SYNTHESIS AND STUDY OF A WELL CRYSTALLIZED CACO3 VATERITE SHOWING A NEW HABITUS

Synthetic CaCO3 vaterite obtained by classical routes consists of shap eless particles. However, owing to their small size (50 nm), the parti cles tend to agglomerate strongly, thus resulting in spherical packs o f 3 mu m average diameter. Transmission electron microscopy studies of isolated particles are therefore very difficult to achieve without su bmitting these aggregates to treatments that could affect their struct ural and textural features. We have synthesized pure vaterite particle s which do not exhibit this agglomeration phenomenon but present a cle arly defined habitus (size, shape, texture). It is therefore possible to prepare microcrystalline monolithic hexagonal platelets of vaterite in the micrometre range that exhibit very good crystallinity. In addi tion, we have carried out an IR study of this pure vaterite and an ass ignment of the different absorption bands is proposed, in comparison w ith the two other CaCO3 modifications.