Ge2Te2
Ge2Te2 has a DFT band gap of 0.15–2.18 eV across 37 reported structures in 21 space groups; its lowest-energy polymorph is trigonal (R3m (No. 160)). Cross-validated across 3 computational databases.
At a glance
Key Properties
Cross-validated computational properties for Ge2Te2, 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.
0.15–2.18 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.
0.000 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)
1 DFT source
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
37
3 databases, 21 space groups
Crystallography
Reported Structures
Lowest-energy structures reported for Ge2Te2, 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. |
|---|---|---|---|---|---|
| R3m (No. 160) | trigonal | 0.56 | 0.0000 | -19.680 | 5.95 |
| Fm-3m (No. 225) | cubic | 0.41 | 0.0203 | -19.660 | 6.13 |
| Pnma (No. 62) | orthorhombic | 0.15 | 0.0280 | -19.652 | 5.57 |
| Pbcn (No. 60) | orthorhombic | 0.00 | 0.1145 | -19.566 | 4.40 |
| R3m (No. 160) | trigonal | 0.70 | 0.1257 | -19.554 | 5.01 |
| Pm-3m (No. 221) | cubic | 0.00 | 0.3256 | -19.354 | 6.54 |
| Cm (No. 8) | monoclinic | 2.18 | 0.8065 | -18.874 | 0.60 |
| P4/nmm (No. 129) | — | — | — | — | — |
| C2/m (No. 12) | — | — | — | — | — |
| R-3m (No. 166) | — | — | — | — | — |
| Pmma (No. 51) | — | — | — | — | — |
| Cmme (No. 67) | — | — | — | — | — |
Reference
Frequently Asked Questions
Common questions about Ge2Te2, answered from cross-validated data.
What is the band gap of Ge2Te2?
Ge2Te2 has a DFT-computed band gap of 0.15–2.18 eV across 37 reported structures.
More questions
Is Ge2Te2 a metal, semiconductor, or insulator?
With a band gap up to 2.18 eV it is a semiconductor.
Is Ge2Te2 thermodynamically stable?
Yes — Ge2Te2 sits on the convex hull (energy above hull 0 eV/atom), i.e. on hull (stable).
What is the crystal structure of Ge2Te2?
The lowest-energy reported polymorph of Ge2Te2 is trigonal symmetry, space group R3m (No. 160).
What is the density of Ge2Te2?
The computed density of the ground-state structure of Ge2Te2 is 5.95 g/cm³.
How many polymorphs of Ge2Te2 are known?
37 structures of Ge2Te2 are reported across 3 databases, spanning 21 distinct space groups.
What elements does Ge2Te2 contain?
Ge2Te2 contains Ge and Te (2 elements).
Where does the data for Ge2Te2 come from?
Ge2Te2 data is cross-referenced from materials_project, aflow.
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Related Compounds
Other Phase-Change Memory Materials in the database.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- aflow — Data from AFLOW. Cite: Curtarolo et al., Comp. Mater. Sci. 58, 218 (2012).
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