Complex Permittivity Measurements at Elevated Temperatures of Zinc Oxide Sintered in Conventional and Microwave Furnaces
D. Gershon,1 J. Calame,1 Y. Carmel,1 T. Antonsen,1 and M. Rosen2
1Institute for Plasma Research, University of Maryland, College Park, Maryland 20742, USA 2
Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA
First World Congress on Microwave Processing, January 5-9, 1997
ABSTRACT. The recent growth in research on microwave processing of materials has been motivated by the hope of achieving superior electrical, optical, thermal, and mechanical properties unattainable by conventional processing methods. Microwave processing of ceramics is a dynamical process encompassing microwave power absorption, thermal and mass transport within the material, and densification. The absorbed microwave power is determined by the imaginary part of the complex permittivity epsilon", of the material and the electric field. The local electric field depends on the magnitude and spatial distribution of the complex permittivity within the materials. Since there is a lack of knowledge in the complex permittivity with respect to temperature and density, it is difficult to model the material's power absorption, temperature distribution, and densification. By measuring complex permittivity over a wide frequency range, the material's polarization mechanisms could be analyzed and future microwave processing system could be optimized.