Morphology control and interlayer pillaring of swellable Na-taeniolite mica crystals

Na-taeniolite (NaMg2LiSi4O10F2) mica crystals were synthesized from nonstoichiometric raw batches containing NaCl as a flux, in order to control the morphology of mica crystals. Swellable Na-taeniolite was obtainable from both stoichiometric and nonstoichiometric batches although small amounts of different products were coprecipitated, depending on the composition of the raw batches. Samples obtained from raw batches containing ≤1 mol NaCl consisted of a single-phase swellable mica. The addition of a small amount of NaCl was effective in controlling the morphology of the mica crystals. Raw batches containing 1 mol NaCl yielded mica crystals having a hexagonal, plate-like morphology with a larger aspect ratio. Alumina-pillared micas prepared from host micas thus obtained from raw batches containing NaCl had larger specific surface areas than those obtained from stoichiometric batches. This suggests that the swellability of mica crystals is also affected by the addition of NaCl.