Effect of Cu2+ substitution on the crystal structure, bond properties, and microwave performance of ZnTiNb2O8 ceramics

Abstract

Dense Zn1-xCuxTiNb2O8 (x = 0.000, 0.002, 0.005, 0.007, 0.010, 0.020, 0.030, 0.040, and 0.050) ceramics were synthesized using a traditional solid-state reaction approach. In the past, CuO was employed as a sintering additive to reduce the sintering temperature. In this paper, the influence of Cu2+ substitution on crystal structure, microstructure, bond properties, and microwave performance in ceramics with rutile-like structure was thoroughly investigated for the first time. According to the microstructures investigation, a moderate degree of Cu2+ substitution was shown to be useful for establishing uniform grain size and limiting dielectric loss. Furthermore, Raman spectroscopy and complex chemical bond theory were used to identify the relationship between microwave performance and intrinsic components in order to further investigate the influence mechanism of microwave performance. The results support that the determining factor of εr value is ionic polarizability. The major factors of Q×f value are the total lattice energy and the FWHM of Ag(2) stretch mode in Raman spectra. In addition, the τf value is mainly regulated by the total bond energy. Especially, the Zn1-xCuxTiNb2O8 (x = 0.005) ceramic exhibited excellent microwave performance: εr = 31.55, Q×f = 62,045 GHz, and τf = −48.01 ppm/°C, making it a viable choice for microwave components.