Synthesis and dielectric properties of a new Mg2CeNbO6.5 ceramic system at microwave frequencies

New microwave dielectric ceramics Mg 2 CeNbO 6.5 were synthesized by solid-state method. The phase, crystal structure, micro-structures and microwave dielectric properties of Mg 2 CeNbO 6.5 ceramics had been investigated in the sintering temperature range of 1225–1325 °C. Two phases were detected by the X-ray diffraction patterns, including the main crystalline phase of CeO 2 and the second phase of Mg 4 Nb 2 O 9 . Well-developed microstructures of the well-dense samples were obtained for samples sintered at 1225–1325 °C. As sintering temperature increased, the τ f values were stable, however, the significant change in the ɛ r values and Q ×  f values were observed. At 1275 °C, the obtained Mg 2 CeNbO 6.5 ceramics had promising excellent microwave dielectric properties: ε r  = 15.38, Q ×  f  = 17,300 GHz and τ f  = − 49.71 ppm/°C.