ISSN:0889-311X    

DOI:10.1080/08893118708081677

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Principles and procedures of diffraction data processing are described. Reflection integration limits are obtained from a least squares analysis of peak profile widths, based on the principles of convolution synthesis of peak profiles. An approximate, empirical thermal diffuse scattering correction is obtained from a least squares analysis of thermal diffuse scattering (TDS) intensity estimates, based on fitting intersecting straight lines to the background profile near the peak limits. Time-dependent scaling according to standard reference reflection intensities is based on least squares fitted scaling polynomials and may be weighted by anisotropic, intensity-dependent or scattering-angle-dependent factors. Inter-set scaling of data subsets and averaging of replicate and equivalent measurements, which includes several criteria for detecting and rejecting outlier measurements, provide a basis for a bivariate analysis of variance on F20and (sin )/λ. Error analysis at each stage of the data processing leading up to the analysis of variance includes propagation of estimated experimental errors, as well as estimates of the statistical errors and of their correlations for the various data processing parameters that are introduced.

ISSN:0889-311X    

DOI:10.1080/08893118708081678

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A set of 102 empirical effective ionic radii applicable to nitrides has been derived from over 500 experimental interatomic distances observed in 324 crystal structure determinations of nitrides, amides, ammines, cyanides, azides, imides, nitrosyls, nitryls and of organometallic compounds. The radii take into account the oxidation numbers and electronic spin states of the cations, and the coordination numbers of both the cations and nitride ions. Cation-nitride interatomic distances can be estimated from the sums of the appropriate radii, on average within less than 0.02 A of the observed experimental distances. These radii are empirically useful, but no physical significance should be attached to them. The dependence of the nitride ion radius on coordination number is greater than that of the oxide ion. Individual cation radii can assume rather different values, depending on whether they are bonded to oxide, sulfide or nitride ions. Effective ionic radii are useful, among other things, for checking that the results of crystal structure determinations are reasonable, and for predicting cation-anion distances to be used as observations in the computer simulation of crystal structures.

ISSN:0889-311X    

DOI:10.1080/08893118708081679

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor