Thermal stability and radiation resistance of tin valent states in the structure of the (As2Se3)1 ? z (SnSe) z ? x (GeSe) x semiconductor glasses

The ratio between the content of bivalent and tetravalent tin atoms in the (As₂Se₃)_{1 − z} (SnSe) _{z − x} (GeSe) _x glasses depends on the rate of quenching of the alloy and on its temperature. Irradiation of these glasses with γ-ray photons brings about a partial oxidation of bivalent tin with formation of amorphous (finely divided) SnO₂ phase blocked by the glass, so that the physicochemical properties of the glasses (density, microhardness, glassformation temperature, and the electrical-conductivity activation energy) are virtually unaffected by irradiation. Original Russian Text ? G.A. Bordovskii, R.A. Kastro, A.V. Marchenko, S.A. Nemov, P.P. Seregin, 2007, published in Fizika i Tekhnika Poluprovodnikov, 2007, Vol. 41, No. 12, pp. 1429–1433.     

Modified linear prediction algorithm for narrowband interference suppression in universal mobile telecommunication system

Narrow band interference (NBI) deteriorates the quality of the spectrum, leading to a poorer performance of modern universal mobile telecommunication system (UMTS) spread spectrum systems. The linear prediction algorithm is one of the most significant techniques to overcome NBI and enhance the performance of UMTS systems. In this paper, a modified linear prediction algorithm is proposed for NBI suppression in a conditionally stationary environment. This modification improves the error energy estimation in the auto‐regression model of the linear prediction. The convergence of the proposed algorithm is evaluated, and its robustness is verified using Kullback–Leibler metrics for conditionally stationary NBI signals. Computer simulations are carried out, and the obtained results demonstrate the performance of the proposed algorithm and its compliance with UMTS protocols. Copyright © 2012 John Wiley & Sons, Ltd.     

Two-electron germanium centers with a negative correlation energy in lead chalcogenides

It is shown that the charge state of the ⁷³Ge antisite defect that arises in anionic sublattices of PbS, PbSe, and PbTe after radioactive transformation of ⁷³As does not depend on the position of the Fermi level, whereas the ⁷³Ge center in cationic sublattices of PbS and PbSe represents a two-electron donor with the negative correlation energy: the Mössbauer spectrum for the n-type samples corresponds to the neutral state of the donor center (Ge²⁺), while this spectrum corresponds to the doubly ionized state (Ge⁴⁺) of the center in the p-type samples. In partially compensated PbSe samples, a fast electron exchange between the neutral and ionized donor centers is realized. It is shown by the method of Mössbauer spectroscopy for the ¹¹⁹Sn isotope that the germanium-related energy levels are located higher than the levels formed in the band gap of these semiconductors by the impurity tin atoms.     

NMR frequencies of domain walls in a (110) plate of yttrium iron garnet upon the magnetization in the $$[\bar 110]$$ direction

Numerical methods have been used to study the shapes of NMR absorption lines of domain walls (DWs) in a (110) plate of yttrium iron garnet upon the magnetization along the \([\bar 1 10]\) direction. NMR spectra obtained from ⁵⁷Fe nuclei located in tetrahedral and octahedral positions in Bloch and Néel walls in a longitudinal and transverse radiofrequency fields have been studied. The dependences of the frequencies of the NMR absorption maxima of DWs on the magnitude of the applied magnetic field permit one to unambiguously determine the type of rotation of magnetization in the transition layer. It is shown that by changing the conditions of excitation of oscillations of the radiofrequency field, signals from nuclei located in various layers of the DW can be obtained.     

Statistics of electrons in PbS with <Emphasis Type="Italic">U</Emphasis> centers

The dependence of the concentration of two-electron tin centers in the intermediate charge state Sn³⁺ in PbS on the correlation energy is obtained using the Gibbs distribution. It is shown that this state cannot be observed by Mössbauer spectroscopy on an ¹¹⁹Sn isotope (due to insufficient sensitivity), but it can manifest itself in the temperature dependence of the hole density in Pb_1?x?ySn_xNa_yS solid solutions.     

Local symmetry and electronic structure of tin atoms in (Pb<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Sn<Subscript>x</Subscript>)<Subscript>1−<Emphasis Type="Italic">z</Emphasis></Subscript>In<Subscript>z</Subscript>Te lattices

Mössbauer spectroscopy of the ¹¹⁹Sn isotope has shown that the superconducting transition in (Pb_1?xSn_x)_1?zIn_zTe solid solutions is not accompanied by a change in the local symmetry of tin atoms or in their electronic structure.