Facile green synthesis of iron oxide nanoparticles via solid-state thermolysis of a chiral, 3D anhydrous potassium tris(oxalato)ferrate(III) precursor

•Four different polymorphs of iron oxide nanoparticles were synthesized.•We obtained α-Fe2O3 nanoparticles with spherical morphology.•We obtained γ-Fe2O3 and Fe3O4 nanoparticles with octahedral morphology.•This work is facile, green and possibility of large scale production.

The iron oxide nanoparticles hematite (α-Fe2O3), maghemite (γ-Fe2O3), magnetite (Fe3O4) and wüstite (FeO) were synthesized via solid-state thermolysis of a chiral, 3D anhydrous potassium tris(oxalato)ferrate(III) (K3[Fe(C2O4)3]) precursor. A controlled heat treatment for the precursor material in air forms these four iron oxide polymorphs. Powder X-ray diffraction (XRD) and Raman spectroscopy were used to identify the different iron oxide nanoparticle polymorphs. The morphology of the obtained iron oxide nanoparticles was determined using a field emission scanning electron microscope (FE-SEM). The magnetic properties of the as-synthesized iron oxide nanoparticles was studied using a superconducting quantum interference device (SQUID), and the results indicated that they are weakly ferromagnetic, ferrimagnetic and paramagnetic in nature.

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