Si-rich Al2O3 films grown by RF magnetron sputtering: structural and photoluminescence properties versus annealing treatment

Silicon-rich Al₂O₃ films (Si_x(Al₂O₃)_1−x) were co-sputtered from two separate silicon and alumina targets onto a long silicon oxide substrate. The effects of different annealing treatments on the structure and light emission of the films versus x were investigated by means of spectroscopic ellipsometry, X-ray diffraction, micro-Raman scattering, and micro-photoluminescence (PL) methods. The formation of amorphous Si clusters upon the deposition process was found for the films with x ≥ 0.38. The annealing treatment of the films at 1,050°C to 1,150°C results in formation of Si nanocrystallites (Si-ncs). It was observed that their size depends on the type of this treatment. The conventional annealing at 1,150°C for 30 min of the samples with x = 0.5 to 0.68 leads to the formation of Si-ncs with the mean size of about 14 nm, whereas rapid thermal annealing of similar samples at 1,050°C for 1 min showed the presence of Si-ncs with sizes of about 5 nm. Two main broad PL bands were observed in the 500- to 900-nm spectral range with peak positions at 575 to 600 nm and 700 to 750 nm accompanied by near-infrared tail. The low-temperature measurement revealed that the intensity of the main PL band did not change with cooling contrary to the behavior expected for quantum confined Si-ncs. Based on the analysis of PL spectrum, it is supposed that the near-infrared PL component originates from the exciton recombination in the Si-ncs. However, the most intense emission in the visible spectral range is due to either defects in matrix or electron states at the Si-nc/matrix interface.     

Feasibility of using neural networks for real-time prediction of the mechanical properties of finished rolled products

This article examines the feasibility of predicting the mechanical properties of hot-rolled steel in flat-rolled-products shop No. 10 with the use of artificial neural networks. The mechanical properties are determined by means of a mathematical model constructed on the basis of data on the chemical composition of heats with allowance for the nominal thickness of the finished product, finishing temperature, and coiling temperature. Implementation of the findings is making it possible to reduce labor costs incurred in sample preparation, reduce metal waste, determine the soundness of batches while strip is being coiled, and eliminate the problems of the statistics-based nondestructive testing method currently in use. __________ Translated from Metallurg, No. 1, pp. 24–26, January, 2007.     

Plane-wave reflection from double arrays of small magnetoelectric scatterers

An analytical model of reflection and transmission of plane waves in double regular arrays of bianisotropic particles is developed. A method to correct approximate values of the particle polarizabilities so that the energy conservation requirements are exactly satisfied is proposed. Double arrays of planar omega particles are studied in detail, and it is shown that very sharp Bragg resonances exist in such arrays. The theory is verified by comparison with numerical simulations based on the method of moments.     

Transverse two-phase flow around a cylindrical heat exchange surface

Particle motion and deposition are modelled numerically on an infinite transversely streamlined cylinder subjected to force factors of a non-turbulent nature.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 59, No. 6, pp. 917–923, December, 1990.