Low-loss microwave dielectric of novel Li1-2xMxVO3 (M = Mg, Zn) (x = 0–0.09) ceramics for ULTCC applications

Abstract

Novel Li1−2xMxVO3 (M = Mg, Zn) (x = 0–0.09) microwave dielectrics suitable for ULTCC (ultra-low temperature co-fired ceramics) applications were synthesized. The X-ray diffraction patterns revealed that all samples were monoclinic structured with a space group of C2/c. Microstructures, lattice parameters, and Raman spectra of the ceramics were also studied. Q×f (Q: quality factor) was mainly controlled by intrinsic and extrinsic loss, while the variation of τf (temperature coefficient of resonant frequency) was related to ceramic bond valence. Poor microwave dielectric properties of pure LiVO3 can be tremendously enhanced by substituting a minute amount of Mg or Zn in place of Li. Excellent properties could be obtained for specimens sintered at 520 °C with an εr of 9.78, a Q×f of 45,600 GHz and an τf of –45 ppm/°C for Li0.98Mg0.01VO3, in addition to an εr (dielectric constant) of 9.25, a Q×f of 33,100 GHz and an τf of –53.6 ppm/°C for Li0.98Zn0.01VO3. Furthermore, the Li0.98Mg0.01VO3 specimen was found to be chemically comparable with the Al electrode. With 2 mol% of TiO2 added, the specimen at 520 °C achieved excellent characteristics which include an εr of 9.2, a Q×f of 30,000 GHz, and an τf of –2.8 ppm/°C, making it a very promising ULTCC dielectric for high-frequency 5 G applications.