Effect of coherency of domain walls on X-ray diffraction diagrams: Case a crystal with a low tetragonality

Les diagrammes de diffraction des rayons X d'une poudre ou d'une ceramique de BaTiO 3 tetragonal ont ete etudies. Une correlation entre les caracteristiques des profils des raies de diffraction (intensite, forme, position,...) et la microstructure en domaines ferroelectriques a ete mise en evidence. A partir d'une approche numerique, le calcul des diagrammes de diffraction montre que la modification des profils des raies de diffraction du compose tetragonal est fortement dependante de la microstructure en domaines ferroelectriques. Ce a du prendre en compte l'existence d'un certain degre de coherence dans les murs de domaines entre deux domaines a 90° adjacents. Il a par ailleurs ete mis en…

Correlation between ball milling conditions and planar effects on Cu-nanostructured powders

It is most often proposed that the process of ball milling introduces a variety of defects (vacancies, dislocations, grain boundaries, stacking faults,...) which raise the free energy of the system making it possible to produce metastable phases. But there are very few investigations that deal with the characterization and quantification of the defects produced in milled powders. XRD is really a valuable technique for a characterization in terms of size and morphology of crystallites and imperfections. In this paper, a new line profile analysis method is proposed in order to take into account the dependence of the crystallite size, of the residual strains as well as of the planar defects, o…

Peculiarities of X-Ray Diffraction in Crystals with Diffuse Boundaries of Twin on System {011}, <011>

Correlation between milling parameters and microstructure characteristics of nanocrystalline copper powder prepared via a high energy planetary ball mill

The microstructure evolution of Cu-nanostructured powders versus the ball milling conditions was investigated by whole peak profile powder pattern modeling method. This method allows defining in some approach the characteristics of as-milled Cu powder microstructure in terms of crystallite size, type and density of dislocations and twin faults density. It is shown that the change of microstructure characteristics of as-milled Cu powder versus the ball milling conditions (under constant time of the ball milling) depend on only some energy parameters of the milling, for example, average size of crystallite is uniquely defined by energy of the shock, whereas the portion of edge and screw compo…