Changes in the crystal system of an ionic nanocrystal during a cation exchange reaction are unusual yet remain to be systematically investigated. In this study, chemical synthesis and computational modeling demonstrated that the height of hexagonal-prism roxbyite (Cu_1.8S) nanocrystals with a distorted hexagonal close-packed sulfide anion (S²⁻) sublattice determines the final crystal phase of the cation-exchanged products with Co²⁺ [wurtzite cobalt sulfide (CoS) with hexagonal close-packed S^2– and/or cobalt pentlandite (Co₉S₈) with cubic close-packed S^2–]. Thermodynamic instability of exposed planes drives reconstruction of anion frameworks under mild reaction conditions. Other incoming cations (Mn²⁺, Zn²⁺, and Ni²⁺) modulate crystal structure transformation during cation exchange reactions by various means, such as volume, thermodynamic stability, and coordination environment.

在阳离子交换反应期间离子纳米晶体的晶体系统的变化是不寻常的，但仍有待系统地研究。在这项研究中，化学合成和计算模型表明，具有扭曲的六方密堆积硫化物阴离子 (S ²⁻ ) 亚晶格的六方棱柱菱镁矿 (Cu _1.8 S) 纳米晶体的高度决定了阳离子交换产物的最终晶相与 Co ²⁺ [纤锌矿硫化钴 (CoS) 与六方密堆积 S ^2–和/或钴镍铁矿 (Co ₉ S ₈ ) 与立方密堆积 S ^2–]。暴露平面的热力学不稳定性驱动了在温和反应条件下阴离子骨架的重建。其他引入的阳离子（Mn ²⁺、Zn ²⁺和Ni ²⁺）在阳离子交换反应期间通过各种方式调节晶体结构转变，例如体积、热力学稳定性和配位环境。