双刚玉系晶态极性磁材料Mn2FeMoO6的常压制备研究

The polar and magnetic double-corundum Mn2FeMoO6 prepared under high pressure exhibits both high ferromagnetic ordering temperature (340 K) and large spontaneous polarization (68 μC/cm2), which make it one of the most promising multiferroic materials for spintronic devices. However, the magnetoelectricity and theoretic optimization model of Mn2FeMoO6 still keep unclear, due to the limitation of polycrystalline sample (random grain/domain boundary effect) and difficulty of single crystal growth under high pressure (complicated operation together with small sample amount and strongly increased melting point), it is thus essential to explore the single crystal growth method of the high-pressure Mn2FeMoO6 phase at ambient pressure. Interfacial induction has been proven to be an effective way to stabilize the high-pressure phase at ambient pressure, as evidenced by our recent preparation of the high-pressure single corundum phase at ambient pressure. However, when comes to double corundum Mn2FeMoO6, it is a challenge to achieve desired cation ordering. Accordingly, in this project we adopt the single crystals of ambient-pressure prepared isostructural compounds as precursors, including Ni2NiTeO6, Li2ZrTeO6, and Li2ZrHfO6, to stabilize the high-pressure Mn2FeMoO6 phase via interfacial induction and atomic scale modulation, and thus achieve a novel structural design and controllable single-crystal growth approach to study the physical properties on the single crystals, clarify the crystal growth mechanism, perform first-principles calculations to fully understand the structure-properties relationship for properties optimization. These findings will guide the discoveries of novel multifunctional materials in double corundum family.

高压合成的双刚玉系极性磁材料Mn2FeMoO6集高铁磁转变温度（340 K）和高电极化常数（68 μC/cm2）于一体，是最具应用前景和竞争力的多铁性自旋电子学器件材料之一。然而，单畴晶态材料苛刻的高压制备条件，严重阻碍了其磁电性能表征及理论模拟优化研究和器件化进程，因此，亟待开展常压制备研究。前驱体晶界诱导法是常压下稳定高压相的有效手段，并在我们近期简单刚玉系高压相的常压制备中得以实现，但当拓展到双刚玉系时存在结构调控问题。本申请拟以可常压下合成的同构Ni2NiTeO6, Li2ZrTeO6，和Li2ZrHfO6单晶为前驱体，通过晶界诱导和原子尺度调制等方法，进行常压下目标相单晶材料的制备，开展其生长机理、磁电耦合机理、以及基于第一性原理的性能优化研究。本项目的顺利开展，将扫清Mn2FeMoO6深入研究和器件化进程中的障碍，并为双刚玉系新材料的开发指明方向。

超高温高压合成可克服磁电的天生互斥性，在极性晶格中纳入磁性离子，制备新型磁电多铁材料，比如室温多铁性Mn2FeMoO6等。然而，极性磁体的超高温高压制备面临两个主要问题：1、试错性超高温高压制备成本居高不下，事倍功半；2、亚稳态低成本大量截留困难。鉴于此，本项目针对性的开展工作，并取得如下主要研究进展：1）发展了超高压加热元件技术，拓展体系，在Mn2BB’O6等体系中制备了系列新型异常钙钛矿材料，研究了其磁电性能，解决了该类材料的铁电机理争端；2）利用同构晶格间失配产生的化学压力，通过相似固溶和拓扑置换，实现了高压亚稳态的有效截留和功能强化；3）理论计算结合逆向设计，建立了大数据驱动-高通量计算下的结构-功能导向超高压合成新范式；4）提出了定向光谱探针植入的化学压力标定策略，建立了物理压力和局域化学压力之间的桥梁，应用于新型功能颜料的设计。上述工作发展了极端超高压固体合成化学方法学，加速了新材料的发现和走向应用。本项目执行期间，共计在J. Am. Chem. Soc.、CCS Chem.、Chem. Mater.、 ACS Appl. Mater. Interfaces、npj Quantum Mater.等期刊发表SCI论文23篇，申请发明专利5项，国际PCT专利2项，软件著作权1件。

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