The In Situ Preparation of Ni-Zn Ferrite Intercalated Expanded Graphite via Thermal Treatment for Improved Radar Attenuation Property.

The composites of expanded graphite (EG) and magnetic particles have good electromagnetic wave attenuation properties in the centimeter band, which is valuable in the field of radar wave interference. In this paper, a novel preparation method of Ni-Zn ferrite intercalated EG (NZF/EG) is provided in order to promote the insertion of Ni-Zn ferrite particles (NZF) into the interlayers of EG. The NZF/EG composite is in situ prepared via thermal treatment of Ni-Zn ferrite precursor intercalated graphite (NZFP/GICs) at 900 °C, where NZFP/GICs is obtained through chemical coprecipitation. The morphology and phase characterization demonstrate the successful cation intercalation and NZF generation in the interlayers of EG. Furthermore, the molecular dynamics simulation shows that the magnetic particles in the EG layers tend to disperse on the EG layers rather than aggregate into larger clusters under the synergy of van der Waals forces, repulsive force, and dragging force. The radar wave attenuation mechanism and performance of NZF/EG with different NZF ratios are analyzed and discussed in the range of 2-18 GHz. The NZF/EG with the NZF ratio at 0.5 shows the best radar wave attenuation ability due to the fact that the dielectric property of the graphite layers is well retained while the area of the heterogeneous interface is increased. Therefore, the as-prepared NZF/EG composites have potential application value in attenuating radar centimeter waves.

1,3,5-Trinitro-2,4-bis-(2-phenyl-ethen-yl)benzene.

In the title compound, C(22)H(15)N(3)O(6), the central benzene ring and one of the phenyl rings are essentially parallel to each other, making a dihedral angle of 1.35 (16)°. The dihedral angle between the two phenyl rings is 83.56 (19)°. Intra-molecular C-H⋯N and C-H⋯O hydrogen bonds occur. In the crystal, mol-ecules are linked through C-H⋯O hydrogen bonds. Furthermore, offset face-to-face π-π inter-actions with centroid-centroid distances of 3.644 (2) Šhelp to stabilize the crystal structure.

4-Methyl-3-nitro-benzaldehyde.

In the crystal structure of the title compound, C(8)H(7)NO(3), mol-ecules are linked through weak inter-molecular C-H⋯O hydrogen bonding.