Microwave dielectric properties of low-temperature sintered Mg3(VO4)2 ceramic

In order to develop a new low-temperature co-fired ceramics (LTCC), the microwave dielectric properties and microstructure of (Mg3−xCox)(VO4)2 ceramics were investigated. The grain growth of Mg3(VO4)2 ceramic was observed as the sintering temperature was increased from 750 to 1050 °C; the maximum Q·f value of 65,440 GHz was obtained at the sintering temperature of 1050 °C. At a sintering temperature of 1075 °C, the Mg3(VO4)2 ceramic decomposed to form the MgO and liquid phases; the Q·f value of the sample decreased. As for the Co substitution for Mg, the XRPD patterns of (Mg3−xCox)(VO4)2 ceramics showed a single phase over the whole composition range; the individual curves indicated the maximum values for density which gradually converge as the sintering temperature is increased but the values shift toward the lower sintering temperatures with Co substitution for Mg. As a result, a Q·f value of 78,906 GHz with a dielectric constant of 9.5 was obtained at x = 2 when the sample was sintered at 900 °C for 5 h in air, whereas the temperature coefficient was −94.5 ppm/°C.