Crystal structure, bond characteristics and microwave dielectric properties of Ce2[Zr1-x(Sr1/3B2/3)x]3(MoO4)9 (B = Ta, Sb) solid solutions

Abstract

A series of Ce2[Zr1-x(A)x]3(MoO4)9 (A = Sr1/3Ta2/3, Sr1/3Sb2/3; x = 0.02, 0.04, 0.06, 0.08 and 0.10) (abbreviated as CZ1-xTx and CZ1-xSx) microwave dielectric ceramics were studied systematically with respect to microstructures, sintering behaviors, crystal structures, microwave dielectric properties and infrared vibrational modes. Density measurements and scanning electron microscopy (SEM) reveal the dense and homogeneous microstructures. X-ray diffraction (XRD) results confirm the formation of solid solutions belonging to the hexagonal system with a R3‾c space group, and the lattice volume increases with raising the doping content. Furthermore, the complex chemical bond theory was used to calculate the intrinsic bond parameters, and the correlations between the microwave dielectric properties and intrinsic bond parameters were established. Finally, far infrared (FIR) spectra reveal that the main polarization contribution stems from the absorptions of the phonon oscillations in these two groups of ceramics. Typically, the optimum microwave dielectric properties are achieved for CZ0.9T0.1 and CZ0.94S0.06 ceramics with εr = 10.24, Q × f = 92,009 GHz (at 9.70 GHz), τf = −8.84 ppm °C−1 and εr = 10.40, Q × f = 82,696 GHz (at 9.69 GHz) and τf = −8.04 ppm °C−1, respectively. Interestingly, the CZ0.9T0.1 ceramic exhibits the maximum Q × f value in the ion doped Ce2Zr3(MoO4)9 ceramics while retaining a good τf = −8.84 ppm °C−1.