H2W2O7
pyrotungstic acid · dihydrogen ditungstate
Pyrotungstic acid is a solid inorganic compound containing tungsten, oxygen, and hydrogen. It is primarily utilized as a precursor in the synthesis of various tungsten-based materials and catalysts.
HOW
Overview
Key Properties
Cross-validated computational properties for pyrotungstic acid, 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.
1.00–2.60 eV
Range across DFT structures
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.
0.054 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.
Metastable
2 DFT sources
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
17
3 databases, 4 space groups
Crystallography
Reported Structures
Lowest-energy structures reported for H2W2O7, 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. |
|---|---|---|---|---|---|
| Fdd2 (No. 43) | orthorhombic | 2.07 | 0.0544 | -8.010 | 5.65 |
| I41/amd (No. 141) | tetragonal | 1.63 | 0.1724 | -7.892 | 5.66 |
| P1 (No. 1) | triclinic | 2.60 | 0.2363 | -7.828 | 5.43 |
| Ima2 (No. 46) | orthorhombic | 1.28 | 0.2696 | -7.795 | 6.05 |
| Ima2 (No. 46) | orthorhombic | 2.21 | 0.3190 | -7.745 | 5.59 |
| I41/amd (No. 141) | tetragonal | 1.00 | 0.4447 | -7.620 | 6.25 |
| Fdd2 (No. 43) | — | — | — | — | — |
| Ima2 (No. 46) | — | — | — | — | — |
| I41/amd (No. 141) | Tetragonal | — | — | — | 5.87 |
| Fdd2 (No. 43) | Orthorhombic | — | — | — | 6.28 |
| Ima2 (No. 46) | — | — | — | — | — |
| I41/amd (No. 141) | Tetragonal | — | — | — | 6.28 |
Uses
Applications
Where pyrotungstic acid is used.
chemical synthesiscatalyst preparationmaterials science research
Reference
Frequently Asked Questions
Common questions about pyrotungstic acid, answered from cross-validated data.
What is H2W2O7?
Pyrotungstic acid is a solid inorganic compound containing tungsten, oxygen, and hydrogen. It is primarily utilized as a precursor in the synthesis of various tungsten-based materials and catalysts.
What is H2W2O7 used for?
pyrotungstic acid (H2W2O7) is used in chemical synthesis, catalyst preparation, and materials science research.
What is the band gap of H2W2O7?
pyrotungstic acid (H2W2O7) has a DFT-computed band gap of 1.00–2.60 eV across 17 reported structures.
Is H2W2O7 a metal, semiconductor, or insulator?
With a band gap up to 2.60 eV it is a semiconductor.
Is H2W2O7 thermodynamically stable?
pyrotungstic acid (H2W2O7) has a lowest energy above hull of 0.054 eV/atom (metastable).
What is the crystal structure of H2W2O7?
The lowest-energy reported polymorph of pyrotungstic acid (H2W2O7) is orthorhombic symmetry, space group Fdd2 (No. 43).
What is the density of H2W2O7?
The computed density of the ground-state structure of pyrotungstic acid (H2W2O7) is 5.65 g/cm³.
How many polymorphs of H2W2O7 are known?
17 structures of H2W2O7 are reported across 3 databases, spanning 4 distinct space groups.
What elements does H2W2O7 contain?
pyrotungstic acid (H2W2O7) contains H, O, and W (3 elements).
Where does the data for H2W2O7 come from?
H2W2O7 data is cross-referenced from materials_project, jarvis, mpaloe.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- jarvis — Data from JARVIS (NIST). Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020).
- mpaloe — Data from mpaloe.
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