Effects of grain size on magnetic and dielectric properties of nano-ferrites at microwave and millimeterwave frequencies

The recent developments in semiconductor technology and nanoelectronics have led to a significant growth in high frequency applications. As the device size becomes smaller and applications shift towards millimeter wavelengths, the need for novel materials capable of handling high frequency has increased. This has generated interest in the study of nano materials for use in high frequency applications. This is possible since at nanoscale sizes, materials can exist in single domain state and thus domain wall resonance can be avoided. The study of electromagnetic properties of such materials is therefore necessary to understand their behavior and potential use in high frequency applications. In this work, M-type hexagonal ferrites of barium and strontium are studied. These materials have been characterized in their solid state [1-2]. However, here samples with same composition but different particle size are studied. One set of samples consists of barium and strontium ferrite with particle size lying in the micrometer range while the particles in the second sample are in the nanometer range. Barium and strontium ferrites are of great interest for high frequency applications due to high internal magnetic anisotropy. This also leads the resonance frequency of these samples to lie in the millimeter wave frequency range.