A fast route to obtain manganese spinel nanoparticles by reduction of K-birnessite

Fabien Giovannelli (1) , T. Chartier (1) , Cécile Autret-Lambert (1) , Fabian Delorme (2, 3) , Mustapha Zaghrioui (4) , Alain Seron (2)

1 GREMAN - UMR 7347 - GREMAN (matériaux, microélectronique, acoustique et nanotechnologies)
2 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
3 Corning Sas
4 LEMA - Laboratoire d'Elaboration des Matériaux à base d'Actinides

The K-birnessite (KxMnO2·yH2O) reduction reaction has been tested in order to obtain manganese spinel nanoparticles. The addition of 0.25 weight percent of hydrazine hydrate, the reducing agent, during 24 hours is efficient to transform the birnessite powder in a hausmanite Mn3O4 powder. Well crystallised square shape nanoparticles are obtained. Different birnessite precursors have been tested and the reaction kinetics is strongly correlated to the crystallinity and granulometry of the precursor. The effects of aging time and hydrazine hydrate amount have been studied. Well crystallised Mn3O4 is obtained in one hour. The presence of feitknechtite (MnO(OH)) and amorphous nanorods has been detected as an intermediate phase during birnessite conversion into hausmanite. The conversion mechanism is discussed.

Keywords: Nanoparticles; Birnessite; Hausmanite; Reduction; Spinel

Domains: Sciences of the Universe [physics]; Earth Sciences

Fabien Giovannelli, T. Chartier, Cécile Autret-Lambert, Fabian Delorme, Mustapha Zaghrioui, et al.. A fast route to obtain manganese spinel nanoparticles by reduction of K-birnessite. Journal of Solid State Chemistry, 2009, 182 (5), p. 1021-1026. ⟨10.1016/j.jssc.2009.01.031⟩. ⟨hal-00512691⟩