Enthalpies of formation of the solid solutions of ZrxY0.5-x/2Ta0.5-x/2O2 (0 ≤ x ≤ 0.2 and 0.65 ≤ x ≤ 1)

Maren Lepple; Kristina Lilova; Carlos G. Levi; Alexandra Navrotsky

doi:10.1557/jmr.2019.213

Enthalpies of formation of the solid solutions of Zr_xY_0.5-x/2Ta_0.5-x/2O₂ (0 ≤ x ≤ 0.2 and 0.65 ≤ x ≤ 1)

Maren Lepple, Kristina Lilova, Carlos G. Levi, Alexandra Navrotsky

Research output: Contribution to journal › Article › peer-review

2 Scopus citations

Abstract

Enthalpies of formation and heat capacities are key parameters for thermodynamic assessments using the CALPHAD method and were determined in this work in the ZrO₂-Y0_.5Ta_0.5O₂ quasibinary system. Zr_xY_0.5-x/2Ta_0.5-x/2O₂ samples with compositions in the monoclinic and tetragonal ZrO₂-based solid solutions (0.65 ≤ x ≤ 1) as well as the two monoclinic (M′ and M) polymorphs of the Y_0.5Ta_0.5O₂-based solid solutions (0 ≤ x ≤ 0.2) were investigated. The enthalpies of the two monoclinic polymorphs M′ and M are essentially the same within experimental uncertainty and have significant energetic stability (enthalpies of formation near -45 kJ/mol) relative to their component oxides. The monoclinic and tetragonal zirconia-rich solid solutions have little energetic stability with respect to ZrO₂, Ta₂O₅, and Y₂O₃ and presumably owe their existence to the configurational entropy. The heat capacities of M′ and M phase are similar and can be estimated from their constituent oxides using the Neumann-Kopp rule.

Original language	English (US)
Pages (from-to)	3343-3350
Number of pages	8
Journal	Journal of Materials Research
Volume	34
Issue number	19
DOIs	https://doi.org/10.1557/jmr.2019.213
State	Published - Oct 14 2019
Externally published	Yes

Keywords

calorimetry
oxide
specific heat

ASJC Scopus subject areas

Materials Science(all)
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering

Access to Document

10.1557/jmr.2019.213

Cite this

@article{46fa89a76d37423488d9f29fd6aa3ed4,

title = "Enthalpies of formation of the solid solutions of ZrxY0.5-x/2Ta0.5-x/2O2 (0 ≤ x ≤ 0.2 and 0.65 ≤ x ≤ 1)",

abstract = "Enthalpies of formation and heat capacities are key parameters for thermodynamic assessments using the CALPHAD method and were determined in this work in the ZrO2-Y0.5Ta0.5O2 quasibinary system. ZrxY0.5-x/2Ta0.5-x/2O2 samples with compositions in the monoclinic and tetragonal ZrO2-based solid solutions (0.65 ≤ x ≤ 1) as well as the two monoclinic (M′ and M) polymorphs of the Y0.5Ta0.5O2-based solid solutions (0 ≤ x ≤ 0.2) were investigated. The enthalpies of the two monoclinic polymorphs M′ and M are essentially the same within experimental uncertainty and have significant energetic stability (enthalpies of formation near -45 kJ/mol) relative to their component oxides. The monoclinic and tetragonal zirconia-rich solid solutions have little energetic stability with respect to ZrO2, Ta2O5, and Y2O3 and presumably owe their existence to the configurational entropy. The heat capacities of M′ and M phase are similar and can be estimated from their constituent oxides using the Neumann-Kopp rule.",

keywords = "calorimetry, oxide, specific heat",

author = "Maren Lepple and Kristina Lilova and Levi, {Carlos G.} and Alexandra Navrotsky",

note = "Funding Information: ML was funded by the German Research Foundation (grant LE-3727/1-1). The calorimetric work at UC Davis was supported by the US Department of Energy, Office of Basic Energy Science, grant DE-FG02-03ER46053 and grant DMR-1105672 from the National Science Foundation. The authors are grateful to Gerald Schmidt for chemical analysis and Chandra A. Macauley and Sergey V. Ushakov for fruitful discussions. Publisher Copyright: Copyright {\textcopyright} 2019 Materials Research Society.",

year = "2019",

month = oct,

day = "14",

doi = "10.1557/jmr.2019.213",

language = "English (US)",

volume = "34",

pages = "3343--3350",

journal = "Journal of Materials Research",

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T1 - Enthalpies of formation of the solid solutions of ZrxY0.5-x/2Ta0.5-x/2O2 (0 ≤ x ≤ 0.2 and 0.65 ≤ x ≤ 1)

AU - Lepple, Maren

AU - Lilova, Kristina

AU - Levi, Carlos G.

AU - Navrotsky, Alexandra

N1 - Funding Information: ML was funded by the German Research Foundation (grant LE-3727/1-1). The calorimetric work at UC Davis was supported by the US Department of Energy, Office of Basic Energy Science, grant DE-FG02-03ER46053 and grant DMR-1105672 from the National Science Foundation. The authors are grateful to Gerald Schmidt for chemical analysis and Chandra A. Macauley and Sergey V. Ushakov for fruitful discussions. Publisher Copyright: Copyright © 2019 Materials Research Society.

PY - 2019/10/14

Y1 - 2019/10/14

N2 - Enthalpies of formation and heat capacities are key parameters for thermodynamic assessments using the CALPHAD method and were determined in this work in the ZrO2-Y0.5Ta0.5O2 quasibinary system. ZrxY0.5-x/2Ta0.5-x/2O2 samples with compositions in the monoclinic and tetragonal ZrO2-based solid solutions (0.65 ≤ x ≤ 1) as well as the two monoclinic (M′ and M) polymorphs of the Y0.5Ta0.5O2-based solid solutions (0 ≤ x ≤ 0.2) were investigated. The enthalpies of the two monoclinic polymorphs M′ and M are essentially the same within experimental uncertainty and have significant energetic stability (enthalpies of formation near -45 kJ/mol) relative to their component oxides. The monoclinic and tetragonal zirconia-rich solid solutions have little energetic stability with respect to ZrO2, Ta2O5, and Y2O3 and presumably owe their existence to the configurational entropy. The heat capacities of M′ and M phase are similar and can be estimated from their constituent oxides using the Neumann-Kopp rule.

AB - Enthalpies of formation and heat capacities are key parameters for thermodynamic assessments using the CALPHAD method and were determined in this work in the ZrO2-Y0.5Ta0.5O2 quasibinary system. ZrxY0.5-x/2Ta0.5-x/2O2 samples with compositions in the monoclinic and tetragonal ZrO2-based solid solutions (0.65 ≤ x ≤ 1) as well as the two monoclinic (M′ and M) polymorphs of the Y0.5Ta0.5O2-based solid solutions (0 ≤ x ≤ 0.2) were investigated. The enthalpies of the two monoclinic polymorphs M′ and M are essentially the same within experimental uncertainty and have significant energetic stability (enthalpies of formation near -45 kJ/mol) relative to their component oxides. The monoclinic and tetragonal zirconia-rich solid solutions have little energetic stability with respect to ZrO2, Ta2O5, and Y2O3 and presumably owe their existence to the configurational entropy. The heat capacities of M′ and M phase are similar and can be estimated from their constituent oxides using the Neumann-Kopp rule.

KW - calorimetry

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KW - specific heat

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