Sintering characteristics and microwave dielectric properties of (Zr_0.8Sn_0.2)TiO₄ ceramics doped with La₂O₃ and MgO

To investigate how addition of La₂O₃ and MgO influenced the structures, phase composition, sintering characteristics, and microwave dielectric properties of (Zr_0.8Sn_0.2)TiO₄ (ZST) ceramics, we synthesized the ceramic samples using solid-state methodology. X-ray diffraction analysis indicated that the doped ZST samples were homogeneous, composed of a single phase with orthorhombic structure. Appropriate content of MgO doping favored grain growth and densification, affected the grain size distribution, and improved the dielectric properties of sintered ZST ceramics. With the sequentially increased in La₂O₃ and MgO contents, a defective ceramic including incomplete growth of grains, the incompact structures and the increasing porosities was formed. To demonstrate excellent microwave dielectric properties, 0.5 wt% La₂O₃ and 1.0 wt% MgO were added to ZST ceramics and sintered at 1320 °C for 5 h. Resulting sintered material had a moderate relative permitivitty (ε_r = 38.44), a superior Q × f value (52670 GHz at 5.6 GHz), and almost zero value for temperature coefficient of resonance frequency (τ_f = 0.81 ppm/°C).