Low-dielectric-loss ZnZrNb2O8 ceramics combined with H3BO3 for low-temperature co-fired ceramics applications

H₃BO₃ was used as the sintering additive to enable Zn_0.997Cu_0.003ZrNb₂O₈ ceramics to accomplish low-temperature sintering and outstanding microwave dielectric performances. Composite ceramics were created using typical solid-state processes. The effects of added H₃BO₃ on the sintering behavior, microstructural characteristics, vibrational properties, and microwave dielectric performances of Zn_0.997Cu_0.003ZrNb₂O₈ + x wt% H₃BO₃ (2 $\le$ x $\le$ 8) ceramics have been systematically investigated by means of X-ray diffraction, Raman scattering spectroscopy, scanning electron microscopy, and complex chemical bond theory. The results of relative density and microscopic morphology demonstrated that the application of an adequate quantity of H₃BO₃ additive can significantly enhance sintering properties. The doped H₃BO₃ alters the inter-ionic interactions so that the structural features become intrinsic to the microwave dielectric performances. The particularly satisfactory microwave dielectric performances (${\epsilon }_r$ = 10.61, $Q\times f$ = 33 980 GHz, and ${\tau }_f$ = -45.10 ppm/°C) were detected in x = 6 ceramic specimens sintered at 950°C, which would make it promising for use in modern low temperature co-fired ceramics technology.