What is Iron Oxide Fe3O4?
Iron Oxide Fe3O4 is a kind of inorganic substance, the chemical formula is Fe3O4, black crystal with magnetic, so it is also known as magnetic iron oxide. It cannot be regarded as Fe(FeO2)2, nor as a mixture of iron oxide FeO and iron oxide Fe2O3, but can be approximately regarded as a compound of ferrous oxide and iron oxide (FeO ·Fe2O3). The substance is insoluble in water, alkali solution, ethanol, ether, and other organic solvents. Natural Iron Oxide Fe3O4 is insoluble in acid solutions and readily oxidizes to Iron Oxide Fe3O4 (Fe2O3) in the air under wet conditions. It is commonly used as a pigment and polish, as well as in the manufacture of audiotapes and telecommunications equipment.
How is Iron Oxide Fe3O4 Produced?
Iron Oxide Fe3O4 is produced by the Schikorr reaction. This reaction converts iron (II) hydroxide (Fe(OH)2) into iron oxide (II, III) (Fe3O4). Under anaerobic conditions, ferrous hydroxide (Fe(OH)2) oxidizes in water to form magnetite and molecular hydrogen. Schikorr 's reaction explains this process.
3Fe(OH)2→Fe3O4 + H2 + 2H2O
What is the difference between Fe2O3 and Fe3O4?
The main difference between Fe2O3 and Fe3O4 is that Fe2O3 is a paramagnetic mineral having only a Fe2+ oxidation state whereas Fe3O4 is a ferromagnetic material having both Fe2+ and Fe3+ oxidation states.
What are the properties of Iron Oxide Fe3O4?
Fe3O4 is ferromagnetic with a Curie temperature of 858 K. There is a phase transition at 120K, called Verwey transition where there is a discontinuity in the structure, conductivity and magnetic properties. This effect has been extensively investigated and whilst various explanations have been proposed, it does not appear to be fully understood.
While it has much higher electrical resistivity than iron metal (96.1 nΩ m), Fe3O4's electrical resistivity (0.3 mΩ m ) is significantly lower than that of Fe2O3 (approx kΩ m). This is ascribed to electron exchange between the FeII and FeIII centers in Fe3O4.
Iron Oxide Fe3O4 applications
Iron Oxide Fe3O4 commonly known as iron oxide black, magnetite, and black iron oxide, can be used in many different fields, for example:
Iron (II, III) oxide is used as a black pigment also known as Mars Black.
It is used in the Haber process as a catalyst.
It is used in the water-gas shift reaction.
Fe3O4 Nanoparticles are used in MRI scanning as contrasts against them.
It protects the steel from rusting.
It is an ingredient in thermite that is used for cutting steel.
It can produce magnetic recording materials, high gradient magnetic separators, microwave absorption materials, special coatings.
