Inorg Chem. 2018 May 7;57(9):4997-5003. doi: 10.1021/acs.inorgchem.8b00018. Epub 2018 Apr 16.
New manganese arsenides CsMnAs, RbMnAs, and KMnAs were synthesized by solid-state reaction. They consist of edge-sharing MnAs tetrahedra, which are a building block similar to those of Fe-based superconductors. CsMnAs and RbMnAs adopt the KCuS-type structure (tetragonal P4/ mmm space group, No. 123) with a MnAs double layer, while KMnAs has the CaFeAs-type structure (orthorhombic Pnma space group, No. 62) with a MnAs tunnel framework. The structural change from CsMnAs and RbMnAs to KMnAs as well as the structural trend of the other ternary A-Mn-As (A = alkali metal) and AE-Mn-As (AE = alkaline-earth metal) compounds is understood as a consequence of reduction of the coordination number around the A and AE sites owing to the decrease of the ionic radius from Cs to Mg. Electrical resistivity measurements confirm that the three new phases are Mott insulators with band gaps of 0.52 (CsMnAs), 0.43 (RbMnAs), and 0.31 eV (KMnAs). Magnetic and heat capacity measurements revealed that CsMnAs and RbMnAs are antiferromagnets without apparent phase transitions below 400 K, which is similar to the magnetism of LaMnAsO and BaMnAs, while the existence of the ferromagnetic component was indicated in KMnAs with a magnetic transition at 179 K.
通过固态反应合成了新的锰砷化物 CsMnAs、RbMnAs 和 KMnAs。它们由共用边的 MnAs 四面体组成，这是类似于 Fe 基超导体的结构单元。CsMnAs 和 RbMnAs 采用 KCuS 型结构（四方 P4/mmm 空间群，No.123），具有 MnAs 双层，而 KMnAs 具有 CaFeAs 型结构（正交 Pnma 空间群，No.62），具有 MnAs 隧道骨架。从 CsMnAs 和 RbMnAs 到 KMnAs 的结构变化以及其他三元 A-Mn-As（A = 碱金属）和 AE-Mn-As（AE = 碱土金属）化合物的结构趋势，被理解为由于 A 和 AE 位周围的配位数减少，导致从 Cs 到 Mg 的离子半径减小的结果。电阻率测量证实，这三个新相是具有 0.52eV（CsMnAs）、0.43eV（RbMnAs）和 0.31eV 带隙的莫特绝缘体。磁性和热容测量表明，CsMnAs 和 RbMnAs 是在 400K 以下没有明显相变的反铁磁体，这与 LaMnAsO 和 BaMnAs 的磁性相似，而在 KMnAs 中存在铁磁成分，在 179K 时发生磁转变。
