Heat-resistant unfired phosphate ceramics with carbon nanotubes for electromagnetic application

Abstract

Composite materials, containing low concentrations of carbon nanotubes (CNTs) of three different diameters and heat‐resistant phosphate ceramic as a matrix were prepared by cold‐pressing method. Their dielectric properties were studied at room temperature in a wide frequency range (20 Hz–1 MHz). It was found experimentally and proved theoretically via modeling of the composites as a random capacitor–resistor–diode network that electrical percolation concentration depends significantly on the diameter of the nanoinclusions. The main conclusion is that the best candidate providing both the lower percolation threshold and high absolute values of ac conductivity is thinner carbon nanotubes (in our particular case, 8–15 nm).

Exploring Carbon Nanotubes/Batio3/Fe3o4 Nanocomposites as Microwave Absorbers

“…Similar multiferroic composites made by combining piezoelectric and magnetostrictive nanoparticles were already investigated in the GHz range of frequencies [26]. The composites were produced as described in [21]. In the present study, commercially available (Aldrich) magnetite Fe 3 O 4 nanoparticles of mean size 50-100 nm, piezoelectric (Aldrich) BaTiO 3 nanoparticles (cubic) of mean size 50 nm, and phosphate matrix [21] in equal mass proportions were used.…”

“…The composites were produced as described in [21]. In the present study, commercially available (Aldrich) magnetite Fe 3 O 4 nanoparticles of mean size 50-100 nm, piezoelectric (Aldrich) BaTiO 3 nanoparticles (cubic) of mean size 50 nm, and phosphate matrix [21] in equal mass proportions were used. For tuning the refractive index of such 3-phase mixture, 0.1 wt.% of MWCNT [27] was also added.…”

“…Another interesting candidate for effective absorbers with refractive index similar to the one displayed in Fig. 9 is based on a phosphate ceramic matrix loaded with MWCNTs content above the percolation threshold [21].…”

“…In the present work, the parameters of absorption of microwave radiation in composites based on a phosphate ceramic matrix [21,22] were analysed. Our recent studies devoted to microwave absorbing materials [10] highlighted the main limitations of several physical parameters (complex effective permittivity, thickness, surface shape, etc.)…”

Effect of magnetic field treatment on the electromagnetic properties of polymer composite based on barium hexaferrite at microwave frequencies

“…Nowadays, electromagnetic (EM) wave absorption polymer composite materials have received much attention due to their wide applications for many electromagnetic compatibility (EMC) intentions [1][2][3][4][5][6][7][8]. Polymer composite materials have more suitable mechanical properties then ceramic composite.…”