摘要:

The EPR spectra of nonstoichiometric rutile and rutile doped with tantalum, niobium, and cerium have been examined at helium temperatures. Ta4+and Nb4+have short spin‐lattice relaxation times and appear to be suitable for cross doping in maser applications.

ISSN:0021-8979    

DOI:10.1063/1.1736120

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Neutron‐induced defects in the graphite lattice are studied by dark‐field transmission electron microscopy. The annealing is followed and the appearance of the defects is interpreted on the basis of the kinematical theory of electron diffraction. A physical interpretation of the observations based on displacement spikes and their annealing is given.

ISSN:0021-8979    

DOI:10.1063/1.1736121

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The textural properties of thin germanium films vacuum evaporated onto hot fused‐quartz substrates have been investigated in detail over the temperature range from ambient to 650°C. The strongest texture characteristic of these films is the [110], which is obtained at substrate temperatures as low as 175°C, and prevails up to about 350°C. For temperatures between 350° and 575°C, competition for growth occurs and the texture varies principally between being powder, [110] and [111]. Above 575°C the [111] texture becomes dominant.

ISSN:0021-8979    

DOI:10.1063/1.1736122

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Recent experiments with Ni‐Cu and Fe‐V alloys indicate that the specific heat at low temperature cannot be described by electronic and lattice terms alone. An attempt is made to explain an additional term in the specific heat of these alloys on the basis of ferromagnetic clusters.

ISSN:0021-8979    

DOI:10.1063/1.1736123

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The optical absorption properties of Co60‐irradiated fused silica and crystalline quartz have been studied in the vacuum‐ultraviolet region. The most prominent absorption band found in both materials has a maximum at 7.6 ev (1620 A). Optical and thermal bleaching experiments indicate that this band is not necessarily complementary to a band at 5.9 ev (2100 A), as has been assumed. Though the 7.6‐ev band has approximately the same intensity in both materials for the same irradiation, the 5.9‐ev band is >20 times more intense in fused silica. The 7.6‐ev band is still present after the 5.9‐ev band has been thermally bleached. Additional absorption bands occur at 8.0 and 8.2 ev. Also, optical and thermal bleaching experiments suggest other absorption bands at 7.2, 7.4, 7.8, and 7.9 ev. Since these bands (particularly the 7.6‐, 8.0‐, and 8.2‐ev bands) occur in high‐purity silica and quartz, it is suggested that they are associated with defects in the quartz structure and are not caused by impurities.

ISSN:0021-8979    

DOI:10.1063/1.1736124

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Sputtering yields for 14 metals from the 4th, 5th, and 6th periods were measured for normally incident Hg+ions at energies between 4–15 kev. The sputtering rate was determined by measuring the time required for the ion beam to pierce a target foil. Results for the various metals show that yields at high energy behave similarly to yields previously found at lower ion energy; i.e., are closely linked to the position of the metal in the periodic chart. Yields increase in the 4th period from Ti through V, Fe, Co, Ni to Cu and in a similar fashion in the 5th period to Ag and in the 6th period to Au. It is believed that Cu, Ag, and Au atoms with their more closely filleddshells behave more nearly like hard spheres and always produce the highest sputtering yields.

ISSN:0021-8979    

DOI:10.1063/1.1736125

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

Radio‐frequency oscillations observed in cesium‐filled thermionic diodes are interpreted on the basis of a model which assumes that the cesium ions oscillate in an excess negative charge potential well outside the cathode. A simplified theoretical treatment shows that the period at the onset of oscillations is linear with cathode‐anode spacing in agreement with experiment, and relates the oscillation period to the ratio of cell current to saturation emission current. It is found that the rapid decrease of oscillation amplitude as the cell current reaches a critical value can be used to measure saturation emission currents.

ISSN:0021-8979    

DOI:10.1063/1.1736126

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

An apparatus is described for the measurement of the internal friction of metals over the temperature range of 4°–300°K at a frequency of the order of 10 cps. The Bordoni internal friction peak was observed in pure polycrystalline copper at 62°K at a frequency of 13.4 cps. By comparison with measurements at higher frequencies, a value of 0.14 ev is deduced for the activation energy. The width of the Bordoni peak is discussed in terms of distributions of activation energies and attempt frequencies.

ISSN:0021-8979    

DOI:10.1063/1.1736127

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

The growth of pure single crystals of ferrites by the Czochralski method is reported. Problems encountered are discussed and a practical solution indicated.

ISSN:0021-8979    

DOI:10.1063/1.1736128

出版商:AIP    

年代:1961

数据来源: AIP

摘要:

A general traveling wave analysis is given for electron beam parametric amplifiers in which the electron dynamical equation in the pump is a Hill's differential equation. Formulas are given for the complex wave number of beam waves, and clear conditions for growing wave solutions are presented. The special case of a sinusoidal pump field variation is treated, and the optimum pumping condition is found to result when the pump frequency is twice the beam natural frequency. It is shown that growing wave solutions exist at pump frequencies which are rational fractions of the beam natural frequency, but that the growth constants for these pumping conditions (at fixed pump power) are orders of magnitude less than under the optimum condition.

ISSN:0021-8979    

DOI:10.1063/1.1736129

出版商:AIP    

年代:1961

数据来源: AIP