Electromagnetic properties of phosphate composite materials with boron-containing carbon nanotubes

The possibility of developing electromagnetic composite materials based on unfired heat-resistant mechanically strong phosphate ceramics has been studied. Boron-containing multiwalled carbon nanotubes and onion-like particles (B-MWCNTs) synthesized by electric-arc evaporation of a graphite rod enriched with boron are used as a functional additive to the phosphate matrix. According to transmission electron microscopy, the average nanoparticle length is $\sim$ 100 nm. According to X-ray photoelectron spectroscopy and X-ray absorption spectroscopy, the boron content in B-MWCNT walls is less than 1 at%, and substitution of carbon atoms with boron leads to the formation of acceptor states in the conduction band. An increase in the electromagnetic response of phosphate ceramics by $\sim$ 53 and $\sim$ 13–15% for 1.5 wt% B-MWCNT additive is detected in quasi-static and gigahertz ranges, respectively. It is assumed that a stronger effect can be achieved using longer B-MWCNTs than those formed under electric arc conditions.