Preparation of three‐dimensional symmetric dendrites of BaWO 4 microcrystals

Three‐dimensional symmetric dendrites of BaWO 4 were prepared by performing solvothermal reactions in water‐hexane bilayer solutions that contained a barium‐oleate complex in the hexane layer and sodium tungstate in the water layer. The barium‐oleate complex in hexane was obtained via a phase transfer reaction in which aqueous Ba 2+ ions pass into the hexane phase with the assistance of sodium oleate, oleic acid, and oleylamine. Each of the BaWO 4 dendrites has a three‐dimensional structure with one trunk along the c ‐axis and a series of four branches perpendicular to the trunk. As the reaction temperature or the amount of oleylamine increases, BaWO 4 dendrites with sharper branches and higher order hierarchical structures are formed. The presence of oleylamine plays an important role in the formation of the hierarchical superstructures of BaWO 4 dendrites.