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

Abstract The BaZnP 2− x Nb x O 7 microwave dielectric ceramics were prepared by solid‐state reaction method to investigate the impact of Nb 5+ on the composition, microstructure, and vibrational properties, as well as sintering characteristics and microwave dielectric properties. The solubility of Nb 5+ in the BaZnP 2− x Nb x O 7 lattice was limited. A moderate amount of Nb 5+ substitution could promote the densification process. The vibrational characteristics of the BaZnP 2 O 7 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) ε 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 × f values. The BaZnP 2− x Nb x O 7 samples sintered at 925°C exhibited the outstanding microwave dielectric properties with x = 0.02: ε r = 7.98, Q × f = 60 615 GHz (tan δ = 2.18 × 10 −4 ; f = 13.21 GHz) and τ f = −52.93 ppm/°C ( ρ bulk = 4.03 g/cm 3 ; ρ r = 92.69%). The proposed ceramic is expected to be used in microwave substrates.