Solid-solid transformation route to nanocrystalline sodalite from Al-PILC at room temperature

The present study describes a solid-solid transformation of nanocrystalline sodalite from the solid gel mixture of Al₂O ₃-pillared montmorillonite (Al-PILC) with sodium hydroxide at room temperature (25 °C) under an ambient atmosphere. Powder X-ray diffraction (XRD) analysis confirms that the X-ray crystalline sodalite products are crystallized after 12 days, whereas infrared absorption (IR) spectra reveal that diagnostic IR absorption peaks due to single four-membered ring of sodalite framework is observed even after 1 day. Scanning electron microscopy (SEM) shows that Al-PILC is transformed into discrete nano-sized sodalite particles (∼50 nm). Although the induction period, the time elapsing before nucleation, for the solid-solid transformation takes much longer (12 days), the nanocrystalline sodalite is successfully obtained at this extremely mild synthetic condition through solid-solid transformation.