Sintering behavior, crystal structures, phonon characteristics and dielectric properties of LiZnPO4 microwave dielectric ceramics

Abstract

Single phase LiZnPO4 (LZP) microwave dielectric ceramics were synthesized via a conventional solid-state ceramic route at different temperatures. Their sintering behavior, crystal structures, phonon characteristics and dielectric properties were studied in detail so as to further expound their physical mechanism of the dielectric respond. The results indicate that the LZP ceramic sintered at 825 °C exhibits a relative dielectric constant of 5.50 and a fine quality factor of 47,207 (f = 15 GHz). Raman vibrational modes below 600 cm−1 are classified as the external modes, which are associated with Li+ and Zn2+ ions, and the internal modes above 600 cm−1 are related to the vibration of the [PO4]3- tetrahedron. On the light of the infrared reflection spectrum, the dielectric properties simulated via the four-parameter semi-quantum model are similar to the measured property values, which demonstrate that the modes of low-frequency are the main factors affecting the dielectric properties. The dielectric constant is inversely related to the P–O bond length and the Raman shift of mode 13 ([PO4]3−tetrahedral vibration). The Q × f value owns a negative correlation with packing fraction and full width at half maximum values of modes 13. That is, the semi-quantitative relationships between the structures and the properties of the LZP ceramics were successfully established as a function of the sintering temperature.