Morphological transformation of hematite nanostructures during oxidation of iron

Abstract

Oxidation of metals usually results in the formation of an oxide nanostructure with poorly controlled growth morphologies. By employing a simple mechanical approach that uses sandblasting to modify the surface roughness of iron substrates, we demonstrate that the morphologies of hematite (α-Fe2O3) nanostructures varying from the growth of one-dimensional nanowires to two-dimensional nanoblades can be achieved during the thermal oxidation of iron. Electron microscopy studies show that the effect of surface sandblasting is to effectively modify the oxide nucleation locations that define the growth shapes. The optical properties of hematite nanowires and nanoblades are examined for the demonstration of the morphology-property correlations.

Morphology, structural and optical properties of iron oxide thin film photoanodes in photoelectrochemical cell: Effect of electrochemical oxidation

“…A sphere is, from thermodynamic point of view, the most favored geometry because its minimal surface/volume ratio decreases the free enthalpy of nucleation [7]. The micrographs for anodized films depict an enhanced surface with increased particles size upon anodization as compared to pristine films particle possibly as a result of increased oxygen content during the treatment [8,12]. Probably a thin layer was formed on top the surface after anodization.…”

Atomic Structural Evolution during the Reduction of α-Fe2O3 Nanowires

“…This yields well-aligned, crystalline α-Fe 2 O 3 nanowires perpendicular to the Fe substrate. 16–19 After the oxidation, the oxygen is pumped out and the chamber is evacuated to ≈ 3×10 −4 Pa again. Subsequently, pure hydrogen gas (99.999 % purity) at a pressure of ≈ 270 Pa is admitted to the vacuum chamber.…”

PECVD of Hematite Nanoblades and Nanocolumns: Synthesis, Characterization, and Growth Model

“…In the last decade, hematite ( α ‐Fe 2 O 3 ) has received remarkable attention by the scientific community, becoming the subject of an increasing number of papers, overcoming the threshold of 1000 documents per year since 2012. The popularity of this material can be first traced back to the fact that many hematite fundamental properties (e.g., magnetic, optical, and electronic) are intrinsically appealing from a technological point of view, and can be widely tuned by tailoring its morphology, texture, and spatial organization on the nanometer scale regime. As a matter of fact, the possibility of fabricating hematite nanowires, nanoblades, nanorings, nanodisks, nanotubes, nanoellipsoids, and so forth, makes this material a versatile workhorse in applications encompassing gas sensing, (photo)catalysis, magnetic storage media, spintronic devices, drug delivery, as well as solar energy production and storage .…”