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The kinetics of diffusion processes occurring during the formation of polycrystalline Si1 –xGex nanostructures (x = 0.20, 0.35) by spark plasma sintering in the temperature range 20–1200°C was studied for the first time. A mechanism for the formation of a SiGe solid solution is proposed as a result of a comprehensive study of the microstructure and phase composition of samples with particle sizes from 150 nm to 100 µm, together with the analysis of experimental sintering maps. It is based on the phenomenon of mutual diffusion of Si and Ge atoms that occurs during the entire sintering process. For the selected sintering modes, the grain size of the formed SiGe corresponds to the size of the initial powder particles. [ABSTRACT FROM AUTHOR]

We present the results of theoretical and experimental studies of the surface-wave Ka-band resonators which are formed by sections of cylindrical waveguides with single-period wall corrugations. The electrodynamic characteristics of such resonance cavities are analyzed within the quasioptical approach and three-dimensional simulation by the finite-difference time-domain method. The results of the theoretical analysis agree quite well with the experimentally measured frequency dependences of the reflection coefficients, which demonstrate the existence of surface modes with different numbers of longitudinal field variations. The measured Q-factors and frequencies of the above-specified modes corresponded well to the calculated values. In order to perform "cold" electrodynamic tests, wideband waveguide converters of the TE mode of the standard rectangular waveguide to the TM mode of an oversized cylindrical waveguide, which have a sufficiently low level of ohmic loss at a conversion efficiency exceeding 95% in the 34–40 GHz frequency range, were manufactured by the the 3D printing method. [ABSTRACT FROM AUTHOR]

The effect of resistive switching in individual dislocations in memristor Ag/Ge/Si(001) structures is demonstrated experimentally using atomic force microscopy with a conducting probe. A hysteresis is found in the current–voltage characteristics of dislocations, which is typical of bipolar resistive switching related to the formation and destruction of an Ag filament in a Ge layer as a result of drift of Ag+ ions along the dislocation core. [ABSTRACT FROM AUTHOR]

The interaction of an aqueous suspension of fine-grained iron with one equivalent of (1-hydroxy-ethylidene)diphosphonic acid (H4L) leads to the formation of poorly soluble iron(II) (1-hydroxy-ethylidene)diphosphonate (FeH2L · H2O), which precipitates from the solution in the form of whiskers. A compound consisting of crystalline and X-ray amorphous fractions, whose structure is based on stacked sheets of whiskers, linked by amorphous phase, was selected from the FeH2L · H2O reaction mixture with morpholine. The compounds have been studied by methods of elemental analysis, scanning electron microscopy, optical microscopy, atomic force microscopy (AFM), and X-ray diffraction (XRD) analysis. [ABSTRACT FROM AUTHOR]

The interaction of an aqueous suspension of fine-grained iron with one equivalent of (1-hydroxy-ethylidene)diphosphonic acid (H4L) leads to the formation of poorly soluble iron(II) (1-hydroxy-ethylidene)diphosphonate (FeH2L · H2O), which precipitates from the solution in the form of whiskers. A compound consisting of crystalline and X-ray amorphous fractions, whose structure is based on stacked sheets of whiskers, linked by amorphous phase, was selected from the FeH2L · H2O reaction mixture with morpholine. The compounds have been studied by methods of elemental analysis, scanning electron microscopy, optical microscopy, atomic force microscopy (AFM), and X-ray diffraction (XRD) analysis. [ABSTRACT FROM AUTHOR]

Abstract: Thermoelectric materials on the basis of SiGe produced by spark plasma sintering are studied. The degree of doping of the initial materials, the degree of mixing of Si and Ge, and the properties of the grain structure of the formed samples are varied. It is established that the use of initial materials doped with donor or acceptor impurities provides a means for controlling the charge-carrier concentration in the sintered samples. It is shown that the charge-carrier concentration has the most profound effect on the energy characteristics (power factor) of thermoelectrics. For structures with the highest charge-carrier concentration, the thermoelectric coefficients can be controlled by varying the degree of mixing of Ge and Si and the degree of uniformity of the distribution of impurities. [ABSTRACT FROM AUTHOR]

Ag/Ge/Si heterostructures with threading dislocations in Ge layer can exhibit resistive switching (RS) in two regimes: (i) bipolar and (ii) volatile unipolar. In both regimes, these structures possess stable states with the ratio of currents in the low-resistance state (LRS) and high-resistance state (HRS) within 1.5–2.7. The volatile unipolar switching can be determined by capturing charge carriers on deep levels related to misfit dislocations at the Ge/Si interface, whereas the bipolar switching is related to the drift of Ag+ ions via threading dislocations. [ABSTRACT FROM AUTHOR]

The reaction of poorly soluble manganese(II) bis(1-hydroxyethylidene)diphosphonate tetrahydrate (Mn(H3L)2•4H2O) with 2-aminoethanol (H2NCH2CH2OH) in an aqueous medium on heating to 70—80 оС causes the initial formation of soluble manganese(II) bis(1-hydroxyethylidene)diphosphonate tris(1-hydroxyethaneaminium) (Mn(H3L)2• •3H2NCH2CH2OH•4H2O), which then disproportionates to slightly soluble manganese(II) (1-hydroxyethylidene)diphosphonate-2-hydroxyethaneaminium (MnH2L•H2NCH2CH2OH) and coordination polymer of 1-hydroxyethylidenediphosphonic acid with 2-aminoethanol containing no metal cations. In the course of the reaction, MnH2L•H2NCH2CH2OH precipitates as whiskers that are grouped into a leaf (lepidoid) structure. The latter was examined by IR spectroscopy, X-ray phase analysis, scanning electron microscopy, atomic force microscopy, optical microscopy, and thermal desorption of nitrogen. The starting and resulting manganese compounds refer to poorly soluble crystalline complexes. The presence of a 2-aminoethanol molecule in the final product leads to an increase in the solubility from 0.40 to 0.54 g in 100 mL of the solution. Poorly soluble MnH2L•H2NCH2CH2OH is easily converted to a soluble form by the treatment with 2-aminoethanol or 2-amino-2-(hydroxy- methyl)propane-1,3-diol (H2NC(CH2OH)3). The agronomical efficiency of a solution of the Mn(H3L)2•3H2NCH2CH2OH•4H2O complex was studied on the cultures of white lupine Degas, spring wheat Ester, spring rape, and pea Stabil. [ABSTRACT FROM AUTHOR]

We report on the investigation of the photoconductivity (PC) in the yttria stabilized zirconia (YSZ) films with embedded Au nanoclusters (NCs). A peak in the PC spectrum corresponding to the plasmon optical absorption resonance in the Au NCs was observed. The temperature dependence of PC near 300 K obeyed Mott law. In this case, the PC was attributed to the heating of the YSZ matrix due to the plasmon optical absorption in the Au NCs (bolometric effect). Near 77 K, the PC did not depend on temperature and was attributed to plasmon-assisted electron transport between the NCs via the vacancy α-band in YSZ. [ABSTRACT FROM AUTHOR]