Production of amorphous Fe-B alloy and α-Fe by chemical reduction of hematite using sodium borohydride

Authors: Resende, V.; Costa, G.; Grave, E.; Datas, L.

Source: Journal of Materials Science, Volume 41, Number 20, October 2006 , pp. 6843-6854(12)

Publisher: Springer

Buy & download fulltext article:

Price: $47.00 plus tax (Refund Policy)

Abstract:

Natural and well-crystallized hematite was suspended in water and treated at room-temperature (RT) with sodium borohydride in acid medium. The product of the reaction is a highly magnetic black powder, which is stable at RT. The NaBH₄ treatment converts about half of the hematite to an amorphous Fe-B alloy and to a small fraction of sub-micron sized, amorphous metallic-Fe nodules. Heating at 400 °C of this composite has resulted in the crystallization and/or oxidation of more than half of the amorphous Fe-B phase to α-Fe and Fe₃O₄ and B₂O₃, respectively. Further, the already present superficial, amorphous metallic Fe is converted to α-Fe and the original, plate like morphology of the hematite has changed to a mix of nodular and acicular particles. After treatment at 800 °C, the metallic Fe and the amorphous Fe-B have completely vanished, and the resulting product consists of hematite and FeBO₃ embedded in a matrix of α-Fe₂O₃.

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s10853-006-0953-3

Affiliations: 1: Email: magela@iceb.ufop.br

Publication date: 2006-10-01