摘要:

In this report, a diffusion analysis has been extended to a lattice containing two interstitial sites, and the results obtained are used to understand: (1) the formation of a nitrided/unnitrided N configuration for intermediate N content and (2) the abnormally small (apparent) diffusion frequency factor, both of which characterize the newly developed R2Fe17nitrides. It turns out that the diffusion mechanism for N atoms in the R2Fe17lattice is a chemical reaction diffusion rather than a free‐diffusion process. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114669

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Media composed of a color former (leuco dye), a developer (phenol compound), and a reversible matrix (steroid) were colored in the crystalline states of the matrix and colorless in the amorphous states. Another medium composed of a color former and a developer serving for a reversible matrix (steroid substituted by a phenol group) was colorless in the crystalline state and colored in the amorphous state. Reversible color changes were possible by a heat treatment. Melting, glass transition, and crystallization temperatures were widely controlled by changing the materials. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114670

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A method to determine the surface anchoring energy of a nematic liquid crystal is proposed. The technique implies the measurements of optical retardation of a nematic cell as a function of a strength and direction of the applied magnetic field. It enables one to get both pretilt angle &agr; and anchoring coefficientWain the course of the same experiment. As an example, both parameters (&agr;=10.9° andWa=1.5×10−5J/m2) are measured at the interface between the nematic 5CB and rubbed polyimide film. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114671

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We suggest that both the Bordoni and the Hasiguti peaks (of the typeP1andP3) be addressed in terms of one basic microscopic mechanism; the nucleation of multikink–antikink pairs in pinned dislocation segments. Correspondingly, the relevant activation energies are multiples of one quantum of energy, the single kink (antikink) rest energy, whence the possibility of ordering these internal friction peaks according to simple spectral series. Such a conclusion appears to be consistent with the experimental data. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114672

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The chemical composition of reactively sputtered TiN was measured with RBS and AES for aspect ratio 2 topography as a function of Ti target nitridation. The bottom of the aspect ratio 2 topography was nitrogen depleted (Ti:N=1.78:1) as compared to the field (Ti:N=1.01:1) for films sputtered with a non‐nitrided target at 20 kW and 400 °C. No such depletion effect was observed for TiN films sputtered with a nitrided target. Thermal annealing of the depleted TiN films at 450 °C in N2restored the composition to near‐stoichiometric.SIMBADsimulation with a saturation‐dependent nitrogen sticking coefficient was used to understand the nature of the nitrogen depletion. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114673

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

High‐resolution x‐ray reciprocal space mapping was employed to determine the in‐depth strain distribution of Si1−xGexfilms with linear composition gradings between 4.2% and 15% Ge per &mgr;m, and thicknesses between 0.4 and 1.7 &mgr;m. The variation of grading and thickness parameters of the samples provides a complete picture of the overall relaxation behavior of linearly graded epilayers. The x‐ray data show a top layer of grading‐dependent residual strain whereas the lower parts of the films are completely and/or partly relaxed with respect to the Si substrate. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114674

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

New features of the nanoscale structure of amorphous (a)‐Si produced by ion‐implantation‐induced amorphization of crystalline (c)‐Si have been determined by the technique of small‐angle x‐ray scattering (SAXS). Si ion energies up to 17 MeV were used to generate a thick amorphous layer (8 &mgr;m) on ac‐Si wafer to enable the SAXS measurements. As‐implanted and thermally annealed (up to 540 °C)a‐Si were studied. No nanovoids were detected within a sensitivity of 0.1 vol %, but the atomic‐scale structure produced a measurable diffuse scattering signal that decreased with increasing anneal temperatures. These measurements show that the known density deficit of 1.8% ina‐Si relative toc‐Si cannot be due to voids and thata‐Si is homogeneous on nm length scale. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114675

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

To characterize putative interactions between freely migrating defects (FMD) and remnants of energetic displacement cascades, radiation‐induced segregation (RIS) in Cu‐1 at. % Au was measured by Rutherford backscattering during separate and simultaneous irradiation at 400 °C with 1.5 MeV He and 800 keV Cu ions. The strong RIS observed during only He irradiation was greatly reduced under simultaneous Cu irradiation at approximately the same displacements per atom rate; increasing the Cu flux by a factor of 5 suppressed the RIS from the He beam almost completely. The suppression of RIS at 400 °C disappeared quickly when the Cu irradiation ceased. These results demonstrate that a transient population of interstitial and/or vacancy clusters from the Cu irradiation greatly reduces the survival rate of FMD produced by the He. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114676

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report a conceptionally new approach to achieve electrostatically induced transport and confinement for spatially indirect excitons. Experimentally, exciton transport is demonstrated in an electric‐field‐tunable GaAs/AlAs coupled quantum well structure, which is configured as a three‐terminal device. In spatially resolved photoluminescence experiments, it is shown that indirect excitons experience a drift field, which is given by an electrostatically induced band‐gap gradient in the plane of the coupled quantum well structure. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114677

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Incorporation kinetics of rare‐earth elements (Er,Pr) in Si during solid source molecular beam epitaxy (MBE) is studied using secondary ion mass spectrometry. Pronounced surface segregation is consistently observed both for Er and Pr in normal MBE growth and their segregation tendencies are even stronger than those of typical dopants. Segregant‐assisted growth (SAG) using Sb was successful in significantly reducing the surface segregation of rare‐earth atoms, thereby opening the possibility of establishing layered structures in normal MBE. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114678

出版商:AIP    

年代:1995

数据来源: AIP