Effects of Cu doping on phase composition, crystal structure, and dielectric properties of CaSiO3 ceramics

The dielectric ceramics of Ca1−xCuxSiO3 (x = 0 − 0.025) were prepared by solid-phase reaction method. The effects of Cu doping on phase composition, crystal structure, and dielectric properties of CaSiO3 ceramics were investigated. XRD results indicated that appropriate content of Cu doping could suppress impurity phases and obtain pure α-CaSiO3 calcined powders. After sintering, α-CaSiO3 phase was the main phase accompanied with a small quantity of impurity phases in undoped ceramics, which transformed to the single β-CaSiO3 phase after Cu doping. The phase transformation could be attributed to the change of the geometric position of SiO4 tetrahedron. SEM images showed that grain morphology changed from irregular and loose particles to dense lath by Cu doping. The Ca0.985Cu0.015SiO3 ceramics sintered at 1125 °C exhibited excellent dielectric properties: εr = 5.22, Q × f = 18,948 GHz, τf =  − 63 ppm/°C, and these make the ceramics promising for use in microwave applications.