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Full-Text Articles in Physics

Spatially Resolved Distribution Function And The Medium-Range Order In Metallic Liquid And Glass, X. W. Fang, Cai-Zhuang Wang, S. G. Hao, Matthew J. Kramer, Yongxin Yao, Mikhail I. Mendelev, Z. J. Ding, Ralph E. Napolitano, Kai-Ming Ho Dec 2011

Spatially Resolved Distribution Function And The Medium-Range Order In Metallic Liquid And Glass, X. W. Fang, Cai-Zhuang Wang, S. G. Hao, Matthew J. Kramer, Yongxin Yao, Mikhail I. Mendelev, Z. J. Ding, Ralph E. Napolitano, Kai-Ming Ho

Materials Science and Engineering Publications

The structural description of disordered systems has been a longstanding challenge in physical science. We propose an atomic cluster alignment method to reveal the development of three-dimensional topological ordering in a metallic liquid as it undercools to form a glass. By analyzing molecular dynamic (MD) simulation trajectories of a Cu64.5Zr35.5 alloy, we show that medium-range order (MRO) develops in the liquid as it approaches the glass transition. Specifically, around Cu sites, we observe “Bergman triacontahedron” packing (icosahedron, dodecahedron and icosahedron) that extends out to the fourth shell, forming an interpenetrating backbone network in the glass. The discovery of ...


Correlation Functions For Ionic Motion From Nmr Relaxation And Electrical Conductivity In The Glassy Fast-Ion Conductor (Li2s)0.56(Sis2)0.44, Ivar Svare, Ferdinando Borsa, D. R. Torgeson, Steve W. Martin Oct 1993

Correlation Functions For Ionic Motion From Nmr Relaxation And Electrical Conductivity In The Glassy Fast-Ion Conductor (Li2s)0.56(Sis2)0.44, Ivar Svare, Ferdinando Borsa, D. R. Torgeson, Steve W. Martin

Materials Science and Engineering Publications

The Li7 NMR spin-lattice relaxation and the electrical conductivity in the typical glassy fast-ion conductor (Li2S)0.56(SiS2)0.44 are discussed from models of Li+ionic motion with distributions of activation energies, as well as from stretched-exponential time-correlation functions. The measured correlation times from the two effects differ by two orders of magnitude, and the derived distributions are shifted greatly relative to each other. We relate the great differences to percolation around the high barriers in the distribution. We present a phenomenological theory that yields good quantitative fits to the observed NMR relaxation with a Gaussian distribution, and ...


Relaxation And Fluctuations In Glassy Fast-Ion Conductors: Wide-Frequency-Range Nmr And Conductivity Measurements, Ferdinando Borsa, D. R. Torgeson, Steve W. Martin, Hitendra K. Patel Jul 1992

Relaxation And Fluctuations In Glassy Fast-Ion Conductors: Wide-Frequency-Range Nmr And Conductivity Measurements, Ferdinando Borsa, D. R. Torgeson, Steve W. Martin, Hitendra K. Patel

Materials Science and Engineering Publications

Li7 nuclear spin-lattice relaxation rates (R1) versus the temperature at several resonance frequencies (4 to 40 MHz) are reported together with the conductivity measurements, σ(ω), in the range 1 Hz to 3.76 MHz on 0.56Li2S+0.44Si2S, a glassy fast-ionic conductor. Both R1 and σ(ω) are fitted consistently over the whole temperature and frequency range by using a stretched-exponential, i.e., exp(-t/τ*c)β for the corresponding correlation functions (CF). Formulas that relate R1(ω) and σ(ω) and that give the asymptotic behavior as functions of T and ω of both quantities are ...


Thermal Conductivity Of Metals At High Temperatures, Paul H. Sidles, G. C. Danielson Dec 1951

Thermal Conductivity Of Metals At High Temperatures, Paul H. Sidles, G. C. Danielson

Ames Laboratory ISC Technical Reports

A new method of measuring thermal diffusivity and hence thermal conductivity of metals is suggested. Like previously reported dynamic methods, this method uses a heat source, whose temperature varies sinusoidally located at one end of an effectively infinite rod. Unlike these methods only one period of the heat wave is required to eliminate the unknown coefficient determining the heat lost by radiation since both velocity and amplitude decrement of the heat wave are measured. The new method is faster in taking data and simpler in computation. The thermoelectric potentials from two thermojunctions are amplified and plotted on a Brown "Electronic ...