Improved Zn0.9Mg0.1Al2O4 Microwave Dielectric Ceramics with High Thermal Conductivity

Zn0.9Mg0.1Al2O4 + x wt.% TiO2 (0 <= x <= 3) microwave dielectric ceramics with relatively high thermal conductivity were prepared by solid-phase reaction. The effects of TiO2 on the crystal phase, micromorphology, microwave dielectric properties, and thermal conductivity of the Zn0.9Mg0.1Al2O4 ceramics were studied. X-ray diffraction analysis, scanning electron microscopy, laser flash measurements, and network analysis were used in this study. The results showed that a small amount of nonstoichiometric compounds appeared in the Zn0.9Mg0.1Al2O4 ceramics with increasing TiO2 content. At the same time, TiO2 doping promoted growth of crystal grains, opened the ion-exchange channels in the system, promoted the sintering reaction, and reduced the sintering temperature of the Zn0.9Mg0.1Al2O4 ceramics. Moreover, addition of TiO2 suppressed the microscopic lattice disorder and macroscopic segregation, leading to an improvement in the dielectric properties and thermal conductivity of the composite ceramics. The Zn0.9Mg0.1Al2O4 + 2 wt.% TiO2 ceramic sintered at 1500 degrees C exhibited the best dielectric performance and thermal conductivity with a dielectric constant of 8.57, Q x f product of 18,0861 GHz, temperature coefficient of resonance frequency of -41.5 ppm/degrees C, and thermal conductivity of 19.67 W/(m K).

Automated summary

The addition of TiO2 to Zn0.9Mg0.1Al2O4 microwave dielectric ceramics promoted crystal grain growth and reduced sintering temperature, leading to improved dielectric properties and thermal conductivity of the material.