Observed data
Experimental or critically evaluated records, retained with their original conditions and uncertainty.
Data & methods
A number without its conditions is only half a fact.
Materials Sandbox keeps identity, method, source, units, uncertainty, license, and review state attached to each scientific claim.
Evidence taxonomy
Five labels, one honest unknown
Observed
First-principles calculation
Numerical results such as DFT records. Useful and model-dependent; common methods can underestimate band gaps.
Assessed model
Outputs from a named equation of state, CALPHAD assessment, or another model inside a stated validity range.
Educational seed
Rounded development fixtures for building the experience. All current numerical seeds require expert review.
Unknown / unsupported
No applicable record or model. The interface preserves the gap instead of replacing it with zero or AI-generated certainty.
Compound finder
Retrieval, not reaction simulation
Selected elements define a chemical-system database query. Actual reaction outcomes additionally depend on composition, phases, temperature, pressure, atmosphere, kinetics, and processing.
Read the distinctionStability diagrams
Computed hulls are approximately 0 K
A Materials Project compositional hull compares modeled energies. It is not an experimental finite-temperature alloy diagram and does not certify synthesizability.
Understand convex hullsCondition controls
Pressure is not density
Seed phase tracks vary temperature at fixed pressure. Density is normally an output, not a substitute pressure input. Unsupported controls remain disabled.
Pressure and models