Low-temperature co-firing of Co1.1Zn0.9TiO4 microwave dielectric ceramics by doping with H3BO3

In this study, Co1.1Zn0.9TiO4 ceramics were sintered at 1200 °C using a solid sintering method. The ceramics exhibited excellent microwave dielectric properties: the quality factor (Q×f) = 55,554.1 GHz, the dielectric constant (εr) = 16.243 and a temperature coefficient of resonant frequency (τf) = −19.88 ppm/°C. X-ray diffraction patterns reveal that Co1.1Zn0.9TiO4 ceramics have a garnet structure, and doping with H3BO3 does not yield any other second phase other than the Co1.1Zn0.9TiO4 phase. The analysis of the SEM images reveals a notable enhancement in grain growth with the increase in the content of added H3BO3. And by incorporating H3BO3 into the system led to the successful decrease, the sintering temperature to below 900 °C. The Co1.1Zn0.9TiO4 + 4 wt% H3BO3 ceramic sintered at 900 °C for 4 h, shows a relatively low dielectric loss, that is, the ceramic retains a relatively good value of Q×f. The detailed microwave dielectric properties of Co1.1Zn0.9TiO4 + 4 wt% H3BO3 ceramic are as follows: Q×f = 33,615.3 GHz (at 10.744 GHz), εr = 16.578, and τf = −20.00 ppm/°C. Additionally, when co-fired with silver (Ag), the ceramic material did not exhibit any reactivity with the Ag electrode. This characteristic could potentially be advantageous in the fabrication of low-temperature ceramics.