Constructing the cationic rattling effect to realize the adjustability of the temperature coefficient in Nd2-Sm O3 microwave dielectric ceramics

In this work, a series of dense Nd2-xSmxO3 (x = 0.0 − 2.0) ceramics were synthesized using a solid-state reaction method at 1400 − 1575 °C. The ceramics were confirmed to be hexagonal at x < 0.5, and a monoclinic phase was observed in the ceramics when x ≥ 1.0. The microwave dielectric properties of Nd2-xSmxO3 (x = 0.0 − 2.0) are εr = 19.48 − 22.96, Q×f = 48,447 (x = 0.0) − 21,363 (x = 0.5) − 34,761 GHz (x = 2.0), and τf = -43.0 − +34.1 ppm/℃. The bond valence theory calculation demonstrates that the change of τf value from negative to positive is mainly affected by the rattling of Sm3+. Moreover, the series of ceramics were exposed to the air for different days to study the problem of rare earth oxide ceramics quickly decomposing in the air and found that Nd0.5Sm1.5O3 ceramic shows stable structure and performance.