Optical and structural characterization of Ge clusters embedded in ZrO2

The change of optical and structural properties of Ge nanoclusters in ZrO2 matrix have been investigated by spectroscopic ellipsometry versus annealing temperatures. Radio-frequency top-down magnetron sputtering approach was used to produce the samples of different types, i.e. single-layers of pure Ge, pure ZrO2 and Ge-rich-ZrO2 as well as multi-layers stacked of 40 periods of 5-nm-Ge-rich-ZrO2 layers alternated by 5-nm-ZrO2 ones. Germanium nanoclusters in ZrO2 host were formed by rapid-thermal annealing at 600-800 ∘C during 30 s in nitrogen atmosphere. Reference optical properties for pure ZrO2 and pure Ge have been extracted using single-layer samples. As-deposited multi-layer structures can be perfectly modeled using the effective medium theory. However, annealed multi-layers demonstrated a significant diffusion of elements that was confirmed by medium energy ion scattering measurements. This fact prevents fitting of such annealed structure either by homogeneous or by periodic multi-layer model

Resonant Raman studies of compositional and size dispersion of CdS₁₋ₓSeₓ nanocrystals in a glass matrix

Resonant Raman scattering spectra of glass-embedded CdS₁₋ₓSeₓ nanocrystals are measured and complemented with TEM and optical absorption as well as photoluminescence data. The selectivity of the resonant Raman process not only for the size, but also for the composition of nanocrystals within the ensemble, is directly observed in the dependence of phonon band frequency, linewidth and shape on the excitation wavelength

ОСОБЛИВОСТІ ХАРЧОВОГО СТАТУСУ У ДІТЕЙ ІЗ ЗАТРИМКОЮ ФІЗИЧНОГО РОЗВИТКУ ТА ШЛЯХИ ЙОГО КОРЕКЦІЇ

In children with retardation of non-endocrine genesis were investigated nutrition, the processes of lipids oxygenation and concomitant somatic pathology. The results allowded to reveal nutritional status disturbances, the impairment of oxygenic metabolism and to decide question about proper pathogenetic therapy. This therapy should contribute to active stimulation of growth processes and to the normalization of inner organs functional condition; it should have minimal side effects and allow to decide polypragmazia problem.У детей с отставанием в росте неэндокринного генеза проводили исследования состояния питания, процессов перекисного окисления липидов, изучали сопутствующую соматическую патологию. Результаты позволили выявить нарушения пищевого статуса, процессов окислительного метаболизма и определиться с рациональной патогенетической терапиею, которая бы содействовала бы активной стимуляции ростових процессов и восстановлению функционального состояния внутренних органов, имела минимальные побочные эффекты и позволила решить проблему полипрагмазии.У дітей із відставанням в рості неендокринного ґенезу досліджувався стан харчування, процеси перекисного окислення ліпідів, супутня соматична патологія. Результати дозволили виявити порушення харчового статусу, процесів окисного метаболізму та визначитися з раціональною патогенетичною терапією, яка б сприяла активній стимуляції ростових процесів та відновленню функціонального стану внутрішніх органів, мала мінімальні побічні ефекти і дозволяла вирішити проблему поліпрагмазії

Fermi Resonance in Phonon Spectra of Quaternary Chalcohenides of the type Cu2ZnGeS4

The experimental resonant and non-resonant Raman scattering spectra of the kesterite structural modification of Cu2ZnGeS4 single crystals are reported. The results are compared with those calculated theoretically within the density functional perturbation theory. For the majority of lines a good agreement (within 2–5 cm−1) is established between experimental and calculated mode frequencies. However, several dominant spectral lines, in particular the two intense fully symmetric modes, are found to deviate from the calculated values by as much as 20 cm−1. A possible reason for this discrepancy is found to be associated with the Fermi resonant interaction between one and two-phonon vibrational excitations. The modelling of spectra, which takes into account the symmetry of interacting states, allows a qualitative description of the observed experimental findings. Due to the similarity of the vibrational spectra of Cu2A II B IV S4 (A  =  Zn, Mn, Cd; B  =  Sn, Ge, Si) chalcogenides, Fermi resonance is argued to be a general phenomenon for this class of compounds

Nanostructured Silver Substrates With Stable and Universal SERS Properties: Application to Organic Molecules and Semiconductor Nanoparticles

Nanostructured silver films have been prepared by thermal deposition on silicon, and their properties as SERS substrates investigated. The optimal conditions of the post-growth annealing of the substrates were established. Atomic force microscopy study revealed that the silver films with relatively dense and homogeneous arrays of 60–80-nm high pyramidal nanoislands are the most efficient for SERS of both organic dye and inorganic nanoparticles analytes. The noticeable enhancement of the Raman signal from colloidal nanoparticles with the help of silver island films is reported for the first time

Sintering and mechanical properties of β‐SiC powder obtained from waste tires

Plasma synthesized SiC powder obtained from quartz and carbonaceous residue of waste tires was successfully sintered at 1925 ℃ by pressureless liquid-phase method using yttria and alumina as sintering aids (T-SiC). Comparison with sintered SiC obtained from commercial powder (C-SiC) put in evidence of similar sintered density (98%T.D.), but much finer microstructure of T-SiC than that of C-SiC. T-SiC also showed higher flexural strength than C-SiC both at room temperature (508 vs. 458 MPa) and at 1500 ℃ (280 vs. 171 MPa). Difference in liquid phase was responsible for the differences in hardness and fracture toughness. The high value of the Young's modulus of T-SiC (427 MPa) confirmed the high degree of sinterability of this powder and that it can be a promising candidate for structural applications with high added value. © 2016, The Author(s)

Theoretical and experimental Raman study of superlattices with GeSi quantum dots

The results of the theoretical and experimental study of Raman scattering in the quantum dot (QD) multilayers are reported. In order to obtain an adequate description of the structure with QDs and correctly explain the experimental Raman spectra, a model is proposed which takes into account the real crystal structure of both the QD and surrounding matrix, as well as the QD-matrix interaction. The secondary quantisation and Green function method were used in the theoretical calculation model. The results obtained show that crystal structures with matrix-embedded QDs can be described as a mixed crystal with specific distribution of "impurities" organised in large "molecules". A qualitative agreement in position and intensity of bands between the calculated and experimental Raman spectra for multilayer Ge/Si QD crystal structure is observed, the doublet character of the bands is explained