Microwave dielectric properties of novel (1 -x)MgTiO_3-xCa_(0.5)Sr_(0.5)TiO_3 ceramics

摘要

In this work, the microstructure and microwave dielectric properties of novel (1 - x)MgTiO_3-xCa_(0.5)Sr_(0.5)TiO_3 (x = 0.035-0.045) ceramics were investigated. The samples were prepared via the solid-state sintering method using the pre-synthesized ultrafine MgTiO_3 and (Ca_(0.5)Sr_(0.5))TiO_3 powders by molten-salt reaction. As the x value increases from 0.035 to 0.045, the quality factor (Q·f) of the samples presents an increase first and then a decrease, reaching the maximum of 70,000 with x = 0.0375. The dielectric constant (ε_r) increases monotonously with the increase of x, which is 20.96 when x = 0.0045. The temperature coefficient of resonant frequency (τ_f) progressively increases with increasing content of Ca_(0.5)Sr_(0.5)TiO_3. When x = 0.004, the obtained 0.96MgTiO_3-0.04Ca_(0.5)Sr_(0.5)TiO_3 ceramics sintered at 1275 °C for 4 h display excellent microwave dielectric properties with an ε_r value of about 20.57, a relatively high Q·f value of roughly 58,000 GHz, and a near-zero τ_f value of approximately -1.16 ppm/°C. Such ceramics might be a good candidate for high-performance microwave dielectric devices.