Data retention ability and number of cycles are key properties of phase change materials in applications. Combining in situ heating transmission electron microscopy with ab initial calculations, we investigated the phase transitions of binary Sb–Te compounds. The calculations indicated that the vacancies in Te sites destroyed the framework of the cubic phase, which agrees well with the absence of cubic phases observed during in situ heating experiments when the Sb concentration exceeded 50%. In contrast, the vacancies in Sb sites stabilized the cubic structure. Further analysis of the charge density maps revealed that the distribution of antibonding electrons may be the origin of the driving force for structural transitions. Furthermore, our results also showed that reducing the vacancies greatly increased the phase transition temperatures of both the amorphous-cubic and cubic-trigonal phases and therefore may improve the data retention ability and cyclability of phase change materials. This result also implies that doping Sb–Te compounds may provide an approach to discover novel phase change materials by reducing the amount of vacancies.

数据保留能力和循环次数是相变材料在应用中的关键特性。结合原位热传输电子显微镜和ab的初始计算，我们研究了二元Sb-Te化合物的相变。计算结果表明，Te位置的空位破坏了立方相的框架，这与当Sb浓度超过50％时在原位加热实验中观察不到立方相的情况相吻合。相反，Sb位点的空位使立方结构稳定。电荷密度图的进一步分析表明，反键电子的分布可能是结构转变驱动力的起源。此外，我们的结果还表明，减少空位会大大增加非晶-立方相和立方-三角形相的相变温度，因此可以提高相变材料的数据保留能力和可循环性。该结果还暗示，掺杂Sb-Te化合物可以通过减少空位的数量提供一种发现新型相变材料的方法。