Analyse des profils de raies de diffraction des rayons X d'un hydroxynitrate de nickel non stoechiométrique
A microcrystalline nonstoichiometric nickel hydroxynitrate Ni(OH) 1+ s(NO 3) 1- s (0.288 ⩽ s ⩽ 0.452) is studied by Fourier X-ray line profile analysis. Corrections for instrumental broadening are performed by LWL deconvolution method. The application of the Houska and Warren's method ( J. Appl. Phys.25, 1503 (1954)), modified by Maire and Méring ( Proc. 4th Conference on Carbon, p. 345, Pergamon Press, New York, 1960) indicates that the line broadening of 00 l reflections is not only due to a small particle size effect, but also to crystal defects involving variable interlayer spacings. Seven samples with different s values are investigated. The results indicate that the crystallites of all specimens are composed of a similar number of layers. The mean squares of the variation of the interlayer spacings range from 0.0148 to 0.0003. The square roots are decreasing linearly with the s parameter. It is believed that the observed distortions arise from an irregular distribution of nitrate ions from one layer to another. As s increases, a progressive regularization of the number of nitrate ions involved in each layer is assumed. Existence proof of a well-crystallized nickel hydroxynitrate Ni 2(OH) 3(NO 3) results from this study.