Correlation between crystal structure and microwave dielectric properties of high-performance Li3Mg4(Nb1-xWx)O8+x/2 ceramics

Abstract

The sintering characteristics and microwave dielectric properties of a series of orthorhombic-phase Li3Mg4(Nb1-xWx)O8+x/2 (0.02 ≤ x ≤ 0.08) ceramics, which were synthesized according to the stacked form solid-phase reaction method within 1075°C–1150 °C, were reported in this work. The influence of W6+ ions on microscopic morphology, crystal structure, and thus on the microwave dielectric properties were analyzed. Moreover, the correlation between the crystal structure and dielectric properties was also established according to the PVL theory. In addition to the extrinsic factor of density, the impacts of intrinsic factors of the average bond ionicity within ceramics, the total lattice energy of Nb|W–O bonds, and the Nb|W–O6 octahedral distortion on the εr, Q×f value, and the τf value were investigated to further reveal the relationship between the crystal structure and properties, respectively. The introduction of W6+ ions into Li3Mg4(Nb1-xWx)O8+x/2 ceramics demonstrated a promising approach to enhance both the Q×f and the τf value. The Li3Mg4(Nb0.96W0.04)O8.02 ceramics sintered at 1125 °C showed exceptional properties with εr ∼ 13.62, Q×f ∼ 151, 300 GHz, and τf ∼ −14.03 ppm/°C and promising potential for applying in communication devices.