Preparation and design of barium feldspar-based microwave dielectric ceramics from graphite tailings

Novel barium feldspar-based microwave dielectric ceramics derived from graphite tailings (BAS-GT) were prepared via the solid-state reaction method. The effects of Sr 2 + substitution on the phase composition, microstructure and microwave dielectric properties of sintered ceramics were investigated. Results demonstrated that the barium feldspar solid solution co-existed with Ca 2 Al 2 SiO 7 when excess Sr 2+ was introduced. The Sr 2+ substitution effectively improved the densification and microwave dielectric properties of the BAS-GT ceramics, especially the quality factor ( Q × f ) and temperature coefficient of resonant frequency ( τ f ), attributed to the optimised phase composition and good sintering behaviour. A component standard for utilising graphite tailings in microwave dielectric ceramics was established. The 10 mol% Sr 2+ substituted BAS-GT ceramic samples sintered at 1150 °C exhibited optimised microwave dielectric properties, with εᵣ  = 7.13, Q × f  = 28,452 GHz, and τ f = –27.12 ppm/°C, indicating significant potential of these ceramics for applications in 5 G wireless communication technology.