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

Abstract

The single-phase, cubic-structured Ba3La(PO4)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: εr = 9.54, Q × f = 32820 GHz, and τf = -43.1 ppm/°C. In addition, the relative density is positively correlated with εr 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 εr, while the lattice energy and bond energy of the P-O bond respectively dominate the Q × f and τf 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 Ba3La(PO4)3 ceramics hold promise for applications in high-frequency microwave communication.