Mechanism of Faces Growth in Preparing Calcium Sulphate Whiskers Using Sodium Oleate

The crystal structure of calcium sulphate whiskers and adsorption of sodium oleate on crystal faces were investigated through methods of solution chemistry calculation, X-ray diffraction analysis and molecular dynamics simulation.Furthermore, the growth of crystal faces was explored in presence of sodium oleate.Results showed that calcium, oxygen and hydrogen atoms were primarily distributed on crystal faces of ( 200) and (400).Interaction energies between sodium oleate and faces of ( 200) and (400) were much smaller than those of other faces.Distances between oleic acid and calcium on crystal faces of ( 200) and (400) were 0.269 nm and 0.237 nm, respectively, which were smaller than those between oleic acid and sodium.It could reasonably deduce that calcium was the active site of crystal faces.The selective adsorption of sodium oleate prevented growths of (200) face and (400) face.Differences in growth rate of crystal faces made whiskers grow along c-axis.