摘要:

Cobalt ferrites, Co3−xFexO4, particularly forxabout or less than 2 are difficultly prepared as single crystal from the melt because they dissociate except at high partial pressures of oxygen. A two‐step procedure is described for obtaining single‐crystal cobalt ferrites from the melt at gas pressures of an atmosphere. The steps involve growth of a two‐phase ``single crystal''—possible because of the congruency of the oxygen lattice of the coexisting oxides. The two‐phase crystal is converted to the single‐phase crystal by appropriate oxidation under conditions in which diffusion is rapid.

ISSN:0021-8979    

DOI:10.1063/1.1702559

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

An investigation of electrical properties of indium oxide single crystals has been made. Indium oxide has been found to be an‐type excess semiconductor over a wide temperature range. The electrical conductivity at room temperature is of the order of 10 &OHgr; cm−1and the mobility is approximately 160 cm2V‐sec−1. The temperature dependence of the mobility has been quantitatively interpreted in terms of lattice and ionized impurity scattering. The donor ionization energy has been found to decrease with increasing impurity concentrations. High ``apparent intrinsic'' conductivity with an activation energy of 1.55 eV has been observed at elevated temperatures.

ISSN:0021-8979    

DOI:10.1063/1.1702560

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

GaAs grown from the vapor phase is found, at near equilibrium, to form nearly spherical crystals bounded by {111} and {110} faces. Under nonequilibrium conditions whiskers are formed which on etching can be made to reveal structure.

ISSN:0021-8979    

DOI:10.1063/1.1702561

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The average transmission of one of the Fabry‐Perot mirrors in a ruby laser has been varied by changing the diameter of a hole in the center of one of the aluminum end coatings. Measurements of the output of the laser as a function of average transmission with fixed input energy show that the output is maximum for a particular value of transmission. The optimum transmission depends upon the input energy. A relationship between the optimum transmission and threshold for stimulated emission is shown.

ISSN:0021-8979    

DOI:10.1063/1.1702562

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The velocity of propagation of the luminous detail in a plasma jet was determined by the time required for transit between photomultiplier stations at different axial positions of an expanded plasma jet. The measurements were synchronized with power supply ripple to eliminate this as a random perturbation.It is found that the luminous fluctuations travel at two velocities. The slower fluctuations move with nearly the calculated speed of the jet and may therefore be ascribed to temperature or possibly composition fluctuations while the (much) faster fluctuations travel with jet speed plus local sonic velocity and are evidently pressure waves.

ISSN:0021-8979    

DOI:10.1063/1.1702563

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The results of a laboratory investigation of silicon—silicon dioxide film produced by high‐temperature thermal oxidation of silicon in water vapor shows that (1) the oxidation rate in steam is dependent on the doping impurity concentration of the crystal, and (2) the oxidation in steam at 970°C for various lengths of time of phosphorus‐diffused wafers with surface concentration of 2×1021cm−3results in an impurity pile‐up region near the silicon surface. On the other hand, boron‐diffused wafers with surface concentration in the order of 5×1018cm−3deplete their impurity concentration near the silicon surface.

ISSN:0021-8979    

DOI:10.1063/1.1702564

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Experimental and theoretical results are given for forward scattering by spheres with radius large compared to wavelength, and with index of refraction &eegr; near unity. Both the intensity and phase of the scattered field (relative to that incident) are measured and computed for several spheres as functions of the separations of transmitter and receiver from the scatterer (sayTandR). The scattering function of primary interest is that which reduces to the usual scattering amplitude in the limit of transmitter and receiver essentially at infinity—say, the functionFsuch thatF→f0asTandR→∞. Differences betweenFandf0arise from ``quadratic phase error'' terms involving not only the apertures of the horns, but also the size and dielectric properties of the scatterer. In the ``mid‐field region,'' where the sphericity of the wavefronts is significant, the magnitude of the corrections introduced inFis of the order of Imf0, and Imf0itself is an order of magnitude smaller than Ref0; consequently, although the ``finite geometry'' has only a second‐order effect on the forward intensity |F|2, it has a first‐order effect on the forward scattered phase arc tan[ImF/ReF]. In addition, since Imf0is proportional to the total scattering cross section, the sphericity of the wavefronts has a first‐order effect on the intensity integrated over all angles. Differences of a hundred percent in the phases ofFandf0may be encountered even in measurements for whichTandRfulfill the usual ``far‐field criterion.'' However, approximations for the far‐field phase may be obtained by extrapolating measurements for several values ofTandRin the usual laboratory geometry.

ISSN:0021-8979    

DOI:10.1063/1.1702565

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Errors in the microwave diagnostics of plasmas were investigated with the use of dielectric and conducting models. The results indicate that plasma property measurements utilizing reflection and transmission techniques are in considerable error for small samples and also that a planar analysis may not be used to infer the properties of a cylindrical plasma.

ISSN:0021-8979    

DOI:10.1063/1.1702566

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Uniaxially and biaxially oriented samples of polyethylene irradiated by &ggr; rays have been investigated at room temperature. Both the tensile strength and the modulus of elasticity are found to increase as the degree of orientation induced by homogeneous deformation increases. But the tensile strength decreases as the dose of &ggr; irradiation increases while the modulus of elasticity increases. The combined effects seem to indicate that the &ggr; irradiation essentially destroys the macromolecular orientation and thus reduces the tensile strength to that of unoriented solid, but with relatively higher elastic modulus as a result of the occurrence of crosslinking.

ISSN:0021-8979    

DOI:10.1063/1.1702567

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Aluminum irradiated at approximately 60°C with neutrons has been examined by transmission electron microscopy. Results differ from those reported by other investigators. Small dislocation loops and larger dislocation rings form during an exposure of 3×1018nvt (E>1 MeV) and increase in number with increasing irradiation dose. It is suggested that the small loops are prismatic loops which arise from the clustering and subsequent collapse of vacancies produced by neutron bombardment. Dislocations which encounter prismatic loops frequently form rings about the loops or other obstacles.

ISSN:0021-8979    

DOI:10.1063/1.1702568

出版商:AIP    

年代:1962

数据来源: AIP