Metastable Ni7B3: A New Paramagnetic Boride from Solution Chemistry, Its Crystal Structure and Magnetic Properties

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• 作者：Kathrin Hofmann ; Nalan Kalyon ; Christine Kapfenberger ; Leo Lamontagne ; Salman Zarrini ; Robert Berger ; Ram Seshadri ; Barbara Albert
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：November 16, 2015
• 年：2015
• 卷：54
• 期：22
• 页码：10873-10877
• 全文大小：365K
• ISSN：1520-510X

文摘

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 掳C. It crystallizes at ca. 350 掳C, then starts decomposing to form Ni₃B and Ni₂B above 375 掳C, and shows an exothermic effect at 424 掳C.