We developed a nanocomposite of Au nanoparticles, functionalized with arginine, and hydroxyapatite that contains Ga3+ ions. This material possesses double antibacterial protection – a contact-based action by the functionalized gold nanoparticles and the antibacterial action of Ga3+ ions. Such nanocomposites with combined antimicrobial effect present an innovative way for prevention and cure of bacterial infections and seem a promising human-friendly alternative for antibiotics and Ag-based antibacterial materials in treatments of infections by bacteria resistant to antibiotics.
COBISS.SI-ID: 30200103
Ag(Nb1−xTax)O3 (x = 0–0.8) ceramics were prepared using a solid-state reaction method, and a single-phase perovskite was identified using XRD for dense ceramics with x = 0–0.65. However, small Ag precipitates and microstructural inhomogeneities were observed using BSE-SEM and EDS. There are four kinds of dielectric abnormalities at RF frequencies, including a new abnormality that has a strong relaxation in the dielectric loss. A ferrielectric-like dielectric tunability was observed at 20–80 °C for x = 0 and 0.2, while the ceramic with x = 0.5 exhibited an antiferroelectric-like dielectric tunability. Furthermore, a transition behaviour was observed for x = 0.35, indicating that the ferrielectric–antiferroelectric transition does not correspond to the M1–M2 phase transition. The microwave dielectric constant of Ag(Nb1−xTax)O3 ceramics reaches its maximum value at x = 0.35, while the Qf value and the temperature coefficient of resonant frequency increase monotonously with the value of x.
COBISS.SI-ID: 29547815
The deoxidation and passivation of a silicon surface represents one of the most important steps in the successful integration of functional oxides with silicon. Due to its reactivity and dissimilar properties with respect to oxides, silicon surfaces are conditioned using various buffer systems. Despite the quality of the resulting surface, these Sr-based buffers have not been commercialized because of the reactivity of the metallic Sr. SrO has demonstrated properties that are competitive with metallic Sr, but a successful integration with silicon has not yet been proven. In the present study we have determined the optimal pulsed-laser deposition (PLD) conditions for the SrO-induced deoxidation of a silicon surface, which results in a 2 × 1 reconstructed surface. Additionally, the as-prepared surface is oxide-free and atomically flat. The results show that the amount of SrO plays the most critical role in the optimization of the whole process. Deposited in batch mode, the amount of SrO affects the morphologies of the surfaces, which change from a dimerized surface to SrO islands and a polycrystalline layer in the final stage. However, in the case of an insufficient amount of deposited SrO, pits are formed on the surface, drastically increasing its roughness. The successful optimization of the PLD conditions for the formation of a SrO buffer layer opens a new pathway for interfacing oxides with silicon.
COBISS.SI-ID: 29705255
In this paper we investigated the gas-releasing reaction which is the most important process in the preparation of foam glass. Carbon and/or manganese oxides (MnO2, Mn2O3, and Mn3O4) were used as the foaming additives. We show that manganese oxides have different functions in the foaming process. MnO2, which use is commonly reported in the literature, has a negative impact on the foaming process as it shifts the foaming to higher temperatures, increases the mass-loss rate, leading to open pores, and burns out the carbon. Instead, Mn2O3 can be used as the foaming agent in an oxidizing atmosphere. In the oxygen-free atmosphere, Mn3O4 can be used as the oxidizing agent, supporting the oxidation of carbon and the foaming process. The redox equilibrium of manganese (Mn2+/Mn3+), influenced by the oxygen partial pressure in the pores and physically dissolved oxygen in the glass, shows the strongest influence on the foaming process.
COBISS.SI-ID: 30219559
In this article we showed how the dielectric properties of the composite powders could be tailored by the particle shape. We found that the composite powder with the composition of 0.98MgTiO3-0.02BaTiO3 exhibited higher permittivity for the BaTiO3 powders with the needle shape than for the spherical particles. The effect of the particle shape was significant already at relatively low contents of BaTiO3. The results, published in this article are also important from the standpoint of measuring the dielectric properties of the powders and also for the fabrication of dielectric composites for RF applications.
COBISS.SI-ID: 29222695