The lattice vibration and microwave dielectric properties of BaZnP2-xNbxO7 ceramics for microwave substrates

The BaZnP2-xNbxO7 microwave dielectric ceramics were prepared by solid-state reaction method to investigate the impact of Nb5+ on the composition, microstructure, and vibrational properties, as well as sintering characteristics and microwave dielectric properties. The solubility of Nb5+ in the BaZnP2-xNbxO7 lattice was limited. A moderate amount of Nb5+ substitution could promote the densification process. The vibrational characteristics of the BaZnP2O7 ceramics were first studied by performing experimental and theoretical Raman and infrared spectroscopy measurements in this work, and their relationship with the microwave dielectric properties was studied. The acquired results showed that (I) epsilon(r) was influenced by both the density and the second phase; (II) the density and full width at half maximum of the Raman vibrational peak played a critical role in affecting the Q x f values. The BaZnP2-xNbxO7 samples sintered at 925 degrees C exhibited the outstanding microwave dielectric properties with x = 0.02: epsilon(r) = 7.98, Q x f = 60 615 GHz (tan delta = 2.18 x 10(-4); f = 13.21 GHz) and tau(f) = -52.93 ppm/degrees C (rho(bulk) = 4.03 g/cm(3); rho(r) = 92.69%). The proposed ceramic is expected to be used in microwave substrates.