Measurement of the dielectric permittivity of powder materials: A general approach by using dielectrophoretic forces

We propose in this work to use the dielectrophoretic forces to estimate the dielectric permittivity of ceramic powders dispersed in a liquid media. When a divergent electric field is applied to the suspension, the dielectrophoretic force will either repel the particles (negative dielectrophoresis, n-DEP) or attract them (positive dielectrophoresis, p-DEP) to the strong electric field gradient. We identify a crossover frequency for the suspension and we are able to estimate the permittivity values of two high permittivity ceramic powders (barium and strontium titanate). The values of the permittivity are in agreement with those obtained by using a Lichtenecker mixing rule in epoxy composites.