Effects of Gd doping on microwave absorption properties and mechanism for CaMnO3 perovskites

ABO3 type perovskite oxides have been widely studied due to their unique structure and special electromagnetic properties. CaMnO3 is well known for its excellent thermoelectric performance and temperature stability. In this paper, Ca1-xGdxMnO3 (x = 0, 0.1, 0.2, 0.3, 0.4) perovskites were comprehensively studied by first-principles calculations and experimental characterizations on their crystal structure and electromagnetic properties to finally elaborate the microwave absorption mechanism. It is found that Gd doping significantly enhances the dielectric polarization effects, resulting in better electromagnetic wave absorption performance than undoped CaMnO3. Especially for CG2MO perovskite, its reflection loss and bandwidth below −10 dB at 2–18 GHz reaches −31.9 dB and 3.3 GHz approximately, exhibiting excellent microwave absorption property. Moreover, the microwave absorption mechanism of CGMO perovskites involves various modes of conductive loss, resonance loss, multiple reflection and scattering as well as the polarization phenomenon including interfacial polarization, dipole polarization and defect polarization. Among them, polarization effects and conductive loss contributes the most to the microwave absorption performance.