Thermodynamic Measurements on Alloys and Compounds in Ag-Au-Se and Ag-Pd systems by the Electromotive Force Method

dc.contributorAalto-yliopistofi
dc.contributorAalto Universityen
dc.contributor.advisorTaskinen, Pekka, Prof., Aalto University, Department of Materials Science and Engineering, Finland
dc.contributor.authorFeng, Dawei
dc.contributor.departmentMateriaalitekniikan laitosfi
dc.contributor.departmentDepartment of Materials Science and Engineeringen
dc.contributor.labMetallurgical Thermodynamic and Modelling Research Groupen
dc.contributor.schoolKemiantekniikan korkeakoulufi
dc.contributor.schoolSchool of Chemical Technologyen
dc.contributor.supervisorTaskinen, Pekka, Prof., Aalto University, Department of Materials Science and Engineering, Finland
dc.date.accessioned2014-11-06T10:00:22Z
dc.date.available2014-11-06T10:00:22Z
dc.date.defence2014-11-28
dc.date.issued2014
dc.description.abstractGold and silver chalcogenides are significant minerals and major carriers of precious metals, and silver palladium alloy is one of the most important silver alloys with various industrial applications. The Ag-Au-Se ternary system and the Ag-Pd binary system have been investigated by the electromotive force (EMF) method in this study. For the Ag-Au-Se ternary system, the numerical values of the standard thermodynamic functions of the compounds Ag2Se (naumannite), AuSe, and Ag3AuSe2 (fischesserite) have been determined by the EMF method in a solid-state galvanic cell with superionic conductor RbAg4I5 and AgI as solid state electrolyte. The compounds Ag2Se, AuSe, and Ag3AuSe2 were synthesized from pure elements in evacuated quartz glass ampoules and then examined to be homogenous by Scanning Electron Microscope (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS). According to the experimental data on the EMF versus temperature, the analytical equations were obtained for the polymorphic forms of the compounds Ag2Se, AuSe, and Ag3AuSe2. The temperature-dependent relationships of the Gibbs energy of formation on the compounds Ag2Se, AuSe and Ag3AuSe2 in their polymorphic forms and the standard thermodynamic functions of the compounds within the temperature range were also obtained. For the Ag-Pd binary system, thermodynamic measurements of silver-palladium binary alloys have been performed over the temperature range 450–750 K by the EMF method with the superionic conductor AgI as the solid electrolyte. The activity and partial molar Gibbs energy of silver were obtained for Ag-Pd alloys over the whole composition range and the thermodynamic properties of palladium were calculated using the Gibbs-Duhem equation. The results show that chemical activities of silver exhibit negative deviations over most of the composition range, and the activities of palladium are characterized by both negative and positive deviations from the ideal Raoultian behavior. The results also show the minimum integral enthalpy of mixing on Ag-Pd alloys is located at 60 at.% Ag. The thermodynamic properties of the Ag-Au-Se ternary system and the Ag-Pd binary system obtained are significant for the production and recycling of precious metals. Moreover, the EMF method has been improved by advanced cell design, gas purification system, as well as temperature measurement, which can be used as an experimental tool for thermodynamic measurement for other alloys and compounds.en
dc.format.extent58 + app. 50
dc.format.mimetypeapplication/pdfen
dc.identifier.isbn978-952-60-5935-8 (electronic)
dc.identifier.isbn978-952-60-5934-1 (printed)
dc.identifier.issn1799-4942 (electronic)
dc.identifier.issn1799-4934 (printed)
dc.identifier.issn1799-4934 (ISSN-L)
dc.identifier.urihttps://aaltodoc.aalto.fi/handle/123456789/14423
dc.identifier.urnURN:ISBN:978-952-60-5935-8
dc.language.isoenen
dc.opnLindberg, Daniel, Dr., Åbo Akademi, Finland
dc.publisherAalto Universityen
dc.publisherAalto-yliopistofi
dc.relation.haspart[Publication 1]: D. Feng, P. Taskinen, F. Tesfaye, Thermodynamic stability of Ag2Se from 350 to 500 K by a solid state galvanic cell, Solid State Ionics II. 231 (2013) 1-4. DOI: 10.1016/j.ssi.2012.10.013
dc.relation.haspart[Publication 2]: D. Feng, P. Taskinen, Thermodynamic properties of Ag3AuSe2 from 300 to 500 K by a solid state galvanic cell, Journal of Alloy and Compounds III. 583 (2014) 176-179. DOI: 10.1016/j.jallcom.2013.08.170
dc.relation.haspart[Publication 3]: D. Feng, P. Taskinen, Thermodynamic stability of AuSe from 400 to 700 K by a solid state galvanic cell, Journal of Chemical Thermodynamics IV. 71 (2014) 98-102. DOI: doi:10.1016/j.jct.2013.11.031
dc.relation.haspart[Publication 4]: D. Feng, P. Taskinen, Thermodynamic properties of Ag3AuSe2, submitted to Physics and Chemistry of Minerals
dc.relation.haspart[Publication 5]: D. Feng, P. Taskinen, Thermodynamic properties of silver-palladium alloys determined by a solid state electrochemical method, Journal of Materials Science, 49 (2014), 5790-5798. DOI: 10.1007/s10853-014-8310-4
dc.relation.ispartofseriesAalto University publication series DOCTORAL DISSERTATIONSen
dc.relation.ispartofseries172/2014
dc.revIpser, Herbert, Prof., University of Vienna, Austria
dc.revOsadchii, E. G., Prof., Russian Academy of Sciences, Russia
dc.subject.keywordelectromotive force methoden
dc.subject.keywordGibbs energyen
dc.subject.keywordentropyen
dc.subject.keywordenthalpyen
dc.subject.otherMetallurgyen
dc.titleThermodynamic Measurements on Alloys and Compounds in Ag-Au-Se and Ag-Pd systems by the Electromotive Force Methoden
dc.typeG5 Artikkeliväitöskirjafi
dc.type.dcmitypetexten
dc.type.ontasotDoctoral dissertation (article-based)en
dc.type.ontasotVäitöskirja (artikkeli)fi
local.aalto.digiauthask
local.aalto.digifolderAalto_63953
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