Formation of variable-composition iron(III) hydrosilicates with the Nhrysotile structure

摘要

The process of formation of iron hydrosilicates (Mg2+,Fe3+)(2-3)Si2O5(OH)(4) was studied. It was shown that the stage of coprecipitation of magnesium and iron hydroxides in the presence of silica nanoparticles forms poorly crystallized layered Mg-Fe double hydroxides having Fe3+ ions in the octahedral sites. Hydrothermal treatment of the mixtures of coprecipitated hydroxides and silica nanoparticles gives rise to layered hydrosilicates, where Fe3+ ions occupy both the octahedral (preferentially) and tetrahedral sires. The possibility of the formation and a fairly stable existence of the variable-composition layered hydrosilicate (Mg2+,Fe3+)(2-3)Si2O5(OH)(4) was shown to correlate with the stability range of its precursor brucite-like Mg-Fe layered double hydroxide.