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Iron oxide is a polymorphic compound

Iron(III) oxide is a polymorphic compound, i.e., it can exist in two or more solid phases that are isochemical but have distinct crystal structures and, thus, different physical properties. Under ambient conditions, four different crystalline polymorphs of iron(III) oxide have been discovered and characterized in detail: (i) α-Fe2O3, mineralogically known as hematite, which has a rhombohedral centered hexagonal crystal structure ( space group with a = 5.034 Å and c = 13.752 Å); (ii) β-Fe2O3, which has a cubic body-centered crystal structure of bixbyite type ( space group with a = 9.393 Å); (iii) γ-Fe2O3, mineralogically known as maghemite, which has a cubic crystal structure of inverse spinel type ( space group with a = 8.351 Å and vacancies disordered over the octahedral cation sites in the crystal lattice); and (iv) ε-Fe2O3, which has an orthorhombic crystal structure (Pna21 space group with a = 5.072 Å, b = 8.736 Å and c = 9.418 Å). While α-Fe2O3 and γ-Fe2O3 are naturally abundant and can be prepared in diverse morphological forms with different sizes by various optimized synthetic routes, β-Fe2O3 and ε-Fe2O3 are rarely observed in nature, and their stability is dependent on the nano dimensional character of their particles. β-Fe2O3 was recently used as a chloroform sensor and identified as a suitable candidate for preparing anodes in lithium-ion batteries14. Ferrimagnetic and superparamagnetic nanoparticles of γ-Fe2O3, the most widely used iron(III) oxide polymorph, have been identified as a possible functional medium for magnetocaloric refrigeration. They also have diverse biomedical applications because they are biocompatible and biodegradable while exhibiting useful magnetic properties; they have been used as MRI contrast agents, carriers for targeted drug delivery, heating units in magnetically-induced cancer therapy (i.e., hyperthermia), and sensors of various biologically important molecules. If you are looking for high quality, high purity, and cost-effective Iron Oxide, or if you require the latest price, please email contact mis-asia.

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