caa a22 4500 475764749 CHVBK 20180406123602.0 cr unu---uuuuu 170329e20000501xx s 000 0 eng 10.1007/s003960050537 doi (NATIONALLICENCE)springer-10.1007/s003960050537 Ocaña M. Instituto de Ciencia de Materiales de Sevilla (CSIC-UNSE), Americo Vespucio s/n, Isla de La Cartuja 41092 Sevilla, Spain, ES aut Uniform particles of manganese compounds obtained by forced hydrolysis of manganese(II) acetate [Elektronische Daten] [M. Ocaña]  Procedures for the preparation at low temperature (80 °C) of uniform colloids consisting of Mn3O4 nanoparticles (about 20 nm) or elongated α-MnOOH particles with length less than 2 μm and width 0.4 μm or less, based on the forced hydrolysis of aqueous manganese(II) acetate solutions in the absence (Mn3O4) or the presence (α-MnOOH) of HCl are described. These solids are only produced under a very restrictive range of reagent concentrations involving solutions of 0.2-0.4 mol dm−3 manganese(II) acetate for Mn3O4 and of 1.6-2 mol dm−3 Mn(II) and 0.2-0.3 mol dm−3 HCl for α-MnOOH. The role that the acetate anions play in the precipitation of these solids is analyzed. It seems that these anions promote the oxidation of Mn(II) to Mn(III), which readily hydrolyze causing precipitation. The evolution of the characteristics of the powders with temperature up to 900 °C is also reported. Thus, Mn3O4 particles transform to Mn2O3 upon calcination at 800 °C; this is accompained by a sintering process. The α-MnOOH sample also experiences several phase transformations on heating. First, it is oxidized at low temperatures (250-450 °C) giving MnO2 (pyrolusite), which is further reduced to Mn2O3 at 800 °C. After this process the particles still retain their elongated shape. Springer-Verlag Berlin Heidelberg, 2000 Key words Manganese oxide nationallicence Manganese oxyhydroxide nationallicence Uniform particles nationallicence Nanoparticles nationallicence https://doi.org/10.1007/s003960050537 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s003960050537 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Ocaña M. Instituto de Ciencia de Materiales de Sevilla (CSIC-UNSE), Americo Vespucio s/n, Isla de La Cartuja 41092 Sevilla, Spain, ES aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer