Original paper

Vermiculite surface structure as imaged by contact mode AFM

Marcos, Celia; Rodríguez, Irene; Clauzio De Rennó, Luís; Paredes, Gnacio J.


The {001} surfaces of three vermiculite samples from different geological origins have been examined with an atomic force microscope (AFM) in the contact mode of operation. Images of the basal O plane of the sheet of tetrahedra and the plane of OH groups of the octahedral sheet of the Mg-interlayer were recorded. Differences in the appearence of the interlayer hydroxide surface of the three vermiculites are attributed to their variable Mg-interlayer contents and the presence of b iotite-vermiculite mixed-layer mineral associated with vermiculite. The mean unit cell dimensions for both cleavage halves in each sample are consistent with those of the bulk structure within experimental error, indicating that the surface structure of neither the tetrahedral sheet, nor the OH plane of the sheet of interlayer show noticeable reconstruction.


key-words: vermiculitesurface structureatomic force microscopy (afm)