Synthesis and microwave dielectric properties of Ca3SnSi2O9 ceramics

Ca3SnSi2O9 ceramics were synthesized and their microwave dielectric properties were investigated. Non-stoichiometric compositions (molar ratio of Ca:Sn:Si = 1:1.2:1) were employed to synthesize pure monoclinic Ca3SnSi2O9 phase when sintering temperature varied between 1400 and 1525 °C. The Ca3SnxSi2O9+δ (x = 1.2) ceramics sintered at 1500 °C exhibited microwave dielectric properties: a dielectric constant (ɛr) of 8.44, a quality factor (Q × f) of 92,000 GHz and a temperature coefficient of resonant frequency (τf) of −60 ppm/°C. Monoclinic Ca3SnSi2O9 phase ceramics have a wide sintering temperature region, excellent sintering behavior and high quality factor. They are promising candidate materials for millimeter-wave devices.

► Monoclinic Ca3SnSi2O9 phase ceramics were synthesized when non-stoichiometric compositions were employed.
► Microwave dielectric properties of Ca3SnxSi2O9+δ (x = 1.2) ceramics were: ɛr = 8.44, Q × f = 92,000 GHz, and τf = −60 ppm/°C.
► The relative density, second phase and microstructures have large influences on dielectric properties of Ca3SnSi2O9 ceramics.
► Monoclinic Ca3SnSi2O9 phase ceramics have a wide sintering temperature region and high quality factor.