摘要:

Crystals of 7‐In2S3, a new modification of indium sulphide, grown by vapour transport, were studied by X‐ray topography (Lang technique) and electron microscopy. The most frequent defects are dislocations with Burgers vector of the typeb= [100]. Growth layers were also observed. Neither the dissociation of dislocations into partials nor any stacking faults could be detected. γ‐In2S3gradually decomposes in the electron microscope by loss of sulphur. This results in an agglomeration of point defects leading to stacking faults surrounded by dislocation loops with b parallel to

ISSN:1600-5767    

DOI:10.1107/S002188987300796X

出版商:International Union of Crystallography    

年代:1973

数据来源: WILEY

摘要:

It is shown theoretically and experimentally that doublet separation is generally unnecessary in Fourier analysis of diffraction profiles, if a good alignment and resolution is employed. Comparisons are given of results employing a direct transform and a least‐squares procedure. Defocusing of the instrument to reduce the doublet resolution and, persumably, the need for doublet separation leads to significantly different result

ISSN:1600-5767    

DOI:10.1107/S0021889873007971

出版商:International Union of Crystallography    

年代:1973

数据来源: WILEY

摘要:

The X‐ray diffraction topograph may be considered as a mapping of a crystal region onto a photographic film or plate. Such a mapping can be described mathematically as a point transformation on a manifold:where majuscules refer to the crystal and minuscules to the topographic image. When the topographic image is distorted because of the diffraction camera geometry, this distortion can be analyzed by utilizing the principles of differential geometry. A procedure for extracting the true spatial configuration from the distorted image is discussed and a specific application presente

ISSN:1600-5767    

DOI:10.1107/S0021889873007983

出版商:International Union of Crystallography    

年代:1973

数据来源: WILEY

摘要:

An X‐ray diffraction analysis has been performed on superlattice crystals which were grown epitaxically by alternately depositing GaAs and GaAs0.5P0.5layers on a gallium arsenide substrate. The periodic change of compositions causes a one‐dimensional periodic lattice distortion along the direction of growth. The periodic lattice distortion gives rise to satellite peaks close to the Bragg reflections of the sphalerite‐type lattice of gallium arsenide. Two models are employed to calculate the X‐ray diffraction intensities: in one the lattice distortion is described by two longitudinal phonons with frequency ω = 0, in the other a periodic step function is used. The X‐ray diffraction data obtained on two samples show that the two alternating layers of different composition are coherent and, therefore, constitute one single‐crystal with its unit cell large (≳ 100 Å) along the growth direction. From the fit of the two models to the data one can determine the period and amplitude of the lattice distortion, the relative thickness of the two layers and the size of the domains which diffract coherently. These parameters are discussed in relation to the physical

ISSN:1600-5767    

DOI:10.1107/S0021889873007995

出版商:International Union of Crystallography    

年代:1973

数据来源: WILEY

摘要:

A doping‐vehicle dependence of the relative substitution of Nd at the two non‐equivalent Ca sites in fluorapatite has been verified. By implication, similar differences may be expected for other rare‐earth dopants in other apatites. Detailed structure refinements based on especially reliable single‐crystal X‐ray diffraction data from (i) undoped, (ii) Nd2O3‐doped, and (iii) NdF3‐doped synthetic fluorapatite were used. An analysis of ratios of site‐occupancy factors, based on Nd3+‐for‐Ca2+as the substitution model, led to the conclusions that (i) Nd substitutes at both Ca(l) and Ca(2) sites in approximately equal atomic fractions in the NdF3‐doped material and (ii) Nd substitutes only at the Ca(2) site in the Nd2O3‐doped material. These results correlate well with reports that neodymium‐doped fluorapatite crystals prepared as solid‐state laser hosts differ in spectra, growth rate, and laser quality with the sour

ISSN:1600-5767    

DOI:10.1107/S0021889873008009

出版商:International Union of Crystallography    

年代:1973

数据来源: WILEY

摘要:

The contrast of dislocations generated by boron diffusion in silicon is studied in detail. The anomalously narrow images observed from an array of emitter‐edge dislocations are explained by considering the effect of the strain fields of neighbouring dislocations. Interactions between emitter‐edge dislocations and dislocations inside the diffused region are described and a mechanism suggested. The existence of strong contrast from pure‐edge dislocations when bothg.b= 0 andg.b∧u= 0 leads to the conclusion that the emitter‐edge dislocations are heavily decorated by precipitate. Burgers vector analysis of the dislocations inside the diffused region supports previous work on phosphorus‐diffused silicon, and indicates that reactions have occurred between these dislocations. The unusual contrast of these dislocations is interpreted using Penning–Polder theory when surface effects are taken into account. Asymmetric reflection `area contrast' is observed from the di

ISSN:1600-5767    

DOI:10.1107/S0021889873008010

出版商:International Union of Crystallography    

年代:1973

数据来源: WILEY

摘要:

The copper‐rich portion of the copper–manganese–tin system was investigated by X‐ray diffraction, electron microprobe, and magnetometric techniques. A model for the ordering taking place in the β phase was established. Two low‐temperature phases for the alloy composition Cu2MnSn were identified, and the existence of the intermetallic compound Cu4MnSn was confirmed. Another low‐temperature phase was found; it is α or β manganese, and its appearance contradicts previous investigations. The saturation magnetizations were measured and correlated with a function of the long‐range ordering in

ISSN:1600-5767    

DOI:10.1107/S0021889873008022

出版商:International Union of Crystallography    

年代:1973

数据来源: WILEY

摘要:

A simple vacuum furnace has been developed to fit on a standard goniometer head for three‐circle neutron diffraction measurements. Fields of up to 104 volt cm−1can be maintained across the crystal at temperatures of up to

ISSN:1600-5767    

DOI:10.1107/S0021889873008034

出版商:International Union of Crystallography    

年代:1973

数据来源: WILEY

摘要:

New formulae are presented for calculating a rotationally symmetrical orientation distribution of a crystallographic direction from the rotationally symmetrical orientation distribution of planes parallel to this direction.

ISSN:1600-5767    

DOI:10.1107/S0021889873008058

出版商:International Union of Crystallography    

年代:1973

数据来源: WILEY

ISSN:1600-5767    

DOI:10.1107/S0021889873008071

出版商:International Union of Crystallography    

年代:1973

数据来源: WILEY