Low temperature sintering and microwave dielectric properties of 7NiNb2O6–9TiO2 ceramics with CuO addition

Abstract

The effects of CuO additive on sintering temperature and microwave dielectric properties of 7NiNb2O6–9TiO2 ceramics prepared by solid-state reaction method have been investigated. The phases and microstructure have also been evaluated using X-ray diffraction and scanning electron microscopy. The pure 7NiNb2O6–9TiO2 ceramics show a high sintering temperature of about 1,200 °C. However, the addition of CuO lowered the sintering temperature of 7NiNb2O6–9TiO2 ceramics from 1,200 to 935 °C due to the CuO liquid-phase. The results showed that the microwave dielectric properties were strongly dependent on densification, crystalline phases and grain size. The 7NiNb2O6–9TiO2 ceramics with the addition of 3.2 wt% CuO sintered at 935 °C afforded excellent dielectric properties of e r = 60.5, Q × f = 10,039 GHz (at 3.8 GHz) and τ f = 62 ppm/°C, which represented very promising candidates for LTCC dielectric materials.