Enhanced effect of non-stoichiometry on the sinterability and microwave dielectric properties of Mg^sub 2+x^SnO^sub 4^ ceramics

Mg^sub 2+x^SnO^sub 4^ microwave dielectric ceramics were prepared by the solid state reaction method. The effect of Mg non-stoichiometry on the sintering behavior, phase structure and microwave dielectric properties of Mg^sub 2+x^SnO^sub 4^ ceramics was investigated. The sinterability and microwave dielectric properties were improved for the samples with slightly excessive amount of Mg (x ≤ 0.15). Especially, the quality factor (Q × f) was significantly enhanced compared with the stoichiometric Mg^sub 2^SnO^sub 4^ (Q × f = 45, 300 GHz). The best overall performance was obtained for the Mg^sub 2.15^SnO^sub 4^ ceramics sintered at 1,620 °C for 4 h ([straight epsilon] ^sub r^ = 7.42, Q × f = 76,800 GHz, τ ^sub f^ = -50 ppm/ °C); this suggests a potential for applications in the millimeter wave range.[PUBLICATION ABSTRACT]