Hofmann Kathrin, Kalyon Nalan, Kapfenberger Christine, Lamontagne Leo, Zarrini Salman, Berger Robert, Seshadri Ram, Albert Barbara
Eduard-Zintl-Institute of Inorganic and Physical Chemistry, Technische Universität Darmstadt , Alarich-Weiss-Str. 12, 64287 Darmstadt, Germany.
Materials Department and Materials Research Laboratory, University of California Santa Barbara , Santa Barbara California 93106, United States.
Inorg Chem. 2015 Nov 16;54(22):10873-7. doi: 10.1021/acs.inorgchem.5b01929. Epub 2015 Nov 2.
We trapped an unknown metastable boride by applying low-temperature solution synthesis. Single-phase nickel boride, Ni7B3, was obtained as bulk samples of microcrystalline powders when annealing the amorphous, nanoscale precipitate that is formed in aqueous solution of nickel chloride upon reaction with sodium tetrahydridoborate. Its crystal structure was solved based on a disordered Th7Fe3-type model (hexagonal crystal system, space group P63mc, no. 186, a = 696.836(4) pm, c = 439.402(4) pm), using synchrotron X-ray powder data. Magnetic measurements reveal paramagnetism, which is in accordance with quantum chemical calculations. According to high-temperature X-ray diffraction and differential scanning calorimetry this nickel boride phase has a narrow stability window between 300 and 424 °C. It crystallizes at ca. 350 °C, then starts decomposing to form Ni3B and Ni2B above 375 °C, and shows an exothermic effect at 424 °C.
我们通过低温溶液合成法捕获了一种未知的亚稳硼化物。当对在氯化镍水溶液中与硼氢化钠反应形成的非晶态纳米级沉淀物进行退火处理时，获得了单相硼化镍Ni7B3的微晶粉末块状样品。利用同步辐射X射线粉末数据，基于无序的Th7Fe3型模型（六方晶系，空间群P63mc，编号186，a = 696.836(4) pm，c = 439.402(4) pm）解析了其晶体结构。磁性测量显示出顺磁性，这与量子化学计算结果一致。根据高温X射线衍射和差示扫描量热法，这种硼化镍相在300至424°C之间具有狭窄的稳定性窗口。它在约350°C结晶，然后在375°C以上开始分解形成Ni3B和Ni2B，并在424°C时显示出放热效应。
