In this work, we report the discovery of a new Ni-based quasi-one-dimensional selenide: Cs_0.9Ni_3.1Se₃. This compound adopts the TlFe₃Te₃-type structure with space group P6₃/m, which consists of infinite [Ni₃Se₃] chains with face-sharing Ni₆ octahedra along the c direction. The lattice parameters are calculated as a = 9.26301(4) Å and c = 4.34272(2) Å, with the Ni–Ni distance in the ab plane as 2.582(3) Å, suggesting the formation of a Ni–Ni metallic bond in this compound. Interestingly, it has been found that Cs_0.9Ni_3.1Se₃ is nonstoichiometric, which is different from the other TlFe₃Te₃-type phases reported so far. Structure refinement shows that the extra Ni atom in the structure may occupy the 2c site, together with Cs atoms. Cs_0.9Ni_3.1Se₃ shows metallic behavior with monotonously decreased resistivity with temperatures from 300 to 0.5 K. Measurements on the magnetic susceptibility display a spin-glass state below 7 K. The specific heat curve gives a Sommerfeld coefficient of 14.6 mJ·K^–2·mol^–1 and a Debye temperature of 143.6 K. The discovery of this new compound enriches the diversity of low-dimensional materials in a transition-metal-based family and also sheds light on the structure–property relationship of this system.

中文翻译：

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Cs _0.9 Ni _3.1 Se ₃：具有自旋玻璃行为的镍基准一维导体

在这项工作中，我们报告发现了一种新的镍基准一维硒化物：Cs _0.9 Ni _3.1 Se ₃。该化合物采用具有空间群P 6 ₃ / m的TlFe ₃ Te ₃型结构，该结构由无限长的[Ni ₃ Se ₃ ]链组成，沿c方向具有面共享Ni ₆八面体。晶格参数的计算公式为a = 9.26301（4）Å和c = 4.34272（2）Å，其中Ni–Ni距离为ab平面为2.582（3）Å，表明在该化合物中形成了Ni-Ni金属键。有趣的是，已经发现Cs _0.9 Ni _3.1 Se ₃是非化学计量的，这与迄今为止报道的其他TlFe ₃ Te ₃型相不同。结构改进表明，结构中多余的Ni原子可能与Cs原子一起占据2c位置。Cs _0.9 Ni _3.1 Se ₃表现出金属行为，其电阻率在300至0.5 K的温度下单调降低。磁化率的测量结果显示低于7 K的自旋玻璃态。比热曲线的Sommerfeld系数为14.6 mJ·K ^{– 2个}·mol ^–1，德拜温度为143.6K。这种新化合物的发现丰富了过渡金属基家族中低维材料的多样性，也阐明了该系统的结构与性质之间的关系。