Enhanced microwave dielectric properties of Al-doping LaBO3 ceramics: Phase, microstructure, electronic structure, and vibration modes

As microwave communication technology advances toward higher frequencies, greater integration, and enhanced adaptability to extreme environments, dielectric materials are required to balance the “ ε r - Q × f - τ f ” parameters. The influence and mechanisms on the phase, microstructure, and microwave dielectric properties of Al-doping LaBO 3 ceramics are systematically investigated. The LaB 1- x Al x O 3 (0≤ x  ≤ 0.08) ceramics were synthesized via the solid-state reaction method. Through first-principles calculations and characterization techniques (XRD, SEM, Raman spectroscopy), the optimization mechanism of Al doping on the microwave dielectric properties of LaBO 3 ceramics has been successfully elucidated. The results indicate that the addition of Al 3+ promotes the formation of LaAlO 3 second phase. This process significantly enhances the densification and grain growth of the ceramic. The best microwave dielectric properties achieved are: ε r  = 13.4, Q × f  = 78991 GHz, τ f  = −26.5 ppm/°C. This work elucidates the physical mechanism by which Al doping synergistically optimizes the microwave dielectric properties of LaBO 3 ceramics through multiple mechanisms.