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Negative Entropy of Mixing for Vanadium-Platinum Solutions

Delaire, O. and Swan-Wood, T. and Fultz, B. (2004) Negative Entropy of Mixing for Vanadium-Platinum Solutions. Physical Review Letters, 93 (18). Art. No. 185704. ISSN 0031-9007. http://resolver.caltech.edu/CaltechAUTHORS:DELprl04

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Abstract

The phonon densities of states for pure vanadium and the solid solutions V-6.25% Ni, Pd, Pt were determined from inelastic neutron scattering measurements. The solute atoms caused a large stiffening of the phonons, resulting in large, negative vibrational entropies of mixing. For V-6.25%Pt, the negative vibrational entropy of mixing exceeds the conventional positive chemical entropy of mixing. This negative total entropy of mixing should extend to lower concentrations of Pt, and the effect on the bcc solvus line is discussed. The experimental data were inverted to obtain interatomic force constants by using a Born–von Kármán model with an iterative optimization algorithm. The stiffening of bonds responsible for the decrease of entropy was found to occur mainly in first-nearest-neighbor solute-host bonds, and correlates in part with the solute metallic radius.


Item Type:Article
Additional Information:©2004 The American Physical Society (Received 9 April 2004; published 29 October 2004) We thank J. G-W. Lin for help with software development. This work was supported by the Department of Energy through the Basic Energy Sciences Grant No. DEFG03-0346055 and BES-MS,W-31-109-ENG-38.
Subject Keywords:entropy; vanadium alloys; platinum alloys; phonons; neutron diffraction; phase diagrams; iterative methods; optimisation; bonds (chemical)
Record Number:CaltechAUTHORS:DELprl04
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:DELprl04
Alternative URL:http://dx.doi.org/10.1103/PhysRevLett.93.185704
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3402
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:05 Jun 2006
Last Modified:26 Dec 2012 08:54

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