Harnessing Cu Incorporation for Achieving Stable Superior Microwave Dielectric Properties in Low Permittivity MgSiO3-Based Ceramics through Effective Phase Transition Suppression

MgSiO3 ceramics with a low dielectric constant are highly promising for application in 5G communication due to their excellent performance and cost-effectiveness. However, the application remains constrained by phase transitions. This study aims to unlock their full potential by introducing Cu ions to mitigate phase transitions, thereby achieving stable and superior performance. Mg1-xCuxSiO3 (0≤x≤0.25) ceramics were synthesized by solid-state method, and the effects of Cu introduction on the crystal structure, phase constitution, microstructure and microwave dielectric properties were systematically investigated. Through XRD patterns and Rietveld refinement, it was found that when x=0, both protoenstatite (PEN) and low-temperature clinoenstatite (CEN) phases coexist due to a phase transition from PEN to CEN. As x increases, the PEN phase dominance rises while the CEN phase diminishes, indicating that the addition of Cu ions inhibits the occurrence of phase transition. At x≥0.2, only the orthoenstatite (OEN) phase was observed. SEM and EDS analyses revealed the beneficial impact of Cu introduction on sintering, yet excessive amounts can lead to abnormal grain growth, local segregation, and uneven distribution of Cu elements, thereby deteriorating microwave dielectric properties. The optimal microwave dielectric performance was achieved at x=0.05: εr=6.2, Qf=93,600 GHz, τf=-33.7 ppm/°C. A one-year long-term comparative study revealed the stabilizing effect of Cu incorporation for obtaining stable excellent performance. These findings underscore the potential of introducing an appropriate amount of Cu to achieve stable and superior microwave dielectric properties in MgSiO3 ceramics, paving the way for practical applications in 5G communication.