Dispersion behavior of ultra fine BaTiO_3 particles in the aqueous solution of ammonium citrate (NH_4-CA) or citric acid lanthanum chelate (NH_4-La-CA) was investigated. The dispersion property was characterized with sedimentation value. It is easier to obtain well dispersed slurry with NH_4La-CA than NH_4-CA. In an attempt to better understand the role of citric acid radical, simulation of the dispersant adsorption on BaTiO_3 particle was performed with universal force field (UFF). It is demonstrated that the interaction between citric acid radical and BaTiO3 particle surface is a weak chemical adsorption. Trivalent citric acid radical is adsorbed on BaTiO3 particle surface with maximal adsorption energy. And, larger molecules of NH_4-La-CA formed by adding La3+ lead to better dispersion property than NH_4-CA.
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