclusion is drawn that this class of processes apparently plays no significant role in arc initiation, and the remaining possibilities are briefly discussed.

ISSN:0021-8979    

DOI:10.1063/1.1722627

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

An isothermal equation of state of a solid is considered, which contains as special cases the equations of Birch, Murnaghan, Bardeen, and others. The equation is generalized to arbitrary temperature by replacing two constants of the equation by temperature‐dependent parameters, whose functional form is determined by considerations of thermodynamic consistency. The thermal properties of the solid implied by this equation of state are examined. It is shown that the generalized equation is consistent with the Mie‐Gru¨neisen relation for the thermal pressure of the lattice, and that the corresponding Gru¨neisen parameter is only slightly dependent on temperature, in general. The form of the generalized equation of state at low temperature is exhibited as an explicit function of volume and temperature for a solid whose heat capacity obeys the Debye law. A comparison with pressure‐volume data of Swenson for potassium at low temperatures shows excellent agreement of the generalized equation of state with experiment.

ISSN:0021-8979    

DOI:10.1063/1.1722628

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The condition of the surface of germanium crystals has been studied by chemical, electron microscope, electron diffraction, and other techniques after several of the standard etching procedures. The surface is often partially covered by particles believed to be germanium monoxide. An etch has been devised which gives a controlled thickness of germanium monoxide on the crystal. Another etch minimizes the oxide formation. A simple light‐scattering method for checking the surface cleanliness is described. The results of surface recombination velocity and channel effect measurements on crystals treated by these methods are described as is a method for obtaining low surface recombination onn‐type crystals.

ISSN:0021-8979    

DOI:10.1063/1.1722629

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

Aluminum, magnesium, and lithium‐magnesium pellets were accelerated to velocities as high as 4.5 km/sec by means of an explosive. The ionization in the trails of these pellets was determined by measuring the reflection of a microwave signal from the trail. It was found that the ion density in the trail is an increasing function of the velocity and for the velocity range between 1 and 4.5 km/sec lies between 1010and 1015electrons per cm of path. It was observed that aluminum pellets do not produce ionization at velocities below approximately 2.9 km/sec, while magnesium leaves an ionized trail at velocities down to approximately 1.6 km/sec and lithium‐magnesium alloy down to approximately 1.3 km/sec.

ISSN:0021-8979    

DOI:10.1063/1.1722630

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

WO3undergoes a phase transformation from monoclinic to orthorhombic at approximately 320°C and from orthorhombic to tetragonal at 720°C. A detailed study of the variation of the unit cell dimensions over the range from room temperature to 1000°C has been carried out using high‐temperature x‐ray diffraction techniques. Some unique features of the apparatus are described in this paper.Between the 320°C and 720°C transformations, theaandcaxes increase uniformly in length while thebaxis decreases. There is a marked increase in the volume of the unit cell below the orthorhombic to tetragonal transformation; the volume decreases sharply in the transformation and resumes its ``normal'' increase above 720°C.

ISSN:0021-8979    

DOI:10.1063/1.1722631

出版商:AIP    

年代:1957

数据来源: AIP