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The vibrational and configurational entropy of disordering in Cu(3)Au

The thermodynamics of disordering in Cu(3)Au have been investigated by measuring the heat capacity of samples with different degrees of long- and short-range order between T = 5 and 720 K using relaxation and differential scanning calorimetry. The heat capacities of L1(2)-ordered and fcc-disordered...

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Autores principales: Benisek, Artur, Dachs, Edgar
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Elsevier 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4394139/
https://www.ncbi.nlm.nih.gov/pubmed/26019405
http://dx.doi.org/10.1016/j.jallcom.2014.12.215
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author Benisek, Artur
Dachs, Edgar
author_facet Benisek, Artur
Dachs, Edgar
author_sort Benisek, Artur
collection PubMed
description The thermodynamics of disordering in Cu(3)Au have been investigated by measuring the heat capacity of samples with different degrees of long- and short-range order between T = 5 and 720 K using relaxation and differential scanning calorimetry. The heat capacities of L1(2)-ordered and fcc-disordered samples show similar behaviour at low temperatures (<300 K). They deviate positively from the linear combination of the end-member heat capacities between ∼30 and 160 K. However, small differences between the two samples exist, as the disordered sample has a larger heat capacity producing a vibrational entropy of disordering of ∼0.05 R. At temperatures higher than 300 K, the heat capacity of the ordered sample shows a prominent lambda-type anomaly at 675 K due to the diffusive L1(2)–fcc phase transition. When starting these measurements with disordered samples, ordering effects are observed between 400 and 620 K, and the disordering reaction is observed at 660 K. Evaluation of the data gives an enthalpy and entropy of disordering at 683 K of 2.0 kJ mol(−1) and 0.39 R, respectively. However, these values increase with increasing temperature, thereby reducing the short-range order. Because the vibrational and configurational disordering effects become active at different temperature regimes, i.e., the vibrational effects at low temperatures (T ≪ 300 K) and the sum of both effects at higher temperatures (T > 300 K), they have been successfully separated.
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spelling pubmed-43941392015-05-25 The vibrational and configurational entropy of disordering in Cu(3)Au Benisek, Artur Dachs, Edgar J Alloys Compd Article The thermodynamics of disordering in Cu(3)Au have been investigated by measuring the heat capacity of samples with different degrees of long- and short-range order between T = 5 and 720 K using relaxation and differential scanning calorimetry. The heat capacities of L1(2)-ordered and fcc-disordered samples show similar behaviour at low temperatures (<300 K). They deviate positively from the linear combination of the end-member heat capacities between ∼30 and 160 K. However, small differences between the two samples exist, as the disordered sample has a larger heat capacity producing a vibrational entropy of disordering of ∼0.05 R. At temperatures higher than 300 K, the heat capacity of the ordered sample shows a prominent lambda-type anomaly at 675 K due to the diffusive L1(2)–fcc phase transition. When starting these measurements with disordered samples, ordering effects are observed between 400 and 620 K, and the disordering reaction is observed at 660 K. Evaluation of the data gives an enthalpy and entropy of disordering at 683 K of 2.0 kJ mol(−1) and 0.39 R, respectively. However, these values increase with increasing temperature, thereby reducing the short-range order. Because the vibrational and configurational disordering effects become active at different temperature regimes, i.e., the vibrational effects at low temperatures (T ≪ 300 K) and the sum of both effects at higher temperatures (T > 300 K), they have been successfully separated. Elsevier 2015-05-25 /pmc/articles/PMC4394139/ /pubmed/26019405 http://dx.doi.org/10.1016/j.jallcom.2014.12.215 Text en © 2015 The Authors http://creativecommons.org/licenses/by/4.0/ This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Benisek, Artur
Dachs, Edgar
The vibrational and configurational entropy of disordering in Cu(3)Au
title The vibrational and configurational entropy of disordering in Cu(3)Au
title_full The vibrational and configurational entropy of disordering in Cu(3)Au
title_fullStr The vibrational and configurational entropy of disordering in Cu(3)Au
title_full_unstemmed The vibrational and configurational entropy of disordering in Cu(3)Au
title_short The vibrational and configurational entropy of disordering in Cu(3)Au
title_sort vibrational and configurational entropy of disordering in cu(3)au
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4394139/
https://www.ncbi.nlm.nih.gov/pubmed/26019405
http://dx.doi.org/10.1016/j.jallcom.2014.12.215
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