Preparation of KHSO 4 /SiO 2 Nanocomposites and Their Physical Properties

A series of SiO 2 /KHSO 4 nanocomposites with various SiO 2 /salt ratios was prepared where the active compound was added before gelation. The sol was prepared by mixing of these hydrogen salts, TEOS (tetraethyl orthosilicate) and water. After gelation and heat treatment (heating slowly to 200–220°C under vacuum), the samples were characterized by X-ray diffraction, Differential Scanning Calorimetry (DSC), IR spectroscopy, Scanning Electron Microscopy (SEM), and High Resolution Transition Electron Microscopy (HR TEM). DSC measurements showed phase transition temperature shifts that depended on the SiO 2 /salt ratio. The properties of the nanocomposite samples were compared with the bulk materials. The shift in the phase transitions to lower temperatures was attributed to the particle size effect.