(5 − x)BaO–xMgO–2Nb2O5 ceramics prepared using a reaction-sintering process

(5 − x)BaO–xMgO–2Nb2O5 (x = 0.5 and 1; 5MBN and 10MBN) microwave ceramics prepared using a reaction-sintering process were investigated. Without any calcinations involved, the mixture of BaCO3, MgO, and Nb2O5 was pressed and sintered directly. MBN ceramics were produced after 2–6 h of sintering at 1350–1500 °C. The formation of (BaMg)5Nb4O15 was a major phase in producing 5MBN ceramics, and the formation of Ba(Mg1/3Nb2/3)O3 was a major phase in producing 10MBN ceramics. As CuO (1 wt%) was added, the sintering temperature dropped by more than 150 °C. We produced 5MBN ceramics with these dielectric properties: ɛr = 36.69, Qf = 20,097 GHz, and τf = 61.1 ppm/°C, and 10MBN ceramics with these dielectric properties: ɛr = 39.2, Qf = 43,878 GHz, and τf = 37.6 ppm/°C. The reaction-sintering process is a simple and effective method for producing (5 − x)BaO–xMgO–2Nb2O5 ceramics for applications in microwave dielectric resonators.