Microwave-Absorbing Polymer-Derived Ceramics from Cobalt-Coordinated Poly(dimethylsilylene)diacetylenes

The microwave absorption materials in the X-band with high-temperature resistance are an important and urgent topic in functional materials. In this article, we present a useful and promising strategy to prepare cobalt-containing microwave absorption ceramics with high-temperature resistance. The polymer-derived ceramics were obtained via pyrolysis of carbon-rich poly(dimethylsilylene)diacetylenes coordinated with octacarbonyldicobalt. XRD and Raman spectra revealed that introduction of cobalt led to in situ formation of cobalt silicide nanocrystals and crystallized carbons (graphitic and tubular carbons), resulting in an enhanced microwave absorption property. The microwave absorption property and bandwidth could be tuned by controlling the cobalt content and annealing temperature of ceramics. When the average real permittivity, imaginary permittivity, and loss tangent of materials increased to 8.06, 3.10, and 0.39, the reflection coefficient (RC) value of as-synthesized ceramics was lower than -10 dB almost across the whole X-band (8.46-12.4 GHz). The minimum RC value of -42.43 dB at 10.55 GHz showed over 99.99% absorption of electromagnetic waves. The high-performance cobalt-containing microwave absorption ceramics possess promising potential in the field of electromagnetic interference protection.