Ultra-low dielectric loss lithium-based, temperature stable microwave dielectric ceramics

Abstract

The low loss and small density of lithium-based microwave dielectric ceramics (MWDCs) make them promising for communication devices such as dielectric filters, antennas, and substrates. In this study, (1- x )[Li 2 Ti 0.98 Mg 0.02 O 2.96 F 0.04 −1 wt%Nb 2 O 5 ]- x Li 3 Mg 2 NbO 6 (LTMN 0.02 -LMN, 0 ≤ x ≤ 0.1) MWDCs fabricated via solid solution reaction were successfully synthesized to obtain a near-zero temperature coefficient of the resonant frequency (τ f ). The X-ray diffraction pattern and Rietveld refinement results showed that a good solid solution was formed and that the phase composition of the LTMN 0.02 system gradually changed from monoclinic to cubic. Scanning electron microscopy images revealed that the microstructure of LTMN 0.02 improved as the LMN content increased. Ultimately, desirable dielectric properties were obtained by sintering at 1220 °C with x = 0.08: ε r ∼18.1, Q × f ∼105,661 GHz, and τ f ∼ + 1.3 ppm/°C. Furthermore, the highest Q × f value (∼131,157 GHz) was achieved in the x = 0.04 composition with relatively homogeneous grains. The high-performance LTMN 0.02 -LMN ceramics developed in this study provide a new alternative material for the dielectric components of communication systems.