Li+ enrichment to improve the microwave dielectric properties of Li2ZnTi3O8 ceramics and the relationship between structure and properties

Abstract

Herein, Li+-enriched Li(1+x)2ZnTi3O8 ceramics are prepared via the solid-phase methods. As x increases, the unit cell volume gradually increases, while the grain size initially increases and then decreases gradually. The Li(1+0.06)2ZnTi3O8 ceramics exhibit the best dielectric properties: εr = 25.92, Q × f = 109534 GHz (@7.37 GHz, which is a 48 % increase compared with the stoichiometric counterpart.), and τf = −8.21 ppm/°C. The complex chemical bond theory and Raman spectroscopy reveal that Ti-O bonds have a significant effect on the dielectric properties. An optimal Li+ enrichment leads to an overall reduction in the distortion of the Li/ZnO4 tetrahedra, resulting in a reduction in τf. First-principles calculations demonstrate that a suitable excess of Li+ leads to an increase in the band-gap as well as an enhanced electron cloud density in the internal space of the Li1/ZnO4 tetrahedra, thereby increasing the Q × f. In summary, Li+-enriched Li(1+0.06)2ZnTi3O8 ceramics are promising for a wide array of applications in microwave communications.