摘要:

The special features of X‐ray energy‐dispersive powder and single‐crystal diffraction using synchrotron radiation are discussed on the basis of experiments performed at the Deutsches Elektronen‐Synchrotron, DESY. The method is shown to be of particular value for fast structure identifications, experiments for which large scattering vectors are important, studies of phase transformations and chemical reactions at elevated temperatures and high‐pressure studies. Studies of time‐dependent phenomena using pulsed external fields ar

ISSN:1600-5767    

DOI:10.1107/S0021889877013910

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

The average size of ThO2crystals clustered in highly hydrolysed thorium nitrate solution has been shown from line broadening to be approximately 40 

ISSN:1600-5767    

DOI:10.1107/S0021889877013922

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

The design and fabrication of a high‐temperature 10 cm back‐reflection symmetrically focusing camera is described. This camera was designed on the focusing principle. A tubular heater was attached to the sample for controlling its temperature to within ±2°C. It is possible to measure precisely the lattice parameters of a powder sample with this camera and study their variation with temp

ISSN:1600-5767    

DOI:10.1107/S0021889877013934

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

A numerical slit‐height correction of small‐angle scattering diagrams without spherical symmetry has been suggested, with an infinitely high primary beam assumed. A program for numerical correction was devised and tested on three theoretical functions. The method was at the same time checked experimentally with a scattering diagram from Nylo

ISSN:1600-5767    

DOI:10.1107/S0021889877013946

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

A computer‐controlled diffractometer has been built which permits intensity measurements to be made in any direction in reciprocal space in the diffraction plane with step sizes down to 0.01′′ of arc. Three examples illustrate the performance and application of the instrument: (a) perfect silicon, (b) gadolinium gallium garnet with growth striations and (c) niobium with low‐angle grain bou

ISSN:1600-5767    

DOI:10.1107/S0021889877013958

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

A new method of texture analysis is presented that possesses the main advantages of both the Bunge–Roe and Williams methods. The general relations between pole densities and orientation distribution are given as well as an example of the result that can be obtained when only a single incomplete pole figure is availabl

ISSN:1600-5767    

DOI:10.1107/S002188987701396X

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

Freezing of liquid samples in a vanadium can filled with quartz wool is found to be a successful way of preparing samples for neutron powder diffraction. A fairly complicated molecular structure – hexafluorobenzene – was chosen for study and the results of a constrained refinement with the programEDINPshow the data to be good. Measurements were taken on the PANDA machine at AERE, Harwell at a temperature of 83 K. The technique should have an advantage over that used at present for the case of plastic crystals where the crystallites are in continual c

ISSN:1600-5767    

DOI:10.1107/S0021889877013971

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

The long‐range order parameter,S, of pure Cu3Au and two Cu3Au alloys containing 0.64 and 1.5 at. % Co was determined over the temperature range 325 to 387°C. In principle, the state of order in the ternary alloy (Cu3Au)1−XCoXis described by two order parametersS1=Aα−Aβ, andS2 =Bβ−Bα whereAα is the fraction of α sites occupied byAatoms,etc. It is shown that S2− S1=Cα−Cβ = 0 as long as the Co atoms are randomly distributed on α and β sites. The values of S were measured at temperature using Warren's method [Warren, B. E. (1969).X‐Ray Diffraction. Reading, Mass.: Addison‐Wesley] applied to powder samples, employing the {110}, {210}, {211}, and {221, 300} superstructure and the {111}, {200}, {220}, {311}, and {222} fundamental reflections. The results on pure Cu3Au are in relatively good agreement with earlier measurements, but in poor agreement with theoretical predictions, especially at temperatures above 360°C. Within the accuracy of the measurements, it is observed that cobalt, which is in solid solution in both alloys, has no effect on the experimentally determined values of S. The root‐mean‐square vibration amplitudes, 〈u2〉1/2, of the Cu and Au atoms at 640°K were also estimated from the data, and it appeared that 〈u2〉1/2Cudecreased slightly with increa

ISSN:1600-5767    

DOI:10.1107/S0021889877013983

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

The three‐dimensional quantitative analysis of the distribution functionf(g) of crystalline orientations requires knowledge of the numerical values of the generalized spherical harmonic function endowed with crystal and sample symmetries. A Fortran program has been written in order to compute this function for cubic or hexagonal crystal symmetry, without a limiting assumption about sample symmetry – except Friedel's law which imposes only a centre of symmetry on the sample. The entire utilization of the relations arising from symmetries allows one to limit the amount of calculation and to obtain the results quickly and easily. This program can be used on a 32‐bit‐word computer of which the compiler does not work with complex

ISSN:1600-5767    

DOI:10.1107/S0021889877013995

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY

摘要:

The correction of instrumental aberration influencing the shape of diffraction lines requires the use of deconvolution processes. Practically, when the half‐height line width of the defect functions is not larger than one sixth of the line to be analysed, deconvolution is useless. The deconvolution processes can be easily performed when the width of the defect functions remains smaller than half the line width. For the two rules, graphs are presented that allow one to predict the adequate slit width and the sample thickness used on a X‐ray goniome

ISSN:1600-5767    

DOI:10.1107/S0021889877014009

出版商:International Union of Crystallography    

年代:1977

数据来源: WILEY