YO2
YO2 is a semiconducting yttrium oxide phase that is thermodynamically unstable and primarily studied for its structural complexity.
About YO2
YO2 is a semiconducting oxide composed of yttrium and oxygen. It represents a complex phase in the yttrium-oxygen system that has been extensively documented across various structural databases. Its electronic character suggests potential utility in specialized semiconductor applications where specific oxide properties are required. Due to its position relative to the thermodynamic hull, it is considered an unstable phase under standard conditions, making its synthesis and characterization a significant challenge for experimentalists. This instability highlights the intricate nature of metal-oxygen bonding in yttrium-based systems.
Key Properties
Cross-validated computational properties for YO2, aggregated across 3 databases.
Band GapEnergy needed to move an electron from the valence band to the conduction band. Lower or zero values tend to behave more metallic; larger gaps are more insulating or semiconducting.
Energy Above HullThermodynamic distance from the most stable set of competing phases. 0 eV/atom is on the convex hull; small positive values may still be experimentally accessible.
StabilityA plain-language summary of the best reported energy-above-hull result. It reflects whether the lowest-energy structure is on, near, or far from the stability hull.
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of YO2. Tight agreement means computed properties can be trusted without re-running calculations.
Agreement ScoreA normalized confidence score summarizing how closely independent DFT databases agree. Higher scores mean tighter cross-source agreement.
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
Reported Structures
Lowest-energy structures reported for YO2, ranked by energy above hull.
| Space GroupSymmetry classification of the crystal arrangement. The number is the international space-group index. | Crystal SystemBroad lattice family, such as cubic, tetragonal, monoclinic, or triclinic, derived from unit-cell symmetry. | Band Gap (eV)Electronic gap calculated for this specific reported structure, measured in electronvolts. | E above hull (eV/atom)Thermodynamic distance from the convex hull for this structure, normalized per atom. Lower is generally more stable. | E/atom (eV)Computed total energy normalized per atom. Use energy above hull, not this value alone, when comparing stability. | Density (g/cm³)Mass per relaxed crystal volume, reported in grams per cubic centimeter. |
|---|---|---|---|---|---|
| — | — | 3.96 | 0.0000 | -3.232 | — |
| P21/m (No. 11) | monoclinic | 0.00 | 0.1824 | -8.581 | 4.50 |
| I4/mmm (No. 139) | tetragonal | 0.00 | 0.2155 | -3.004 | — |
| C2/c (No. 15) | monoclinic | 0.27 | 0.2812 | -8.482 | 3.85 |
| P21/c (No. 14) | monoclinic | 0.00 | 0.3174 | -8.446 | 3.64 |
| C2/c (No. 15) | monoclinic | 0.00 | 0.3174 | -8.446 | 3.64 |
| Cmcm (No. 63) | orthorhombic | 0.16 | 0.3384 | -2.881 | — |
| — | — | 0.00 | 0.4048 | -2.827 | — |
| — | — | 0.00 | 0.4400 | -2.792 | — |
| — | — | 0.00 | 0.5856 | -2.647 | — |
| — | — | 0.00 | 2.3578 | -0.875 | — |
| P1 (No. 1) | triclinic | — | — | — | 2.18 |
Applications
Where YO2 is used.
Patent Landscape
1 patent reference YO2 or close compositional variants.
| Patent | Title | Assignee | Granted |
|---|---|---|---|
| 8497542 | ZrXHfYSn1-X-YO2 films as high K gate dielectrics | — | — |
Frequently Asked Questions
Common questions about YO2, answered from cross-validated data.
What is YO2?
YO2 is a semiconducting yttrium oxide phase that is thermodynamically unstable and primarily studied for its structural complexity.
What is YO2 used for?
What is the band gap of YO2?
Is YO2 a metal, semiconductor, or insulator?
Is YO2 thermodynamically stable?
What is the crystal structure of YO2?
What is the density of YO2?
How many polymorphs of YO2 are known?
What elements does YO2 contain?
Where does the data for YO2 come from?
How It Compares
As a unique oxide phase, YO2 exists as an outlier in the landscape of yttrium oxides, which are more commonly found in highly stable, stoichiometric forms. Unlike the more robust and widely utilized yttrium sesquioxide, this compound occupies a metastable region that necessitates precise control over synthesis environments to observe its structural characteristics.
Data sources & attribution
- oqmd — Data from the OQMD (oqmd.org). Cite: Saal et al., JOM 65, 1501 (2013); Kirklin et al., npj Comp. Mater. 1, 15010 (2015). (CC-BY-4.0)
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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