Effect of sintering aid on microwave dielectric behaviors of Ni0.5Ti0.5NbO4 ceramics for LTCC applications

The effects of ZnO glass addition on the microwave dielectric properties of Ni_0.5Ti_0.5NbO₄ (NTN) ceramics prepared by solid-state reaction method have been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The pure NTN ceramics have ε_r of 60.6, Q × f value of 70,100 GHz, and τ_f value of 76.6 ppm ^°C⁻¹ sintered at 1140 °C for 6 h. The results indicate that the addition of ZnO can effectively benefit the densification and further improve the dielectric constant. Moreover, the lower sintering temperature of NTN ceramics from 1140 to 930 °C is obtained by the addition of ZnO glass. However, an excess of ZnO suppresses the grain growth and decreases the Q × f value of NTN ceramics. The NTN ceramics with 2 wt% ZnO sintered at 930 °C for 6 h possess promising microwave dielectric properties: ε_r of 56.3, Q × f value of 67,000 GHz, and τ_f value of 78.6 ppm °C⁻¹, which shows that the materials are suitable for low-temperature co-fired ceramics applications.