PO2
PO2 is a wide-band-gap insulating phosphorus oxide that is considered a promising candidate for synthesis due to its near-stable thermodynamic profile.
About PO2
PO2 is a phosphorus oxide characterized by its insulating electronic nature and wide band gap. As a material that sits near the thermodynamic hull, it represents a compelling subject for experimental synthesis and structural investigation within the phosphorus-oxygen system. Its structural complexity is highlighted by a vast array of reported configurations across crystalline databases. The compound's proximity to stability suggests that it may be accessible under specific processing conditions, making it a point of interest for researchers exploring non-traditional phosphorus-based frameworks. Its insulating behavior positions it as a potential candidate for dielectric applications or as a component in specialized electronic thin films.
Key Properties
Cross-validated computational properties for PO2, aggregated across 2 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 PO2. 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 PO2, 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. |
|---|---|---|---|---|---|
| — | — | 4.34 | 0.0126 | -2.137 | — |
| C2/c (No. 15) | monoclinic | 4.52 | 0.0217 | -7.368 | 2.50 |
| — | — | 1.05 | 0.3501 | -1.799 | — |
| — | — | 0.35 | 0.5263 | -1.623 | — |
| Cm (No. 8) | monoclinic | 0.00 | 0.6801 | -6.709 | 1.28 |
| — | — | 0.00 | 0.8258 | -1.324 | — |
| — | — | 0.00 | 3.3315 | 1.182 | — |
| P1 (No. 1) | triclinic | — | — | — | 4.79 |
| P1 (No. 1) | triclinic | — | — | — | 3.53 |
| P1 (No. 1) | triclinic | — | — | — | 5.09 |
| P1 (No. 1) | triclinic | — | — | — | 3.38 |
| P1 (No. 1) | triclinic | — | — | — | 3.39 |
Applications
Where PO2 is used.
Patent Landscape
2 patents reference PO2 or close compositional variants.
| Patent | Title | Assignee | Granted |
|---|---|---|---|
| 4374816 | Process for producing hypo-phosphorous acid (H.sub.3 PO.sub.2) and non-transition metal hypophosphites | — | — |
| 4265866 | Process for producing hypophosphorous acid (H.sub.3 PO.sub.2) and non-transition metal hypophosphites | — | — |
Frequently Asked Questions
Common questions about PO2, answered from cross-validated data.
What is PO2?
PO2 is a wide-band-gap insulating phosphorus oxide that is considered a promising candidate for synthesis due to its near-stable thermodynamic profile.
What is PO2 used for?
What is the band gap of PO2?
Is PO2 a metal, semiconductor, or insulator?
Is PO2 thermodynamically stable?
What is the crystal structure of PO2?
What is the density of PO2?
How many polymorphs of PO2 are known?
What elements does PO2 contain?
Where does the data for PO2 come from?
How It Compares
As a phosphorus oxide with significant structural diversity, PO2 serves as an intriguing case study in the broader landscape of p-block oxides. While many phosphorus oxides are well-characterized, this specific stoichiometry remains a challenging target for synthesis, occupying a unique position in the chemical space where structural variety is high but thermodynamic stability is finely balanced.
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)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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