ABSTRACT The growth mechanism of α‐hemihydrate gypsum (α‐HH) in Na 2 SO 4 solution is still undefined. In this work, we constructed the solution‐crystal models to investigate the growth morphology of α‐HH in Na 2 SO 4 solution system by molecular dynamics simulation. The attachment energy (AE) model was used to predict the growth behavior of α‐HH, revealing that the (002), (200), (110), and (1–10) crystal faces are dominant, with the (002) face exhibiting the highest attachment energy and predicted fastest growth rate. Molecular dynamics simulations of α‐HH in Na₂SO₄ solution with varying mass fractions (2%–12%) revealed that the interaction energy between the solution layer and crystal faces follows the order: (002) > (1–10) ≈ (110) > (200). Radial distribution function analysis indicated the presence of hydrogen bonds, chemical bonds, van der Waals forces, and electrostatic interactions between the solution layer and crystal faces. Notably, the diffusion coefficients of Na⁺ and SO₄ 2 ⁻ ions were highest on the (002) crystal face, suggesting enhanced diffusion on this face. These findings provide insights into the structural and morphological transformations during α‐HH crystal growth, offering a foundation for optimizing growth conditions, manipulating crystal size and morphology, and ultimately guiding the production of high‐quality α‐HH crystals.
Zhang et al. (Fri,) studied this question.