摘要:

Crystalline quartz shocked parallel to theXaxis was luminescent at pressures greater than 30 and 40 kbar in the −Xand +Xorientations, respectively. Fused quartz and crystalline quartz shocked parallel to theYandZaxes exhibited practically no luminescence at pressures below 120 kbar. From consideration of (1) the almost instantaneous appearance of the light patterns, (2) a comparison of the electrical results of Neilson, Benedick, and Graham with the luminescence, and (3) sodium present in the quartz, it is suggested that luminescence in quartz shocked parallel to theXaxis is caused by the combined effects of piezoelectric voltage and shock compression. The light observed in crystalline quartz shocked parallel to theYandZaxes and in fused quartz is attributed to triboluminescence.

ISSN:0021-8979    

DOI:10.1063/1.1714581

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The characteristics of cobalt films of initial purity 99.91% and 99.999% prepared by vacuum evaporation on various substrates were studied. Variables were substrate type (KCl, NaCl, and natural graphite), substrate temperature, vacuum during evaporation, and vacuum cleavage vs cleavage in air. Epitaxial fcc cobalt films could be obtained on KCl and NaCl, and ``semiepitaxial'' hcp cobalt films could be obtained on graphite. The change in texture of the films upon annealing and their subsequent transformation behavior is discussed.

ISSN:0021-8979    

DOI:10.1063/1.1714582

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The interaction of an elastic wave with the two‐dimensional bound spin waves of a Bloch wall is investigated. Our formulation shows that the 180° Bloch wall couples only with the shear waves while the 90° wall couples with both longitudinal and shear waves. We have computed the spin‐wave amplitude, the power absorbed, the change in the modulus, and theQof the interaction for both these cases. The major effect comes from the coupling of the 90° wall with the longitudinal waves which yields, for iron, a 0.1% to 1.0% change in the elastic constant and a logarithmic decrement of approximately 0.02 for a density of Bloch walls equal to 330/cm.

ISSN:0021-8979    

DOI:10.1063/1.1714583

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Single crystals of rutile, grown by the Verneuil method, have been chemically thinned and examined by electron transmission microscopy. The density and distribution of dislocations agree with that expected from etch pit data. This density is at least two orders of magnitude below that for rutile films formed by oxidizing titanium carbide. The etching of dislocations and stacking faults is described.Some preliminary results of high‐temperature studies in the microscope are reported. These include the discovery of a hitherto unknown slip system, {001} ⟨100⟩.

ISSN:0021-8979    

DOI:10.1063/1.1714584

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Using a xenon arc lamp source with a spectral distribution extending from 10 000 to 5000 Å, we have found it possible to generate a detectable nonlinear sum spectrum in ADP over the range from 5000 to 2700 Å. This sum signal distribution has a spectrometer‐limited resolution of 20 Å which is sufficiently good to resolve line structure and to permit a comparison of this structure with the xenon lamp line spectrum. It is found that the greater part of the sum signal consists of a structureless background which is attributed to nonlinear mixing involving the xenon blackbody continuuum spectrum. A computer program was used to calculate the expected sum signal distribution assuming that the nonlinear polarization constant is independent of frequency. The calculated spectrum agrees qualitatively with the sum signal spectrum obtained experimentally.

ISSN:0021-8979    

DOI:10.1063/1.1714585

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The effect of diffusions and heat treatments on faulted epitaxial materials has been investigated using thinned‐film electron microscopy. Samples of epitaxial silicon were grown with a deliberately high concentration of stacking faults for these studies. Heat treatment were performed in N2and He ambient at 1000°, 1100°, 1200°, and 1300°C. Diffusion consisted of a 1050°C heat treatment for 30 min in P2O5(platinum box technique) to give a high concentration layer (> 1020/cm3). Heat treatments alone had a minor effect on the faulted material. The diffusion process, on the other hand, caused major alteration in the nature and density of faults. Stacking faults were altered to the extent that the orderly striped contrast disappeared and was replaced by individual or piled‐up groups of dislocations. Large clusters of precipitate were observed inside stacking fault regions and on helical dislocations. Dislocation climb was detected as indicated by a large number of helical dislocations.The presence of a ``necklace of precipitate'' associated with stacking faults and dislocations illustrates the role played by these faults as nucleation sites. Such precipitation occurring in an active device region might well be sufficient to drastically alter or destroy the device.

ISSN:0021-8979    

DOI:10.1063/1.1714586

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A new method for the study of radiative recombination in uniformly doped semiconductors has been developed and applied top‐type gallium arsenide. The bulk quantum efficiency is obtained by measurement of photoluminescence as a function of the penetration length of the exciting radiation. Using an estimated electron mobility, the total recombination lifetime of electrons (minority carriers) is found from this photoluminescence measurement and also independently by the measurement of surface photovoltage. The radiative lifetime is determined from the bulk quantum efficiency and the total electron lifetime. The model on which these measurements are based accounts for the principal factors affecting the intensity of photoluminescence, i.e., bulk quantum efficiency, surface recombination, and refraction and reflection of luminescence at the sample surface. The model is consistent with the experimental data for thep‐type gallium arsenide samples studied.The bulk quantum‐efficiency values obtained here are 8% at 300°K and 28% at 80°K for two higher‐efficiency samples and 6 times lower for a third sample. The radiative lifetime of electrons is found to be approximately 2×10−8sec at 300°K, and 3×10−10sec at 80°K. The total lifetime of electrons (minority carriers) is found to be approximately 1.5×10−9sec at 300°K and 10−10sec at 80°K for the two higher‐efficiency samples, and 10−10sec at both temperatures for the third sample.

ISSN:0021-8979    

DOI:10.1063/1.1714587

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A modified Frenkel—Kontorova dislocation model, with a piecewise linear substrate potential, is extended to two dimensions to describe the entire slip plane of the dislocation with one kink. Accurate solutions are found, with the aid of several analytic techniques and a digital computer, for the static configuration under applied stress. The kink Peierls stress &sgr;k P, the kink widthw, and the kink energyF, are determined for a range of values of &ggr;, the perfect crystal shear strength. &sgr;k Pis found to be very sensitive to &ggr;, and to have maxima of the order of 10−6to 10−5, in units of the shear modulus.wandEare less sensitive to &ggr;;wranges from ∼4 to ∼30 lattice parameters, whileEvaries from several hundred to several thousand degrees Kelvin for typical crystal parameters.

ISSN:0021-8979    

DOI:10.1063/1.1714588

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Powder‐pattern peaks of cold‐worked and annealed fcc Cu‐Zn and Cu‐Sn filings were measured with a diffractometer using filtered Cu radiation. The plots of the lattice parameterahkl, calculated from the peak maximum position of the individual (hkl) reflections, as a function of cos&thgr;·cot&thgr; proved to be linear for all annealed powder samples. The large scatter of the individualahklvalues of the cold‐worked filings could be related to the deformation stacking‐fault probability &agr;=&agr;′‐&agr;″ (intrinsic‐fault probability &agr;′ and extrinsic‐fault probability &agr;″), segregation &Dgr;x, and internal stresses &sgr;. The lattice parameters (a0)CWof the cold‐worked filings of the Cu‐Zn alloys were larger, whereas (a0)CWof the Cu‐Sn alloys were smaller than the corresponding (a0)Annvalues of the annealed filings. The deformation‐fault probability &agr; increases with increasing solute concentration.The combined twin‐fault probabilities &bgr; and extrinsic‐fault probability &agr;″, i.e., 4.5 &agr;″+&bgr;, were determined from the displacements of the center of gravity from the peak maximum positions of the (111) and (200) reflections. Fourier analysis of the line shapes allowed the determination of the fault probabilities [1.5(&agr;′+&agr;″)+&bgr;], the average domain sizeD, and the rms strain components in the [111] direction. Using the quantities &agr;′‐&agr;″, 4.5 &agr;″+&bgr;, and 1.5(&agr;′+&agr;″)+&bgr; and solving for &agr;′, &agr;″, and &bgr;, no evidence of the occurrence of extrinsic faults in the cold‐worked filings could be found. The values of 1.5 &agr;′+&bgr; calculated from line broadening agree rather well with those obtained from lattice‐parameter and center‐of‐gravity changes, indicating that intrinsic deformation and twin stacking faults are the primary causes of the broadening and shifts of the powder‐pattern peaks from cold‐worked &agr;‐Cu‐Zn and &agr;‐Cu‐Sn filings.

ISSN:0021-8979    

DOI:10.1063/1.1714589

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A scheme that is analogous to the operation of a heat engine is proposed for exciting maser action in the far infrared and submillimeter parts of the spectrum. A beam of hot molecules interacts through distant collisions with a cold gas of another species at very low pressure. Certain energy levels in the hot gas are cooled faster than others owing to coincidental resonances in the spectra of the two gases. In the partially cooled nonequilibrium state, population inversions are possible in the hot species.To demonstrate feasibility, the interaction between pure rotational states of HCl and HF is discussed in detail. Barring unforeseen experimental difficulty (e.g., chemical activity of HF) the Schawlow‐Townes condition for maser action can be satisfied by theJ=3 → 2 transition in HF at 123.1 cm−1, or 81.25 &mgr;.

ISSN:0021-8979    

DOI:10.1063/1.1714590

出版商:AIP    

年代:1965

数据来源: AIP