Synthesis of Magnesium Nickel Boride Aggregates via Borohydride Autogenous Pressure

We demonstrate synthesis of the ternary intermetallic MgNi₃B₂ using autogenous pressure from the reaction of NaBH₄ with Mg and Ni metal powder. The decomposition of NaBH₄ to H₂ and B₂H₆ commences at low temperatures in the presence of Mg and/or Ni and promotes formation of Ni-borides and MgNi₃B₂ wit...

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Bibliographic Details
Published in:Materials 2018-03, Vol.11 (4), p.480
Main Authors: Shahbazi, Mahboobeh, Cathey, Henrietta E, Mackinnon, Ian D R
Format: Article
Language:English
Subjects:
Aggregates
Borides
Chemical synthesis
Decomposition reactions
Diamagnetism
Ferromagnetism
Magnetic measurement
Metal powders
Nickel
Temperature
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Summary:We demonstrate synthesis of the ternary intermetallic MgNi₃B₂ using autogenous pressure from the reaction of NaBH₄ with Mg and Ni metal powder. The decomposition of NaBH₄ to H₂ and B₂H₆ commences at low temperatures in the presence of Mg and/or Ni and promotes formation of Ni-borides and MgNi₃B₂ with the increase in temperature. MgNi₃B₂ aggregates with Ni-boride cores are formed when the reaction temperature is >670 °C and autogenous pressure is >1.7 MPa. Morphologies and microstructures suggest that solid-gas and liquid-gas reactions are dominant mechanisms and that Ni-borides form at a lower temperature than MgNi₃B₂. Magnetic measurements of the core-shell MgNi₃B₂ aggregates are consistent with ferromagnetic behaviour in contrast to stoichiometric MgNi₃B₂ which is diamagnetic at room temperature.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma11040480