Relationship between Rattling Mg2+ ions and anomalous microwave dielectric behavior in Ca3-xMg1+xLiV3O12 ceramics with garnet structure

Ca3-xMg1+xLiV3O12 (0 <= x <= 1) ceramics with cubic-garnet-structure were synthesized by the solid-phase reaction. The replacement of Ca2+ with the smaller Mg2+ exerted an increasingly strong "rattling" effect at the A site of Ca3-xMg1+xLiV3O12. With increased Mg2+, epsilon(r) increased from 10.5 +/- 0.1 to 15.4 +/- 0.1 and epsilon(corr) increased from 11.0 +/- 0.1 to 16.0 +/- 0.1, whereas the theoretical epsilon(th) decreased from 12.0 +/- 0.1 to 10.5 +/- 0.1. epsilon(corr) was higher than epsilon(th) due to the "rattling" effect. The enhanced "rattling" effect caused of to increase rapidly from -64.1 +/- 1.0 ppm/degrees C to +267.2 +/- 1.0 ppm/degrees C. With increased x, Q x f decreased from 74,700 +/- 500 GHz to 15,370 +/- 500 GHz, due to the decreased packing fraction, increased FWHM of the A(1g) modes, and enhanced "rattling" effect. Additionally, the chemical compatibility between Ca2.75Mg1.25LiV3O12 and Ag electrodes was confirmed, indicating this material's potential for LTCC.