31^st Materials Science and Engineering Conference: Advancement & Innovations

Cu-doped NiZn ferrites are typical electromagnetic wave absorbers which absorption capacity (calculated from experimental measures of complex permeability and complex permittivity for a given frequency range) is related to thickness body and especially and more critical to its microstructure. Ideal microstructure would consist of sintered bodies with no porosity, small average grain size and narrow grain size distribution. Moreover, the finer grain sizes the better absorption capacity. Literature shows that physical properties of ceramic bodies improve when particle-size distribution decreases from the micro-scale to the nanoscale. Ferrites from nanoparticles have been sintered controlling average grain size and relative density with sintering temperature. Green microstructure has been set constant using uniaxial dry pressing at 200 MPa as the shaping method. Sintered microstructure has been observed by Scanning Electron Microscopy (SEM), obtaining the average grain size by image analysis of the SEM micrographs. Relative density was determined by the Archimedes method, using true density material value. Magnetic permeability was measured in the frequency range from 1 MHz to 3 GHz by using an Agilent model E4991 ARF impedance analyzer with the 16454A test fixture and this later parameter has been related to average grain size and relative density. Finally, the results obtained from nano-particulate ferrite powder have been compared with those previously obtained from micro-particulate ferrite powders, noting an improvement in performance.