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Phase Diagrams

Explore thermodynamic stability through convex hull analysis and phase diagram visualization.

Apr 10, 20265 min read
phase-diagram
thermodynamics
stability
convex-hull

Phase Diagrams

MatCraft generates computed phase diagrams using formation energy data from the Materials Project. Phase diagrams reveal thermodynamic stability relationships between competing phases in a chemical system.

What Is a Phase Diagram?

A phase diagram maps the thermodynamically stable phases as a function of composition. For a binary system A-B, it shows which compounds (if any) are stable at each composition ratio. The convex hull connects the lowest-energy phases — materials on the hull are thermodynamically stable, while those above it are metastable or unstable.

Generating a Phase Diagram

  1. Navigate to the Phase Diagram tool from the dashboard
  2. Enter the chemical system (e.g., "Li-Fe-O" or "Ti-O")
  3. Click Generate to compute the convex hull

MatCraft queries the Materials Project for all known phases in the system and computes the convex hull from their formation energies.

Reading the Diagram

  • Points on the hull (solid circles): Thermodynamically stable phases
  • Points above the hull (open circles): Metastable phases with positive energy above hull
  • Hull edges: Lines connecting stable phases represent two-phase equilibrium regions
  • Ehull value: The vertical distance from a point to the hull, in eV/atom

Supported Systems

  • Binary (2 elements): 2D convex hull plot (composition vs. energy)
  • Ternary (3 elements): Triangular phase diagram with color-mapped stability
  • Quaternary (4 elements): Tetrahedral projection (limited visualization)

Interactivity

  • Hover over any phase to see its formula, formation energy, and energy above hull
  • Click a phase to navigate to its material detail page
  • Toggle between showing all phases or only stable phases
  • Adjust the energy scale to zoom into the near-hull region

Applications

  • Stability assessment: Check if a candidate material is thermodynamically stable
  • Decomposition products: Identify what phases a metastable material would decompose into
  • Synthesis guidance: Stable phases are more likely to be synthesizable
  • Competing phases: Understand which phases compete at a given composition

API Access

bash
curl "https://api.matcraft.ai/api/v1/electronic/phase_diagram?system=Li-Fe-O"

Returns the convex hull data including all phases, their formation energies, hull distances, and the vertices of the stable hull.