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Open AccessArticle

Single Step Process for Crystalline Ni-B Compounds

Institute for Future Environments and Science and Engineering Faculty, Queensland University of Technology (QUT), Brisbane QLD 4001, Australia
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Materials 2018, 11(7), 1259; https://doi.org/10.3390/ma11071259
Received: 8 June 2018 / Revised: 15 July 2018 / Accepted: 20 July 2018 / Published: 22 July 2018
Crystalline Ni2B, Ni3B, and Ni4B3 are synthesized by a single-step method using autogenous pressure from the reaction of NaBH4 and Ni precursors. The effect of reaction temperature, pressure, time, and starting materials on the composition of synthesized products, particle morphologies, and magnetic properties is demonstrated. High yields of Ni2B (>98%) are achieved at 2.3–3.4 MPa and ~670 °C over five hours. Crystalline Ni3B or Ni4B3 form in conjunction with Ni2B at higher temperature or higher autogenous pressure in proportions influenced by the ratios of initial reactants. For the same starting ratios of reactants, a longer reaction time or higher pressure shifts equilibria to lower yields of Ni2B. Using this approach, yields of ~88% Ni4B3 (single phase orthorhombic) and ~72% Ni3B are obtained for conditions 1.9 MPa < Pmax < 4.9 MPa and 670 °C < Tmax < 725 °C. Gas-solid reaction is the dominant transformation mechanism that results in formation of Ni2B at lower temperatures than conventional solid-state methods. View Full-Text
Keywords: nickel boride synthesis; sodium borohydride; microprobe analysis; microstructure; autogenous pressure nickel boride synthesis; sodium borohydride; microprobe analysis; microstructure; autogenous pressure
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MDPI and ACS Style

Shahbazi, M.; Cathey, H.; Danilova, N.; Mackinnon, I.D. Single Step Process for Crystalline Ni-B Compounds. Materials 2018, 11, 1259.

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