A high dielectric energy storage performance is achieved in a 0.85Bi _0.5 Na _0.5 TiO ₃ –0.15NaNbO ₃ lead-free ferroelectric ceramic via composition and microstructure engineering.

A flat Luneburg lens antenna for Ku-band (12—18 GHz) applications is proposed and designed using ceramic 3-D printing. Metamaterial structures and transformation optics technology are used to realize the gradient dielectric constant, compress the height, and reduce the weight of the Luneburg lens. The proposed 3-D printed Luneburg lens, combined with a 10-dB standard gain horn antenna, obtained an antenna gain up to 19.1 dBi over the operating frequency and the thickness reduction of 78%. In addition, the ability of the flat Luneburg lens to perform passive beam scanning with limited power loss is achieved. This exploration of ceramic 3-D printing can serve as reference for the development of ceramic components with complex structures.