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

• Published in: Journal of solid state chemistry Vol. 182; no. 5; pp. 1021 - 1026
• Main Authors: Giovannelli, F., Chartier, T., Autret-Lambert, C., Delorme, F., Zaghrioui, M., Seron, A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.05.2009; Elsevier
• Subjects: ALKALI METAL COMPOUNDS; Birnessite; CHALCOGENIDES; CHEMICAL REACTIONS; Cross-disciplinary physics: materials science; rheology; Earth Sciences; ELECTRON MICROSCOPY; Exact sciences and technology; Hausmanite; HYDRAZINE; KINETICS; MANGANESE COMPOUNDS; MANGANESE OXIDES; Materials science; MICROSCOPY; MINERALS; Nanoparticles; Nanoscale materials and structures: fabrication and characterization; NANOSCIENCE AND NANOTECHNOLOGY; NANOSTRUCTURES; NITROGEN COMPOUNDS; Other topics in nanoscale materials and structures; OXIDE MINERALS; OXIDES; OXYGEN COMPOUNDS; Physics; POTASSIUM COMPOUNDS; Quantum wires; REACTION KINETICS; REDUCING AGENTS; REDUCTION; Sciences of the Universe; Spinel; SPINELS; TRANSITION ELEMENT COMPOUNDS; TRANSMISSION ELECTRON MICROSCOPY; Nanoparticles; Birnessite; Hausmanite; Reduction; Spinel; Crystallinity; Precursor; Manganese oxides; Strong correlation; Spinels; Reaction kinetics; Square shape; Aging; Hydrazine; Nanorod; Nanostructured materials; Hydrates; Manganese
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2009.01.031

The K-birnessite (K x MnO 2· yH 2O) 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 Mn 3O 4 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 Mn 3O 4 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. TEM image showing Mn 3O 4 particle after treatment of birnessite with an addition of hydrazine during 24 hours.