摘要:

The effect of small‐angle multiple scattering on a number of general structural parameters and on the segment distribution function has been studied using a representative correlation function of the type γ = exp (−r/lp). The results show that size parameters can be severely underestimated if the presence of multiple scattering is not taken into consideration and that the exact form of the segment distribution function is considerably affected even if the contributions from multiple scattering are relatively s

ISSN:1600-5767    

DOI:10.1107/S0021889872008623

出版商:International Union of Crystallography    

年代:1972

数据来源: WILEY

摘要:

A convenient method for film X‐ray microdensitometer measurement of integrated reflexions is discussed in which the intensity is converted to the amplitude of a chart recorder using an empirical calibration. Applications of the method are give

ISSN:1600-5767    

DOI:10.1107/S0021889872008635

出版商:International Union of Crystallography    

年代:1972

数据来源: WILEY

摘要:

The preparation and structure of the double oxide CuCo2O4, the existence of which has been disputed, are discussed. This compound, a spinel of lattice parametera= 8.084 Å, can be obtained in the simple way proposed by Holgersson&Karlsson in 1929. A comparison is made with the spinel ZnCo2O4, whose cell parameter a is 8.088 Å. X‐ray powder diffraction data for both compounds are i

ISSN:1600-5767    

DOI:10.1107/S0021889872008647

出版商:International Union of Crystallography    

年代:1972

数据来源: WILEY

摘要:

A FORTRAN IV computer program has been written for the elaboration of X‐ray intensities diffracted by liquid, amorphous and microcrystallized substances. The experimental data, corrected for both polarization and absorption, after conversion into absolute units are inverted into radial distribution functions. Various possibilities are provided for the inversion of the intensity data. Results are then plotted with the IBM 1627 data plot accessor

ISSN:1600-5767    

DOI:10.1107/S0021889872008659

出版商:International Union of Crystallography    

年代:1972

数据来源: WILEY

摘要:

X‐ray diffraction methods are applied to determine the cation distribution and the oxygen positional parameter in low‐substituted magnetites with Al3+, Ga3+, or In3+as substituents. It is possible to conclude that the tetrahedral site preference increases in the sequence Al3+, Fe3 +, In≃Ga3+, in good agreement with magnetic properties of similar systems and with theoretical considerations of various authors. The presence of a part of the Al3+ions in tetrahedral sites is Confirmed by means of the Mössbauer effect. Reliability of the methods and errors are discussed. X‐ray methods such as these appear to be potentially applicable for industrial checks in ferrite pr

ISSN:1600-5767    

DOI:10.1107/S0021889872008660

出版商:International Union of Crystallography    

年代:1972

数据来源: WILEY

摘要:

Differential response errors due to dispersion and the Lorentz factor have tan3θ dependence for the powder diffractometer and should thus become critical for Bragg angles greater than ~ 155°, 2θ. The magnitude of these errors is demonstrated by measuring centroids and peaks at Bragg angles up to 170°, 2θ using Seeman–Bohlin geometry. Lattice parameters calculated from a single high angle centroid fall up to 0.0008 Å below the values obtained by extrapolation using the data of many profiles. No significant deviation using peak positions was observed within the limits of experimental error. While these errors are considered to be significant for residual stress measurements they can be ignored for routine lattice parameter deter

ISSN:1600-5767    

DOI:10.1107/S0021889872008672

出版商:International Union of Crystallography    

年代:1972

数据来源: WILEY

摘要:

Three‐dimensional orientation distribution functions were calculated from (111), (200), (220) and (311) pole figures for α‐copper–zinc alloys in the concentration range from 0 to about 30% zinc. The pole figures were measured by neutron diffraction. The main feature of the texture transition is a continuous shortening or cut off of the tube of preferred orientations present in the copper texture beginning with the end orientation ~(12) [11]. This orientation has nearly completely disappeared at about 5% zinc. Simultaneously its twin orientation (011) [100]appears. A second feature is the continuous decrease of maximum density of all texture components over the whole concentration range. The results support Wassermann's theory of mechanical twinning as the reason for the texture tran

ISSN:1600-5767    

DOI:10.1107/S0021889872008684

出版商:International Union of Crystallography    

年代:1972

数据来源: WILEY

摘要:

In order to test the collimation correction methods routinely applied to small‐angle X‐ray scattering data, scattering curves for several samples have been obtained both with a Kratky camera and with a Beeman four‐slit collimation system. Since the two collimation systems used quite different slit arrangements, there were appreciable differences in the measured curves obtained with the two systems for a given sample. However, after the appropriate collimation corrections had been applied, the corrected curves were nearly identical. This agreement, which is not surprising because of the thorough tests previously applied to collimation correction procedures, indicates that in the correction of experimental curves, no unforeseen problems appear that are not present in the earlier, more idealized tests, which employed test functions to simulate experimental curves. A comparison has been made of a few other properties of the two collimation systems, including the intensity obtainable for a given resol

ISSN:1600-5767    

DOI:10.1107/S0021889872008696

出版商:International Union of Crystallography    

年代:1972

数据来源: WILEY

摘要:

Diffusion experiments involving Pu–Cu, PuGa–Cu and PuGa–Ni couples, have brought into evidence the binary compounds PuCu2and PuCu4, a ternary compound PuCu3with variable small amounts of gallium and the ternary compounds Pu2Ni2Ga and PuNiGa. The crystalline parameters of these compounds were determined by the Debye–Scherrer method using alloys obtained by direct processing. Powder X‐ray diffraction showed the isomorphism of PuCu2with CeCu2and that all the above compounds are ort

ISSN:1600-5767    

DOI:10.1107/S0021889872008702

出版商:International Union of Crystallography    

年代:1972

数据来源: WILEY

ISSN:1600-5767    

DOI:10.1107/S0021889872008714

出版商:International Union of Crystallography    

年代:1972

数据来源: WILEY