Spin frustration in maghemite nanoparticles

A different degree of internal structural disorder is observed in almost identical and uniform gamma -Fe2O3 nanoparticles of about 3.5 +/- 0.6 nm, prepared by laser pyrolysis, by high-resolution transmission electron microscopy (HRTEM) and Mossbauer spectroscopy. This structural disorder is responsible for a different degree of spin frustration that takes place not only at the surface but also inside the particles depending on the preparation method and it has a great influence on the magnetic properties of the material. (C) 2001 Elsevier Science Ltd. All rights reserved.