MMSD Staff Release 2025 Version of SRD31, Phase Equilibria Diagrams (PED)

Phase Equilibria Diagrams (PED) Version 6.0 of SRD31 is now commercially available with a new custom windowing system that improves and streamlines use of the product. This new release adds 165 new Figures with 755 phase diagrams that provide processing information for 170 material systems not previously covered by the database. More than 45% of the new content is relevant to the recovery and recycling of critical minerals, including rare‐earth metals, and advanced nuclear‐energy reactors.

The PED application provides a searchable database with a total of 34,000 phase equilibrium diagrams which provide fundamental information needed to discover or optimize materials for numerous applications ranging from semiconductors to cement to biomarkers. The data include experimental and calculated diagrams for a wide range of nonorganic material‐types including oxides and mixed systems with oxides, chalcogenides (sulfides, selenides, tellurides), pnictides (N, P, As, Sb, Bi), actinides (U, Pu, Th) and actinidesurrogates (Ce), oxy‐cation systems (e.g. molybdates, vanadates), semiconductors (Si, Ge, Sn), group‐3 systems (B, Al, Ga, In, Tl), and salts, including mixed systems with salts. 

The phase diagrams in the SRD31 collection serve as critically evaluated maps of the equilibrium chemical and structural behaviors exhibited by inorganic systems. For commercially important materials, the phase diagrams provide critical starting information to devise processing schemes that facilitate quality‐assurance efforts and optimize properties for specific applications. For the exploration and design of new materials, including computational studies, the diagrams provide fundamental information on the occurrence and chemical composition of existing compounds as well as their thermodynamic properties. New content for the PED database is extracted bimonthly from newly published scientific literature; NIST guidelines are used by subject‐matter experts to write critical evaluations of the research and to standardize presentation of the diagrams. Editing and production are carried out by PED Data Center staff based at the Gaithersburg NIST campus. Further information is available on the SRD31 project webpage.

The customer‐community for SRD31 includes more than 450 users conducting materials research in industrial, academic, and government laboratories located in the U.S. and 38 countries. Materials covered by this database are used across a broad spectrum of technologies in applications such as optoelectronics, thermal‐barrier coatings, chemical sensors, energy converters, solar cells, nuclear waste reprocessing, nuclear‐reactor technology, photovoltaics, pigments, fuel cells, catalysts, thermoelectrics, capacitors, transducers, thermoluminescence, batteries, photovoltaics, video displays, lasers, spintronics, data‐storage, electrolytic refining, metallurgical processing, semiconductor manufacturing, bioceramics, and dental restoration. 

The new content provided in Version 6.0 continues to reflect the explosion of research on the fundamental properties of materials needed to enable the transition to lower‐cost and more efficient technologies and approaches to manufacturing, including the processing of raw materials and recycling/recovery of critical minerals from secondary sources or low‐grade ores. 25% of the new Figures in this version include information for the rare earth metals including neodymium, gadolinium, praseodymium, and samarium. Extensive studies of materials for advanced nuclear energy technology are also evident in this release – more than 20% of the new Figures are pertinent to molten‐salt nuclear reactors (complex salt systems for fuel; thorium fuel‐cycle; corrosion) and immobilization/processing of radioactive waste. Other new chemical systems and diagrams in v.6.0 address needs to advance a variety of applications such as hydrogen‐production by electrolysis of water, thermal‐energy storage and heat‐transfer media for concentrated solar power (CSP), lead‐free photovoltaics with high conversion efficiencies, optical information‐processing, batteries, semiconductors (processing and new materials), next‐generation electronics (e.g. phase‐change memories, topological insulators for quantum memories), lasers for optoelectronics, and advanced dental porcelain and other biomaterials.

SRD31 Version 6.0 is available for purchase as a PC product from NIST and also as an online subscription from the American Ceramic Society. NIST staff and Associates with computers having NIST IP addresses (Gaithersburg and Boulder) can access SRD31 online free of charge at Phase Online.

Interested parties outside of NIST can download a free demonstration version of SRD 31 in lieu of purchasing the PC product (at NIST SRD31). In addition to displaying the full functionality of the application, this free version includes a comprehensive, searchable cumulative index of all materials systems covered in the contents of the database, including the new content added in this release. 

Materials researchers please note: The PED Editor, custom software developed by NIST staff, is available for free download (at NIST SRD31) and can be used 1) to digitize phase diagrams and 2) to extract data from phase diagrams or other two‐dimensional scientific drawings.