Properties of Powders Synthesized from Aqueous Solutions of Sodium Silicate and Iron Sulfate

The phase composition of the powder synthesized from aqueous solutions of sodium silicate Na2SiO3 and iron sulfate FeSO4 at the molar ratio Fe/Si = 2, as determined by x-ray diffraction (XRD) data, included hydrated sodium iron sulfate Na2Fe(SO4)2 <middle dot> 4H2O and an x-ray amorphous product based on hydrated iron and silicon oxides. The phase composition of the powder obtained by fourfold washing of the synthesized powder in distilled water was represented by an x-ray amorphous product.Following firing in the air at temperatures ranging from 400 to 1200 degrees C, hematite (Fe2O3) and cristobalite (SiO2) were identified in powder samples and the corresponding ceramics. Following firing at 900 degrees C in graphite powder bedding, the phase composition of ceramic samples included magnetite (Fe3O4), laihunite (Fe4.74(SiO4)3), and fayalite (Fe2SiO4). The powder prepared from the product isolated from the mother liquor included hydrated sodium iron sulfate, Na2Fe(SO4)2 <middle dot> 4H2O, and sodium iron sulfate hydroxide hydrate (metasideronatrite), Na4Fe2(SO4)4(OH)2 <middle dot> 3H2O. Following heat treatment at 400 degrees C, sodium iron sulfate (Na3Fe(SO4)3) was identified as the predominant phase in the powder. Powders resulting from the interaction of aqueous solutions of sodium silicate and iron sulfate can be used in the manufacture of high-temperature dyes and materials with magnetic properties, the creation of analogs of lunar or Martian regolith, as well as the development of functional (cathode) materials for Na-ion batteries.