Dielectric properties of magnesium oxide at microwave frequency

To understand the role of a residual MgO phase plays inside a ceramic body, a simple magnesium oxide ceramics was prepared to investigate its microwave dielectric properties. The ε_r and τ_f values of specimens using simple MgO only vary in a small range at the investigated temperatures (1400-1550 °C) implying they are not sensitive to the sintering temperature. However, the Q × f is strongly related to the density of the ceramics and a high Q × f of ∼113,600 GHz can be achieved by sintering the specimen at 1490 °C for 4 h. It indicates MgO may exist as a low-loss dielectric inside a dense ceramic body at microwave frequency.