State of Manganese Ions in the Structure of Corundum Synthesized in Supercritical Water Fluidстатья
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Дата последнего поиска статьи во внешних источниках: 19 сентября 2015 г.
Аннотация:The kinetics and formation mechanism of doped corundum (α-Al2O3) from hydrargillite (γ-Al(OH)3)
in supercritical water fluid (SCWF) in the presence of manganese ions are studied. It was ascertained that due to the reversible dehydroxylation in an aqueous medium, solidphase transformation of hydrargillite into boehmite (γ-AlOOH) and then into corundum occurs with the formation of wellfaceted corundum microcrystals that are uniformly doped with manganese. It was found that when Mn2+ or MnO4- ions are introduced into the reaction medium, Mn5+, Mn4+, Mn3+, and Mn2+ ions are observed in the synthesized corundum. Meanwhile, the manganese ions form a complex defect in the corundum structure, which comprisesoxygen vacancies and hydroxyl groups. The defects in corundum that emerge upon doping with manganesein SCWF are different from those in corundum doped during hightemperature synthesis.