Sintering temperature dependences of x[(Mg_0.6Zn_0.4)_0.95Co_0.05]₂TiO₄–(1 − x)Ca_0.8Sr₂TiO₃ microwave dielectric ceramics with a zero temperature coefficient of resonant frequency

Abstract

High-quality x[(Mg_0.6Zn_0.4)_0.95Co_0.05]₂TiO₄–(1 − x)Ca_0.8Sr₂TiO₃ ceramics were prepared by solid-state reaction. The products were characterized by scanning electron microscopy, X-ray diffraction, and network analyzer. [(Mg_0.5Zn_0.5)_0.95Co_0.05]₂TiO₄ has a dielectric constant (ε_r) of ~18, a high quality factor (Q × f) of ~206,000 GHz, and a temperature coefficient of resonant frequency (τ_f) of ~−20.8 ppm/°C. To produce a temperature-stable material, Ca_0.8Sr_0.2TiO₃, which has a large positive τ_f value of 400 ppm/°C, was added to [(Mg_0.5Zn_0.5)_0.95Co_0.05]₂TiO₄. 0.93[(Mg_0.5Zn_0.5)_0.95Co_0.05]₂TiO₄ –0.07Ca_0.8Sr_0.2TiO₃ has an excellent combination of microwave dielectric properties: ε_r ~18.24, Q × f ~130,000 (at 9 GHz), and τ_f ~1 ppm/°C sinter at 1175°C, and can be utilized in the fabrication of microwave devices. Therefore, a band-pass filter is designed and simulated using the proposed dielectric to study its performance.