Wenyi Li,Feng Li,Xiaoming Qiu,Chuangchuang Gong,Min Jiang,Zhenxin Zhao,Xiaomin Wang
Owing to the intrinsic dielectric-magnetic coupling loss mechanism, perovskite-type lanthanide-transition metal oxide (LaTMO 3 ) is considered as a promising candidate for electromagnetic wave absorbing material, but unmodified LaTMO 3 suffers from limited polarization processes and weak super-exchange magnetic response. Herein, we manipulate the TM-O bond properties by regulating the configuration entropy of transition metal sites to address such issues within single-phase LaTMO 3 . Elaborate structural characterization and P-V-L bond theory demonstrate quantitatively the optimization of electromagnetic wave absorption performance mainly stems from the synergistic improvement in TM-O bond distortion degree and covalency, as well as the formation of diverse super-exchange pathways. Consequently, the high entropy La(Cr 0.2 Mn 0.2 Fe 0.2 Co 0.2 Ni 0.2 )O 3 exhibits a minimum reflection loss of −50.68 dB, an effective absorption bandwidth covering entire Ku band of 7.6 GHz. The radar cross section of the structure with La(Cr 0.2 Mn 0.2 Fa 0.2 Co 0.2 Ni 0.2 )O 3 coating are less than −10 dBm 2 within the incident angles -60-60°. This study contributes to a deeper understanding of design and preparation of efficient broadband electromagnetic wave absorbing materials.
Currently, research on A 3+ B 3+ O 3 - type microwave dielectric ceramics is scarce. To address these challenges, a novel perovskite - type LaTmO 3 ceramic with a single phase orthorhombic structure (space group Pnma (62)) was synthesized via the solid state reaction method at 1450–1575 °C. Furthermore, SEM was employed to observe the microstructure of the sample, and Raman spectroscopy was utilized to analyze the impact of lattice vibrations on dielectric loss. Additionally, calculations based on the complex chemical bond theory revealed that the values of the εᵣ , Q×f , and τ f were influenced by bond ionicity, lattice energy, and bond energy, respectively. The LaTmO 3 ceramic sintered at 1525 °C demonstrated optimal microwave dielectric properties: Q×f = 179,601 ± 9579 GHz (at 8.4 GHz), εᵣ = 27.8 ± 0.18, and τ f = +9.8 ± 1.5 ppm/°C. Moreover, HFSS simulations demonstrated the applicability of LaTmO 3 in dielectric resonator antennas, achieving >90 % radiation efficiency, about 5.5 dBi gain, and 130 MHz bandwidth at 4.7 GHz, highlighting its potential for 5G oriented components.
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