Low-loss and temperature-stable (1-x)Li2TiO3-xLi(3)Mg(2)NbO(6) microwave dielectric ceramics

摘要

Low-loss (1 - x)Li2TiO3-xLi(3)Mg(2)NbO(6) (LT-LMN, 0.02 <= x <= 0.08) microwave dielectric ceramics (MDCs) with rock salt structures were fabricated via a traditional solid-state reaction route. Li3Mg2NbO6 was used as a Li2TiO3 compensator to improve temperature stability. Scanning electron microscope observations and X-ray diffraction analyses were used to investigate the microstructures and crystalline structures of the ceramics, respectively. We demonstrated a correlation between macroscopic "dark hole" phenomena and the microwave dielectric properties (MDPs) of LT-LMN ceramics by analysing the valence states of Ti ions and the content of oxygen vacancies using X-ray photoelectron spectra. We continuously added Li3Mg2NbO6 to pure Li2TiO3 to form MDCs, and found that at x = 0.04, (1 - x)Li2TiO3-xLi(3)Mg(2)NbO(6) ceramics achieved a near-zero resonance-frequency temperature coefficient (tau(f)). 0.96Li(2)TiO(3)-xLi(3)Mg(2)NbO(6) ceramics sintered at 1250 degrees C had excellent MDP values: appropriate permittivity (epsilon(r)) = 19.12, high quality factors (Q x f) = 70814 GHz (at 6.105 GHz), and tau(f) = 2.6 ppm/degrees C. This indicates that LT-LMN ceramics are promising materials for high-selectivity microwave ceramic dielectric substrates.