# O–Zr system

> O–Zr system: 205 accepted literature values (phase equilibrium 61, phase transition 54, heat capacity / entropy / enthalpy 26, formation 26) and 0 calculated phase diagram(s) from ORCHID, each value with evidence class, source, page and quote.

HTML: https://data.orchid-project.org/systems/O-ZR.html · Markdown: https://data.orchid-project.org/systems/O-ZR.md

205 accepted literature values from 4 paper(s) (experimental 117, model 85, unspecified 3); 0 calculated phase diagram(s). 16 further extracted value(s) not accepted by the reader-agreement checks are only in the JSON/CSV.

Data: [JSON](https://data.orchid-project.org/literature/systems/O-ZR.json) · [CSV](https://data.orchid-project.org/systems/O-ZR.csv) · [interactive explorer](https://orchid-project.org/data-explorer/#O-ZR) · [phases (15)](https://data.orchid-project.org/phases/pages/O-ZR.html) · [papers (bibliography)](https://data.orchid-project.org/bibliography/pages/systems/O-ZR.html) · [Markdown](https://data.orchid-project.org/systems/O-ZR.md)

Table: Accepted values by evidence class

| Evidence class | Values |
|---|---:|
| experimental | 117 |
| model | 85 |
| unspecified | 3 |

Table: Accepted values by property group

| Property group | Values |
|---|---:|
| invariant reaction | 19 |
| phase transition | 54 |
| phase equilibrium | 61 |
| formation | 26 |
| heat capacity / entropy / enthalpy | 26 |
| activity / EMF / Gibbs energy | 14 |
| other property | 5 |

Convex hulls: [Materials Project DFT hull](https://data.orchid-project.org/hulls/dft-mp/O/O-ZR.json) · [OQMD DFT hull](https://data.orchid-project.org/hulls/dft-oqmd/O/O-ZR.json) · [CALPHAD hull ZrO-01Lia-LB](https://data.orchid-project.org/hulls/calphad-sgte/O/O-ZR--ZrO-01Lia-LB.json) · [CALPHAD hull ZrO-02Arr](https://data.orchid-project.org/hulls/calphad-sgte/O/O-ZR--ZrO-02Arr.json) · [CALPHAD hull ZrO-04Che](https://data.orchid-project.org/hulls/calphad-sgte/O/O-ZR--ZrO-04Che.json) · [CALPHAD hull ZrO-04Wan](https://data.orchid-project.org/hulls/calphad-sgte/O/O-ZR--ZrO-04Wan.json) · [CALPHAD hull ZrO-06Wan](https://data.orchid-project.org/hulls/calphad-sgte/O/O-ZR--ZrO-06Wan.json) · [CALPHAD hull ZrO-98Che](https://data.orchid-project.org/hulls/calphad-sgte/O/O-ZR--ZrO-98Che.json)

## Invariant reactions (literature)

Table: Invariant reactions reported in the literature for the O–Zr system (19)

| T (K) | Reaction / phases | Compositions (mole fraction) | Class | Source | Location | Quote |
|---:|---|---|---|---|---|---|
| 3067 | congruent melting: liquid -> γ-ZrO2 | liquid: O 0.6576; γ-ZrO2: O 0.6576 | model | [1] Wang 2004 | Table 5, p. 9, row 8; `ORC-XYH6TRS3EM` |  |
| 2983 | congruent melting: liquid -> γ-ZrO2 | liquid: O 0.666; γ-ZrO2: O 0.666 | model | [1] Wang 2004; _cites Abriata 1986_ [doi](https://doi.org/10.1007/bf02881546) | Table 5, p. 9, row 7; `ORC-3SUNON5CWB` |  |
| 2403.15 | congruent melting: L -> HCP | HCP: O 0.25 | experimental | [2] Arroyave 2002 | Table 1, p. 12, row 7; `ORC-CUWFDAB5E4` |  |
| 2403 | congruent melting: liquid -> hcp | liquid: O 0.25; hcp: O 0.25 | model | [1] Wang 2004; _cites Abriata 1986_ [doi](https://doi.org/10.1007/bf02881546) | Table 5, p. 9, row 9; `ORC-KL6PNMG6ID` |  |
| 2402 | congruent melting: liquid -> hcp | liquid: O 0.29; hcp: O 0.29 | model | [1] Wang 2004 | Table 5, p. 9, row 10; `ORC-GVXEHZPYBD` |  |
| 2400.95 | congruent melting: L -> HCP | HCP: O 0.275 | model | [2] Arroyave 2002 | Table 1, p. 12, row 8; `ORC-UFW6S2DR7V` |  |
| 2347.15 | eutectic: L -> HCP + γ ZrO2-x | L: O 0.4122; HCP: O 0.311; γ ZrO2-x: O 0.6254 | model | [2] Arroyave 2002 | Table 1, p. 12, row 4; `ORC-DGMIHRUCGC` |  |
| 2344 | eutectic: liquid -> hcp + γ-ZrO2 | liquid: O 0.402; hcp: O 0.31; γ-ZrO2: O 0.617 | model | [1] Wang 2004 | Table 5, p. 9, row 4; `ORC-QPQHLFNMY5` |  |
| 2338 | eutectic: liquid -> hcp + γ-ZrO2 | liquid: O 0.4; hcp: O 0.35; γ-ZrO2: O 0.62 | model | [1] Wang 2004; _cites Abriata 1986_ [doi](https://doi.org/10.1007/bf02881546) | Table 5, p. 9, row 3; `ORC-NNA3G7IN2G` |  |
| 2335.15 | eutectic: L -> HCP + γ ZrO2-x | L: O 0.4; HCP: O 0.35; γ ZrO2-x: O 0.62 | experimental | [2] Arroyave 2002 | Table 1, p. 12, row 3; `ORC-B26JGXCV4F` |  |
| 2250.15 | L + (HCP) -> BCC | L: O 0.1003; (HCP): O 0.2217; BCC: O 0.105 | model | [2] Arroyave 2002 | Table 1, p. 12, row 2; `ORC-KFKCZADFIU` |  |
| 2243.15 | L + (HCP) -> BCC | L: O 0.1; (HCP): O 0.195; BCC: O 0.105 | experimental | [2] Arroyave 2002 | Table 1, p. 12, row 1; `ORC-7XQIPML4FG` |  |
| 2243.15 | peritectic |  | experimental | [2] Arroyave 2002 | p. 2; `ORC-TDB2WQTM2E` | “This phase has a maximum oxygen solubility of 10.5 at.% at 1970°C, which is the temperature of the peritectic reaction.” |
| 2243 | liquid + hcp -> bcc | liquid: O 0.1; hcp: O 0.195; bcc: O 0.105 | model | [1] Wang 2004; _cites Abriata 1986_ [doi](https://doi.org/10.1007/bf02881546) | Table 5, p. 9, row 1; `ORC-ARPB74UKRX` |  |
| 2241 | liquid + hcp -> bcc | liquid: O 0.0985; hcp: O 0.19; bcc: O 0.0999 | model | [1] Wang 2004 | Table 5, p. 9, row 2; `ORC-OGOOJEOVTP` |  |
| 1803.15 | γ ZrO2-x -> HCP + β ZrO2-x | γ ZrO2-x: O 0.6349; HCP: O 0.3041; β ZrO2-x: O 0.665 | model | [2] Arroyave 2002 | Table 1, p. 12, row 6; `ORC-HSMKMPNFWY` |  |
| 1799 | γ-ZrO2 -> hcp + β-ZrO2 | γ-ZrO2: O 0.638; hcp: O 0.309; β-ZrO2: O 0.66667 | model | [1] Wang 2004 | Table 5, p. 9, row 6; `ORC-4N2ADTT5VI` |  |
| 1798.15 | γ ZrO2-x -> HCP + β ZrO2-x | γ ZrO2-x: O 0.636; HCP: O 0.312; β ZrO2-x: O 0.665 | experimental | [2] Arroyave 2002 | Table 1, p. 12, row 5; `ORC-QAHYC6BQDX` |  |
| 1798 | γ-ZrO2 -> hcp + β-ZrO2 | γ-ZrO2: O 0.636; hcp: O 0.312; β-ZrO2: O 0.665 | model | [1] Wang 2004; _cites Abriata 1986_ [doi](https://doi.org/10.1007/bf02881546) | Table 5, p. 9, row 5; `ORC-EYVEADJXPY` |  |

## Formation enthalpies

Literature values in kJ/mol-atom where the per-atom basis is known. DFT columns: the lowest-energy entry at the same composition (Materials Project 2026.04.13, OQMD v1.8; different energy references, never averaged), from [dft_parity.json](https://data.orchid-project.org/literature/dft_parity.json).

Table: Enthalpies of formation, O–Zr system (26)

| Phase | Compound | Value | T (K) | Class | MP DFT (kJ/mol-atom) | OQMD DFT (kJ/mol-atom) | Source | Location | Quote |
|---|---|---:|---:|---|---:|---:|---|---|---|
| Zr2O | [Zr2O](https://data.orchid-project.org/compounds/Zr2O.html) | -286 kJ/mol-atom |  | model | -192.087 (mp-aaabqwvt) | -186.602 (oqmd-2030404) | [2] Arroyave 2002 | Table 3, p. 18, row 11; `ORC-5H3ZBHLINP` |  |
| Zr2O | [Zr2O](https://data.orchid-project.org/compounds/Zr2O.html) | -198 kJ/mol-atom |  | model | -192.087 (mp-aaabqwvt) | -186.602 (oqmd-2030404) | [2] Arroyave 2002 | Table 3, p. 18, row 12; `ORC-KT33P27SP4` |  |
| Zr3O | [Zr3O](https://data.orchid-project.org/compounds/Zr3O.html) | -214 kJ/mol-atom |  | model | -149.095 (mp-aaabfyna) | -142.679 (oqmd-5214) | [2] Arroyave 2002 | Table 3, p. 18, row 9; `ORC-7W5PN7OFFN` |  |
| Zr3O | [Zr3O](https://data.orchid-project.org/compounds/Zr3O.html) | -151 kJ/mol-atom |  | model | -149.095 (mp-aaabfyna) | -142.679 (oqmd-5214) | [2] Arroyave 2002 | Table 3, p. 18, row 10; `ORC-M4AH3ZCSWD` |  |
| Zr6O | [Zr6O](https://data.orchid-project.org/compounds/Zr6O.html) | -122 kJ/mol-atom |  | model |  | -82.626 (oqmd-2132007) | [2] Arroyave 2002 | Table 3, p. 18, row 7; `ORC-7VDSRZVXQA` |  |
| Zr6O | [Zr6O](https://data.orchid-project.org/compounds/Zr6O.html) | -93 kJ/mol-atom |  | model |  | -82.626 (oqmd-2132007) | [2] Arroyave 2002 | Table 3, p. 18, row 8; `ORC-ETH3ALOXOH` |  |
| ZrO0.5 | [Zr2O](https://data.orchid-project.org/compounds/Zr2O.html) | -286 kJ/mol-atom |  | model | -192.087 (mp-aaabqwvt) | -186.602 (oqmd-2030404) | [2] Arroyave 2002 | Table 2, p. 17, row 5; `ORC-B66ZOF6RPG` |  |
| ZrO0.5 | [Zr2O](https://data.orchid-project.org/compounds/Zr2O.html) | -217 kJ/mol-atom |  | model | -192.087 (mp-aaabqwvt) | -186.602 (oqmd-2030404) | [2] Arroyave 2002 | Table 2, p. 17, row 6; `ORC-532CQNUDES` |  |
| ZrO2 |  | -1101 kJ/mol (basis unstated) | 298.15 | model |  |  | [3] CHEN 2004; _cites Liang 2001_ | Table 2, p. 3, row 6; `ORC-VKOW7JMG67` |  |
| ZrO2 |  | -1100.8 kJ/mol (basis unstated) | 298.15 | experimental |  |  | [3] CHEN 2004; _cites Huber 1964_ | Table 2, p. 3, row 2; `ORC-HYAEJ3WDYQ` |  |
| ZrO2 |  | -1100.7 kJ/mol (basis unstated) | 298.15 | model |  |  | [3] CHEN 2004 | Table 2, p. 3, row 7; `ORC-TVSCV5S6Q3` |  |
| ZrO2 |  | -1100.6 kJ/mol (basis unstated) | 298.15 | experimental |  |  | [3] CHEN 2004; _cites Kornilov 1967_ | Table 2, p. 3, row 3; `ORC-SNG6VNMBGO` |  |
| ZrO2 |  | -1100.6 kJ/mol (basis unstated) | 298.15 | model |  |  | [3] CHEN 2004; _cites Ackermann 1975_ | Table 2, p. 3, row 4; `ORC-UIQ7XPTRO2` |  |
| ZrO2 |  | -1097.46 kJ/mol (basis unstated) | 298.15 | model |  |  | [3] CHEN 2004; _cites Chase 1985_ | Table 2, p. 3, row 5; `ORC-KUB2D3A4PC` |  |
| ZrO2 |  | -1094.1 kJ/mol (basis unstated) | 298.15 | experimental |  |  | [3] CHEN 2004; _cites Humphrey 1954_ | Table 2, p. 3, row 1; `ORC-4I4UZK2EY5` |  |
| ZrO2 | [ZrO2](https://data.orchid-project.org/compounds/ZrO2.html) | -573 kJ/mol-atom |  | model | -367.957 (mp-aaaaaefy) | -350.528 (oqmd-3278) | [2] Arroyave 2002 | Table 2, p. 17, row 1; `ORC-UT4GG4A3ZU` |  |
| ZrO2 | [ZrO2](https://data.orchid-project.org/compounds/ZrO2.html) | -366 kJ/mol-atom | 298.15 | experimental | -367.957 (mp-aaaaaefy) | -350.528 (oqmd-3278) | [2] Arroyave 2002 | Table 2, p. 17, row 2; `ORC-T64EA4SVSN` |  |
| ZrO3 | [ZrO3](https://data.orchid-project.org/compounds/ZrO3.html) | -644 kJ/mol-atom |  | model |  | -239.971 (oqmd-825016) | [2] Arroyave 2002 | Table 2, p. 17, row 3; `ORC-5NHXC6TIGO` |  |
| ZrO3 | [ZrO3](https://data.orchid-project.org/compounds/ZrO3.html) | -411 kJ/mol-atom |  | model |  | -239.971 (oqmd-825016) | [2] Arroyave 2002 | Table 2, p. 17, row 4; `ORC-BQTDFV2XVC` |  |
| monoclinic ZrO2 |  | -1100.97 kJ/mol (basis unstated) | 298.15 | model |  |  | [1] Wang 2004; _cites Liang 2001_ | Table 3, p. 6, row 8; `ORC-F6NCSYDKXL.fbb5b1` |  |
| monoclinic ZrO2 |  | -1100.92 kJ/mol (basis unstated) | 298.15 | experimental |  |  | [1] Wang 2004; _cites Huber 1964_ [doi](https://doi.org/10.1021/j100792a052) | Table 3, p. 6, row 3; `ORC-O2N4Y6PU3L` |  |
| monoclinic ZrO2 |  | -1100.69 kJ/mol (basis unstated) | 298.15 | model |  |  | [1] Wang 2004; _cites Chen 2004_ | Table 3, p. 6, row 10; `ORC-E5CPA7HYOF.222153` |  |
| monoclinic ZrO2 |  | -1100.57 kJ/mol (basis unstated) | 298.15 | unspecified |  |  | [1] Wang 2004; _cites Dinsdale 2003_ | Table 3, p. 6, row 11; `ORC-XPXHLUS742.b1fdcc` |  |
| monoclinic ZrO2 |  | -1100.57 kJ/mol (basis unstated) | 298.15 | model |  |  | [1] Wang 2004; _cites Du 1992_ [doi](https://doi.org/10.1111/j.1151-2916.1992.tb04384.x) | Table 3, p. 6, row 7; `ORC-WVWMHM2MNK.d74e97` |  |
| monoclinic ZrO2 |  | -1100.56 kJ/mol (basis unstated) | 298.15 | experimental |  |  | [1] Wang 2004; _cites Kornilov 1967_ | Table 3, p. 6, row 4; `ORC-BCTQCRDUEV` |  |
| monoclinic ZrO2 |  | -1100.31 kJ/mol (basis unstated) | 298.15 | model |  |  | [1] Wang 2004; _cites Arroyave 2002_ [doi](https://doi.org/10.1016/s0364-5916%2802%2900027-5) | Table 3, p. 6, row 9; `ORC-GJPSMMKMUH.3afd39` |  |

## Other properties

### Phase transition (54)

Table: Phase transition, O–Zr system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Phase transition | 973 K | 973 | polymorphic: α ↔ γ | experimental | [1] Wang 2004; _cites Lee 2003_ [doi](https://doi.org/10.1557/jmr.2003.0125) | Table 2, p. 5, row 46; `ORC-ADEZRYNNA3` |  |
| Phase transition | 1043 K | 1043 | polymorphic: α ↔ γ | experimental | [1] Wang 2004; _cites Molodetsky 1998_ [doi](https://doi.org/10.1524/zpch.1998.207.part_1_2.059) | Table 2, p. 5, row 45; `ORC-Y5EV2A4E7I` |  |
| Phase transition | 1286 K | 1286 | polymorphic: α ↔ β | experimental | [1] Wang 2004; _cites Suresh 2003_ [doi](https://doi.org/10.1557/jmr.2003.0406) | Table 2, p. 5, row 7; `ORC-ZMHQDF22DK` |  |
| Phase transition | 1387 K | 1387 | polymorphic: α ↔ β | model | [1] Wang 2004; _cites Chen 2004_ | Table 2, p. 5, row 14; `ORC-2ITSY4DI2W` |  |
| Phase transition | 1395 K | 1395 | polymorphic: α ↔ β | experimental | [1] Wang 2004; _cites Yashima 1995_ [doi](https://doi.org/10.1111/j.1151-2916.1995.tb08642.x) | Table 2, p. 5, row 5; `ORC-HA765CAHBX` |  |
| Phase transition | 1420 K | 1420 | polymorphic: α ↔ β | experimental | [1] Wang 2004; _cites Kirillin 1966_ | Table 2, p. 5, row 3; `ORC-SNATMOFD7C` |  |
| Phase transition | 1423 K | 1423 | polymorphic: α ↔ β | experimental | [1] Wang 2004; _cites Ya 1979_ | Table 2, p. 5, row 4; `ORC-R2DWAN5VIX` |  |
| Phase transition | 1435 K | 1435 | polymorphic: α ↔ β | experimental | [1] Wang 2004; _cites Jerebtsov 2001_ | Table 2, p. 5, row 6; `ORC-ACAUZDCJXN` |  |
| Phase transition | 1443 K | 1443 | polymorphic: α ↔ β | model | [1] Wang 2004; _cites Subbarao 1981_ | Table 2, p. 5, row 9; `ORC-HWZUPLQJ46` |  |
| Phase transition | 1454 K | 1454 | polymorphic: α ↔ β | model | [1] Wang 2004; _cites Du 1992_ [doi](https://doi.org/10.1111/j.1151-2916.1992.tb04384.x) | Table 2, p. 5, row 11; `ORC-OZD5L5O57F` |  |
| Phase transition | 1475 K | 1475 | polymorphic: α ↔ β | experimental | [1] Wang 2004; _cites Sh 1965_ | Table 2, p. 5, row 2; `ORC-6TZPY62QQC` |  |
| Phase transition | 1476 K | 1476 | polymorphic: α ↔ β | model | [1] Wang 2004; _cites Liang 2001_ | Table 2, p. 5, row 12; `ORC-MHHSP6KTB5` |  |
| Phase transition | 1478 K | 1478 | polymorphic: m-ZrO2 \<-> t-ZrO2; _alloy: Zr 0.333333_ | model | [3] CHEN 2004; _cites Liang 2001_ | Table 3, p. 5, row 17; `ORC-4MHWYLA5SN` |  |
| Phase transition | 1478 K | 1478 | polymorphic: m-ZrO2 \<-> t-ZrO2; _alloy: Zr 0.333333_ | model | [3] CHEN 2004; _cites Chase 1985_ | Table 3, p. 5, row 14; `ORC-5CR7D6HX4U` |  |
| Phase transition | 1478 K | 1478 | polymorphic: m-ZrO2 \<-> t-ZrO2; _alloy: Zr 0.333333_ | experimental | [3] CHEN 2004; _cites Coughlin 1950_ | Table 3, p. 5, row 1; `ORC-EI7XRTRJQO` |  |
| Phase transition | 1478 K | 1478 | polymorphic: m-ZrO2 \<-> t-ZrO2; _alloy: Zr 0.333333_ | model | [3] CHEN 2004; _cites Abriata 1986_ | Table 3, p. 5, row 15; `ORC-FICB5P54HB` |  |
| Phase transition | 1478 K | 1478 | polymorphic: m-ZrO2 \<-> t-ZrO2; _alloy: Zr 0.333333_ | model | [3] CHEN 2004; _cites Ackermann 1975_ | Table 3, p. 5, row 13; `ORC-HIXPBIWAXD` |  |
| Phase transition | 1478 K | 1478 | polymorphic: α ↔ β | model | [1] Wang 2004; _cites Ackerman 1975_ | Table 2, p. 5, row 8; `ORC-HLB2SFKSJ4` |  |
| Phase transition | 1478 K | 1478 | polymorphic: α ↔ β | experimental | [1] Wang 2004; _cites Coughlin 1950_ [doi](https://doi.org/10.1021/ja01161a106) | Table 2, p. 5, row 1; `ORC-IJIJBN75AN` |  |
| Phase transition | 1478 K | 1478 | polymorphic: α ↔ β | model | [1] Wang 2004; _cites Dinsdale 2003_ | Table 2, p. 5, row 15; `ORC-OODV5RNUN4` |  |
| Phase transition | 1478 K | 1478 | polymorphic: α ↔ β | model | [1] Wang 2004; _cites Arroyave 2002_ [doi](https://doi.org/10.1016/s0364-5916%2802%2900027-5) | Table 2, p. 5, row 13; `ORC-VCJLHPKC7S` |  |
| Phase transition | 1478 K | 1478 | polymorphic: α ↔ β | model | [1] Wang 2004; _cites Abriata 1986_ [doi](https://doi.org/10.1007/bf02881546) | Table 2, p. 5, row 10; `ORC-XK4T4M2VM3` |  |
| Phase transition | 1478.15 K | 1478.15 | /3 ZrO2-z + a Zr02\_= | experimental | [2] Arroyave 2002; _cites Ackerman 1975_ | p. 3; `ORC-W6J73SQWVD` | “At 1205°C, this phase transforms to a Zr02\_= \[15\].” |
| Phase transition | 1798.15 K | 1798.15 | other: 7 ZrO2-x ~- HCP +/3 Zr02\_= | experimental | [2] Arroyave 2002; _cites Rauh 1980_ | p. 3; `ORC-CR5NTR5F7M` | “It has also been observed \[13\] that there exists an invariant transformation 7 ZrO2-x ~- HCP +/3 Zr02\_= at 1525°C.” |
| Phase transition | 2558 K | 2558 | polymorphic: β ↔ γ | experimental | [1] Wang 2004; _cites Smith 1962_ | Table 2, p. 5, row 16; `ORC-PQFN3INWDD` |  |
| Phase transition | 2566 K | 2566 | polymorphic: β ↔ γ | experimental | [1] Wang 2004; _cites Wolten 1963_ | Table 2, p. 5, row 17; `ORC-EBOGVK742Q` |  |
| Phase transition | 2573 K | 2573 | polymorphic: β ↔ γ | experimental | [1] Wang 2004; _cites Ruh 1970_ | Table 2, p. 5, row 19; `ORC-5DGHVE5N7E` |  |
| Phase transition | 2627 K | 2627 | polymorphic: β ↔ γ | model | [1] Wang 2004; _cites Liang 2001_ | Table 2, p. 5, row 25; `ORC-QOXWKTWVIO` |  |
| Phase transition | 2641 K | 2641 | polymorphic: β ↔ γ | model | [1] Wang 2004; _cites Arroyave 2002_ [doi](https://doi.org/10.1016/s0364-5916%2802%2900027-5) | Table 2, p. 5, row 26; `ORC-6BIZE6ORVH` |  |
| Phase transition | 2642 K | 2642 | polymorphic: β ↔ γ | model | [1] Wang 2004; _cites Du 1992_ [doi](https://doi.org/10.1111/j.1151-2916.1992.tb04384.x) | Table 2, p. 5, row 24; `ORC-SMEHSXGINP` |  |
| Phase transition | 2643 K | 2643 | polymorphic: β ↔ γ | model | [1] Wang 2004; _cites Subbarao 1981_ | Table 2, p. 5, row 22; `ORC-DPNYHBM3VB` |  |
| Phase transition | 2645 K | 2645 | polymorphic: β ↔ γ | experimental | [1] Wang 2004; _cites Viechnicki 1965_ | Table 2, p. 5, row 18; `ORC-STETQG5EZL` |  |
| Phase transition | 2647 K | 2647 | polymorphic: β ↔ γ | model | [1] Wang 2004; _cites Chen 2004_ | Table 2, p. 5, row 27; `ORC-NJBE3EXN7W` |  |
| Phase transition | 2650 K | 2650 | polymorphic: β ↔ γ | model | [1] Wang 2004; _cites Abriata 1986_ [doi](https://doi.org/10.1007/bf02881546) | Table 2, p. 5, row 23; `ORC-4OFAZTAJJM` |  |
| Phase transition | 2650 K | 2650 | polymorphic: β ↔ γ | model | [1] Wang 2004; _cites Ackerman 1975_ | Table 2, p. 5, row 21; `ORC-MIFNLXVLTJ` |  |
| Phase transition | 2650 K | 2650 | polymorphic: β ↔ γ | model | [1] Wang 2004; _cites Dinsdale 2003_ | Table 2, p. 5, row 28; `ORC-UMOSCP3W3R` |  |
| Phase transition | 2650.15 K | 2650.15 | 7 Zr02\_= + /3 Zr02-= | experimental | [2] Arroyave 2002; _cites Ackerman 1975_ | p. 3; `ORC-OXC2RUEXLJ` | “the non-stoichiometric region of the phase being stable at temperatures as low as 1525°C \[15\], \[7\], \[14\] which is much lower than the coherent transformation to the/3 Zr02-= phase(,-, 2377°C \[15\]).” |
| Phase transition | 2950 K | 2950 | other: γ ↔ L | experimental | [1] Wang 2004; _cites Clausing 1932_ [doi](https://doi.org/10.1002/zaac.19322040105) | Table 2, p. 5, row 30; `ORC-2IX5FG22AX` |  |
| Phase transition | 2950 K | 2950 | other: γ ↔ L | model | [1] Wang 2004; _cites Arroyave 2002_ [doi](https://doi.org/10.1016/s0364-5916%2802%2900027-5) | Table 2, p. 5, row 42; `ORC-6J7TC6KONT` |  |
| Phase transition | 2953 K | 2953 | other: γ ↔ L | experimental | [1] Wang 2004; _cites Latta 1970_ [doi](https://doi.org/10.1016/0022-3115%2870%2990218-7) | Table 2, p. 5, row 34; `ORC-5A5GTIPCIS` |  |
| Phase transition | 2953 K | 2953 | other: γ ↔ L | model | [1] Wang 2004; _cites Subbarao 1981_ | Table 2, p. 5, row 37; `ORC-KKY3I7QKKX` |  |
| Phase transition | 2960 K | 2960 | other: γ ↔ L | experimental | [1] Wang 2004; _cites Henning 1925_ [doi](https://doi.org/10.1007/bf01591647) | Table 2, p. 5, row 29; `ORC-JOXIQIZNH4` |  |
| Phase transition | 2961 K | 2961 | other: γ ↔ L | model | [1] Wang 2004; _cites Liang 2001_ | Table 2, p. 5, row 41; `ORC-IHL5VM5CRT` |  |
| Phase transition | 2972 K | 2972 | other: γ ↔ L | experimental | [1] Wang 2004; _cites Noguchi 1966_ [doi](https://doi.org/10.1016/0038-092x%2866%2990014-4) | Table 2, p. 5, row 33; `ORC-BZGY5GABD5` |  |
| Phase transition | 2983 K | 2983 | other: γ ↔ L | model | [1] Wang 2004; _cites Du 1992_ [doi](https://doi.org/10.1111/j.1151-2916.1992.tb04384.x) | Table 2, p. 5, row 39; `ORC-5QWJ3WZCAR` |  |
| Phase transition | 2983 K | 2983 | other: γ ↔ L | experimental | [1] Wang 2004; _cites Ackerman 1977_ | Table 2, p. 5, row 35; `ORC-C7NUBLTP3M` |  |
| Phase transition | 2983 K | 2983 | other: γ ↔ L | model | [1] Wang 2004; _cites Chen 2004_ | Table 2, p. 5, row 43; `ORC-CPHLOJIAGR` |  |
| Phase transition | 2983 K | 2983 | other: γ ↔ L | experimental | [1] Wang 2004; _cites Lambertson 1965_ | Table 2, p. 5, row 31; `ORC-DVR67PTKQO` |  |
| Phase transition | 2983 K | 2983 | other: γ ↔ L | model | [1] Wang 2004; _cites Abriata 1986_ [doi](https://doi.org/10.1007/bf02881546) | Table 2, p. 5, row 38; `ORC-XIPOAGWKQ4` |  |
| Phase transition | 2983.15 K | 2983.15 | congruent melting | experimental | [2] Arroyave 2002 | p. 3; `ORC-BRZQHHTZG6` | “The 7 Zr02-= phase exhibits a congruent melting point at 2710°C.” |
| Phase transition | 2983.15 K | 2983.15 | congruent melting | experimental | [2] Arroyave 2002 | p. 2; `ORC-XCDQEWT3ZF` | “It has also been observed that at the stoichiometric composition Zr02, the high temperature cubic phase (7 Zr02\_=) melts congruently at 2710°C.” |
| Phase transition | 2985 K | 2985 | other: γ ↔ L | model | [1] Wang 2004; _cites Chevalier 1998_ [doi](https://doi.org/10.1016/s0022-3115%2898%2900450-4) | Table 2, p. 5, row 40; `ORC-D5TU4WHNLQ` |  |
| Phase transition | 2985 K | 2985 | other: γ ↔ L | model | [1] Wang 2004; _cites Dinsdale 2003_ | Table 2, p. 5, row 44; `ORC-FDB5RQGCH3` |  |
| Phase transition | 2995 K | 2995 | other: γ ↔ L | experimental | [1] Wang 2004; _cites Noguchi 1966_ [doi](https://doi.org/10.1016/0038-092x%2866%2990014-4) | Table 2, p. 5, row 32; `ORC-IFXXZY3L3Y` |  |

### Phase equilibrium (61)

Table: Phase equilibrium, O–Zr system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Phase composition |  | 1530 | α + ZrO2; _ZrO2: O 0.665, Zr 0.335_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 2; `ORC-XFL3DOOWVL` |  |
| Phase composition |  | 1530 | β + α + ZrO2; _β: O 0.04, Zr 0.96; ZrO2: O 0.665, Zr 0.335_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 1; `ORC-5G2HDZYYQ7` |  |
| Phase composition |  | 1546 | α; _α: O 0.298, Zr 0.702_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 1; `ORC-BMZL3A5YGB` |  |
| Phase composition |  | 1580 | α + ZrO2; _α: O 0.285, Zr 0.715_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 3; `ORC-I7A7UNGB3Y` |  |
| Phase composition |  | 1630 | α + ZrO2; _α: O 0.305, Zr 0.695_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 5; `ORC-TK35TNO3WY` |  |
| Phase composition |  | 1630 | β + α; _β: O 0.059, Zr 0.941; α: O 0.305, Zr 0.695_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 4; `ORC-K2IATKK72P` |  |
| Phase composition |  | 1730 | α + ZrO2; _ZrO2: O 0.665, Zr 0.335_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 9; `ORC-63OU4GB736` |  |
| Phase composition |  | 1730 | α + ZrO2; _α: O 0.312, Zr 0.688_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 8; `ORC-7DWGZ5FJFA` |  |
| Phase composition |  | 1730 | β + α; _α: O 0.15, Zr 0.85_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 7; `ORC-JAYULMPWRH` |  |
| Phase composition |  | 1730 | β + α + ZrO2; _β: O 0.07, Zr 0.93; α: O 0.312, Zr 0.688; ZrO2: O 0.665, Zr 0.335_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 6; `ORC-X75VJZAETG` |  |
| Phase composition |  | 1830 | α + ZrO2; _ZrO2: O 0.635, Zr 0.365_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 13; `ORC-FYELJBDYFN` |  |
| Phase composition |  | 1830 | α + ZrO2; _α: O 0.304, Zr 0.696_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 12; `ORC-GL5LE54R4G` |  |
| Phase composition |  | 1830 | β + α; _α: O 0.165, Zr 0.835_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 11; `ORC-DWW5KXYC6C` |  |
| Phase composition |  | 1830 | β + α + ZrO2; _β: O 0.082, Zr 0.918; α: O 0.304, Zr 0.696; ZrO2: O 0.635, Zr 0.365_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 10; `ORC-2IF3YVVCVO` |  |
| Phase composition |  | 1930 | α + ZrO2; _α: O 0.317, Zr 0.683_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 16; `ORC-BFCSBA52AF` |  |
| Phase composition |  | 1930 | α + ZrO2; _ZrO2: O 0.632, Zr 0.368_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 17; `ORC-C6CRXRTGXN` |  |
| Phase composition |  | 1930 | β + α; _α: O 0.175, Zr 0.825_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 15; `ORC-IEETB6E2GQ` |  |
| Phase composition |  | 1930 | β + α + ZrO2; _β: O 0.1, Zr 0.9; α: O 0.317, Zr 0.683; ZrO2: O 0.632, Zr 0.368_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 14; `ORC-Q7LZTOX23Q` |  |
| Phase composition |  | 2030 | α + ZrO2; _ZrO2: O 0.63, Zr 0.37_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 21; `ORC-DZ44WL7M2H` |  |
| Phase composition |  | 2030 | α + ZrO2; _α: O 0.325, Zr 0.675_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 20; `ORC-MNTY2CPI6T` |  |
| Phase composition |  | 2030 | β + α; _α: O 0.182, Zr 0.818_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 19; `ORC-M6G2R6P23X` |  |
| Phase composition |  | 2030 | β + α + ZrO2; _β: O 0.111, Zr 0.889; α: O 0.325, Zr 0.675; ZrO2: O 0.63, Zr 0.37_ | experimental | [4] Chevalier 1998; _cites Gebhardt 1961_ [doi](https://doi.org/10.1016/0022-3115%2861%2990075-7) | Table 11, p. 12, row 18; `ORC-YFTSU3VZSD` |  |
| Phase composition |  | 2088 | α + ZrO2 + ZrO2-x; _ZrO2-x: O 0.6305, Zr 0.3695; ZrO2: O 0.6305, Zr 0.3695_ | experimental | [4] Chevalier 1998; _cites Tanabe 1987_ [doi](https://doi.org/10.1016/s0039-6028%2887%2980071-7) | Table 13, p. 13, row 1; `ORC-OTWN3U4C3P` |  |
| Phase composition |  | 2089 | α; _α: O 0.329, Zr 0.671_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 2; `ORC-7CHXOKTNE7` |  |
| Phase composition |  | 2145 | β; _β: O 0.048, Zr 0.952_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 34; `ORC-O5MVT22ASE` |  |
| Phase composition |  | 2148 | α + ZrO2 + ZrO2-x; _ZrO2-x: O 0.6274, Zr 0.3726; ZrO2: O 0.6274, Zr 0.3726_ | experimental | [4] Chevalier 1998; _cites Tanabe 1987_ [doi](https://doi.org/10.1016/s0039-6028%2887%2980071-7) | Table 13, p. 13, row 2; `ORC-BPKVQY5C7F` |  |
| Phase composition |  | 2158 | α; _α: O 0.334, Zr 0.666_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 3; `ORC-6QR4HTRY7M` |  |
| Phase composition |  | 2191 | β; _β: O 0.073, Zr 0.927_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 33; `ORC-DNPHSQWYGR` |  |
| Phase composition |  | 2218 | α + ZrO2 + ZrO2-x; _ZrO2-x: O 0.6256, Zr 0.3744; ZrO2: O 0.6256, Zr 0.3744_ | experimental | [4] Chevalier 1998; _cites Tanabe 1987_ [doi](https://doi.org/10.1016/s0039-6028%2887%2980071-7) | Table 13, p. 13, row 3; `ORC-JKMC2PX3Y2` |  |
| Phase composition |  | 2229 | ZrO2; _ZrO2: O 0.635, Zr 0.365_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 5; `ORC-JPV4NBMYUP` |  |
| Phase composition |  | 2234 | L; _L: O 0.063, Zr 0.937_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 30; `ORC-45PFIJEC2L` |  |
| Phase composition |  | 2241 | β; _β: O 0.094, Zr 0.906_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 32; `ORC-BCVZZIKH4G` |  |
| Phase composition |  | 2243 | α; _α: O 0.195, Zr 0.805_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 29; `ORC-LYG5Y2ACOL` |  |
| Phase composition |  | 2243 | α + ZrO2 + ZrO2-x; _ZrO2-x: O 0.6277, Zr 0.3723; ZrO2: O 0.6277, Zr 0.3723_ | experimental | [4] Chevalier 1998; _cites Tanabe 1987_ [doi](https://doi.org/10.1016/s0039-6028%2887%2980071-7) | Table 13, p. 13, row 4; `ORC-2VELFZS4YW` |  |
| Phase composition |  | 2243 | β; _β: O 0.105, Zr 0.895_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 31; `ORC-QAUC42XHYJ` |  |
| Phase composition |  | 2253 | α; _α: O 0.337, Zr 0.663_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 4; `ORC-I5PA2G5GMQ` |  |
| Phase composition |  | 2254 | L; _L: O 0.107, Zr 0.893_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 20; `ORC-JM4CZKYK3I` |  |
| Phase composition |  | 2282 | ZrO2; _ZrO2: O 0.628, Zr 0.372_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 6; `ORC-3PRLVLBL5P` |  |
| Phase composition |  | 2293 | α + ZrO2 + ZrO2-x; _ZrO2-x: O 0.6259, Zr 0.3741; ZrO2: O 0.6259, Zr 0.3741_ | experimental | [4] Chevalier 1998; _cites Tanabe 1987_ [doi](https://doi.org/10.1016/s0039-6028%2887%2980071-7) | Table 13, p. 13, row 5; `ORC-N4GXVD55UO` |  |
| Phase composition |  | 2297 | L; _L: O 0.12, Zr 0.88_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 21; `ORC-7MCCDYINLJ` |  |
| Phase composition |  | 2318 | α + ZrO2 + ZrO2-x; _ZrO2-x: O 0.6221, Zr 0.3779; ZrO2: O 0.6221, Zr 0.3779_ | experimental | [4] Chevalier 1998; _cites Tanabe 1987_ [doi](https://doi.org/10.1016/s0039-6028%2887%2980071-7) | Table 13, p. 13, row 6; `ORC-FGW7K237HH` |  |
| Phase composition |  | 2328 | ZrO2; _ZrO2: O 0.624, Zr 0.376_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 7; `ORC-2ZFJW57WNU` |  |
| Phase composition |  | 2338 | L; _L: O 0.4, Zr 0.6_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 25; `ORC-6BM5LZRCRN` |  |
| Phase composition |  | 2338 | α; _α: O 0.35, Zr 0.65_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 26; `ORC-DQLTOTJG3F` |  |
| Phase composition |  | 2360 | α; _α: O 0.33, Zr 0.67_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 27; `ORC-LN6PLUVLBO` |  |
| Phase composition |  | 2364 | ZrO2; _ZrO2: O 0.622, Zr 0.378_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 12; `ORC-M3T4AHKFMF` |  |
| Phase composition |  | 2381 | L; _L: O 0.33, Zr 0.67_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 24; `ORC-VLWSOIU4RV` |  |
| Phase composition |  | 2392 | L; _L: O 0.42, Zr 0.58_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 11; `ORC-UABZOF5VKD` |  |
| Phase composition |  | 2393 | L; _L: O 0.231, Zr 0.769_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 22; `ORC-BVLGIXDDHU` |  |
| Phase composition |  | 2396 | L; _L: O 0.412, Zr 0.588_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 9; `ORC-TDFXXXO7KN` |  |
| Phase composition |  | 2401 | L; _L: O 0.42, Zr 0.58_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 8; `ORC-FESF57UNUH` |  |
| Phase composition |  | 2401 | L; _L: O 0.403, Zr 0.597_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 10; `ORC-SIYAJ27YUW` |  |
| Phase composition |  | 2403 | L; _L: O 0.24, Zr 0.76_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 23; `ORC-WWMZLDTGNJ` |  |
| Phase composition |  | 2403 | α; _α: O 0.25, Zr 0.75_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 28; `ORC-R445AOELVE` |  |
| Phase composition |  | 2417 | ZrO2; _ZrO2: O 0.616, Zr 0.384_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 13; `ORC-7AQL7Q7PJU` |  |
| Phase composition |  | 2475 | ZrO2; _ZrO2: O 0.613, Zr 0.387_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 14; `ORC-J633QWFP4M` |  |
| Phase composition |  | 2517 | ZrO2; _ZrO2: O 0.611, Zr 0.389_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 15; `ORC-UVDWAEX5CZ` |  |
| Phase composition |  | 2525 | ZrO2; _ZrO2: O 0.611, Zr 0.389_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 16; `ORC-INGXLHD52P` |  |
| Phase composition |  | 2586 | ZrO2; _ZrO2: O 0.608, Zr 0.392_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 17; `ORC-4LFVZIEC4J` |  |
| Phase composition |  | 2650 | ZrO2; _ZrO2: O 0.614, Zr 0.386_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 18; `ORC-GNWJV2X24Q` |  |
| Phase composition |  | 2677 | ZrO2; _ZrO2: O 0.616, Zr 0.384_ | experimental | [4] Chevalier 1998; _cites Ackermann 1977_ | Table 12, p. 12, row 19; `ORC-BP44DYNIUU` |  |

### Heat capacity / entropy / enthalpy (26)

Table: Heat capacity / entropy / enthalpy, O–Zr system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Entropy; _printed: S(ZrO2)_ | 50.72 J/mol (basis unstated)/K | 298.15 | ZrO2; _alloy: Zr 0.333333_ | model | [3] CHEN 2004; _cites Liang 2001_ | Table 1, p. 3, row 6; `ORC-5YCRQZON3U.2b6b29` |  |
| Entropy; _printed: S(ZrO2)_ | 50.33 J/mol (basis unstated)/K | 298.15 | ZrO2; _alloy: Zr 0.333333_ | experimental | [3] CHEN 2004; _cites Kelley 1944_ | Table 1, p. 3, row 1; `ORC-OOZB5LGXAO` |  |
| Entropy; _printed: S(ZrO2)_ | 50.359 J/mol (basis unstated)/K | 298.15 | ZrO2; _alloy: Zr 0.333333_ | model | [3] CHEN 2004; _cites Chase 1985_ | Table 1, p. 3, row 5; `ORC-QGUS63XPN5.ebfb5f` |  |
| Entropy; _printed: S(ZrO2)_ | 49.79 J/mol (basis unstated)/K | 298.15 | ZrO2; _alloy: Zr 0.333333_ | experimental | [3] CHEN 2004; _cites Tojo 1999_ | Table 1, p. 3, row 3; `ORC-QNNBZBMKXP.26b640` |  |
| Entropy; _printed: S(ZrO2)_ | 50.71 J/mol (basis unstated)/K | 298.15 | ZrO2; _alloy: Zr 0.333333_ | model | [3] CHEN 2004; _cites Ackermann 1975_ | Table 1, p. 3, row 4; `ORC-XJOFV243UT.8de5e2` |  |
| Entropy; _printed: S(ZrO2)_ | 49.8 J/mol (basis unstated)/K | 298.15 | ZrO2; _alloy: Zr 0.333333_ | model | [3] CHEN 2004 | Table 1, p. 3, row 7; `ORC-Y7QFWUUIQA.2e72f4` |  |
| Entropy | 50.71 J/mol (basis unstated)/K | 298.15 | monoclinic ZrO2; _alloy: Zr 0.333333_ | experimental | [1] Wang 2004; _cites Kelly 1961_ | Table 3, p. 6, row 2; `ORC-3SNHZDZ55Y` |  |
| Entropy | 49.79 J/mol (basis unstated)/K | 298.15 | monoclinic ZrO2; _alloy: Zr 0.333333_ | experimental | [1] Wang 2004; _cites Tojo 1999_ [doi](https://doi.org/10.1006/jcht.1998.0481) | Table 3, p. 6, row 6; `ORC-BZJMSBBPAB.8a2017` |  |
| Entropy | 49.8 J/mol (basis unstated)/K | 298.15 | monoclinic ZrO2; _alloy: Zr 0.333333_ | model | [1] Wang 2004; _cites Chen 2004_ | Table 3, p. 6, row 10; `ORC-E5CPA7HYOF.ae9a56` |  |
| Entropy | 50.73 J/mol (basis unstated)/K | 298.15 | monoclinic ZrO2; _alloy: Zr 0.333333_ | model | [1] Wang 2004; _cites Liang 2001_ | Table 3, p. 6, row 8; `ORC-F6NCSYDKXL.90d5eb` |  |
| Entropy | 50.36 J/mol (basis unstated)/K | 298.15 | monoclinic ZrO2; _alloy: Zr 0.333333_ | model | [1] Wang 2004; _cites Arroyave 2002_ [doi](https://doi.org/10.1016/s0364-5916%2802%2900027-5) | Table 3, p. 6, row 9; `ORC-GJPSMMKMUH.36bb89` |  |
| Entropy | 50.35 J/mol (basis unstated)/K | 298.15 | monoclinic ZrO2; _alloy: Zr 0.333333_ | model | [1] Wang 2004; _cites Du 1992_ [doi](https://doi.org/10.1111/j.1151-2916.1992.tb04384.x) | Table 3, p. 6, row 7; `ORC-WVWMHM2MNK.99958c` |  |
| Entropy | 50.35 J/mol (basis unstated)/K | 298.15 | monoclinic ZrO2; _alloy: Zr 0.333333_ | unspecified | [1] Wang 2004; _cites Dinsdale 2003_ | Table 3, p. 6, row 11; `ORC-XPXHLUS742.96ca74` |  |
| Heat capacity; _printed: Cp(ZrO2)_ | 56.5 J/mol (basis unstated)/K | 298.15 | ZrO2; _alloy: Zr 0.333333_ | experimental | [3] CHEN 2004; _cites Nevitt 1990_ | Table 1, p. 3, row 2; `ORC-2SRBY3OAOB` |  |
| Heat capacity; _printed: Cp(ZrO2)_ | 63.43 J/mol (basis unstated)/K | 298.15 | ZrO2; _alloy: Zr 0.333333_ | model | [3] CHEN 2004; _cites Liang 2001_ | Table 1, p. 3, row 6; `ORC-5YCRQZON3U.b6979c` |  |
| Heat capacity; _printed: Cp(ZrO2)_ | 56.191 J/mol (basis unstated)/K | 298.15 | ZrO2; _alloy: Zr 0.333333_ | model | [3] CHEN 2004; _cites Chase 1985_ | Table 1, p. 3, row 5; `ORC-QGUS63XPN5.3d4d9c` |  |
| Heat capacity; _printed: Cp(ZrO2)_ | 56.14 J/mol (basis unstated)/K | 298.15 | ZrO2; _alloy: Zr 0.333333_ | experimental | [3] CHEN 2004; _cites Tojo 1999_ | Table 1, p. 3, row 3; `ORC-QNNBZBMKXP.f86597` |  |
| Heat capacity; _printed: Cp(ZrO2)_ | 56.02 J/mol (basis unstated)/K | 298.15 | ZrO2; _alloy: Zr 0.333333_ | model | [3] CHEN 2004; _cites Ackermann 1975_ | Table 1, p. 3, row 4; `ORC-XJOFV243UT.890ffc` |  |
| Heat capacity; _printed: Cp(ZrO2)_ | 57.21 J/mol (basis unstated)/K | 298.15 | ZrO2; _alloy: Zr 0.333333_ | model | [3] CHEN 2004 | Table 1, p. 3, row 7; `ORC-Y7QFWUUIQA.aa2b26` |  |
| Heat capacity | 56.14 J/mol (basis unstated)/K | 298.15 | monoclinic ZrO2; _alloy: Zr 0.333333_ | experimental | [1] Wang 2004; _cites Tojo 1999_ [doi](https://doi.org/10.1006/jcht.1998.0481) | Table 3, p. 6, row 6; `ORC-BZJMSBBPAB.e77723` |  |
| Heat capacity | 57.21 J/mol (basis unstated)/K | 298.15 | monoclinic ZrO2; _alloy: Zr 0.333333_ | model | [1] Wang 2004; _cites Chen 2004_ | Table 3, p. 6, row 10; `ORC-E5CPA7HYOF.349c85` |  |
| Heat capacity | 63.43 J/mol (basis unstated)/K | 298.15 | monoclinic ZrO2; _alloy: Zr 0.333333_ | model | [1] Wang 2004; _cites Liang 2001_ | Table 3, p. 6, row 8; `ORC-F6NCSYDKXL.bfb2bf` |  |
| Heat capacity | 56.5 J/mol (basis unstated)/K | 298.15 | monoclinic ZrO2; _alloy: Zr 0.333333_ | experimental | [1] Wang 2004; _cites Nevitt 1990_ [doi](https://doi.org/10.1111/j.1151-2916.1990.tb07619.x) | Table 3, p. 6, row 5; `ORC-FZR7H2LS6G` |  |
| Heat capacity | 55.9 J/mol (basis unstated)/K | 298.15 | monoclinic ZrO2; _alloy: Zr 0.333333_ | model | [1] Wang 2004; _cites Arroyave 2002_ [doi](https://doi.org/10.1016/s0364-5916%2802%2900027-5) | Table 3, p. 6, row 9; `ORC-GJPSMMKMUH.b98040` |  |
| Heat capacity | 56.12 J/mol (basis unstated)/K | 298.15 | monoclinic ZrO2; _alloy: Zr 0.333333_ | model | [1] Wang 2004; _cites Du 1992_ [doi](https://doi.org/10.1111/j.1151-2916.1992.tb04384.x) | Table 3, p. 6, row 7; `ORC-WVWMHM2MNK.ae8c81` |  |
| Heat capacity | 56.04 J/mol (basis unstated)/K | 298.15 | monoclinic ZrO2; _alloy: Zr 0.333333_ | unspecified | [1] Wang 2004; _cites Dinsdale 2003_ | Table 3, p. 6, row 11; `ORC-XPXHLUS742.c02df2` |  |

### Activity / EMF / Gibbs energy (14)

Table: Activity / EMF / Gibbs energy, O–Zr system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Activity; _printed: a(Zr)_ | 0.29 unspecified | 2100.15 |  | model | [2] Arroyave 2002 | p. 16; `ORC-J7JMIFQGDS.81a221` | “This activity was measured to be 0.68, having pure zirconium at 1827°C as the reference state. Our model predicts that under this conditions, the activity of Zirconium must be 0.29.” |
| Activity; _printed: a(Zr)_ | 0.68 unspecified | 2100.15 |  | experimental | [2] Arroyave 2002 | p. 16; `ORC-J7JMIFQGDS.b09e21` | “This activity was measured to be 0.68, having pure zirconium at 1827°C as the reference state.” |
| Activity Zr; _printed: a(Zr)_ | 0.52 1 | 1800 | Zr (S, saturated with O) + ZrO2-x(S) | experimental | [4] Chevalier 1998; _cites Ackermann 1979_ | Table 15, p. 13, row 1; `ORC-HWNW22IGSK` |  |
| Activity Zr; _printed: a(Zr)_ | 0.532 1 | 1800 | Zr (S, saturated with O) + ZrO2-x(S) | model | [4] Chevalier 1998 | Table 15, p. 13, row 2; `ORC-RW2GX3LC53` |  |
| Activity Zr; _printed: a(Zr)_ | 0.538 1 | 1900 | Zr (S, saturated with O) + ZrO2-x(S) | model | [4] Chevalier 1998 | Table 15, p. 13, row 4; `ORC-2NT25W4LY7` |  |
| Activity Zr; _printed: a(Zr)_ | 0.57 1 | 1900 | Zr (S, saturated with O) + ZrO2-x(S) | experimental | [4] Chevalier 1998; _cites Ackermann 1979_ | Table 15, p. 13, row 3; `ORC-UBXYTU5W5D` |  |
| Activity Zr; _printed: a(Zr)_ | 0.544 1 | 2000 | Zr (S, saturated with O) + ZrO2-x(S) | model | [4] Chevalier 1998 | Table 15, p. 13, row 6; `ORC-BIL75ZNXUQ` |  |
| Activity Zr; _printed: a(Zr)_ | 0.62 1 | 2000 | Zr (S, saturated with O) + ZrO2-x(S) | experimental | [4] Chevalier 1998; _cites Ackermann 1979_ | Table 15, p. 13, row 5; `ORC-LMWJ55G7T2` |  |
| Activity Zr; _printed: a(Zr)_ | 0.547 1 | 2100 | Zr (S, saturated with O) + ZrO2-x(S) | model | [4] Chevalier 1998 | Table 15, p. 13, row 8; `ORC-JM4IMX2E46` |  |
| Activity Zr; _printed: a(Zr)_ | 0.67 1 | 2100 | Zr (S, saturated with O) + ZrO2-x(S) | experimental | [4] Chevalier 1998; _cites Ackermann 1979_ | Table 15, p. 13, row 7; `ORC-RITIXFWOK3` |  |
| Activity Zr; _printed: a(Zr)_ | 0.72 1 | 2200 | Zr (S, saturated with O) + ZrO2-x(S) | experimental | [4] Chevalier 1998; _cites Ackermann 1979_ | Table 15, p. 13, row 9; `ORC-4ZNQRDPH5A` |  |
| Activity Zr; _printed: a(Zr)_ | 0.572 1 | 2200 | Zr (S, saturated with O) + ZrO2-x(S) | model | [4] Chevalier 1998 | Table 15, p. 13, row 10; `ORC-YSSQBA4HLU` |  |
| Activity Zr; _printed: a(Zr)_ | 0.604 1 | 2300 | Zr (S, saturated with O) + ZrO2-x(S) | model | [4] Chevalier 1998 | Table 15, p. 13, row 12; `ORC-5P2GX5PFM2` |  |
| Activity Zr; _printed: a(Zr)_ | 0.78 1 | 2300 | Zr (S, saturated with O) + ZrO2-x(S) | experimental | [4] Chevalier 1998; _cites Ackermann 1979_ | Table 15, p. 13, row 11; `ORC-TLVM5YXFZN` |  |

### Other property (5)

Table: Other property, O–Zr system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Other; _printed: enthalpy of transformation_ | 9700 unspecified ± 1100 | 973 |  | experimental | [1] Wang 2004; _cites Lee 2003_ [doi](https://doi.org/10.1557/jmr.2003.0125) | p. 4; `ORC-N4LWMCT746.448680` | “The enthalpies of formation of cubic yttria-stabilized zirconia with different compositions were measured by high temperature solution calorimetry and oxide melt solution calorimetry \[24,25\]. The enthalpy of the α ↔ γ transformation was then extrapolated to be 13 500 ± 2200 J mol-1 at 1043 K and 9700 ± 1100 J mol-1 at 973 K, respectively.” |
| Other; _printed: enthalpy of transformation_ | 13500 unspecified ± 2200 | 1043 |  | experimental | [1] Wang 2004; _cites Molodetsky 1998_ [doi](https://doi.org/10.1524/zpch.1998.207.part_1_2.059) | p. 4; `ORC-N4LWMCT746.9df33e` | “The enthalpies of formation of cubic yttria-stabilized zirconia with different compositions were measured by high temperature solution calorimetry and oxide melt solution calorimetry \[24,25\]. The enthalpy of the α ↔ γ transformation was then extrapolated to be 13 500 ± 2200 J mol-1 at 1043 K and 9700 ± 1100 J mol-1 at 973 K, respectively.” |
| Other; _printed: enthalpy of transformation_ | 9200 unspecified ± 1200 | 1043 |  | model | [1] Wang 2004; _cites Molodetsky 1998_ [doi](https://doi.org/10.1524/zpch.1998.207.part_1_2.059) | p. 4; `ORC-VC3VJKA5MQ` | “However, Lee et al. \[25\] also got a modified result 9200 ± 1200 J mol-1 at 1043 K by using the original experimental data of \[24\].” |
| Other; _printed: enthalpy of transformation_ | 5175.24 unspecified ± 616.1 | 1435 |  | experimental | [1] Wang 2004; _cites Jerebtsov 2001_ | p. 4; `ORC-HQXEKEHAGS` | “(differential thermal analysis) method, Jerebtsov et al. \[19, 23\] determined the enthalpy of the α ↔ β transformation in their experimental studies of phase diagrams involving ZrO2 systems, and obtained the value of 5175.24 ± 616.1 J mol-1 at about 1435 K.” |
| Other; _printed: enthalpy of the α ↔ β transformation_ | 5272 J mol-1 | 1475 |  | experimental | [1] Wang 2004; _cites Sh 1965_ | p. 4; `ORC-CTPA52PFMD` | “Tsagareishvili and Gvelesiani \[16\] reported a value of 5272 J mol-1 at 1475 K.” |

## Sources

Reporting papers the values were read from (a value cited from another work names that work in its row).

1. Chong Wang, Matvei Zinkevich, Fritz Aldinger, On the thermodynamic modeling of the Zr–O system, Calphad 28, 281-292 (2004). [doi:10.1016/j.calphad.2004.09.002](https://doi.org/10.1016/j.calphad.2004.09.002)
2. Raymundo Arroyave, Larry Kaufman, Thomas W. Eagar, Thermodynamic modeling of the ZrO system, Calphad 26, 95-118 (2002). [doi:10.1016/s0364-5916(02)00027-5](https://doi.org/10.1016/s0364-5916%2802%2900027-5)
3. M CHEN, B HALLSTEDT, L GAUCKLER, Thermodynamic modeling of the ZrO2–YO1.5 system, Solid State Ionics 170, 255-274 (2004). [doi:10.1016/j.ssi.2004.02.017](https://doi.org/10.1016/j.ssi.2004.02.017)
4. P.Y. Chevalier, E. Fischer, Thermodynamic modelling of the O–U–Zr system, Journal of Nuclear Materials 257, 213-255 (1998). [doi:10.1016/s0022-3115(98)00450-4](https://doi.org/10.1016/s0022-3115%2898%2900450-4)

## Please cite

- R. Arróyave, J. Saal, D. Shin, ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature (version 2026.10; Version 1, machine-extracted), Zenodo (2026). https://doi.org/10.5281/zenodo.23735569
- R. Arróyave, J. Saal, D. Shin, ORCHID-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD) (version 2026.10), Zenodo (2026). https://doi.org/10.5281/zenodo.23735891
- R. Arróyave, J. Saal, D. Shin, ORCHID data: umbrella record of the ORCHID datasets (version 2026.10; Version 1, machine-extracted), Zenodo (2026). https://doi.org/10.5281/zenodo.23736065

Also cite the original source of every value you use (paper_citation / paper_doi, and cited_dois for values the paper cites from earlier work); A. Jain et al., The Materials Project: A materials genome approach to accelerating materials innovation, APL Materials 1 (2013) 011002, https://doi.org/10.1063/1.4812323 (CC BY 4.0); J. E. Saal et al., JOM 65 (2013) 1501, https://doi.org/10.1007/s11837-013-0755-4 and S. Kirklin et al., npj Comput. Mater. 1 (2015) 15010, https://doi.org/10.1038/npjcompumats.2015.10 (CC BY 4.0); B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, https://doi.org/10.1016/j.calphad.2025.102833 (CC BY 4.0), and the original assessment named in each file.

Version 1, machine-extracted: values were read by language-model readers constrained to quote their source and checked automatically, and the release was then audited on the printed pages by adversarial audits, an independent second review of fit-facing records and a preliminary human review of a frozen sample. Flags such as accepted and ESPEI-ready record screening results, not certification; known issues are listed in the release notes.

```bibtex
@misc{orchid_literature_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735569},
  url       = {https://doi.org/10.5281/zenodo.23735569},
  note      = {Version 1, machine-extracted}
}

@misc{orchid_hulls_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD)}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735891},
  url       = {https://doi.org/10.5281/zenodo.23735891}
}

@misc{orchid_data_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID data: umbrella record of the ORCHID datasets}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23736065},
  url       = {https://doi.org/10.5281/zenodo.23736065},
  note      = {Version 1, machine-extracted}
}
```

---

Derived data CC BY 4.0 ([licence](https://creativecommons.org/licenses/by/4.0/)): cite ORCHID ([CITATION.cff](https://data.orchid-project.org/CITATION.cff)) and the original sources. Quotes are short excerpts kept so that each value can be checked; they remain under the publishers' copyright and are not relicensed. Source papers, page images and full text are not redistributed. Field reference: [SCHEMA.md](https://data.orchid-project.org/literature/SCHEMA.md). Machine-readable guide: [llms.txt](https://data.orchid-project.org/llms.txt). Found an error? The report link of a value (Markdown: its id, ORC-..., in the Location column) opens a pre-filled GitHub issue, https://github.com/orchid-calphad/orchid-data/issues/new?template=report-value-error.yml&record_id=\<id>, carrying only the record id, source and value; [how to contribute](https://orchid-project.org/contribute/).