ELECTRICAL CHARACTERISTICS OF HIGHLY-ABSORBING CERAMICS IN THE AlN–SiC SYSTEM

Abstract

The electrical characteristics of two highly-absorbing composite materials in the AlN–SiC system are compared at a frequency of 10.3 GHz. To reliably estimate the dielectric constant and dielectric loss tangent of such highly-absorbing materials, the waveguide method with partial filling of the waveguide is recommended. The dependence of the electrical characteristics of the samples on their phase composition, the ratio of nonconductive and conductive phases, and the nature of the distribution of these phases in the microstructure of the samples is established. The composition of samples 1 and 2 was 57.2AlN–37.9SiC–4.9Y₃Al₅O₁₂ and 42.3AlN–49.9SiC–7.8Y₃Al₅O₁₂, respectively. There were also a small amount of titanium carbide, sialon, and other additives. In the crystal structure of composite materials, practically no solid solutions are formed between AlN and SiC. The agreement between the direct current resistivity values of the composites and the results of high-frequency measurements is shown. Test materials 1 and 2 are characterized by a dielectric loss tangent of 0.30 and 0.49; the actual part of the dielectric constant is ε' = 33.4 and 60.6; the imaginary part of the dielectric constant is ε'' = 10.1 and 29.5; resistivity at a voltage of 1 V equals 3.78 • 10⁸ and 8.90 • 10⁵ Ohm • cm, respectively