A new low-loss microwave dielectric ceramic GaNbO4

In this study, the preparation, phase constitution, microstructure and dielectric properties of GaNbO4 ceramics were investigated. Prepared via traditional solid-state reaction method at 1000-1080 °C, the GaNbO4 ceramics existed as a composite of two allomorphic GaNbO4 phases: α-GaNbO4 (monoclinic, space group P2/c, Z = 2) and β-GaNbO4 (monoclinic, space group C2, Z = 4). The contents of α and β GaNbO4 phases changed with the change of sintering temperature. The GaNbO4 ceramics showed a microstructure with closely packed grains in two different sizes and shapes. The GaNbO4 sintered at 1060 °C exhibited typical values of εr = 15.8, Q × f = 101,000 GHz and τf = −63.4 ppm/°C.