Mechanism of crystal growth habit modifiers on the morphology of α-CaSO₄·0.5H₂O crystal

Crystal growth habit modifiers were used to control the morphology of α-CaSO₄·0.5H₂O crystal prepared by hydrothermal method. The mechanism of habit modifiers controlling the crystal shape of α-CaSO₄·0.5H₂O of habit modifiers was discussed on the basis of influences of habit modifiers on the shape of crystal terminal ends and the structures of crystal faces. The results show that Al³⁺ and organic acids all can change the morphology of α-CaSO₄·0.5H₂O crystal and the crystal faces they affected are different. Al³⁺ mainly act on the {001} faces. When organic acids exist alone, they would adsorb on the pyramidal faces of α-CaSO₄·0.5H₂O crystal terminal ends. When Al³⁺ coexist with organic ions, they would form complex ions and adsorb on the {001} faces of α-CaSO₄·0.5H₂O crystal.