Outstanding high-temperature microwave absorption properties of La0.9Sr0.1MnO3/Ba3.75La9.5Ti18O54 composite ceramics

Abstract

High-temperature microwave-absorbing materials are crucial for achieving radar stealth in high-speed equipment. In response to this necessity, we investigated xLa0.9Sr0.1MnO3/(1-x)Ba3.75La9.5Ti18O54 composite ceramics under variable temperatures, where x ranges from 20 to 50 wt%. X-ray diffraction analysis indicates the coexistence of La0.9Sr0.1MnO3 and Ba3.75La9.5Ti18O54 when x ranges from 20 to 30 wt%, transforming into a perovskite-structured solid solution with a higher proportion of La0.9Sr0.1MnO3. Variable-temperature direct current conductivity reveals a controllable transition from dielectric behavior to semiconductor behavior, resulting in the dielectric properties of composite ceramics shifting from low-loss to high-loss characteristics. For x values ranging from 20 wt% to 40 wt%, there consistently exists a corresponding temperature and frequency range ensuring specific absorption performance. Notably, the composite ceramic with x=30 wt% and a thickness of 1.1 mm demonstrates an effective absorption bandwidth (RL<-10 dB) of 1.75 GHz within the temperature range of 400–600℃. These findings suggest that composite ceramics comprising La0.9Sr0.1MnO3 and Ba3.75La9.5Ti18O54 hold promise as high-temperature microwave-absorbing materials.