Robust electronic properties of monolayer BeO against molecule adsorption.

The stability of two-dimensional (2D) materials upon exposure to ambient conditions is significant for their applications. In this paper, the air stability of the BeO monolayer with and without vacancy defects is carefully studied via DFT calculations. Our results suggest high structural and electronic stability of BeO monolayers upon exposure to O2, N2, CO2 and H2O even with Be vacancies. O vacancies are not favorable in free-standing BeO monolayers and can be easily healed by H2O or CO2 adsorption. Due to the high stability, large band gap and atomic flat surface, BeO monolayers are expected to be an ideal encapsulation material for 2D electronic devices.

Weak Localization in Polycrystalline Tin Dioxide Films.

The electrical and magnetotransport properties of nanocrystalline tin dioxide films were studied in the temperature range of 4-300 K and in magnetic fields up to 8 T. SnO2-δ films were fabricated by reactive direct current (DC) magnetron sputtering of a tin target with following 2 stage temperature annealing of synthesized samples. The nanocrystalline rutile structure of films was confirmed by X-ray diffraction analysis. The temperature dependences of the resistance R(T) and the negative magnetoresistance (MR) were explained within the frame of a model, taking into account quantum corrections to the classical Drude conductivity. Extracted from the R(T) and R(B) dependences electron dephasing length values indicate the 3D character of the weak localization (WL) in our samples.

The Phosphate-Based Composite Materials Filled with Nano-Sized BaTiO3 and Fe3O4: Toward the Unfired Multiferroic Materials.

The composite material filled with nano-sized BaTiO3 and Fe3O4 was designed and studied. The aluminium phosphate ceramics was used as a matrix. The XRD analysis demonstrates only the crystalline structure of the fillers used. The thermogravimetric analysis proves the thermal stability of the composites up to 950 K. The Maxwell-Wagner relaxation was observed in the dielectric spectra of the investigated composites. The dielectric spectroscopy proves the close contact between the nanoparticles with the different ferroic ordering. The phosphate-based composites have been proved to be a prospective candidate for the multiphase multiferroic materials design and development.

Electromagnetic and optical responses of a composite material comprising individual single-walled carbon-nanotubes with a polymer coating.

The composites and thin films comprising individual single-walled carbon nanotubes with a polymer coating (p-CNTs) have been prepared and their electromagnetic responses have been studied in a wide range from low-frequency (25-107 Hz) up to the infrared region. In spite of the high volume fraction of the nanotubes (up to 3.3%), the polymer coating prevents direct p-CNT contacts and the formation of the percolation network in those composites, so that p-CNTs interact only via the electromagnetic coupling. Thereby it is an ideal model system to verify experimentally the fundamental issues related to carbon nanotube electromagnetics, such as the influence of inter-tube electron tunneling on the localized plasmon resonance in the terahertz range, or the infrared absorption enhancement of polymer molecules attached to the nanotube surface. Along with addressing the fundamentals, applied carbon nanotube electromagnetics got insights important for the applications of p-CNT based composites as dielectric media in the terahertz regime. In particular, we found that the real part of the permittivity of the p-CNT film in the terahertz range is rather competitive, i.e. 8-13, however the loss tangent is not so small (0.4-0.6) as has been predicted. The way to increase p-CNT terahertz performance is also discussed.