Thermodynamic properties and phase equilibria for Pt-Rh alloys

K. T. Jacob; Shashank Priya; Yoshio Waseda

doi:10.1007/s11661-998-0076-3

Thermodynamic properties and phase equilibria for Pt-Rh alloys

K. T. Jacob, Shashank Priya, Yoshio Waseda

Materials Science and Engineering

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22 Scopus citations

Abstract

The activity of rhodium in solid Pt-Rh alloys is measured in the temperature range from 900 to 1300 K using the solid-state cell Pt-Rh, Rh + Rh₂O₃/(Y₂O₃)ZrO₂/Pt _1-xRh_x + Rh₂O₃, Pt-Rh The activity of platinum and the free energy, enthalpy, and entropy of mixing are derived. Activities exhibit moderate negative deviation from Raoult's law. The mixing properties can be represented by a pseudosubregular solution model in which excess entropy has the same type of functional dependence on composition as the enthalpy of mixing, ΔH = X_Rh (1 - X_Rh)[-10,970 + 45X_Rh] J/mol ΔS^E = X_Rh (1 - X_Rh)[-3.80 + 1.55 × 10^-2 X_Rh] J/mol·K The negative enthalpy of mixing obtained in this study is in qualitative agreement with predictions of semiempirical models of Miedema and co-workers and Colinet et al. The results of this study do not support the solid-state miscibility gap suggested in the literature, but are consistent with liquidus data within experimental uncertainty limits.

Original language	English (US)
Pages (from-to)	1545-1550
Number of pages	6
Journal	Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume	29
Issue number	6
DOIs	https://doi.org/10.1007/s11661-998-0076-3
State	Published - 1998

All Science Journal Classification (ASJC) codes

Condensed Matter Physics
Mechanics of Materials
Metals and Alloys

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title = "Thermodynamic properties and phase equilibria for Pt-Rh alloys",

abstract = "The activity of rhodium in solid Pt-Rh alloys is measured in the temperature range from 900 to 1300 K using the solid-state cell Pt-Rh, Rh + Rh2O3/(Y2O3)ZrO2/Pt 1-xRhx + Rh2O3, Pt-Rh The activity of platinum and the free energy, enthalpy, and entropy of mixing are derived. Activities exhibit moderate negative deviation from Raoult's law. The mixing properties can be represented by a pseudosubregular solution model in which excess entropy has the same type of functional dependence on composition as the enthalpy of mixing, ΔH = XRh (1 - XRh)[-10,970 + 45XRh] J/mol ΔSE = XRh (1 - XRh)[-3.80 + 1.55 × 10-2 XRh] J/mol·K The negative enthalpy of mixing obtained in this study is in qualitative agreement with predictions of semiempirical models of Miedema and co-workers and Colinet et al. The results of this study do not support the solid-state miscibility gap suggested in the literature, but are consistent with liquidus data within experimental uncertainty limits.",

author = "Jacob, {K. T.} and Shashank Priya and Yoshio Waseda",

year = "1998",

doi = "10.1007/s11661-998-0076-3",

language = "English (US)",

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journal = "Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science",

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TY - JOUR

T1 - Thermodynamic properties and phase equilibria for Pt-Rh alloys

AU - Jacob, K. T.

AU - Priya, Shashank

AU - Waseda, Yoshio

PY - 1998

Y1 - 1998

N2 - The activity of rhodium in solid Pt-Rh alloys is measured in the temperature range from 900 to 1300 K using the solid-state cell Pt-Rh, Rh + Rh2O3/(Y2O3)ZrO2/Pt 1-xRhx + Rh2O3, Pt-Rh The activity of platinum and the free energy, enthalpy, and entropy of mixing are derived. Activities exhibit moderate negative deviation from Raoult's law. The mixing properties can be represented by a pseudosubregular solution model in which excess entropy has the same type of functional dependence on composition as the enthalpy of mixing, ΔH = XRh (1 - XRh)[-10,970 + 45XRh] J/mol ΔSE = XRh (1 - XRh)[-3.80 + 1.55 × 10-2 XRh] J/mol·K The negative enthalpy of mixing obtained in this study is in qualitative agreement with predictions of semiempirical models of Miedema and co-workers and Colinet et al. The results of this study do not support the solid-state miscibility gap suggested in the literature, but are consistent with liquidus data within experimental uncertainty limits.

AB - The activity of rhodium in solid Pt-Rh alloys is measured in the temperature range from 900 to 1300 K using the solid-state cell Pt-Rh, Rh + Rh2O3/(Y2O3)ZrO2/Pt 1-xRhx + Rh2O3, Pt-Rh The activity of platinum and the free energy, enthalpy, and entropy of mixing are derived. Activities exhibit moderate negative deviation from Raoult's law. The mixing properties can be represented by a pseudosubregular solution model in which excess entropy has the same type of functional dependence on composition as the enthalpy of mixing, ΔH = XRh (1 - XRh)[-10,970 + 45XRh] J/mol ΔSE = XRh (1 - XRh)[-3.80 + 1.55 × 10-2 XRh] J/mol·K The negative enthalpy of mixing obtained in this study is in qualitative agreement with predictions of semiempirical models of Miedema and co-workers and Colinet et al. The results of this study do not support the solid-state miscibility gap suggested in the literature, but are consistent with liquidus data within experimental uncertainty limits.

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Thermodynamic properties and phase equilibria for Pt-Rh alloys

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