The reaction mechanism of a M (M = Mn, Fe, Co and Ni) atom inserted into a Fe8O12 cage

The reaction process of a M (M = Mn, Fe, Co and Ni) atom associated and then interpolated into a Fe8O12 cage is calculated by using a PBE exchange–correlation functional. The results reveal that Mn@Fe8O12 core@shell cluster possesses lower symmetry than the other MFe8O12 (M = Fe, Co and Ni) core@shell clusters. The MFe8O12 cages are more stable than the Fe8O12 cage and the corresponding M@Fe8O12 core@shell clusters. The M@Fe8O12 core@shell clusters are difficult to form via higher energy barriers. The M atom association ability of the Fe8O12 cage is as follows: Fe > Co > Ni > Mn. All the M association and interpolation Fe8O12 clusters have higher chemical activity.