Fig. 1. Synthesis of the SiCnws/BSAS ceramic heterojunction and microstructure characterization. (a) Schematic illustration of the synthesis procedure. (b) Structure schematic diagrams of the samples, insert: BSE images. (c) Original morphology of SiCnws and (d-f) its distribution in samples.

Fig. 2. Microstructure characterization and component investigation on the SiCnws/BSAS ceramic heterojunction. TEM images of (a) sample S10, (b) SiCnws, and (c) BSAS. (d, g) HRTEM images for selected interface. SAED pattern of (e) SiCnws in grain E, and (f) Celsian-like BSAS in grain F. FFT images of (h) Paracelsian-like BSAS in area H, and (i) Celsian-like BSAS in area I. (j) Schematic diagram of in-plane chemical ordering of SiCnws and BSAS. (k) EDS element mapping of sample S10. (l) XRD pattern of the samples and raw powders.

Fig. 3. Electromagnetic absorption performance for the SiCnws/BSAS ceramic heterojunction. (a-d) Contours of reflection loss (RL) values of sample S0, S10, S20 and S30, respectively. The curves of effective absorption band (RL ≤ -10 dB) for (e) sample S10 and (f) sample S20 with thickness below 2.0 mm.

Fig. 4. Analysis of the SiCnws/BSAS ceramic heterojunction evolution on conductive and polarization loss. (a) Valence band XPS spectrum of BSAS and SiCnws. Insert: magnified image of a local area. (b) Energy gap of BSAS and SiCnws. Insert: the calculated energy gap value by UV-vis diffuse reflectance spectrum. (c) Schematic illustration for the transfer and separation of charge carriers on SiCnws/BSAS heterojunction. (d) Permittivity parameters for BSAS (sample S0). Insert: the corresponding Cole-Cole plots. The ratio of permittivity of the SiCnws/BSAS heterojunction to BSAS: (e) real part, (f) imaginary part. (g) Cole-Cole plots for sample S10. (h) Schematic diagram of polarization mechanism: I defect polarization, II interfacial polarization. (i) Conductive loss and polarization loss for the samples.

Fig. 5. Analysis of electromagnetic absorption performance of the SiCnws/BSAS ceramic heterojunction under variable-temperature. (a-f) Contours of reflection loss (RL) values of sample S10 from 100 to 600 °C, respectively. (g) Curves of minimum value of RL at different temperatures vary with thickness. (h) Proportion of effective absorption bandwidth covering X-band from 100 to 600 °C with thickness below 2.0 mm (sample S10).

Fig. 6. Analysis of the effect of temperature change on conductive and polarization loss. The ratio of permittivity of sample S10 at different temperatures to room temperature: (a) real part, (b) imaginary part. (c) Fitted conductivity and (d) fitted relaxation time of sample S10 at different temperatures. Insert of (d): Schematic diagram of heterogeneous interface as polarization center. (e) Conductive loss and polarization loss for sample S10 at different temperatures. (f) Schematic illustration of electromagnetic absorption mechanisms for the SiCnws/BSAS heterojunction.

Fig. 7. Environmental adaptation of the SiCnws/BSAS ceramic heterojunction. (a) Schematic illustration of the environmental adaptation. (b) Curves of effective absorption bandwidth (EAB, reflection loss ≤ -10 dB) for original sample S10 with thickness below 2.0 mm. (c-f) The curves of EAB for sample S10 after 7 days incubation in pH = 5.6 solution, pH = 8.5 solution, 600 °C static air, and 600 °C water vapor with thickness below 2.0 mm, respectively.