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

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 Pr 1-x Ba x MnO 3 (x = 0, 0.02, 0.04, 0.06) were successfully designed and fabricated by a sol–gel combustion method. The Ba 2+ doping amount played a dominant role in adjusting the electromagnetic (EM) functions of the PrMnO 3 ceramics. X-ray diffraction and refinement results illustrated that Ba 2+ doping had no effect on the main phase of PrMnO 3 , 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 Mn 4+ /Mn 3+ ratio due to oxygen vacancies decreased owing to the addition of Ba 2+ , 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 Ba 2+ content. The Pr 0.98 Ba 0.02 MnO 3 sample exhibited the best EMW absorption ability; the minimum reflection loss (RL min ) was -46.45 dB (absorption rate of 99.99%), and the matching thickness was 3.7 mm. The maximum bandwidth of the Pr 0.98 Ba 0.02 MnO 3 sample was 6.16 GHz, while the thickness of the absorbing coating was only 2.5 mm. When d  = 5.5 mm, Pr 0.94 Ba 0.06 MnO 3 achieved an RL of -18.97 dB at 5.04 GHz (C band). This shows that Pr 0.94 Ba 0.06 MnO 3 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 Pr 1-x Ba x MnO 3 make it a promising candidate for microwave absorbers.