NpO2
Neptunium dioxide · Neptunium(IV) oxide
Neptunium dioxide is a stable ceramic compound consisting of neptunium and oxygen. It is primarily utilized in nuclear research and as a precursor for the production of other neptunium-based materials.
NpO
Overview
Key Properties
Cross-validated computational properties for Neptunium dioxide, aggregated across 4 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.
Metallic / not reported
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.
0.000 eV/atom
Best (lowest) across sources
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.
On hull (stable)
2 DFT sources
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
39
4 databases, 12 space groups
Validation
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of NpO2. 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.
1.00 / 1.00
Trust tier: medium
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
0.000 eV
EAH spread across sources
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
2
jarvis, materials_project
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
All match
Crystallography
Reported Structures
Lowest-energy structures reported for NpO2, 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. |
|---|---|---|---|---|---|
| Fm-3m (No. 225) | cubic | 0.00 | 0.0000 | -11.216 | 11.20 |
| Cm (No. 8) | Monoclinic | — | — | — | 13.29 |
| Cm (No. 8) | Monoclinic | — | — | — | 7.06 |
| Fm-3m (No. 225) | Cubic | — | — | — | 10.91 |
| C2 (No. 5) | Monoclinic | — | — | — | 7.52 |
| C2/m (No. 12) | Monoclinic | — | — | — | 6.98 |
| C2/m (No. 12) | Monoclinic | — | — | — | 7.04 |
| Cm (No. 8) | Monoclinic | — | — | — | 5.53 |
| Cm (No. 8) | Monoclinic | — | — | — | 7.66 |
| P3m1 (No. 156) | Trigonal | — | — | — | 6.61 |
| P2/m (No. 10) | Monoclinic | — | — | — | 5.51 |
| C2/m (No. 12) | Monoclinic | — | — | — | 6.08 |
Uses
Applications
Where Neptunium dioxide is used.
Nuclear fuel researchTarget material for isotope productionRadiochemical studies
Reference
Frequently Asked Questions
Common questions about Neptunium dioxide, answered from cross-validated data.
What is NpO2?
Neptunium dioxide is a stable ceramic compound consisting of neptunium and oxygen. It is primarily utilized in nuclear research and as a precursor for the production of other neptunium-based materials.
More questions
What is NpO2 used for?
Neptunium dioxide (NpO2) is used in nuclear fuel research, target material for isotope production, and radiochemical studies.
What is the band gap of NpO2?
Neptunium dioxide (NpO2) is computed to be metallic (no band gap) in the reported DFT structures.
Is NpO2 a metal, semiconductor, or insulator?
Computed band structures report no gap, so it is metallic.
Is NpO2 thermodynamically stable?
Yes — Neptunium dioxide (NpO2) sits on the convex hull (energy above hull 0 eV/atom), i.e. on hull (stable).
What is the crystal structure of NpO2?
The lowest-energy reported polymorph of Neptunium dioxide (NpO2) is cubic symmetry, space group Fm-3m (No. 225).
What is the density of NpO2?
The computed density of the ground-state structure of Neptunium dioxide (NpO2) is 11.20 g/cm³.
How many polymorphs of NpO2 are known?
39 structures of NpO2 are reported across 4 databases, spanning 12 distinct space groups.
What elements does NpO2 contain?
Neptunium dioxide (NpO2) contains Np and O (2 elements).
Where does the data for NpO2 come from?
NpO2 data is cross-referenced from materials_project, mpaloe, jarvis, cod.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- mpaloe — Data from mpaloe.
- jarvis — Data from JARVIS (NIST). Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020).
- cod — Data from the Crystallography Open Database. Cite: Grazulis et al., Nucleic Acids Res. 40, D420 (2012).
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