Structural and magnetic properties of α-Fe2O3 nanoparticles

✍ Scribed by Lorenza Suber; Antoni García Santiago; Dino Fiorani; Patrizia Imperatori; Alberto Maria Testa; Massimo Angiolini; Amelia Montone; Jean L. Dormann

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 320 KB
• Volume: 12
• Category: Article
• ISSN: 0268-2605
• DOI: 10.1002/(sici)1099-0739(199805)12:5<347::aid-aoc729>3.0.co;2-g

✦ Synopsis

The magnetic properties of a-Fe 2 O 3 nanoparticles of different shapes (spherical, rhombohedral and acicular), prepared as powders by a chemical route, have been investigated. The particle size effect on the Morin transition (T M = 263 K in the bulk system) have been studied by analyzing the temperature dependence of the zero-field-cooled (ZFC) and fieldcooled (FC) magnetization. For spherical (average diameter between 10 and 50 nm) and rhombohedral (edge between 30 and 350 nm) particles, the Morin temperature was found to decrease with decreasing particle size and increasing magnetic field. On the other hand, acicular particles (major axis between 300 and 700 nm, minor axis between 70 and 100 nm) do not show the Morin transition, unless annealed.