The phase transition process of the MnO₂ phase with increases in Co²⁺ doping can be described by the Ouroboros symbol. The undoped sample is pure δ-MnO₂ with nanosheets structures. Then a small amount of Co²⁺ ions changes the final products and generates α-MnO₂ nanofibres in the δ-MnO₂ matrix. The products become pure α-MnO₂ with an appropriate amount of Co added. However, when the Co amount continues to increase, the amount of α-MnO₂ decreases in the products and turns back to form pure δ-MnO₂ in the end. Analysing the electromagnetic absorption performance, the relationship between the properties and the proportion of δ-MnO₂/α-MnO₂ in the powders adjusted by Co²⁺ doping has been explored, and the composites of δ-/α-MnO₂ show better absorption ability than the single-phase samples. As a result, the optimal reflection loss (RL) is −54.8 dB, and the effective absorption bandwidth can cover the Ku band at a thickness of 2.2 mm and the X band at a thickness of 3.1 mm with 50 wt.% filler loading ratios. This research might shed new light on the improvement of novel microwave absorption materials.

中文翻译：

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提供Co 2+离子后，MnO 2中的纳米片和纳米线结构之间的转变及其在微波吸收中的应用

MnO ₂相的相变过程随着Co ²⁺掺杂的增加而可以用Ouroboros符号来描述。未掺杂的样品是纯δ-的MnO ₂与纳米片的结构。然后钴的少量²⁺离子改变终产物，并生成α-MnO的_2个在δ-MnO的纳米纤维₂矩阵。所述产品成为纯α-MnO的₂用Co的适当量加入。然而，当钴量继续增加时，α-MnO的量₂在产品下降和折回以形成纯δ-的MnO ₂到底。分析所述电磁吸收性能，-MnO的δ的属性和的比例之间的关系₂ /α-MnO的₂中的Co调整粉末²⁺掺杂已探索，和δ-/α-MnO的复合材料₂显示更好吸收能力比单相样品高。结果，最佳的反射损耗（RL）为-54.8 dB，并且有效填充带宽可以以50重量％的填充剂填充率覆盖厚度为2.2 mm的Ku带和厚度为3.1 mm的X带。 。该研究可能为新型微波吸收材料的改进提供新的思路。