From Layered Antiferromagnet to 3D Ferromagnet: LiMnBi-to-MnBi Magneto-Structural Transformation
From Layered Antiferromagnet to 3D Ferromagnet: LiMnBi-to-MnBi Magneto-Structural Transformation
复制标题
DOI：
10.1021/acs.chemmater.3c00140
复制
发表时间：
2023-04
影响因子：
8.6
通讯作者：
中科院分区：
文献类型：
--
作者：
采用两步固相反应法合成了金属间化合物LiMnBi。基于原位高温粉末X射线衍射数据，选择850 K的合成温度。LiMnBi晶体为层状PbClF结构（100 K时a= 4.3131（7）Ω，c= 7.096（1）Ω，P4/nm空间群，Z= 2）。LiMnBi结构由[MnBi]和Li层交替构成，如从单晶X射线衍射数据确定的。磁性测量和固态7 Li核磁共振数据收集的多晶LiMnBi样品表明，在340 K的Mn亚晶格的长程反铁磁有序，没有超导电性检测到5 K。LiMnBi对空气和水敏感。在有氧条件下，Li可以从LiMnBi结构中提取出来，形成Li 2 O/LiOH和MnBi（NiAs结构类型，P63/mmc）。所获得的MnBi多晶型物先前被报道为最强的无稀土铁磁体之一，但其粉末形式的本体合成是繁琐的。从三元LiMnBi到铁磁MnBi的磁结构转变涉及Li脱嵌时MnBi 4四面体的凝聚，并且是LiMnBi独有的。相比之下，铁磁性MnBi不能从同构NaMnBi和KMnBi或从结构相关的CaMn 2Bi 2获得。在LiMnBi的情况下，这种独特的转变被认为是由于其产生MnBi的合适反应性和[MnBi]层之间的有利层间距离，而NaMnBi和KMnBi结构类似物中的层间距离不利地长。层状LiMnBi在不同化学环境下的脱锂研究表明，MnBi的产率取决于所用溶剂的类型和反应动力学。缓慢的速率和温和的反应介质导致高分数的MnBi产物。“所制备的”MnBi的饱和磁化强度是预期值81.3emu/g的约50%。总的来说，这项研究增加了一个失踪的成员，家庭的三元磷族化合物，并说明如何软化学方法可以用来获得“难以合成”的化合物。
The intermetallic compound LiMnBi was synthesized by the two-step solid-state reaction from the elements. A synthesis temperature of 850 K was selected based on in situ high-temperature powder X-ray diffraction data. LiMnBi crystalizes in the layered-like PbClF structure type (a= 4.3131(7) Å,c= 7.096(1) Å at 100 K,P4/nmmspace group,Z= 2). The LiMnBi structure is built of alternating [MnBi] and Li layers, as determined from single-crystal X-ray diffraction data. Magnetic property measurements and solid-state7Li nuclear magnetic resonance data collected for polycrystalline LiMnBi samples indicate the long-range antiferromagnetic ordering of the Mn sublattice at ∼340 K, with no superconductivity detected down to 5 K. LiMnBi is air- and water-sensitive. Under aerobic conditions, Li can be extracted from the LiMnBi structure to form Li2O/LiOH and MnBi (NiAs structure type,P63/mmc). The obtained MnBi polymorph was previously reported to be one of the strongest rare-earth-free ferromagnets, yet its bulk synthesis in powder form is cumbersome. The proposed magneto-structural transformation from ternary LiMnBi to ferromagnetic MnBi involves condensation of the MnBi4tetrahedra upon Li deintercalation and is exclusive to LiMnBi. In contrast, ferromagnetic MnBi cannot be obtained from either isostructural NaMnBi and KMnBi or from the structurally related CaMn2Bi2. Such a distinctive transformation in the case of LiMnBi is presumed to be due to its fitting reactivity to yield MnBi and a favorable interlayer distance between [MnBi] layers, while the interlayer distance in NaMnBi and KMnBi structural analogues is unfavorably long. The studies of delithiation from layered-like LiMnBi under different chemical environments indicate that the yield of MnBi depends on the type of solvent used and the kinetics of the reaction. A slow rate and mild reaction media lead to a high fraction of the MnBi product. The saturation magnetization of the “as-prepared” MnBi is ∼50% of the expected value of 81.3 emu/g. Overall, this study adds a missing member to the family of ternary pnictides and illustrates how soft-chemistry methods can be used to obtain “difficult-to-synthesize” compounds.