Estimation of permittivity of a compact crystal by dielectric measurements on its powder: A stochastic mixture model for the powder-dielectric

A stochastic mixture model is proposed for the dielectric formed by the powder of an isotropic polycrystalline material included in an embedding medium of air or a non-polar substance. The relevant expression of the complex dielectric constant of the mixture is obtained in terms of the dielectric parameters of the mixture constituents and the volume fraction of the crystalline material. Hence the possibility of deducing the dynamic state dielectric characteristics of the solid (compact) crystal from the measured data on the powder is indicated. Theoretical results obtained for 1-cyanoadamantane using the present model over a wide spectral range (1 kHz to 1 GHz) are compared with corresponding experimental data available elsewhere. Results due to the present method agree more closely with the measured values for both low and high volume fractions, when compared with the results based on other existing models due to Bottcher and Looyenga.