摘要:

Positive ions sputtered from copper under a variety of different bombardment and surface conditions have been mass analyzed and found to include species characteristic of the incident ions (``reflected'' ions), of copper and some of its compounds, and of alkali metal impurities. A model is described which accounts for most of the properties of the ``reflected'' ions, not in terms of reflection but in terms of the amount of gas trapped and released by the surface. The ionizing agent is unknown but is thought to be the bombarding ions (or their secondary electrons) rather than the surface. The Cu+ions, on the other hand, seem to be surface ionized sputtered particles originating from patches of high local work function. Yield data seem to correlate qualitatively with probable changes in work function caused by adsorption of impurities, sputtering, or vacuum annealing. The CuO+peak is believed to be caused by dissociation and ionization of cuprous oxide molecules under the action of the ion bombardment. The rates of formation and disappearance of this peak were studied under various circumstances. An unusually high sputtering rate was found to occur at an argon bombarding energy of 75 ev. Na and K impurities sputtered from and ionized by the copper surface showed some interesting transient effects which can be interpreted in terms of a low sputtering probability compared to the base metal. The relevance of these experiments to sputtering theories, ion pumping, oxidation, cleanup, and surface ionization theory is discussed.

ISSN:0021-8979    

DOI:10.1063/1.1777185

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A method is described for orienting germanium crystals in the [111] direction with an accuracy within six minutes of arc.N‐type germaniun is alloyed by liquid indium. The indium is then etched off and the resulting alloy pits are inspected by means of interference fringes. The information obtained from these pictures is used to determine the orientation with the accuracy noted above. An alternate method is described using information obtained from delineatedP‐Njunctions on two angle lapped bevels.

ISSN:0021-8979    

DOI:10.1063/1.1777186

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

An increase in stacking fault probability associated with a solute with the same atomic size but a higher valence than the solvent was found by comparing filed Ag and Ag‐6 at. % Al. The stacking fault and twin fault probabilities in ordered Cu3Au, where the atoms differ in size only, were higher than for either pure Cu or Au after deformation at and below room temperature. The stacking fault probability was lower in filings of quenched Cu3Au and Cu‐14.3 at. % Al alloys, than in slowly cooled specimens. There is a close correlation between measured fault probabilities and available data on fault energies and Fermi surface configurations.Twin faults were found in Cu‐base alloys deformed at room temperature as well as at low temperatures.Stacking faults in filings of Cu‐14.3 at. % Al annealed out in two stages. The second stage was associated with recrystallization, with an activation energy similar to that for interdiffusion in this system. Twin faults were more stable than stacking faults.

ISSN:0021-8979    

DOI:10.1063/1.1777187

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Expressions for the propagation of a circularly polarized microwave through a plasma parallel to a uniform and static magnetic field are derived from the Boltzmann equation and, alternately, from the equation of motion of an individual electron. Both methods yield identically the same formulation in which effects of the random motion of the electrons are predicted to result from (i) the Doppler shift due to electron motion parallel to the direction of propagation, (ii) electron free paths extending over distances significant compared to the attenuation length, and (iii) variation of collision frequency with electron velocity. The results of a numerical study of the propagation of a right‐handed wave indicate that the first two of these effects are important in the region of cyclotron resonance even at moderate temperatures (e.g., in re‐entry plasmas) provided that the collision frequency is small compared to the signal radian frequency. Substantial reduction of the attenuation of a right‐handed wave in a plasma may be achieved by means of a magnetic field aligned parallel to the direction of propagation. The cyclotron frequency must be of the order of the signal radian frequency or larger and such that the enhanced attenuation arising from the electron random motion is avoided. The effectiveness of a given magnetic field in reducing the attenuation increases with decreasing ratio of collision frequency to signal radian frequency.

ISSN:0021-8979    

DOI:10.1063/1.1777188

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The effects of chain irregularities, treated as randomly introduced copolymeric units and of added monomeric diluents, on the nucleation rate of crystallizing polymeric systems have been calculated. A marked attenuation in the nucleation rate is expected under certain conditions as a consequence of the varying composition of the melt. The decrease in the nucleation rate becomes more pronounced at the lower undercoolings and as the concentration of the noncrystallizing component increases.The Avrami mathematical formulation for the kinetics of phase changes can be generalized to allow for nucleation and growth rates which vary with the amount of material transformed. The resulting isotherms for copolymers are no longer superposable, superposability being characteristic of crystallization under conditions of constant nucleation and growth. Possible error in the interpretation of crystallization kinetics utilizing the simplified version of Avrami's equation is pointed out, as is the extreme sensitivity of the crystallization process to the presence of small amounts of chain irregularities.

ISSN:0021-8979    

DOI:10.1063/1.1777189

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Young's modulus and internal friction of natural crystals of &agr;‐Fe2O3(Congonhas, Brazil) were measured as functions of temperature in the region of the Morin transition with and without a 1570‐oe magnetic field. Nonelastic components of strain occur and these, we suggest, are due to stress‐induced changes in the directions of the magnetization vectors.

ISSN:0021-8979    

DOI:10.1063/1.1777190

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Direct evidence is presented that ⟨100⟩ dielectric breakdown dendrites on LiF cleavage surfaces are grooved features that are flanked by volume ⟨110⟩ channels. The dendrite has presumably resulted from disruptive forces attending an electronic breakdown process. No evidence of primary involvement of dislocations in the process of dielectric breakdown was found. Indirect evidence is presented thatYbranches and the etch features surrounding random sites represent the surface intersections of ⟨110⟩ spikes that are associated with submerged electrical breakdown paths. The existence of the ⟨110⟩ dielectric breakdown dendrite and its relationship to theYbranch is noted.

ISSN:0021-8979    

DOI:10.1063/1.1777191

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

High explosive driving systems and high‐speed optical techniques have been used to investigate the compressional behavior ofx‐cut,y‐cut, andz‐cut quartz crystals and fused quartz up to about 750 kbar pressure. In both forms of silica two‐wave structures over a wide pressure range are identified as resulting from unusually high Hugoniot elastic limits. In crystalline quartz a dependence of the pressure of these elastic limits on driving shock pressure and sample thickness is associated with a relaxation‐time phenomenon connected with the transition from elastic to fluid‐like flow. Recovery experiments are reported which confirm a previous observation that sufficiently high shock pressures result in the transition of crystalline quartz to the fused state, and the implications of the compression data in this regard are discussed. Observations on fused quartz deomonstrate that shock‐wave loading results in both the anomalous compression at low pressures and the compaction phenomena above 100 kbar which have been reported from hydrostatic experiments.

ISSN:0021-8979    

DOI:10.1063/1.1777192

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A high accuracy lattice constant determination of a specimen is possible through the analysis of the x‐ray diffraction image known as Kossel lines. In the present work general formulas are derived by which the lattice constant can be obtained from the Kossel line picture. The lattice constant of a nickel specimen is then measured to demonstrate the applicability of the method.

ISSN:0021-8979    

DOI:10.1063/1.1777193

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The dc Sumoto effect is explained in terms of an abnormal fall of potential near one of the electrodes. Experimental evidence is cited to support this theory.

ISSN:0021-8979    

DOI:10.1063/1.1777194

出版商:AIP    

年代:1962

数据来源: AIP