Synthesis of stoichiometric Y₂Si₂O₇ powders by sonohydrolysis-assisted sol–gel route

Abstract

Stoichiometric compounds Y₂Si₂O₇ were synthesised by an intensified sonohydrolysis–condensation reaction using hydrate yttrium nitrate and tetraethyl orthosilicate as starting materials. The resulting powders were characterized by means of thermo gravimetric–differential thermal analysis, high temperature X-ray diffraction, electron probe microanalysis, scanning electron microscopy, laser scattering particle size analyzer, N₂ adsorption–desorption isotherms measurements and specific surface area analysis. We found that the phase formation and texture were very dependent on the sol–gel process parameters such as starting compounds, catalyst, water content, molar ratios of Y³⁺/Si⁴⁺ and other experiment conditions. The combined effects of polyethylene glycol and acetic acid on the prepared powders have been discussed. The investigation on thermal stability of the obtained disilicate is also presented for potential high temperature membrane or thermal barrier/environmental barrier coating application.