Laser-Induced Hematite/Magnetite Phase Transformation
authors Ferreira, NM; Ferro, MC; Gaspar, G; Fernandes, AJS; Valente, MA; Costa, FM
nationality International
journal JOURNAL OF ELECTRONIC MATERIALS
author keywords Laser surface treatment; localized transformation; iron oxide; Fe2O3; Fe3O4 bi-layer
keywords PROCESSING PARAMETERS; MICROSTRUCTURE; DENSIFICATION; NANOPARTICLES; KINETICS; POWDER; SIZE
abstract The goal of this work was to demonstrate the viability of using laser irradiation to promote the development of a magnetite/hematite bi-layer structure. Local heating by laser irradiation induces a hematite redox mechanism, promoting a phase transition of hematite (Fe2O3) into magnetite (Fe3O4). A relationship between laser feed rate, laser power and the top layer grain size was established. The average grain size increased from 3 mu m to 10 mu m when the laser power increased from 50 W to 100 W. Raman spectroscopy results demonstrated that residual hematite coexists on the magnetite top layer, distributed mostly along the grain boundaries. Electrical conductivity measurements of the irradiated regions confirmed the effectiveness of the laser surface treatment in promoting the local phase transformation of hematite into magnetite, with consequent enhancement of electrical conductivity. The maximum conductivity, 2.8 mS/m, was thus reached for the highest laser power used, 100 W. This phase transformation can be used on other materials to produce bi-layer structure, presenting an important factor for future applications and development using this technique.
publisher SPRINGER
issn 0361-5235
isbn 1543-186X
year published 2020
volume 49
issue 12
beginning page 7187
ending page 7193
digital object identifier (doi) 10.1007/s11664-020-08535-7
web of science category Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Physics, Applied
subject category Engineering; Materials Science; Physics
unique article identifier WOS:000583441400001
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journal impact factor 1.774
5 year journal impact factor 1.684
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