Chapter 27 Electrical Properties of Lithium Ferrite Nanoparticles Dispersed in a Styrene- Isoprene-Styrene Copolymer Matrix

摘要

The main goal of this work was the preparation and study of a composite material by dispersing lithium ferrite particles in a polymeric matrix. The matrix selected was styrene-b-isoprene-b-styrene (SIS) copolymer. Lithium ferrite (LiFe_5O_8) is an attractive material for several potential technological applications, due to its physical properties LiFe_5O_8 crystallites were obtained by controlled heat-treatments of homogeneous Li_2O-Fe_2O_3 powders prepared by wet ball-milling method and using lithium and iron nitrates as raw materials. To achieve an effective dispersion of particles, we modified its surface. The structure of the composites, containing modified and unmodified ferrite particles, was studied by XRD and Raman spectroscopy. The dielectric properties were analyzed in the frequency range between 10~(-1) and 10~6 Hz, and as a function of the temperature between -73 and 127 °C. The frequency dependence of the ac conductivity is characterized by a low frequency region of constant conductivity followed by a frequency dependent conductivity. This behavior was interpreted using the Jonscher power law.