title: Preparation and mechanism of nano mullite powders from kaolin via open hydrothermal process.
abstract: Nano mullite powders have been synthesized from calcined kaolin via open hydrothermal process. The powder product was characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) with selected area electron diffraction (SAED) analysis. The results indicated that single phase puncheon-shaped nano mullite with about 140-360 nm in length and 50-80 nm in diameter is produced when synthesized in 4 mol/L NaOH solution at 100 degrees C for 4 h. The grain size of mullite decrease slightly with increasing reaction time from 0 h to 4 h. In addition, nuclear magnetic resonance (NMR) analysis confirms presence of Al3+ during the whole reaction process, which indicates that there is an absence of growth units of mullite in the open hydrothermal system and the mullite precursor mainly underwent a solution process during open hydrothermal treatment.
authors.forename: Jinhong
authors.initials: J
authors.lastname: Li
authors.forename: Lingxin
authors.initials: L
authors.lastname: Tong
authors.forename: Xiang
authors.initials: X
authors.lastname: Wang