Microwave dielectric properties of silico-carnotite Ca3M2Si3O12 (M= Yb, Y) ceramics synthesized via high energy ball milling

The Ca3M2Si3O12 (M = Yb, Y) ceramics with orthorhombic silico-carnotite structure were fabricated via high-energy ball milling and solid-state reaction route. Dense Ca3Yb2Si3O12 and Ca3Y2Si3O12 ceramics sintered at 1260 °C and 1240 °C revealed promising microwave dielectric properties with εr = 9.2 and 8.7, Q×f = 56,400 GHz and 29,094 GHz, τf = −77.5 ppm/°C and −76.8 ppm/°C, respectively. The connection between crystal structure and Q×f values of Ca3M2Si3O12 (M = Yb, Y) ceramics was discussed with respect to the packing fraction, and their intrinsic microwave dielectric properties were examined using the infrared reflectivity spectra analysis. The thermal stability of Ca3Yb2Si3O12 was improved successfully by forming 0.91Ca3Yb2Si3O12‐0.09CaTiO3 composite ceramics with τf = +2.9 ppm/°C, εr = 12.93 and Q×f = 26,729 GHz.