Ge2Sb2Te5
GST · GST-225
Ge2Sb2Te5 is a semiconducting phase-change alloy widely used for high-speed, non-volatile data storage applications.
About GST
Ge2Sb2Te5 is a prominent semiconducting phase-change material that plays a foundational role in non-volatile memory technologies. Its ability to undergo reversible structural transitions between disordered and ordered phases allows it to store information with high efficiency and reliability.
As a thermodynamically stable compound near the hull, it is highly synthesizable and widely utilized in data storage applications. Its unique electronic properties make it a cornerstone for researchers developing next-generation high-speed memory architectures.
Key Properties
Cross-validated computational properties for GST, aggregated across 7 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 Ge2Sb2Te5. 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 Ge2Sb2Te5, 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. |
|---|---|---|---|---|---|
| — | — | 0.43 | 0.0048 | -0.106 | — |
| P-3m1 (No. 164) | trigonal | 0.26 | 0.0118 | -4.027 | 6.24 |
| — | — | 0.21 | 0.0199 | -0.091 | — |
| P-3m1 (No. 164) | trigonal | 0.04 | 0.0224 | -0.099 | — |
| P-3m1 (No. 164) | trigonal | 0.00 | 0.0232 | -4.016 | 6.01 |
| Cm (No. 8) | monoclinic | 0.00 | 0.0430 | -0.079 | — |
| Cm (No. 8) | monoclinic | 0.02 | 0.0541 | -3.985 | 5.94 |
| P-3m1 (No. 164) | trigonal | 0.00 | — | -3.754 | 6.04 |
| P-3m1 (No. 164) | trigonal | 0.00 | — | -3.754 | 6.04 |
| P-3m1 (No. 164) | trigonal | — | — | — | 6.32 |
| P-3m1 (No. 164) | trigonal | — | — | — | 6.27 |
| Cm (No. 8) | monoclinic | — | — | — | 5.94 |
Synthesis Routes
Literature-extracted synthesis procedures targeting Ge2Sb2Te5.
Applications
Where GST is used.
Frequently Asked Questions
Common questions about GST, answered from cross-validated data.
What is Ge2Sb2Te5?
Ge2Sb2Te5 is a semiconducting phase-change alloy widely used for high-speed, non-volatile data storage applications.
What is Ge2Sb2Te5 used for?
What is the band gap of Ge2Sb2Te5?
Is Ge2Sb2Te5 a metal, semiconductor, or insulator?
Is Ge2Sb2Te5 thermodynamically stable?
What is the crystal structure of Ge2Sb2Te5?
What is the density of Ge2Sb2Te5?
How many polymorphs of Ge2Sb2Te5 are known?
How is Ge2Sb2Te5 synthesized?
What elements does Ge2Sb2Te5 contain?
Where does the data for Ge2Sb2Te5 come from?
How It Compares
Within the phase-change memory materials class.
Within the family of phase-change memory materials, Ge2Sb2Te5 is arguably the most extensively studied and optimized member, often serving as the benchmark for performance against simpler binary counterparts like GeTe or Sb2Te3. While materials like AgSbTe2 are explored for specific thermoelectric or phase-change tuning, Ge2Sb2Te5 remains the industry standard due to its balanced switching kinetics and structural stability.
Related Compounds
Other Phase-Change Memory Materials in the database.
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)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- aflow — Data from AFLOW (aflow.org). Cite: Curtarolo et al., Comp. Mater. Sci. 58, 218 (2012). (CC-BY-4.0)
- cod — Data from the Crystallography Open Database (crystallography.net/cod/). Cite: Grazulis et al., J. Appl. Cryst. 42, 726 (2009). (CC0-1.0)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
- nomad — Data from NOMAD (nomad-lab.eu). Cite: Draxl & Scheffler, J. Phys. Mater. 2, 036001 (2019). (CC-BY-4.0)
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