Synthesis, crystal structure, and magnetic properties of a one-dimensional chain antiferromagnet NiC2O4·2NH3
Synthesis, crystal structure, and magnetic properties of a one-dimensional chain antiferromagnet NiC2O4·2NH3
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一维链状反铁磁体NiC2O4·2NH3的合成、晶体结构及磁性能
DOI：
10.1016/j.jssc.2022.123360
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发表时间：
2022
影响因子：
3.3
通讯作者：
Poeppelmeier, Kenneth R.
中科院分区：
文献类型：
--
作者：
Ding, Fenghua;Griffith, Kent J.;Zhang, Chi;Zhan, Jing;Lu, Hongcheng;Poeppelmeier, Kenneth R.
采用水热法合成了NiC 2 O 4·2NH 3，并用X射线单晶衍射对其结构进行了解析。NiC_2O_4·2NH_3晶体属中心对称单斜晶系，空间群为C_2/m（no.12），晶胞参数为a = 10.767（5）B = 5.414（2），c = 5.005（2），β = 96.3（4）°。NiO 4 N2八面体通过共享的C2 O 42 −单元以平行模式排列，从而形成沿着b轴延伸的线性一维（1D）链。这些线性链被NH3分子沿a轴沿着隔开，并通过氢键相互弱耦合。1H和13 C固态NMR分别在−115（3）ppm和−312（5）ppm处显示了NiC 2 O 4·2NH 3的各向同性共振，氨质子和草酸碳通过费米接触相互作用从d8 Ni（II）顺磁移动。从自旋边带流形的模拟中确定了1H和13 C的室温顺磁位移各向异性分别为400（30）ppm和780（40）ppm。磁化率在T（χmax）= 35 K附近出现极大值，表明Ni-C_2 O_4-Ni链上存在沿着发展良好的自旋-自旋相关。没有观察到长程有序下降到2 K，这是进一步证实了热容的结果。链内相互作用J/kof −31.0 K通过用一维自旋链模型拟合数据来估计。在2K的等温磁化曲线显示了在5 T附近的场致相变。9 T时的磁化强度值仅为0.087 μB，远未达到饱和。磁性测试结果表明NiC 2 O 4·2NH 3是一种良好的一维链状量子反铁磁体。
NiC2O4·2NH3was synthesized hydrothermally, and its structure was solved by single-crystal X-ray diffraction. Accordingly, NiC2O4·2NH3crystallizes in the centrosymmetric monoclinic space groupC2/m(no. 12) with lattice parameters ofa= 10.767(5) Å,b= 5.414(2) Å,c= 5.005(2) Å andβ= 96.3(4)°. The NiO4N2octahedra align in a parallel pattern through shared C2O42−units and thus form linear one-dimensional (1D) chains extending along theb-axis. These linear chains are separated along thea-axis by NH3molecules and weakly coupled with each other through hydrogen bonding.1H and13C solid-state NMR revealed isotropic resonances at −115(3) ppm and −312(5) ppm, respectively, for NiC2O4·2NH3, the ammonia protons and oxalate carbons being paramagnetically shifted via the Fermi contact interaction fromd8Ni(II). Room-temperature paramagnetic shift anisotropies of 400(30) ppm for1H and 780(40) ppm for13C were determined from simulations of the spinning sideband manifolds. Magnetic susceptibility shows a broad maximum aroundT(χmax) = 35 K, suggesting well-developed spin–spin correlations along the Ni–C2O4–Ni chains. No long-range order is observed down to 2 K, which is further confirmed by heat capacity results. The intrachain interactionJ/kof −31.0 K is estimated by fitting the data with a 1D spin chain model. The isothermal magnetization curve at 2 K shows a field-induced phase transition around 5 T. The magnetization value at 9 T is only 0.087 μB, which is far from saturation. All magnetic results indicate NiC2O4·2NH3is a good 1D chain quantum antiferromagnet.