A novel Li2TiO3-Li2CeO3 ceramic composite with excellent microwave dielectric properties for low-temperature cofired ceramic applications

A novel low-temperature sinterable (1 − x)Li2TiO3-xLi2CeO3 (x = 0.08 − 0.16 in molar) microwave dielectric ceramic was successfully prepared by a conventional solid-state reaction method. The X-ray diffraction and scanning electron microscopy analysis revealed the coexistence of two phases with different structures owing to their good chemical stability. Their relative content was easily adjusted to achieve near-zero temperature coefficient of the resonant frequency (τf) according to the mixing rule of dielectrics. The low-temperature sintering and desirable microwave dielectric properties can be simultaneously achieved by adding Li2CeO3 to the Li2TiO3 matrix owing to its low-firing characteristic and opposite-sign τf. The composite ceramics with x = 0.14 could be well sintered at 850 °C and exhibited excellent microwave dielectric properties of εr ∼ 21.2, Qxf∼ 59,039 GHz and τf ∼−7.4 ppm/°C. In addition, no chemical reaction was identified between the matrix phase and Ag, suggesting that the Li2TiO3-Li2CeO3 ceramics might be promising candidates for low-temperature co-fired ceramic applications.