Nucleation and Growth Mechanism of Barium Titanate Nanoblocks in Hydrothermal Process Using Aqueous Titanium Compound

Barium titanate (BT) nanoblocks were synthesized by using aqueous sources of barium and titanium. To analyze the growth mechanism of nanoblocks, a kind:of sampling hydrothermal vessel was employed to timely observe the reaction of precursor solution. During the nucleation and ripening process, intermediate of nanoblocks were taken out directly from reacting solution to analyze. BT nuclei grew directly in the Ti-based gel through an in situ growth mechanism. An oriented attachment phenomenon could be observed among neighboring nuclei. The Ostwald ripening process played a role in the growth of monodispersed BT nanoblocks. Diversified surface morphology of intermediate nanocrystals indicates that the chelating effect of oleate anions is unequal for all of the {100} crystal facets. After 24 h, agglomeration of nanoblocks occurred in Ti gel and formed BT mesoclusters with highly crystalline structure. The kinetics. of the BT duster was related with the oriented attachment mechanism. NanoblOcks Overlapped with the edge corner section, which caused the formation of nanometer-sized spaces. The unique connecting architecture was conducive to fusing or eliminating those high-energy crystal facets of nanoblocks. These clusters with porous structure pave the way for application of BT nanocrystals in the energy-related industries based on surface chemistry instead of internal electronic properties.