Phase composition, dielectric properties, bond characteristics, and Raman spectra of NaAg1-xBix/3MoO4 ceramics synthesized at ultra-low temperature

In this study, the NaAg1-xBix/3MoO4 (x = 0.06, 0.12, 0.18, and 0.24) ceramics were successfully synthesized via solid-state reaction at 400-535 degrees C. Notably, the NaAg0.82Bi0.06MoO4 ceramic exhibited exceptional dielectric properties at 450 degrees C (epsilon r = 7.39 f 0.05, Q x f = 18,867 f 1480 GHz, tau f =-84.8 f 1.3 ppm/degrees C). The Rietveld refinement confirmed its spinel-like structure belonging to the Fd-3m (227) space group, along with the formation of a Na0.5Bi0.5MoO4 secondary phase, as supported by SEM and EDS analyses. Further investigation revealed that the Na0.5Bi0.5MoO4 phase adversely impacted the Q x f value, while the relative density positively correlated with Q x f. Based on the Shannon additivity rule, the contribution of Bi3+ ions to epsilon r was elucidated. The P-V-L theory provided a theoretical foundation for understanding the dielectric behavior of NaAg1-xBix/ 3MoO4 ceramics. Additionally, Raman spectroscopy directly confirmed the enhancement of molecular polarizability by Bi3+ ions and disclosed a negative correlation between the A1g vibration mode and Q x f, further elucidating the intimate link between internal lattice vibrations and microwave dielectric properties.