CrP2O7
chromium(III) pyrophosphate · chromium pyrophosphate
CrP2O7 is a semiconducting chromium-based phosphate compound known for its structural complexity and metastable nature.
About chromium(III) pyrophosphate
CrP2O7 is a semiconducting transition-metal phosphate that exhibits significant structural complexity. As a metastable phase, it represents a specialized member of the phosphate family, characterized by a robust framework that accommodates chromium in a distinct coordination environment.
Its importance lies in its role as a model system for understanding the interplay between transition metal centers and phosphate polyanions. The compound is frequently studied for its potential in catalytic and electrochemical applications, where its electronic properties can be tuned through structural modification.
Key Properties
Cross-validated computational properties for chromium(III) pyrophosphate, 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 CrP2O7. 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 CrP2O7, 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. |
|---|---|---|---|---|---|
| P21 (No. 4) | monoclinic | 0.00 | 0.0000 | -2.128 | — |
| C2 (No. 5) | monoclinic | 0.00 | 0.0115 | -2.116 | — |
| C2 (No. 5) | monoclinic | 0.00 | 0.0115 | -2.116 | — |
| C2 (No. 5) | monoclinic | 0.00 | 0.0115 | -2.116 | — |
| P21 (No. 4) | monoclinic | 0.59 | 0.0254 | -7.968 | 2.91 |
| P21/c (No. 14) | monoclinic | 0.00 | 0.0264 | -7.967 | 2.94 |
| P21/c (No. 14) | monoclinic | 0.00 | 0.0332 | -7.960 | 2.82 |
| P21/c (No. 14) | monoclinic | 0.47 | 0.0547 | -7.939 | 3.06 |
| C2/c (No. 15) | monoclinic | 0.36 | 0.0561 | -7.937 | 3.17 |
| C2 (No. 5) | monoclinic | 0.83 | 0.0663 | -7.927 | 3.24 |
| P21/c (No. 14) | monoclinic | 0.00 | 0.0822 | -7.911 | 2.72 |
| P-1 (No. 2) | triclinic | 0.00 | 0.0933 | -7.900 | 2.93 |
Applications
Where chromium(III) pyrophosphate is used.
Frequently Asked Questions
Common questions about chromium(III) pyrophosphate, answered from cross-validated data.
What is CrP2O7?
CrP2O7 is a semiconducting chromium-based phosphate compound known for its structural complexity and metastable nature.
What is CrP2O7 used for?
What is the band gap of CrP2O7?
Is CrP2O7 a metal, semiconductor, or insulator?
Is CrP2O7 thermodynamically stable?
What is the crystal structure of CrP2O7?
How many polymorphs of CrP2O7 are known?
What elements does CrP2O7 contain?
Where does the data for CrP2O7 come from?
How It Compares
Within the transition-metal phosphates class.
Within the broad class of transition-metal phosphates, CrP2O7 occupies a distinct niche compared to battery-focused materials like LiFePO4 or LiMnPO4. While those lithium-containing siblings are optimized for ion mobility and redox stability, CrP2O7 serves as a structural analog to TiP2O7, offering a different electronic landscape that is less focused on traditional intercalation and more on fundamental solid-state chemistry.
Related Compounds
Other Transition-Metal Phosphates in the database.
Data sources & attribution
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- 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)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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