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An urgent problem of radio engineering and radioelectronics nowadays is the synthesis of composite materials with preset parameters that can be used as electronics engineering materials. Of special interest are MW range wide-band electromagnetic radiation absorbers. Special attention is paid to materials on the basis of ferromagnetic metals that are capable of effectively absorbing and reflecting incident waves and having a clear nanostructure. Development of nanocapsulated metals will allow controlling the parameters of newly designed materials. This is achieved with the use of polymer matrices, e.g. pyrolyzed polyacrylonitrile (PPAN). This work is a theoretical study of a PPAN monolayer model containing pairs of transition metal atoms iron, nickel and cobalt which possess ferromagnetic properties, in Fe-Co, Ni-Co and Fe-Ni combinations, with silicon amorphizing admixture. We studied the geometrical structure of the metal composite systems which are modeled as PPAN molecular clusters the centers of which are voided of six matrix material atoms, the resultant defects (the so-called pores) being filled with pairs of the metal atoms being studied. The metal containing monolayer proved to be distorted in comparison with the initially planar PPAN monolayer. We plotted single-electron spectra of the composite nanosystems and characterized their band gaps. The presence of metal atoms reduces the band gap of a metal composite as compared with pure PPAN. We determined the charges of the metals and found electron density transfer from metal atoms to their adjacent PPAN monolayer atoms. We calculated the average bond energy of the test metal composite systems and proved them to be stable. The studies involved the use of the density functional theory (DFT) method with the B3LYP functional and the 6-31G(d) basis.

The work deals with obtaining nickel metal-carbon nanocomposites based on IR-pyrolyzed polyacrylonitrile and nickel chloride hexahydrate and a study of the structural characteristics of the synthesized material. Nanocomposites have been prepared under IR-based precursor pyrolysis of polyacrylonitrile (PAN) and nickel chloride hexahydrate (NiCl2·6H2O). Pyrolysis has been carried out in the 150–700 °C temperature range. The grown nanocomposites are a two-phase system of the carbon matrix formed during carbonization of PAN and distributed in the nickel nanoparticles (nickel oxide). The average size of the nanoparticles in the nanocomposite was 15–25 nm. The effect of IR precursor pyrolysis temperature on the size of the nickel nanoparticles has been studied. We have determined that the size distribution of nickel nanoparticles is determined by the temperature of nanocomposite synthesis. While the temperature increases the prevailing average particle size of the metal increases and the distribution is blurred and shifts towards larger sizes. By calculating the total Gibbs energy of possible reduction reactions of nickel chloride and oxide pyrolysis PAN products we have shown the possibility of the formation of nanocomposites comprising nickel oxide nanoparticles which can be reduced to zero-valence state at higher temperature IR heating (more than 5000 °C).