Pu Yuguang, Moseley Duncan, He Zhen, Pitike Krishna Chaitanya, Manley Michael E, Yan Jiaqiang, Cooper Valentino R, Mitchell Valerie, Peterson Vanessa K, Johannessen Bernt, Hermann Raphael P, Cao Peng
Department of Chemical and Materials Engineering, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
Sci Adv. 2023 Sep 22;9(38):eadi8809. doi: 10.1126/sciadv.adi8809. Epub 2023 Sep 20.
High-entropy oxides (HEOs) have aroused growing interest due to fundamental questions relating to their structure formation, phase stability, and the interplay between configurational disorder and physical and chemical properties. Introducing Fe(II) and Mn(II) into a rocksalt HEO is considered challenging, as theoretical analysis suggests that they are unstable in this structure under ambient conditions. Here, we develop a bottom-up method for synthesizing Mn- and Fe-containing rocksalt HEO (FeO-HEO). We present a comprehensive investigation of its crystal structure and the random cation-site occupancy. We show the improved structural robustness of this FeO-HEO and verify the viability of an oxygen sublattice as a buffer layer. Compositional analysis reveals the valence and spin state of the iron species. We further report the antiferromagnetic order of this FeO-HEO below the transition temperature ~218 K and predict the conditions of phase stability of Mn- and Fe-containing HEOs. Our results provide fresh insights into the design and property tailoring of emerging classes of HEOs.
高熵氧化物（HEOs）因其与结构形成、相稳定性以及构型无序与物理和化学性质之间的相互作用等基本问题而引起了越来越多的关注。将Fe(II)和Mn(II)引入岩盐型高熵氧化物被认为具有挑战性，因为理论分析表明，在环境条件下它们在这种结构中是不稳定的。在此，我们开发了一种自下而上的方法来合成含锰和铁的岩盐型高熵氧化物（FeO-HEO）。我们对其晶体结构和随机阳离子位点占有率进行了全面研究。我们展示了这种FeO-HEO改善的结构稳健性，并验证了氧亚晶格作为缓冲层的可行性。成分分析揭示了铁物种的价态和自旋状态。我们进一步报道了这种FeO-HEO在转变温度~218 K以下的反铁磁序，并预测了含锰和铁的高熵氧化物的相稳定性条件。我们的结果为新兴高熵氧化物类别的设计和性能定制提供了新的见解。
