Multicomponent equiatomic high entropy oxides - synthesis and magneto-electronics properties

多组分等原子高熵氧化物 - 合成和磁电子性能

• 批准号: 400731580
• 负责人: Professor Dr.-Ing. Horst Hahn
• 金额: --
• 依托单位: Institut für Nanotechnologie (INT)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/400731580?language=en
• 关键词: Multicomponent; equiatomic; entropy; oxides; synthesis

Multicomponent high entropy oxides (HEOs) represent a group of single phase oxide solid solutions consisting of five or more cations in nearly equiatomic proportion. Although the field of HEO is barely five years old, several intriguing structural and functional features of different classes of HEOs have been already reported, which include some of our own pioneering investigations performed within the framework of the initial funding period. More specific achievements of the initial funding period are as follows: (a) discovery of rare-earth transition metal based perovskite-HEOs (P-HEOs) and anionic disordered high entropy oxyfluorides (HEOFs), (b) demonstration of the superior electrochemical performance of rocksalt-HEOs and HEOFs as anodes and cathodes for Li-ion batteries (d) elucidation of the reversibly controlled band structure of fluorite-HEOs and finally, (e) the observation of exotic magnetic phenomena stemming from the extreme chemical disorder in P-HEOs, such as exchange bias, large magneto-crystalline anisotropy, large coercive fields at room temperature, etc. These results are the outcome of rather fundamental but diverse investigations, intended to scout whether the field of HEOs is worth studying. In effect, this pioneering research has already highlighted the plethora of unprecedented physico-chemical phenomena that the multicomponent high entropy based design approach can offer. The main thrust of this research proposal will be the introduction of a new class of materials to the field of magneto-electronics with either enhanced or hitherto unknown functionalities by using chemical disorder on both cationic and anionic sites offered by the high entropy based approach. The group of rare-earth transition metal P-HEOs is chosen as the primary HEO-class for this exploration based on the already obtained results, which indicate their strong inherent connection between the chemical disorder, prominent structural distortions and stabilization of unusual spin-electronic states. Naturally, P-HEOs as a material class is also an optimal choice due to the overwhelming richness of the physical properties of the parent perovskites, e.g., colossal magnetoresistance, magneto-electronic phase separation, Mott transitions, spin-electron correlations, magneto-electric effect, etc. The modi operandi for tuning the exchange interactions among the constituent transition metal cations and thereby the magneto-electronic features will include electron or hole doping by altering the cationic sub-lattice(s), external strain introduction by epitaxial thin film deposition and reversible insertion and extraction of anions (O2- or F-) via heat treatments or electrochemistry. Our group’s long term experience on thin film deposition, magnetism, magneto-electronics/-ionics and electrochemical control of magnetism in combination with the newly gained expertise on HEOs will be utilized to achieve the envisaged goal of “novel magneto-electronics with HEOs”.

多组分高熵氧化物（HEO）是指由五个或五个以上的阳离子组成的单相氧化物固溶体。虽然HEO领域只有五年的历史，但已经报道了不同类别HEO的几个有趣的结构和功能特征，其中包括我们自己在初始资助期框架内进行的一些开创性研究。在最初供资期间取得的更具体成就如下：（a）发现稀土过渡金属基钙钛矿-HEO（P-HEO）和阴离子无序高熵氧氟化物（HEOFs），（B）证明岩盐-HEO和HEOFs作为锂离子电池的阳极和阴极的上级电化学性能，（d）阐明萤石-HEO的可逆控制能带结构，以及最后，（e）观测到P-HEO中极端化学无序所产生的奇异磁现象，如交换偏置、大磁晶各向异性、室温下的大矫顽场等。实际上，这项开创性的研究已经突出了多组分高熵设计方法所能提供的大量前所未有的物理化学现象。这项研究计划的主旨是将一类新的材料引入磁电子学领域，通过使用基于高熵的方法提供的阳离子和阴离子位点上的化学无序来增强或迄今未知的功能。稀土过渡金属P-HEO组被选为主要的HEO类的基础上，已经获得的结果，这表明它们之间的化学无序，突出的结构扭曲和不寻常的自旋电子状态的稳定性强的内在联系的探索。自然地，P-HEO作为材料类别也是最佳选择，因为母体钙钛矿的物理性质极其丰富，例如，巨磁阻、磁电相分离、Mott跃迁、自旋-电子相关性、磁电效应等。用于调节组成过渡金属阳离子之间的交换相互作用并由此调节磁电特征的方法将包括通过改变阳离子子晶格的电子或空穴掺杂，通过外延薄膜沉积引入外部应变，以及通过热处理或电化学可逆地插入和提取阴离子（O2-或F-）。我们小组在薄膜沉积、磁性、磁电子学/离子学和磁性电化学控制方面的长期经验，以及新获得的HEO专业知识，将用于实现“新型磁电子学与HEO”的设想目标。