Morphological evolution in nanostructured secondary phases in entropy stabilized oxides
Morphological evolution in nanostructured secondary phases in entropy stabilized oxides
复制标题
熵稳定氧化物中纳米结构第二相的形态演化
DOI：
10.1016/j.matchar.2022.112301
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发表时间：
2022
影响因子：
4.7
通讯作者：
Schoenung, Julie M.
中科院分区：
文献类型：
--
作者：
Dupuy, Alexander D.;Schoenung, Julie M.
高熵氧化物（HEO），含有等摩尔比的五个或更多的氧化物组分，最近出现作为一个重要的一类材料，具有各种有趣的性能。一些但不是全部的HEO系统可以被分类为熵稳定氧化物（ESO）材料，这意味着它们具有通过熵稳定的相态。在这些材料中，亚稳熵稳定和平衡焓稳定相态之间的竞争导致可逆的熵相变和热处理后的第二相的形成。第二相的形态（即，利用聚焦离子束（FIB）层析成像技术，首次对（Co，Cu，Mg，Ni，Zn）O中的富铜尖晶石和富钴尖晶石进行了三维可视化。观察到的富铜tenquiry的第二相表现为几个高度复杂的颗粒形态与功能的纳米制度。这些形态的影响，热处理条件和相互作用的富钴尖晶石第二相。此外，形态取决于第二相颗粒本身的尺寸，随着颗粒变大，形态从球形演变为针状，再演变为片状。这些结果表明，可以实施几种策略来操纵的第二相的形态，使得有可能工程散装ESO材料具有特定的微观结构特征。形成复杂纳米结构的能力将为控制ESO材料的行为和扩展其可能的应用提供强有力的策略。
High entropy oxides (HEO), containing equimolar ratios of five or more oxide components, have emerged recently as an important class of materials with a variety of interesting properties. Some, but not all, HEO systems can be classified as entropy stabilized oxide (ESO) materials, which means they have a phase state that is stabilized by entropy. In these materials, the competition between the metastable entropy stabilized and equilibrium enthalpy stabilized phase states leads to a reversible entropic phase transformation and the formation of secondary phases after heat treatment. The morphologies of the secondary phases (i.e., Cu-rich tenorite and Co-rich spinel) in bulk (Co,Cu,Mg,Ni,Zn)O were visualized in three dimensions for the first time by using focused ion beam (FIB) tomography. The Cu-rich tenorite secondary phase is observed to manifest as several highly complex particle morphologies with features in the nanometric regime. These morphologies are influenced by heat treatment conditions and the interaction with the Co-rich spinel secondary phase. Additionally, the morphology is dependent on the size of the secondary phase particles themselves, with the morphology evolving from spheres, to needles, to plates as the particles get larger. These results indicate that several strategies can be implemented to manipulate the morphologies of the secondary phases, making it possible to engineer bulk ESO materials with specific microstructural features. The ability to form complex nanostructured architectures will provide a powerful strategy for controlling behavior and expanding the possible applications of ESO materials.