Crystal structure and microwave dielectric characteristics of ixiolite ceramics with molybdenum ion modification and tri-layered structure

The ZnTi1−xMoxNb2O8 (0.000 ≤ x ≤ 0.060) microwave dielectric ceramics were prepared through traditional solid-state reaction. Mo4+ substitution for Ti4+ can markedly improve the microwave dielectric characteristics of ZnTiNb2O8 system. In the microstructures investigation, a suitable degree of Mo4+ substitution was shown to be useful for creating uniform grain size and minimizing dielectric loss. Raman spectroscopy and complex chemical bond theory analyses demonstrate that the bond ionicity of NbO bond is the intrinsic component influencing the εr value. The lattice energy of NbO bond, bond valence of Cation-O bond, and the FWHM of Raman spectra were the primary determinants of Q×f value. The τf value is mostly determined by variations in NbO bond energy and the bond valence of Cation-O bond. When x = 0.010, ZnTi0.990Mo0.010Nb2O8 ceramics exhibit excellent microwave dielectric characteristics: εr = 33.91, Q×f = 64,136 GHz, and τf = − 50.57 ppm/°C. Furthermore, in order to improve the temperature coefficient of resonant frequency (τf values close to zero) for the ZnTi0.990Mo0.010Nb2O8 ceramics, the TiO2 and laminated co-firing technique were used to adjust the comprehensive microwave dielectric characteristics of the ZnTiNb2O8 system. When the mass fraction of the TiO2 layer reaches 0.03 wt% after sintering at 1150 °C, the tri-layer structural ZTMN-0.03TO-ZTMN ceramics obtain outstanding microwave dielectric characteristics: εr = 41.52, Q×f = 50,827 GHz, and τf = − 2.59 ppm/°C, and these characteristics make them potential for usage in 5G communications. •A two-step strategy is proposed to improve the comprehensive microwave dielectric properties of ZnTiNb2O8 systems.•The effects of Mo4+ substitution on the crystal structure, microstructure, bonding properties, and microwave dielectric characteristics of rutile-like structural ceramics were comprehensively investigated.•Ceramic of ZnTi0.990Mo0.010Nb2O8 sintered at 1150 °C for 6 h exhibit excellent microwave dielectric characteristics: εr= 33.91, Q×f = 64,136 GHz, and τf = − 50.57 ppm/°C.•The bond ionicity of NbO bond is the intrinsic component influencing the εr value. The lattice energy of NbO bond, bond valence of Cation-O bond, and the FWHM of Raman spectra were the primary determinants of Q×f value. The τf value is mostly controlled by variations in NbO bond energy and the bond valence of Cation-O bond.•The microwave dielectric characteristics of the ZnTiNb2O8 system were comprehensively adjusted by the