STRUCTURAL PECULIARITIES IN MAGNETIC SMALL PARTICLES

Nanostructured magnetic materials, consisting of nanometer-sized cryst allites, are currently a developing subject. Evidence has been accumul ating that they possess properties that can differ substantially from those of bulk materials. This paper illustrates how Mossbauer spectros copy can yield useful information on the structural peculiarities asso ciated with these small particles. As illustrations, metallic iron and iron-oxide systems are considered in detail. The subjects discussed i nclude: (1) phase stabilities in small particles, (2) deformed or nons ymmetrical atomic arrangements in small particles, and (3) peculiar ma gnetic structures or non-collinear spin arrangements in small magnetic oxide particles that are correlated with lower specific magnetization s as compared to the bulk values.