Rod-shaped barium sulfate particles from a completely inorganic system

Rod-shaped barium sulfate particles can be formed from purely inorganic systems at 75 °C and these particles are single crystals elongated in the c-axis. This c-axis growth promotion relative to the other crystal faces is absent when the cation impurities are absent suggesting a specific interaction of the cations with the growing crystal. Attempts have been made to determine the cause of this c-axis growth promotion, but no one mechanism appears to adequately explain this effect and it may be due to a combination of different impacts. The same cations do not induce rod-shaped particles at 25 °C, thus suggesting an important role of kinetics in the crystallization of these particles. Finally, previous reports suggesting that the formation of rod-like particles is due to the presence of an organic additive may be incorrect as sufficient sodium ions may have been present to give these particles even in their absence.