Determination of local resistivity in ceramic composites by electron microscopy

Ceramic composite materials with both conducting and insulating phases are widely used to tailor the electrical properties of ceramic components for use in heaters, LTCC-based sensors, and other applications. The electrical properties strongly depend on the homogeneity of distribution of the conducting component. Results of investigations on composites BN/TiB2, Si3N4/MoSi2, and ZrO2/Al2O3/Ti(C,N) using a low-voltage field-emission scanning electron microscope (FESEM) revealed a relationship between the phase contrast in the images and the local electrical conductivity, which made it possible to distinguish grains that made up the three-dimensional conductive network from isolated grains. With this information, the electrical properties of composite materials can be better understood and control of the reliability and aging of such materials is enabled.