Abstract

The morphology of barium sulfate (BaSO₄), synthesized using the hydrothermal reaction of Ba^II–aminocarboxylate chelating precursors, was investigated. The precursors ethylenediaminetetraacetic acid (EDTA), bis(2-aminoethyl)ethyleneglycoltetraacetic acid (EGTA) and nitrilotriacetic acid (NTA) were dissolved by heating, resulting in the formation of BaSO₄ with rod-like, rhombohedral and spindle-shaped morphologies, respectively. Changing the chelating reagent resulted in the formation of BaSO₄ with differing morphologies. There was a correlation between the morphology of BaSO₄ and the dissociation constant of the Ba^II–aminocarboxylic acid complexes. When the dissociation constant was small, BaSO₄ formed rhombohedral morphologies, when it was large, spindle-shaped morphologies were formed. N 1s XPS measurements indicated that the aminocarboxylic acid was adsorbed on the surface of the precipitated particles. Comparison of the peak intensity X-ray diffraction patterns of EDTA and EGTA showed growth of the {101} face when EDTA was used.