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Full-Text Articles in Physical Sciences and Mathematics

Sulfur Vacancies In Photorefractive Sn2P2S6 Crystals, Eric M. Golden, Sergey A. Basun, A. A. Grabar, I. M. Stoika, Nancy C. Giles, D. R. Evans, Larry E. Halliburton Dec 2014

Sulfur Vacancies In Photorefractive Sn2P2S6 Crystals, Eric M. Golden, Sergey A. Basun, A. A. Grabar, I. M. Stoika, Nancy C. Giles, D. R. Evans, Larry E. Halliburton

Faculty Publications

A photoinduced electron paramagnetic resonance (EPR) spectrum in single crystals of Sn2P2S6 (SPS) is assigned to an electron trapped at a sulfur vacancy. These vacancies are unintentionally present in undoped SPS crystals and are expected to play an important role in the photorefractive behavior of the material. Nonparamagnetic sulfur vacancies are formed during the initial growth of the crystal. Subsequent illumination below 100 K with 442 nm laser light easily converts these vacancies to EPR-active defects. The resulting S = 1/2 spectrum shows well-resolved and nearly isotropic hyperfine interactions with two P ions and two Sn ions. Partially resolved interactions …


Experimental Tests Of Free-Volume Tracer Diffusion In Water And Other Solvents, Daniel Spiegel, Paulses C. Kollie, Scott J. Van Tilburg Mar 2014

Experimental Tests Of Free-Volume Tracer Diffusion In Water And Other Solvents, Daniel Spiegel, Paulses C. Kollie, Scott J. Van Tilburg

Physics and Astronomy Faculty Research

Using forced Rayleigh scattering, the tracer diffusion of methyl red through water and eight other solvents at different temperatures is investigated and the results are compared to the Cohen-Turnbull theory of free-volume diffusion. In seven solvents the effective non-Arrhenius activation energy measured experimentally agrees with the Cohen-Turnbull energy. In water, however, the diffusion can be described mathematically by the free volume model but there is a disagreement of more than an order of magnitude between these energies. We propose that the unique "zero point" free volume forced onto water by the strong hydrogen bonding requires a different mechanism for tracer …


Polarization Of Bi2te3 Thin Film In A Floating-Gate Capacitor Structure, Hui Yuan, Kai Zhang, Haitao Li, Hao Zhu, John E. Bonevich, Helmut Baumgart, Curt A. Richter, Qiliang Li Jan 2014

Polarization Of Bi2te3 Thin Film In A Floating-Gate Capacitor Structure, Hui Yuan, Kai Zhang, Haitao Li, Hao Zhu, John E. Bonevich, Helmut Baumgart, Curt A. Richter, Qiliang Li

Electrical & Computer Engineering Faculty Publications

Metal-Oxide-Semiconductor (MOS) capacitors with Bi2Te3 thin film sandwiched and embedded inside the oxide layer have been fabricated and studied. The capacitors exhibit ferroelectric-like hysteresis which is a result of the robust, reversible polarization of the Bi2Te3 thin film while the gate voltage sweeps. The temperature-dependent capacitance measurement indicates that the activation energy is about 0.33 eV for separating the electron and hole pairs in the bulk of Bi2Te3, and driving them to either the top or bottom surface of the thin film. Because of the fast polarization speed, potentially excellent …


Structural, Physical, And Electrical Properties Of Boro-Vanadate-Iron Glasses Doped With K_2o Alkali, Harshvadan R. Panchal Jan 2014

Structural, Physical, And Electrical Properties Of Boro-Vanadate-Iron Glasses Doped With K_2o Alkali, Harshvadan R. Panchal

Turkish Journal of Physics

The structural, physical, and electrical properties of semiconducting oxide glasses with composition xK_2O: (95-X) [B_2O_3: 2V_2O_5]: 5Fe_2O_3 (0 \le x \le 30) have been studied. The glasses were prepared by splat-quenching method. Fourier transform infrared spectroscopy (FTIR) studies of these glasses were carried out to study the effect of the modifier and glass former in the glasses. These changes in the molecular structure, bond length, and vibrational group were studied in the spectral range of 400-1350 cm^{-1}. The increase in the intensity and shifting of vibrational bands occurred towards lower wave numbers at 1400-1350 cm^{-1}, 1200 cm^{-1}, and 100-940 cm^{-1}. …