α-Fe2O3 Nanostructures: Bridging Morphology with Magnetic and Antimicrobial Properties

Abstract

Highly crystalline hematite (α-Fe₂O₃) nanostructures (NSs) with distinct morphology hold vital significance, not only for fundamental knowledge of magnetic properties but also offering potential applications from biomedical to data storage to semiconductor industry, etc. α-Fe₂O₃ NSs with various shapes are examined to reveal the intrinsic relationship between the shape anisotropy and magnetic properties. Herein, different morphologies of α-Fe₂O₃ NSs, such as spherical, cubic, plate-like, rhombohedral, and hexagonal bipyramid are synthesized, by controlled hydrothermal method. The impact of shape and size on the optical and structural characteristics through UV–vis absorption spectroscopy and X-ray diffraction is analyzed. Advanced nanomaterial techniques such as transmission electron microscopy are utilized to explore and confirm the morphology and size of NSs. Subsequently magnetic properties of the α-Fe₂O₃ NSs, such as magnetic saturation (M_s), coercivity (H_c), and remanent magnetization (M_r), are measured. Careful analysis of magnetic data reveals Morin transition around 200 K for cubic, plate-like, and rhombohedral samples, whereas the spherical and hexagonal bipyramid samples illustrate the superparamagnetic behavior in the temperature range of 150–300 K. Finally, the antibacterial characteristics of NSs against Escherichia coli using a microplate reader for monitoring the bacterial growth are investigated.