Thermal evolution of the morphology, structure, and optical properties of multilayer nanoperiodic systems produced by the vacuum evaporation of SiO and SiO2

The alternate vacuum evaporation of SiO and SiO₂ from separate sources is used to produce amorphous a-SiO _x /SiO₂ multilayer nanoperiodic structures with periods of 5–10 nm and a number of layers of up to 64. The effect of annealing at temperatures T _a = 500–1100°C on the structural and optical properties of the nanostructures is studied. The results of transmission electron microscopy of the samples annealed at 1100°C indicate the annealing-induced formation of vertically ordered quasiperiodic arrays of Si nanocrystals, whose dimensions are comparable to the a-SiO _x -layer thickness in the initial nanostructures. The nanostructures annealed at 1100°C exhibit size-dependent photoluminescence in the wavelength range 750–830 nm corresponding to Si nanocrystals. The data on infrared absorption and Raman scattering show that the thermal evolution of structural and phase state of the SiO _x layers with increasing annealing temperature proceeds through the formation of amorphous Si nanoinclusions with the subsequent formation and growth of Si nanocrystals.     

Structure Factor and Distribution Function of Degenerate Bose Gases Without Anomalous Averages

The structure factor and single-particle distribution function of degenerate Bose gas are calculated within the canonical ensemble without using anomalous averages. The hypothesis about the C-number behavior of the particle density operator with zero momentum (in the Bose condensate) is accepted. The poles of the “density-density” Green function and the single-particle Green’s function are identical and correspond to the well known spectrum of phonon-roton excitations.     

Capacitors with nonlinear characteristics based on stabilized zirconia with built-in gold nanoparticles

It is shown that capacitors based on stabilized zirconia with gold nanoparticles exhibit nonlinear properties: the admittance of these capacitors depends on the amplitude of the control voltage, test-signal frequency, and temperature. The nonlinearity is due to electron capture by traps generated during nanoparticle formation. The possibility of determining the trap parameters by measuring the capacitor admittance has been established.     

Velocity profile in ultraviscous-liquid flow in the screw channels of extrusion machines

A method of solving the flow problem for a nonlinear ultraviscous liquid in a screw channel in the Stokes approximation is outlined, together with the results.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 61, No. 3, pp. 392–398, September, 1991.