Abstract: The sub-micron barium sulfate was prepared with sodium sulfate（Na₂SO₄），barium chloride（BaCl₂），and nano- barium sulfate（nano-sized BaSO₄）seeds as raw materials.Scanning electron microscopy（SEM） and laser particle size analyzer were used to study the effects of process conditions on the morphology，particle size，and particle size distribution of the barium sulfate product.Results show that the particle size of the BaSO₄ product deceases and the size distribution becomes narrower gradually with the increase of the concentration of reactants.The particle size and size distribution increase，when the two reactants were added at the same time or the reaction was conducted at high temperature. The sub-micron BaSO₄ particles with 260 nm were obtained while 0.5 mol/L BaCl₂ was drop-wised added in 0.5 mol/L Na₂SO₄ containing nano-sized BaSO₄ seeds at 40 ℃.

Key words: nano-sized BaSO₄, sub-micron BaSO₄, seeds, particle size