Electromagnetic wave absorption properties of Pr1-xBaxMnO3 ceramics prepared by a sol–gel combustion method

Abstract

Manganese-based rare-earth perovskite oxides with excellent dielectric loss and effective magnetic loss have attracted considerable attention as microwave-absorbing materials. Herein, irregular spherical particles of Pr1-xBaxMnO3 (x = 0, 0.02, 0.04, 0.06) were successfully designed and fabricated by a sol–gel combustion method. The Ba2+ doping amount played a dominant role in adjusting the electromagnetic (EM) functions of the PrMnO3 ceramics. X-ray diffraction and refinement results illustrated that Ba2+ doping had no effect on the main phase of PrMnO3, but it caused lattice distortion and led to changes in the lattice constant of the material. The magnetisation curves did not reach saturation, and the materials had low coercivity at room temperature. Fluctuations in the Mn4+/Mn3+ ratio due to oxygen vacancies decreased owing to the addition of Ba2+, as demonstrated by the X-ray photoelectron spectroscopy analysis. It was observed that the absorption of electromagnetic wave (EMW) energy could be effectively controlled by adjusting the Ba2+ content. The Pr0.98Ba0.02MnO3 sample exhibited the best EMW absorption ability; the minimum reflection loss (RLmin) was -46.45 dB (absorption rate of 99.99%), and the matching thickness was 3.7 mm. The maximum bandwidth of the Pr0.98Ba0.02MnO3 sample was 6.16 GHz, while the thickness of the absorbing coating was only 2.5 mm. When d = 5.5 mm, Pr0.94Ba0.06MnO3 achieved an RL of -18.97 dB at 5.04 GHz (C band). This shows that Pr0.94Ba0.06MnO3 also has good microwave absorption ability in the low-frequency C band, and its RL peak conformed to the nλ/4 cancellation law at a given thickness. The results show that the low-cost sol–gel combustion synthesis process and lightweight, wideband, and strong absorption ability of Pr1-xBaxMnO3 make it a promising candidate for microwave absorbers.