Effect of the Content and Particle Size Distribution of Molybdenum on the Dielectric Characteristics and Electromagnetic Energy Absorption of AlN–Mo Composites

This paper reports experimentally determined values for the dielectric permittivity ε' and dielectric loss tangent tanδ of pressureless sintered AlN based composites with conductor (Mo) particles in a wide range from zero to the critical concentration of molybdenum particles, i.e., near the percolation threshold. It is shown that, in the studied composites, both the real ε' and imaginary ε'' parts of the dielectric permittivity monotonically grow with increasing content of conductor particles, reach maximum values near the percolation threshold, and equal to ε' = 25–32–48. The microwave energy absorption of AlN–Mo composites with different content and size distribution of conductor particles was measured. The relationship between the dielectric losses ε'' and the level of microwave absorption L depending on the content of conductor particles near the percolation threshold was established.