Structure, bond characteristics, and microwave dielectric properties of Ba3La(PO4)3 ceramic

The single-phase, cubic-structured Ba 3 La(PO 4 ) 3 ceramics were synthesized using the traditional solid-state reaction method. The ceramic sintered at 1375 °C exhibited a relative density of 95.4 %, indicative of a dense microstructure and excellent sintering characteristics. Furthermore, they displayed remarkable microwave dielectric properties : ε r  = 9.54, Q × f  = 32820 GHz, and τ f  = −43.1 ppm/°C. In addition, the relative density is positively correlated with ε r and Q × f of ceramics. According to the complex chemical bond theory, the ionicity of the Ba/La–O bond has a more significant impact on the ε r , while the lattice energy and bond energy of the P–O bond respectively dominate the Q × f and τ f values. Moreover, the results from Raman spectroscopy indicate that several prominent Raman bands are associated with the vibration of the P–O bond. These findings suggest that Ba 3 La(PO 4 ) 3 ceramics hold promise for applications in high-frequency microwave communication.