Novel shape evolution of BaMoO4 microcrystals

Dendritic BaMoO4 microcrystals with lengths of about 5−15 μm were synthesized simply under ambient conditions by a microemulsion-mediated method within an ultrashort time. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and field-emission scanning electron microscopy (FESEM), which showed that the products were in pure tetragonal BaMoO4 structure and that an individual dendrite had a long central stem with four array shrunken branches. Detailed studies revealed that the formation of these 3-D structures was strongly dependent on the composition of the microemulsion. At prolonged aging time, the dendrites evolved into rods and further into particles, driven by the lattice distortion energy required to evolve the crystal from a metastable to a stable state. This novel crystal shape evolution provides insight into crystallization behavior given that the growth history and shape evolution process have traditionally been poorly understood.