Iron Oxide Fe2O3 Magnetic Powder

Iron oxide or ferric oxide with the formula of Fe­₂O₃ is an inorganic compound known to be one of the three main oxides of iron occurring naturally in a mineral called magnetite.

Iron oxide has a unique supermagnetic property with an easy separation method when applied as suspension in solutions and applications in biomedical, agricultural and environmental sectors. Nanografi leverages the remarkable properties of iron oxide powder to innovate and enhance various nanotechnology-based solutions in these critical industries.

Introduction

Unique properties of iron oxide powder make it possible to modify/functionalize them using several inorganic and organic compounds namely starches, polyelectrolytes, and nonionic detergents for even more applications based on their predominant surface chemistry potentials. Iron oxide is considered as the most common magnetic particle and powder to be applied in biomedical applications via applying an external magnetic field ¹. 

Properties of Iron Oxide

Generally, there are as many as 16 different types of iron oxide occurring naturally as a result of oxidation reaction between iron (III) and oxygen with the most common oxides as alpha iron oxide (α-Fe₂O₃) called hematite, gamma iron oxide (g-Fe₂O₃) named maghemite and Fe3O4 (magnetite). Iron oxides have found various applications since they are cost-effective and more importantly, prevalent. Such properties make them promising agents in numerous biological and geological processes as catalysts and pigments. In addition to their industrial and commercial value, iron oxides are particularly well-known compounds in technological applications and scientific research as well. The versatile nature of iron oxides has motivated researchers to precisely concentrate on obtaining fine crystals and powders of iron oxide with even more uses. It has been demonstrated that particles and crystals with ferromagnetic properties show considerable magnetic, semiconducting and supermagnetic characteristics ².

Iron oxides are among the compounds with ferromagnetic properties capable of being magnetic when placed in an external magnetic fields. This property turns out to be a desirable characteristic when they are obtained with controlled size and crystalline morphology. Fine particles of iron oxide have also been the center of attention due to their low toxicity along with their magnetic properties with an easy separation method when applied in medical diagnostics and in magnetic resonance imaging (MRI). Iron oxides applications in macroscopic scales and its reactivity is a determining factor. However, they adopt pyrophoric behavior when they are synthesized in smaller sizes in the macron and nano scales. As a semiconductor material, iron oxide has a negative temperature efficient of resistance. This quality of high resistance α-Fe₂O₃ has found applications in humidity determining sensors. The attempt to synthesize favorable iron oxide powders has led to the emergence of numerous synthesis methods ³.

Ionic oxides are considered as the most studied metal oxides due to their higher surface reactivity and the so-called magnetism. Moreover, they are regarded as environmentally friendly materials and the promise of modern-age sustainable chemistry. Specifically, α-Fe₂O₃ shows antiferromagnetic properties at lower temperatures of -13°C and weak ferromagnetism between the temperatures -13°C up to 600°C. Preparation process is taking the advantage of precipitation and thermal decomposition approaches in the liquid phase. g-Fe₂O₃ with a cubic structure is basically a metastable and converted form of α-Fe₂O₃ at elevated temperatures. g-Fe₂O₃ exhibits ferromagnetic properties but the ultrafine particles smaller than 10 nm turn out to be superparamagnetic. The thermal dehydration is the procedure applied for the production of g-Fe₂O₃. Another most common method involves the careful oxidization of Fe₃O₄. It should be noted that g-Fe₂O₃ particles can be obtained by the thermal decomposition of iron oxalate.

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Synthesis and Preparation of Iron Oxide Powder

The attempt to synthesize favorable iron oxide powder has led to development of numerous techniques known as precipitation, precursor-based technique, sol-gel, combustion hydrothermal and solvent evaporation. A study has suggested a method to obtain nanocrystalline iron oxide powder where ferric chloride is hydrolyzed at 100°C in the presence of hydrochloric acid. In another method, three dimensional (3D) flower-like nanostructured iron oxide is synthesized using precursor rout and the reaction of tetra butyl ammonium bromide, ethylene glycol and ferric chloride as starting reagents at 450°C for 3 hours. The preparation of α-Fe₂O₃ is carried out by sol-gel method and the reagents like ethylene glycol, monomethyl ether and iron nitrate through annealing at the temperatures starting from 400 up to 700°C. In a report, the reverse micellar approach is applied to fabricate iron oxalate nanorods using cetyl-trimethyl ammonium bromide as a surfactant. In so doing, iron oxide particles with spherical morphology can be obtained through the decomposition of the iron oxalate nanorods at 500°C. In a method, the hydrothermal technique is applied to synthesize α-Fe₂O₃ with micro-pine structure by autoclaving K₃[(Fe(CN)₆] for 2 days. The reaction between Fe(CO)₅ and oleic acid takes place in dehydrated (CH₃)₃NO and argon atmosphere in the presence of hexane as the medium to finally lead to nanocrystalline iron oxide product. In a method, a nonhydrolytic precursor is suggested based on Fe(cupfferon)₃ in dry trioctylamine at 300°C in argon atmosphere. It should be taken into consideration that most of these methods seem to have limitations like the use of expensive metal complexes as the starting reagents and difficult synthesis procedure, rare materials, strong acids and bases as well as frequent use of organic solvents ³. While seeking to improve methods for synthesizing iron oxide powder with environmental considerations, blog posts and research on the synthesis of reduced graphene oxide (rGO) can serve as a valuable resource for nanomaterial synthesis and applications.

Iron Oxide Powder Applications

Iron oxide is predominantly employed as the feedstock of the iron and steel industries and alloy manufacturing as a whole. Iron oxides are used in polishing applications, pigment production, magnetic recording fabrication, photocatalysis and medicine. Fine particles of iron oxide have applications as the final polish on metallic lenses, jewelry and cosmetics. The use of iron oxide in the pigment production results in the so-called pigment brown 6, pigment brown 7 and pigment red 101. Some of these pigments like pigment brown 6 and pigment red 101 are recognized and approved by the United States Food and Drug Administration with applications in the cosmetics production. In addition to this, iron oxides are used the preparation of dental composites together with titanium oxide. Considering the magnetic property of iron oxides, it is most commonly employed in the fabrication of different types of magnetic recordings and storages like discs for data storage and magnetic tapes. Also, iron oxides are extensively used as a photoanode agent in solar water oxidation. However, its application in this case and its efficiency is somehow limited by a short diffusion length of 2 to 4 nm of photo-excited charge carriers as well as fast recombination that requires a large overpotential to get the reaction started. A lot of research is carried out in order to improve iron oxides performance based on the surface functionalization and the use of substitute crystal phases such as β-Fe₂O₃. 

Conclusion

The abundance of iron and its chemical and electronic state as well as its reactivity with atmospheric oxygen and many other elements has led to an enormous amount of iron oxide reserves and resources in inorganic ores and minerals. Additionally, iron oxides are widely found in most parts of the Earth with a considerably huge amount of applications as well as accessibility and cheap price. Industrial, medical, scientific and technological sectors all take the advantage of iron oxides versatility.

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References

Ferromagnetism - Wikipedia. (n.d.). Retrieved February 12, 2024, from https://en.wikipedia.org/wiki/Ferromagnetism

Iron Oxide Nanoparticles/Nanopowder and Applications - Nanografi Nano Technology. (n.d.). Retrieved February 12, 2024, from https://nanografi.com/blog/iron-oxide-nanoparticlesnanopowder-and-applications/

Pant, P., Naik, B. D. & Ghosh, N. N. Synthesis of α-Fe2O3 nano powder by simple chemical method. Mater. Technol. 24, 213–216 (2009).

Schwertmann, U. 1 Introduction to the iron oxides.

Synthesis of Reduced Graphene Oxide - Nanografi Nano Technology. (n.d.). Retrieved February 12, 2024, from https://nanografi.com/blog/synthesis-of-reduced-graphene-oxide/

Zia, M., Phull, A. R. & Ali, J. S. challenges of iron oxide nanoparticles. 49–67 (2016).