Rayons X et Matière

J. Phys. IV France 08 (1998) Pr5-85-Pr5-89
DOI: 10.1051/jp4:1998512

Cell parameters refinements showing an influence of the chemical nature of the grain surface on the crystalline characteristics of fine grained powders

P. Sarrazin^{1, 2}, F. Bernard², G. Calvarin³, J.C. Niepce² and B. Thierry<sup>1

1</sup>  Laboratoire des Matériaux Avancés Céramiques, Université de Valenciennes, CRITT "Céramiques Fines Techniques", Z.I. Champ de l'Abbesse, 59600 Maubeuge, France
²  Laboratoire de Réactivité des Solides, UMR 5613 du CNRS, BP. 400, 21011 Dijon, France
³  Laboratoire de Chimie-Physique du Solide, URA 453 du CNRS, École Centrale de Paris, 92295 Chatenay-Malabry, France

Abstract
The evolution of the cristalline state of fine grained BaTiO₃ powders has been investigated by X-ray diffraction during desorption - adsorption cycles in order to study the effect of the chemical nature of the surface of fine grains on their interna1 crystalline structure. A weak but significant increase in the cell parameter has been observed after adsorption of water on a nanometric BaTiO₃ powder, showing that the physico-chemical interactions between the solid and the adsorbent are responsible for a tension state in the material. Similar evolution has been previously observed on nanometric MgO powders ; this phenomenon can be generalized to all kind of fine grained materials.

© EDP Sciences 1998