Phase Transformation of Iron Oxide Nanoparticles from Hematite to Maghemite in Presence of Polyethylene Glycol: Application as Corrosion Resistant Nanoparticle Paints

Pavani Katikaneani,Ramu Banavath,Ajay Kumar Vaddepally,Narender Reddy Tippana,Srivani Kommu

doi:10.1155/2016/1328463

Pavani Katikaneani, Ramu Banavath + Show 3 more

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https://doi.org/10.1155/2016/1328463

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Abstract

This work proposes a simple method for the efficient and rapid synthesis of hematite (α-Fe2O3) nanostructures based on simple heating method under ambient conditions. Polyethylene glycol (PEG) is employed as a structure directing agent in driving the morphology and phase transformation. Typically, Fe2O3 nanoparticles of size below 50 nm were synthesized at temperature around 500°C. The morphology and mechanism of formation of the nanocapsules and then aggregation of nanocapsules to form larger size nanoclusters were studied by scanning electron microscopy and energy dispersive X-ray spectroscopy. Interestingly, this work demonstrates the structural phase transformation of hematite (α-Fe2O3) to maghemite (γ-Fe2O3) upon addition of different amounts of PEG (say 0.066 M, 0.133 M, and 0.2 M) and then heat treating at 500°C. The prepared powders were used in nanoparticle paint preparation and applied as corrosion resistant coatings on iron samples. Polarization studies performed on the paint coatings made out of all the prepared samples showed size-dependent corrosion resistance. As the particle size decreases, the surface area increases and so the corrosion resistance also increases.

Highlights

From the last few decades, transition metal oxide nanoparticles have attracted tremendous interest due to their promising applications as electrode materials for rechargeable solidstate batteries [1, 2], as efficient catalysts for fuel-cell reactions [3, 4], and as nanoscale magnetic models for understanding nanomagnetism [5, 6]
As hematite is the most stable and ntype semiconductor under ambient conditions, it is widely used as catalysts, gas sensors, and pigments due to its high resistance to corrosion and low cost
It can be used as a starting material for the synthesis of maghemite (γ-Fe2O3) and magnetite (Fe3O4), which have been intensively pursued for technological applications in the last few decades [10]

Summary

Introduction

From the last few decades, transition metal oxide nanoparticles have attracted tremendous interest due to their promising applications as electrode materials for rechargeable solidstate batteries [1, 2], as efficient catalysts for fuel-cell reactions [3, 4], and as nanoscale magnetic models for understanding nanomagnetism [5, 6]. Hematite is the main source of the iron for the production of steel and it is paramagnetic, readily attacked by acids, and reddish brown in colour. As hematite is the most stable and ntype semiconductor under ambient conditions, it is widely used as catalysts, gas sensors, and pigments due to its high resistance to corrosion and low cost. It can be used as a starting material for the synthesis of maghemite (γ-Fe2O3) and magnetite (Fe3O4), which have been intensively pursued for technological applications in the last few decades [10]

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Conclusion