Effect of the polymeric matrix on the structural and magnetic properties of hematite/polymer composites

The magnetic properties of hematite (alpha-Fe2O3) nanoparticles synthesized by in situ thermal decomposition of an iron-mercaptide precursor in polymeric matrices are studied. In Polystyrene, nano-particles with average size similar to 20 nm can be produced that show ferromagnetic behavior with no Morin transition for temperatures as low as 10 K. Poly (9-vinylcarbazole)-based nanocomposites, produced by the same synthesis process, show a different magnetic behavior with a clear Morin transition. The effect of the polymeric matrix on the structural and magnetic properties of dispersed hematite nanoparticles is discussed. It is concluded that, in heavily viscous medium, the ability to control the particle growth and distribution is compromised.