Room‐Temperature Synthesis of Aragonite Crystals at an Expanding Liquid–Liquid Interface in a Radial Hele–Shaw Cell

Large quantities of extremely fine aragonite needles (see Figure, top image) have been synthesized at room temperature at an expanding liquid–liquid interface in a radial Hele–Shaw cell. By simple variation of the experimental conditions, hollow, cylindrical aragonite/calcite crystals (see Figure, bottom image) may also be obtained. It is believed that this method can be extended to other materials and nanostructures.