Microwave absorption properties of ZnCo2O4 and MnCo2O4 powders synthesized by oxalate-assisted hydrothermal method

Abstract

Zinc and manganese spinel cobaltites were prepared by hydrothermal method using oxalic acid as precipitant. The structural, microstructural, and magnetic and microwave absorption properties were analyzed by various characterization methods. The ZnCo2O4 nanoparticles were arranged as lamellar-like morphology, while the MnCo2O4 powders were composed of the large octahedral particles. The ZnCo2O4 powders showed the ferromagnetic behavior with the higher magnetization of 3 emu/g at 15 kOe than that of the MnCo2O4 powders (1.5 emu/g). The ZnCo2O4 powders had the better microwave absorption performances, including a minimum reflection loss of −40 dB and an effective absorption bandwidth of 3.6 GHz in Ku band at a matching thickness of 1.6 mm. However, the MnCo2O4 powders absorbed a great fraction (60%) of X band at a matching thickness of 2.4 mm with a minimum reflection loss of −43 dB.