Synthesis of three-dimensional hierarchical BaCrO₄ dendrites

3-D hierarchical superstructures of BaCrO₄ were prepared by a hydrothermal reaction of Ba(NO₃)₂ and Na₂CrO₄ in an aqueous-hexane bilayer system. A surfactant mixture of oleylamine and oleic acid was used to form hydrophobic barium oleate micelles. During the hydrothermal process, aqueous CrO₄ ²⁻ anions reacted at the interface with Ba²⁺ cations in the hexane phase to form BaCrO₄ crystals. 3-D hierarchical dendritic BaCrO₄ formed with a trunk and aligned, cruciform series of branches perpendicular to it. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) confirmed that both trunk and branches preferentially grew in the direction. The dendrites formed through epitaxial growth.