V. Tsegelnik

Bio: V. Tsegelnik is an academic researcher from Saint Petersburg State University. The author has contributed to research in topics: Ionic conductivity & Conductivity. The author has an hindex of 5, co-authored 6 publications receiving 135 citations.

Percolation transition in Ag-doped germanium chalcogenide-based glasses: conductivity and silver diffusion results

Abstract: Conductivity and silver diffusion measured using a 110m Ag tracer have been investigated in AgGeS and AgGeSbSe glasses with silver concentration ranging from 0.008 to 25 at.% Ag. It has been found that the room-temperature conductivity in both systems increases by 9.0–9.5 orders of magnitude with increasing silver content, and its activation energy decreases from ∼ 1 to 0.4 eV. Accordingly, the silver tracer diffusion coefficient at 298 K increases by 5.0–5.5 orders of magnitude with similar decrease of the diffusion activation energy. A comparison of the conductivity and silver diffusion results clearly shows that the ionic transport is predominant in the two systems, even at lowest Ag concentrations. The Haven ratio, H R , decreases with increasing silver content: extremely diluted glasses (0.008–0.1 at.% Ag) exhibit H R ≈ 1; Ag-rich vitreous alloys are characterized by H R = 0.2–0.4. The composition dependencies of the ionic conductivity, σ i , and silver tracer diffusion coefficient, D Ag , exhibit two drastically different transport regimes at low (≤ 2–5 at.%) and high (> 10 at.%) silver concentrations. A power-law composition dependence of σ i and D Ag over 2.5 orders of magnitude in the Ag concentration and 3.5–5.0 orders of magnitude in the ionic conductivity (2–3 orders of magnitude in the diffusion coefficient) is observed at low silver concentrations. This transport regime is attributed to percolation in the critical region just above the percolation threshold. Recent theoretical considerations (the dynamic structure model and statistical (occupation) effects on percolative ionic conduction) are also in good agreement with experimental findings. After essential structural transformations of the glass network on the short- and intermediate-range scales at higher silver content (> 10 at.%), the ionic transport is not caused any more by percolation, i.e., it becomes network-dependent with a strongly correlated motion of the Ag + ions.

Tracer and surface spectroscopy studies of sensitivity mechanism of mercury ion chalcogenide glass sensors

Abstract: Sensitivity mechanism of mercury ion microsensors based on AgBr–Ag 2 S–As 2 S 3 thin films has been investigated using 110 Ag tracer exchange experiments, X-ray photoelectron spectroscopy (XPS) and secondary neutral mass spectroscopy (SNMS). It was found that non-linear sensor response in Hg(NO 3 ) 2 solutions is caused by at least two principal potential-generating processes: (i) Hg 2+ to Ag + ion exchange, and (ii) chemical reactions at the membrane surface involving silver and mercury species.

64CU Tracer Diffusion in Copper Chalcogenide Glasses

Abstract: at. % Cu. The diffusion coefficients in the CuI­As2Se3 system appear to be by three orders of magnitllde higher compared to those in the CU2Se-As2Se3 glasses. The observed differences between the two systems are discussed and compared with superionic conducting silver chalcogenidl! glasses. Introduction In spite of similarities in the electronic structure, ionic radii and first nearest-neighbour environment of Cu and Ag in chalcogenide glasses, these two glass families exhibit drastically different ion transport properties. Ag-rich sulphide and selenide glasses belong to fast ion conductors [1] but copper chalcogenide glassy systems appear to be amorphous semiconductors with predominant hole conductivity

Microelectronic programmable device and methods of forming and programming the same

Abstract: A microelectronic programmable structure and methods of forming and programming the structure are disclosed. The programmable structure generally include an ion conductor and a plurality of electrodes. Electrical properties of the structure may be altered by applying a bias across the electrodes, and thus information may be stored using the structure.

Programmable microelectronic devices and methods of forming and programming same

Abstract: A microelectronic programmable structure and methods of forming and programming the structure are disclosed. The programmable structure generally include an ion conductor and a plurality of electrodes. Electrical properties of the structure may be altered by applying a bias across the electrodes, and thus information may be stored using the structure.

Topics in the theory of amorphous materials

Abstract: In this Colloquium, I describe some current frontiers in the physics of semiconducting amorphous materials and glasses, including a short, but self-contained discussion of techniques for creating computer models, among them the quench from the melt method, the Activation-Relaxation Technique, the decorate and relax method, and the experimentally constrained molecular relaxation scheme. A representative study of an interesting and important glass (amorphous GeSe3:Ag) is provided. This material is a fast-ion conductor and a serious candidate to replace current FLASH memory. Next, I discuss the effects of topological disorder on electronic states. By computing the decay of the density matrix in real space, and also computing well-localized Wannier functions, we close with a quantitative discussion of Kohn’s Principle of Nearsightedness in amorphous silicon.