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Xu et al. Soft Sci. 2025, 5, 43 https://dx.doi.org/10.20517/ss.2025.63 Page 7 of 16

Figure 3. Microstructure characterization of Ti CT and Ti CT /Si N aerogel. (A) Image of Ti CT /Si N sample; (B) SEM image of
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pure Ti CT ; (C) SEM image of Ti CT /Si N ; (D) Cross-sectional SEM image of Ti CT /Si N ; (E) SEM image of Ti CT ; (F) SEM image
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of Ti CT /Si N ; (G-N) EDS maps of Ti CT /Si N . SEM: Scanning electron microscope; EDS: energy dispersive X-ray spectroscopy;
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HAADF: high-angle annular dark-field.
rougher [Figure 3C and Supplementary Figure 3]. Guided by the quarter-wavelength theory, after Si N
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incorporation the interlayer spacing shrinks from 30 µm to 23 µm. This reduction increases the effective
propagation path, satisfying the λ/4 condition around 10 GHz and thereby intensifying multiple internal
reflections and attenuation . The smaller spacing also enlarges the distributed capacitance between
[58]
adjacent Ti CT sheets, enhancing interfacial polarization and dielectric loss through stronger capacitive
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coupling. Simultaneously, the Si N layer lowers the local effective permittivity near the surface while
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narrowing the spacing, improving impedance matching and allowing more electromagnetic energy to
penetrate the material. The thickness of the Si N layer was determined to be 1.4 μm at the Ti CT /Si N
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cross-section [Figure 3D]. The formation of the Si N -Ti CT -Si N sandwich structure was clearly observed.
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This structure reduces the reflection of electromagnetic waves through progressive impedance matching. A
closer examination of the Ti CT microstructure revealed interconnected pillars between the layers. These
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