Effect of Varying Graphite Concentration on Electrodynamic Properties of AlN-Based Composite Materials

The electrodynamic properties of new composite materials, produced by free sintering based on AlN with the addition of 1–5 wt % of diamond powder, were investigated in the frequency range of 1–10 GHz. Structural and phase composition studies revealed a graphitization process of diamond powder during sintering. According to X-ray phase analysis, after refining the results using the Rietveld method, the graphite phase content was 0.8, 1.7, and 3.8 wt % for materials with the addition of 1, 3, and 5 wt % of diamond powder before sintering, respectively. The investigation of electrodynamic characteristics demonstrated an increase in both real and imaginary dielectric permittivity with increasing graphite concentration. Dielectric loss at a frequency of 10 GHz increased from 0.05 to 0.08 for composites as the graphite phase concentration increased from 0.8 to 3.8 wt %.