Investigation low-temperature densification and dielectric properties of glass/Al₂O₃/nano-TiO₂ ceramics for microwave applications

A commercial SiO₂-Al₂O₃-CaO-based commercial glass, Al₂O₃, and nano-TiO₂ were used as initial materials. Glass/Al₂O₃/TiO₂ samples were fabricated using the uniaxial dry pressing method, using C55 with 15 wt% TiO₂, 23 wt% TiO₂ and 36 wt% TiO₂. The optimum bulk density temperature for the C55 was 800 ˚C, for the C55-15 T was 900 ˚C, for the C55-23 T was 900 ˚C, for the C55-36 T was 1000 ˚C. TiO₂ neither chemically reacted with the other phases nor decomposed with temperature which was critical to increasing the dielectric constant. The C55-36 T sample was highlighted for its low sintering temperature of 1000 °C, high dielectric constant values (18.92 at 5 MHz, 17.40 at 1 GHz, and 17.03 at 10 GHz), low dielectric loss (0.0058 at 5 MHz, 0.0063 at 1 GHz, and 0.0075 at 10 GHz), as well as a near-zero temperature coefficient (1.7 ppm/°C) along with high mechanical properties.