Bonding characteristics, electrical and microwave/terahertz dielectric properties of novel low-permittivity Li2CuP2O7 pyrophosphate ceramic for Sub-6G band applications

In this study, a novel low-permittivity Li 2 CuP 2 O 7 pyrophosphate ceramic with a monoclinic structure (space group C 2/ c ) was fabricated via solid-state reaction. The highest density was observed in Li 2 CuP 2 O 7 ceramic at 750 °C, leading to optimal dielectric properties: ε r = 4.81, Q×f = 65,826 GHz, and τ f = −25.89 ppm/°C. Lattice vibration characteristics were investigated via Raman and FT-IR spectroscopy, while the optical bandgap was determined through UV-Vis spectroscopy. Electrical properties were examined, and the migration mechanism of ions within this structure was further investigated. The P-V-L theory and the atomistic modelling results are in mutual agreement, collectively elucidating the relationship between structure and performance. The terahertz frequency response was also evaluated. Finally, a 5G-compatible patch antenna was developed using Li 2 CuP 2 O 7 ceramic, thereby validating its practical application potential in advanced communication systems.