The materials of The International Scientific – Practical Conference is presented below.
The Conference reflects the modern state of innovation in education, science, industry and social-economic sphere, from the standpoint of introducing new information technologies.
It is interesting for a wide range of researchers, teachers, graduate students and professionals in the field of innovation and information technologies.
We have studied the solid state dewetting of ten monolayer sthick Ag film deposited on periodicall ypatterned Si(557) surface. The annealing of the system in the ultra-high vacuum at the temperatures between 300 and 400°C resulted in full agglomeration of the film and formation of faceted single crystalline Ag nanoparticles exhibiting bimodal size distribution.We demonstrated that some particles contain screw dislocations producing a step on the upper particle facet.We related the bimodality in particles distribution with the ability of dislocation containing Ag particles to evolve by Ostwald ripening mechanism.
Composite materials based on heterogeneous membranes MK-40 modified by a thin layer of homogeneous cation-exchange perfluorinated sulfo membrane MF-4SK doped with 2 and 5% ceria are prepared. The transport characteristics of these membranes in different ionic forms are studied. It is shown that the conductivity of ionic forms of membranes increases in the sequence Li+ < Na+ < К+ < H+. In all these forms except for the lithium form, the membrane containing 2% ceria has the highest conductivity. Modification leads to a considerable increase in selectivity of membranes which manifests itself as a decrease in transport numbers of anions (from 0.006 for the original membrane to 0.002 for the membrane with 5% ceria). The higher selectivity with respect to the transfer of nitrate ions as compared with chloride ions is observed.
In pnictide RbEuFe4As4, superconductivity sets in at 36 K and coexists, below 15−19 K, with the long-range magnetic ordering of Eu 4f spins. Here we report scanning tunneling experiments performed on cold-cleaved single crystals of the compound. The data revealed the coexistence of large Rb-terminated and small Eu-terminated terraces, both manifesting 1 × 2 and \sqrt 2 × \sqrt 2 reconstructions. On \sqrt 2 × \sqrt 2 surfaces, a hidden electronic order with a period ∼5 nm was discovered. A superconducting gap of ∼7 meV was seen to be strongly filled with quasiparticle states. The tunneling spectra compared with density functional theory calculations confirmed that flat electronic bands due to Eu 4f orbitals are situated ∼1.8eV below the Fermi level and thus do not contribute directly to Cooper pair formation.
Single crystals of Pr3+ doped hexa-aluminate Sr0.7La0.3Mg0.3Al12O19 (ASL) were prepared for spectroscopic characterization. We investigated their optical spectroscopic properties in σ and π polarization of light. Absorption spectra were recorded in extended spectral range, 400 nm–5400 nm. Energies of Pr3+ crystal field states were determined. In addition to the major D3h sites, minor sites were found. Judd-Ofelt analysis was performed: the J-O parameters Ωt were determined to be 1.06 x 10^-20 cm-2, 2.31 x 10^-20 cm-2 and 3.43 x 10^-20 cm-2 for t = 2, 4 and 6, respectively. The radiative lifetime was 38 μs for the emitting state 3P0.
We have studied high-resolution low-temperature IR luminescence and absorption spectra of undoped high-quality SiC single crystals of the 4H and 6H hexagonal modifications. Narrow lines with a width of smaller than 0.2 cm–1 have been revealed, with some of which being observed for the first time. We have found that some of the lines in the 4H and 6H modifications have similar structures; however, the lines in SiC-4H are shifted to the high-energy part of the spectrum by ~180 cm–1. For the most intense quartet in the range of 1.3 μm, we have succeeded in constructing the energy structure of levels for both the 4H modification and the 6H modification based on their luminescence and absorption spectra.
Single NV centers in HPHT IIa diamond are fabricated by helium implantation through lithographic masks. The concentrations of created NV centers in different growth sectors of HPHT are compared quantitatively. It is shown that the purest f001g growth sector (GS) of HPHT diamond allows to create groups of single NV centers in predetermined locations. The f001g GS HPHT diamond is thus considered a good material for applications that involve single NV centers.
Recent theoretical studies predict the suppressed ferroelectric instability in orthorhombic Pnma perovskites and experimental evidence is due. We observed significant softening at cooling of the lowest-frequency polar phonon at the Brillouin zone center in the Pnma antiferromagnetic fluoroperovskite NaMnF3 that is the direct proof of the theoretically predicted ferroelectric instability. In contrast to oxides where the hybridization plays the dominant role, the effective ionic charges in fluoroperovskites are close to their nominal valencies that confirms the geometric origin of the observed incipient ferroelectricity. Furthermore, below the Néel temperature, the softening phonon clearly shows a strong coupling with the magnetic subsystem as a result of dynamical modulation of the superexchange interaction. Our findings clarify microscopic mechanisms of the incipient multiferroicity in the Pnma fluoroperovskites and reveal still unexplored opportunities of this class of materials for further research and potential applications.
In “Lattice dynamics and structure of the new langasites Ln3CrGe3Be2O14 (Ln ¼ La, Pr, Nd): vibrational spectra and ab initio calculations” , experimental and calculated results on lattice dynamics of the recently discovered new compounds La3CrGe3- Be2O14, Pr3CrGe3Be2O14, and Nd3CrGe3Be2O14 are reported. These compounds belong to the langasite series and constitute a new class of low-dimensional antiferromagnets. The data presented in this article includes IR diffuse transmission spectra of powder samples of Ln3CrGe3Be2O14 (Ln ¼ La, Pr, Nd) registered at room temperature with a Bruker 125HR Fourier spectrometer, Raman spectra taken in the backscattering geometry (also at room temperature) with a triple monochromator using the line 514, 5 nm of an argon laser as an excitation, results of the DFT calculations with the B3LYP and PBE0 hybrid functionals on the optimized crystal structures, eigenfrequencies and eigenvectors of the normal vibrational modes. These data can be used to analyse electronphonon interaction and multiferroic properties of the new langasites and to compare the lattice dynamics of different langasites.
The kinetics of the electronic transitions within the f -shell of Dy3+ ions were studied with monitoring near- and mid-IR luminescence decay under pulsed laser excitation at 1.3 μm. The luminescence decay curves were found to be profoundly non-exponential in all bands in the range between 1.3-5.5 μm. Such behavior is attributed to cross-relaxation and up-conversion processes dominating in relaxation of Dy3+ ions from the laser-excited multiplet 6H9-2+6F11-2. We suggest that strong collective phenomena occurring under relatively low concentrations are due to anomalous clustering of Dy3+ ions. The cross-relaxation enables an efficient population of 6H13-2 and 6H11-2 multiplets, offering this material as an active medium for a 3-μm and 4.3-μm lasers.