Effects of La3+ or Ti4+ doping on dielectric and microwave absorption performance of CaMnO3 in the 8.2–18 GHz

In this paper, CaMnO3 and Ca0.97La (or Ti)0.03MnO3 powders were synthesized using mechanical ball milling technique and sintered at 1100°C for 12 h in an air atmosphere. Results showed that all the samples are single phase with an orthorhombic symmetry. Compared with the pure CaMnO3 sample, the Ca0.97La0.03MnO3 and Ca0.97Ti0.03MnO3 samples have higher complex permittivity and better microwave absorbing properties. These changes are caused by the doping-ion incorporating in CaMnO3 lattice and Ca vacancies, which could result in abundant dipoles and the local charge accumulation. The Ca0.97Ti0.03MnO3 sample exhibited the best microwave absorption performance, i.e. the minimum reflection loss was -46.9 dB with a matching thickness of 2.2 mm and effective absorption bandwidth reached 5.2 GHz with a thickness of only 1.8 mm. This study demonstrates that the CaMnO3 would be a potential material in the microwave absorbing field and needs further research.