Oxides and the high entropy regime: A new mix for engineering physical properties
Oxides and the high entropy regime: A new mix for engineering physical properties
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DOI：
10.1557/adv.2020.295
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发表时间：
2020-07
期刊：
影响因子：
0.8
通讯作者：
P. Meisenheimer;J. Heron
中科院分区：
文献类型：
--
作者：
P. Meisenheimer;J. Heron
历史上，热是氧化物材料发现和设计的标准。在这种情况下，可以利用高度受控的薄膜外延来显示体相和界面相，这在体相平衡相图中是不存在的。随着最近熵稳定氧化物的发现，熵和无序工程已经实现为一种正交方法。这导致了对高熵氧化物--多组分氧化物的研究的成核和快速增长，其中配置熵很大，但其对其稳定的贡献不必很大，或者目前尚不清楚。目前的研究表明，熵增强了物种的化学溶解度，并可以实现新的立体化学构型，从而导致新相和新组成的快速发现。这项研究已经超越了理解熵在稳定和实现新晶体结构中的作用的研究，现在包括物理性质以及局部和全球无序的作用。在这里，回顾了关于介电和磁性的主要观察结果。这些材料最近被观察到显示出一致的对称性破缺、金属-绝缘体转变和磁性，为这些和潜在的其他功能现象的工程化铺平了道路。令人兴奋的是，这些氧化物中的无序允许自旋、轨道、电荷和晶格自由度之间的新的相互作用，以设计物理行为。考虑到熵氧化物材料的独特特性，我们还对其应用领域的现状和前景进行了展望。
Historically, the enthalpy is the criterion for oxide materials discovery and design. In this regime, highly controlled thin film epitaxy can be leveraged to manifest bulk and interfacial phases that are non-existent in bulk equilibrium phase diagrams. With the recent discovery of entropy-stabilized oxides, entropy and disorder engineering has been realized as an orthogonal approach. This has led to the nucleation and rapid growth of research on high-entropy oxides–multicomponent oxides where the configurational entropy is large but its contribution to its stabilization need not be significant or is currently unknown. From current research, it is clear that entropy enhances the chemical solubility of species and can realize new stereochemical configurations which has led to the rapid discovery of new phases and compositions. The research has expanded beyond studies to understand the role of entropy in stabilization and realization of new crystal structures to now include physical properties and the roles of local and global disorder. Here, key observations made regarding the dielectric and magnetic properties are reviewed. These materials have recently been observed to display concerted symmetry breaking, metal-insulator transitions, and magnetism, paving the way for engineering of these and potentially other functional phenomena. Excitingly, the disorder in these oxides allows for new interplay between spin, orbital, charge, and lattice degrees of freedom to design the physical behavior. We also provide a perspective on the state of the field and prospects for entropic oxide materials in applications considering their unique characteristics.