Epitaxial growth of single-crystalline barium carbonate microcone arrays on (104) face of calcite

Heteroepitaxial growth of single-crystalline witherite (BaCO₃) microcone arrays on the (104) face of calcite (CaCO₃) was realized, by the interface-coupled dissolution-precipitation reaction in water/ethanol at roomtemperature. The witherite microcone long axis was parallel to the [001] direction of witherite and [001] direction of the calcite substrate. The top of the microcones appeared as uniformtri-symmetrical hexagons while the long axis of the witherite microcones was parallel to the electron beam. The witherite microcones increased in size and decreased in length:diameter ratio with extending crystallization time. The size and morphology of the epitaxially grown witherite could be tuned by changing the water:ethanol volume ratio, or the Ba(NO₃)₂ concentration of the precursor solution. Increasing the water:ethanol volume ratio or Ba(NO₃)₂ concentration yielded smaller, denser witherite single-crystalline microstructures. The witherite microcone arrays were thought to form by the synergetic epitaxial growth of witherite and dissolution of calcite. Carbonate crystals of witherite and calcite contained middle-high misfits on calcite (104) and (001) faces. Witherite microcones may have grown epitaxially on these two calcite faces, according to the Volmer-Weber model.