Nanoneedles of maghemite iron oxide prepared from a wet chemical route

• Published in: Materials research bulletin 2003-02, Vol.38 (3), p.461-467
• Main Authors: Fang, Jiye, Kumbhar, Amar, Zhou, Weilie L, Stokes, Kevin L
• Format: Article
• Language: English
• Subjects: ASPECT RATIO; CHEMICAL PREPARATION; Chemical synthesis; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electron microscopy; Exact sciences and technology; FERRITES; Fine-particle systems; IRON OXIDES; Magnetic materials; MAGNETIC PROPERTIES; Magnetic properties and materials; MATERIALS SCIENCE; MICROEMULSIONS; Nanoscale materials and structures: fabrication and characterization; NANOSTRUCTURES; Physics; Small particles and nanoscale materials; SQUID DEVICES; Studies of specific magnetic materials; THERMAL GRAVIMETRIC ANALYSIS; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION
• ISSN: 0025-5408; 1873-4227
• DOI: 10.1016/S0025-5408(02)01066-8

Nanometer-sized maghemite iron oxide (γ-Fe 2O 3) particles were produced first by synthesis of a precursor, γ-FeO(OH), in a surfactant-less microemulsion and subsequent heat treatment of the γ-FeO(OH). The precursors and γ-Fe 2O 3 powder were characterized using thermogravimetric analysis (TGA), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Susceptometer from Quantum Design (SQUID) measurements. TGA and XRD analysis indicated the formation of single cubic phase when the samples were heat-treated at 240 °C. TEM reveals that the γ-Fe 2O 3 particles are needle-shaped with an aspect ratio of ∼20; typically 5–10 nm wide and over 150 nm long. It was found that these microemulsion-derived γ-Fe 2O 3 nanoneedles possess an intrinsic coercivity of 28 Oe at 300 K and 950 Oe at 2 K.