摘要:

An empirical model spectral line shape has been considered for theR1andR2fluorescence lines of ruby to investigate the possibility of improvements in the precision and the reproducibility of pressure measurements at high temperature using the ruby fluorescence technique. Other advantages, such as using the ruby method to obtain a simultaneous measurement of pressure and temperature or to obtain quantitative estimates of pressure distributions under nonhydrostatic conditions, have also been considered.

ISSN:0021-8979    

DOI:10.1063/1.334837

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

This paper deals with the nonlinear quasi‐fracture behavior of polymers. Using the finite element method, the quasi‐fracture model composed of an isolated craze opening with a nonlinear boundary envelope forces represented by oriented fibril domains is analyzed in simply‐stressed rectangular plate. The stress distribution, the displacement profile, as well as the yield or plastic or flow zone adjacent to the craze tips are obtained. It is found that the variation of the stress distribution near the craze tip is not as sharp as that for an elastic crack. The initial load required for yielding or flowing is greater for the quasifracture as compared with that for a classical fracture. Under the same load the yeild or flow zone is somewhat smaller as compared with that obtained on the basis of linear elastic‐plastic fracture mechanics theory.

ISSN:0021-8979    

DOI:10.1063/1.334838

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The threshold values for the field‐induced cholesteric to nematic phase transition are described as crossover points of the free energy levels of the textures concerned. Known expressions for these energy levels as a function of an electric field are extended with a surface interaction term. By interpretation of experimental results in terms of the equations derived, the surface interaction energy is calculated both for planar and homeotropically aligned cholesteric liquid‐crystal mixtures. Besides differences between planar and homeotropic wall alignment a difference between two types of planar wall alignment can now be understood, too. Additionally, the method appears very useful for calculating the twist elastic constantK22.

ISSN:0021-8979    

DOI:10.1063/1.334839

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

This study was directed toward exploring the relationship between the implant conditions and the depth and nature of the amorphous layers generated in silicon. Interest in amorphous layer morphology stems from its role in affecting crystal defects remaining after amorphous‐to‐crystalline transformation. High‐dose implants of As, P, and B were used to generate buried and surface amorphous layers at slightly higher than room temperature. The amorphous layer depths were measured and the depth‐fluence and depth‐energy relationships were compared with Brice’s analysis. It was found that good fits were obtained for a threshold damage density of 2.5×1020keV cm−3for As and 1.0×1021keV cm−3for P. For B, the results could be described by a threshold damage density of 5.0×1021keV cm−3or greater. Lower weight ion implantations exhibit a greater tendency to generate buried amorphous layers as well as to generate amorphous layers which include a smaller fraction of the total implanted fluence than is found for heavier ion implantations. These two factors make it more likely for residual crystal defects to be associated with lower weight ion implant distributions.

ISSN:0021-8979    

DOI:10.1063/1.334840

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Variable oblique alignment of nematic liquid crystals has been achieved on microscopically inhomogeneous surfaces. The surfaces consist of small patches favoring vertical (homeotropic) alignment surrounded by a matrix favoring a planar alignment. The construction of these surfaces employs randomly distributed microscopic metal islands formed by certain metals as vapor‐deposited films. Larger scale periodic patterns were made as well to verify the techniques. The results are interpreted in terms of a continuum elasticity theory and azimuthal degeneracy is also discussed.

ISSN:0021-8979    

DOI:10.1063/1.334841

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The drag force acting on a kink moving rigidly and uniformly along the dislocation line and in the atmosphere of mobile octahedral (heavy) interstitials is investigated numerically in anisotropic body‐centered‐cubic metals. It is shown by extensive computer modeling experiments that the drag force versus normalized kink velocity plot goes through a maximum which is composed of three subpeaks, one acoustic and two optical in character. The acoustic part and the optical mode‐2 are strongly and selectively associated with the isotropic and the pure shear parts of the elastic dipole tensor of the interstitial species, respectively. An extremely accurate and the concise analytical expression is deduced for the linear viscosity regime which exhibits the behavior of Navier–Stokes fluids, which can be used directly in Snoek–Ko¨ster relaxation. The flow stress theory of Seeger for the ultrahigh‐purity body‐centered‐cubic metals is extended and coupled with the present treatment of the kink dragging which yields an excellent agreement with the dynamical strain aging experiments in Fe‐C and Fe‐N alloys.

ISSN:0021-8979    

DOI:10.1063/1.334789

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Strain behavior of polycrystalline Nb thin films deposited onto oxidized silicon substrates using an electron gun in a high vacuum system was studied by an x‐ray diffraction technique. The sign and magnitude of strain in Nb thin films were found to have a strong dependence on the film thickness. For films thinner than approximately 10 nm, the compressive strain was observed, which was considered to be due to diffusion of impurity atoms, most likely oxygen, into grain boundaries of Nb films within an extremely short distance from the film surface. For thicker films, the tensile strain was observed and a strong dependence of the strain (normal to the film surface) on crystal orientations of grains was observed. This dependence agreed very well with the one calculated using a biaxial stress model. The biaxial stress applied in the planar direction was calculated to be 1.0×1010dyne/cm2from the measured strain values. The present result indicates that the strain in the Nb films is not induced by temperature increase during the film preparation, but it is more likely due to grain growth during and/or immediately after the film deposition. Based on the biaxial stress model and strain distributions parallel and normal to the substrate planes and strain energies stored in grains with different crystal orientations were calculated.

ISSN:0021-8979    

DOI:10.1063/1.334790

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Dislocation generation in silicon substrates at Si3N4/SiO2film edges is investigated after thermal treatment at 900–1200 °C for 2 h in a N2atmosphere. In order to explain the obtained experimental results, we propose a model to calculate stresses in silicon at the film edge. In the present model, it is assumed that the SiO2film is a Maxwell viscoelastic solid, and stress values are obtained using the finite element method and analytical solutions under plain strain conditions. The calculated results show that the shape of the stress distribution at the Si3N4/SiO2film edge is different from that at the Si3N4film edge, and that stress in the former is small in comparison with that at the latter. As a result, it is proved that the present model gives a physical interpretation for the suppression of dislocation generation with Si3N4/SiO2films.

ISSN:0021-8979    

DOI:10.1063/1.334791

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A sample with the configuration Si (111)/single crystalline Pd2Si/polycrystalline Pd2Si/Pd is used to study the dominant moving species during subsequent Pd2Si formation by annealing at 275 °C. The interface between monocrystalline and polycrystalline Pd2Si is used as a marker to monitor the dominant moving species. The result shows that Pd is the dominant moving species in the monocrystal. off

ISSN:0021-8979    

DOI:10.1063/1.334792

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A novel use of Ti marker is introduced to investigate the moving species during Pd2Si formation on ⟨111⟩ and ⟨100⟩ Si substrates. Silicide formed from amorphous Si is also studied using a W marker. Although these markers are observed to alter the silicide formation in the initial stage, the moving species can be identified once a normal growth rate is resumed. It is found that Si is the dominant moving species for all three types of Si crystallinity. However, Pd will participate in mass transport when Si motion becomes obstructed. off

ISSN:0021-8979    

DOI:10.1063/1.334793

出版商:AIP    

年代:1985

数据来源: AIP