MatML

MatML, short for Materials Markup Language, is an XML-based data exchange standard designed to facilitate the interoperability of materials information. It provides a formal schema for representing data about materials, including composition, structure, properties, and processing history, to enable reliable exchange between databases, simulation codes, and analysis tools. The overarching aim is to improve data sharing, reproducibility, and automation in materials research.

The MatML model centers on core entities such as Material, Phase, Property, Method, State, and Process. A Material records identifying information and can include composition (elements and amounts) as well as structural descriptions. A Phase captures phase-specific characteristics or crystal structure details. A Property stores a measured or calculated quantity with its value, unit, and optional uncertainty. Method describes how the data were obtained, while Process and Condition detail how a material was prepared or the environmental conditions during measurement or simulation. The relationships among materials, measurements, simulations, and provenance are defined to support data integration and traceability.

MatML emphasizes extensibility and machine readability through XML namespaces, enabling rich metadata and connections between materials, properties, and processing histories. This supports automated data ingestion, search, and reuse across diverse software tools and databases, promoting interoperability in materials data workflows.

Adoption of MatML has varied across communities and projects. It has influenced subsequent discussions and developments in materials informatics standards and remains a reference example of structured materials data exchange, with ongoing efforts to broaden coverage to additional property types and non-crystalline materials.