Structure and magnetic properties of iron oxide dispersed silver based nanocluster composite

Magnetic nanocomposites composed of iron oxide and silver were fabricated b y an inert gas condensation (IGC) method combined with co-evaporation, in s itu oxidation, and in situ compaction techniques. The particle sizes of com posite powder were controlled by varying helium gas pressure between 1 and 10 Torr, with the smallest one being about 10 nm at 1.0 Torr. The nanostruc ture of the composites was characterized by TEM. The magnetization behavior s were analyzed taking into account both the paramagnetic (PM) and ferromag netic (FM) contributions to investigate the correlation between the nanostr ucture and the magnetic properties. It was found that some composites exhib it the superparamagnetism evidencing magnetically isolated grains as a sing le domain. TEM observation assisted with EDX revealed that iron nanocluster of a few nanometers size were surrounded by silver grains. Variation of th e magnetic property of the nanocluster composites was also related to nanoc luster size and heat treatment in an oxygen atmosphere. (C) 2000 Kluwer Aca demic Publishers.