Optimized Synthesis of the Elusive ε-Fe2O3 Phase via Sol−Gel Chemistry

• DOI: 10.1021/cm048628m
• Publication Date: 2004-12-07T05:52:36Z
• Authors: Mihaela Popovici; Martí Gich; Daniel Nižňanský; Anna Roig; Cecilia Savii; Lluís Casas; Elies Molins; Karel Zaveta; Corina Enache; Jordi Sort; Sophie de Brion; Gerard Chouteau; Josep Nogués
• Keywords: 02 engineering and technology; 0210 nano-technology

e-Fe2O3 nanoparticles embedded in a SiO2 matrix have been synthesized by sol−gel chemistry and high temperature heat treatments. Virtually pure e-Fe2O3 (in excess of 93%) is obtained, although a two-phase mixture, e-Fe2O3 + α-Fe2O3, is observed for Fe2O3/SiO2 ratios greater than 37 wt %. The e-Fe2O3 nanoparticles are stable up to ∼1600 K. Optimized e-Fe2O3 nanoparticles are ferrimagnetic, with a Curie temperature TC ≈ 510 K, and remarkably high values of room-temperature coercivity, HC = 20 kOe.