Hosokawa Saburo
Elements Strategy Initiative for Catalysts and Batteries, Kyoto University, Kyoto, Japan.
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto, Japan.
Front Chem. 2019 Jan 28;7:8. doi: 10.3389/fchem.2019.00008. eCollection 2019.
The rare earth-iron mixed oxide (REFeO) is an attractive material in fields such as electronic, magnetic, and catalytic research. Generally, orthorhombic REFeO (-REFeO) with a perovskite structure is better known than hexagonal REFeO (-REFeO), because REFeO is thermodynamically stable for all RE elements. However, -REFeO has a very interesting crystal structure in which a RE and Fe layer are alternately stacked along the -axis in the unit cell; nevertheless, synthesis of the -REFeO belonging to metastable phase can be problematic. Fortunately, solution-based synthetic methods like solvothermal or coprecipitation synthesis have recently enabled the selective synthesis of -REFeO and -REFeO with comparative ease. Although the electronic and magnetic properties of -REFeO have typically been evaluated, recent research has also revealed excellent catalytic properties that enable environmental cleanup reactions such as hydrocarbon or CO oxidation. This mini-review introduces a synthetic method for controlling the crystal structure between orthorhombic and hexagonal REFeO and the catalytic performance of -REFeO-based materials.
稀土 - 铁混合氧化物（REFeO）是电子、磁性和催化研究等领域中一种具有吸引力的材料。一般来说，具有钙钛矿结构的正交晶系REFeO（-REFeO）比六方晶系REFeO（-REFeO）更为人所知，因为REFeO对于所有稀土元素来说在热力学上都是稳定的。然而，-REFeO具有一种非常有趣的晶体结构，其中在晶胞中稀土和铁层沿 - 轴交替堆叠；尽管如此，属于亚稳相的 -REFeO的合成可能存在问题。幸运的是，最近基于溶液的合成方法，如溶剂热合成或共沉淀合成，已经能够相对容易地选择性合成 -REFeO和 -REFeO。尽管 -REFeO的电子和磁性性质通常已经得到评估，但最近的研究还揭示了其优异的催化性能，能够实现烃类或CO氧化等环境净化反应。这篇小型综述介绍了一种控制正交晶系和六方晶系REFeO之间晶体结构的合成方法以及 -REFeO基材料的催化性能。
