Chemical short-range order in liquid LiPb alloys

Ruppersberg, H.; Reiter, Harold

doi:10.1088/0305-4608/12/7/005

Cited by 136 publications

(44 citation statements)

References 25 publications

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“…The wave vector dependence of the quasielastic integrated intensity Z q , shown in Fig. 2(a), peaks at about 1.5 Å 21 , that is a wave number corresponding to the maximum of S͑Q͒ as shown by previous quasielastic scattering results [15] and diffraction [16]. Apart from the incoherent scattering from the Li, such scattering is thus ascribed to the concentration fluctuations.…”

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confidence: 58%

High-Frequency Dynamics in a Molten Binary Alloy

et al. 1998

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Heavily damped excitations are found in molten Li 4 Pb by inelastic neutron scattering. The experiment covered a kinematic range which enabled an unambiguous characterization of such excitations by means of the study of the wave vector dependence of their frequencies, lifetimes, and signal amplitudes. It is shown that the excitations being sampled exhibit features which substantially deviate from those expected for the propagation of an acoustic mode (which should involve in-phase atomic displacements). [S0031-9007(98) [7,8], and even some semimetallic liquids [9]. The most salient feature of such dynamic phenomena concerns their frequencies, which are well above those expected for a continuation to large wave vectors of hydrodynamic sound. In fact, kinetic-theory predictions [6] portray such excitations as being supported by the light component only so that they apparently travel with phase velocities close to those characteristic of the pure component, which are well above those given by the elastic constants of the mixture.Results from experiment and computer simulation on a variety of systems [1][2][3][4][5][6][7][8] can show well defined, heavily damped or overdamped features in S͑Q, v͒. If the motions being sampled are heavily damped or overdamped, only broad shoulders are visible, so that characteristic frequencies are usually obtained from peaks in the generalized susceptibility x͑Q, v͒~vS͑Q, v͒, or in the longitudinal current correlation function J 1 ͑Q, v͒ v͞Q 2 x͑Q, v͒ (for a comment on the meaning of such frequencies, see Ref.[10]). Such frequencies v Q are oftentimes converted to phase velocitieshv Q ͞Q. From the exploration of the phase velocity trend within the low-Q region, the presence of a mode of acoustic nature (where atoms involved execute in-phase displacements) propagating with a velocity well above that corresponding to hydrodynamic sound, has been inferred.The points which still are subject to controversy regard (a) the adequacy of discussing the nature on excitations appearing at relatively large-Q in terms of constructs which only retain full sense within the realm of hydrodynamics (i.e., a sound mode), and (b) the assignment of the observed frequencies, to a definite underlying microscopic mechanism, in the absence of further information such as the Q dependence of the excitation amplitude (which provides a direct insight into the phase relationships of the motions being sampled at a given frequency). Observation of clear nonacoustic modes at high frequencies was reported years ago for molten salts [4]. It was rationalized in terms of opticlike vibrations, but it has hardly ever been discussed within the present context. Also, excitations with frequencies well above hydrodynamic sound not involving propagation of longitudinal sound have been found in experiments in some molecular [7] or even metallic [9] liquids.The main thrust behind the substantial experimental effort witnessed in recent times for the scrutiny of this class of systems [1,2,5] was motivated by predictions made from ...

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confidence: 58%

High-Frequency Dynamics in a Molten Binary Alloy

et al. 1998

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“…Moreover, the study of the mixing behaviours of the initial melt at different temperatures experimentally have many constraints, such as difficulty in controlling temperatures, tedious, time consuming, high economical costs and developing new devices having high temperature and corrosion resistances. These difficulties have been to some extent resolved by theoretician by developing different modeling equations (Flory, 1942;Jordan, 1970;Bhatia & Hargrove, 1974;Lele & Ramchandrarao, 1981;Ruppersberg & Reiter, 1982;Hoshino, 1983;Young, 1992;Singh & Sommer, 1992;Budai, Benko & Kaptay, 2005;Kaptay, 2008Kaptay, , 2015Adhikari, Singh & Jha, 2010;Adhikari, 2011;Yadav, Jha & Adhikari, 2014) to study the mixing behaviours of the liquid alloys at the melting temperatures and interpolating/extrapolating these results at different elevated temperatures. In the light of such fundamental importance, we have extended regular associated solution model (Jordan, 1970;Lele & Ramchandrarao, 1981;Adhikar, Singh & Jha, 2010;Adhikari, 2011;Yadav, Jha & Adhikari, 2014) and employed it to predict the thermodynamic, structural and surface properties of the liquid Tl−Na alloys at higher temperatures (Yadav et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Theoretical Modeling to Predict the Thermodynamic, Structural, Surface and Transport Properties of the Liquid Tl−Na Alloys at different Temperatures

2017

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Theoretical modeling equations are developed by extending regular associated solution model to predict the thermodynamic and structural properties of the liquid Tl−Na alloys at higher temperatures. The thermodynamic properties have been predicted by computing activities of unassociated monomers ( and ) and free energy of mixing ( ) at temperatures 673 K, 773 K, 873 K and 973 K. The structural properties have been predicted by computing concentration fluctuation in long wavelength limit ( ), short range order parameter ( ) and ratio of mutual to intrinsic diffusion coefficients ( ) at aforementioned temperatures. These properties have been then correlated with the modified Butler's model to predict the surface properties, such as surface concentrations of free monomers ( and ) and surface tension ( ) of the alloy at above mentioned temperatures.

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“…It is as low as -0.2814 at IIA K. In this context we may recall that for complete ordering ^ must attain a minimum value of -1. Though the ordering in molten LiCd is much larger than in the Li-Mg system [19] (ax = -0.04 for Li0 7Mg0 3), but it is comparable to the value of the order parameter of Li-Pb alloys [20] (ax = -0.23 for Li0 ?Pb0 5). It may be pointed out that and Scc(0) of Li-Cd and Li-Pb differ markedly but y.y for the first coordination shell in the two cases is very much alike.…”

Section: Chemical Short Range Order Parametermentioning

confidence: 90%

Quasi-Chemical Model for Liquid Li-Cd Alloys

Prasad

Singh

1989

Zeitschrift Für Naturforschung A

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The quasi-chemical model based on pairwise interactions is used to study the concentration dependent thermodynamic properties of Li-Cd liquid alloys. Special attention is given to the concentration-concentration correlation function in the long wavelength limit [Scc(O)] and the chemical short-range order parameter (CSRO). The activity, free energy of mixing, Scc(O) and CSRO are computed as functions of temperature and concentration.

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Chemical short-range order in liquid LiPb alloys

Cited by 136 publications

References 25 publications

High-Frequency Dynamics in a Molten Binary Alloy

High-Frequency Dynamics in a Molten Binary Alloy

Theoretical Modeling to Predict the Thermodynamic, Structural, Surface and Transport Properties of the Liquid Tl−Na Alloys at different Temperatures

Quasi-Chemical Model for Liquid Li-Cd Alloys

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