Frequently Asked Questions

Are all published diagrams and commentaries included in the database?
The Phase Equilibria Diagrams Online Database includes all ACerS/NIST commentaries and diagrams published in any format at the time of release.

Which browser(s) are recommended for the best experience using this application?
During development of the PED application, a large number of browsers and versions of browsers were tested. Google Chrome proved to be the most reliable and provides the best user experience.

Am I permitted to republish the content contained in the ACerS-NIST Phase Equilibria Diagrams Online Search database?
Yes, but you must properly cite the source:
Phase Equilibria Diagrams Online Database (NIST Standard Reference Database 31), The American Ceramic Society and the National Institute of Standards and Technology, 2024. Figure Numbers ____, ____;  https://www.nist.gov/srd/nist-standard-reference-database-31 .

Do I need a separate PDF Viewer

To open PED Figures you will need an application for viewing PDF files. However, most browsers now contain a built-in PDF viewer. If you'd like, you can use another PDF viewer such as Adobe Reader or Foxit PDF Reader.

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Common Tasks

All published ACerS/NIST phase equilibria diagrams and commentaries can be retrieved using the Phase Equilibria Diagrams (PED) Online Search application.

Please Note: The PED Figure Search page includes help icons located near each of the functional buttons. The icons are toggled to be visible or not using the Show(Hide) Help Icon button located on the left side of the interface. Clicking on each information icon will launch a dialog that will provide you with instructions for using the feature found next to the icon.

Search Commentaries and Diagrams
The content can be searched by
  • Chemical System
  • Author's Last Name
  • PED Volume
  • Language
  • Publication Year
  • Figure Number
  • Commentary text (phrase or keywords)
In the resulting search return list, the selected PED figure will be outlined in blue and the diagram(s) associated with that figure will be listed under the diagram thumbnail view on the right.

View Diagrams
The PED Viewer displays the corresponding diagram that the user has selected by clicking on any of the View Diagram button, the thumbnail view on the right of the interface, or the diagram number under the thumbnail view on the right of the interface. Instructions for using the PED Viewer are available from the PED Viewer page ( also linked here ).

PED files can be downloaded for use with the legacy PED Viewer using the download icon next to the diagram number of the selected diagram.

View Figures
View Figure displays the complete PED Figure (as previously published in the hard-copy books) as a printable PDF file which can be saved: Chemical System, Figure Number, References, Commentary, Footnotes, Editors, and diagram(s).

PED Figure Manipulation
Note: The content included in the ACerS-NIST Phase Equilibria Diagrams Online database is copyrighted. While the database enables you to copy and paste a diagram for personal use, no part of this software or the content contained within can be used beyond the limits of Sections 107 and 108 of the U.S. Copyright Law without paying the appropriate fee to the Copyright Clearance Center or contacting NIST or The American Ceramic Society for permission. See the Contact Us section for more information.

Cumulative Index
This function will return a list of all published figures in the database. The list can be sorted by clicking the title bar for any of the columns (PED Figure No., PED Volume, Chemical System(s), Authors, or Publication Year). When sorted by Chemical System, the user obtains the electronic equivalent of the hard-copy Cumulative Indices that were previously published after each book was released. This new feature provides a shortcut - the user can display the same list by leaving the search "Components or Elements" field blank, choosing "All" from the PED Volume. drop-down list, and clicking Search.

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Chemical System Designation Rules

The rules governing assignment of the chemical system limit the components that can be manually entered in the search window to those selectable in the pull-down menu.

Users familiar with the series of published volumes of Phase Equilibria Diagrams (Phase Diagrams for Ceramists) are aware that chemical designation and sort order rules have varied among the hard-copy volumes. Chemical system designations have been reassigned in some cases to form a set consistent with the rules outlined below. Therefore, the current chemical systems for some PED Figures may vary from those in the previously published hard-copy books.

Chemical system classifications are designed generally to name the simplest possible chemical components and these are not necessarily the end-members of the diagram. Mixed compounds are not used in the assignment of chemical systems (with the exception of oxides of elements that are not solids at ambient temperature (e.g., C, N, S, CI), see below). For example, BaTiO3, Mg2SiO4, KAlCl4, etc., do not appear in the chemical systems index. The diagram MgSiO3-CaSiO3 will be classified by the simplest component oxides CaO-MgO-SiO2. The binary system NaAlCl4-KAlCl4 will be classified by the simplest component compounds NaCl-KCl-AlCl3. The simplest components are frequently those compounds that would be used in the laboratory to synthesize the more complex compound.

System designations may include chemical elements or chemical compounds. A glance at the chemical systems index yields the following typical examples:

  1. Oxygen-containing components including metals are given as the oxides if the oxide of the metal is a solid at ambient temperature. No oxyanion or oxycation of the metal is designated in the chemical system. All oxides are listed by the valence of the metal regardless of mixed ions, for example, MnO-Mn2O3 or MnO2.
  2. FeO is designated as an oxide, although it is well known that this material is not stoichiometric and its composition is deficient in oxygen. Similarly, Fe3O4, a mixed oxide, is listed as FeO-Fe2O3. In other words, the category oxygen with one or more metal components is used only when either oxygen or metal occurs as one of the phases in the diagram.
  3. For oxides of elements that are not solids at ambient temperature (e.g., C, N, S, CI), the chemical component is given as the desired oxysalt, for example, Na2SO4, BaCO3, KClO4. (Note that a general search for carbonates could be done by entering C-O.)
  4. Chemical elements are used as system components under the following conditions.
    • An end-member of the diagram is a chemical element.
    • The system contains compounds of elements for which formal oxidation states cannot be readily assigned. (All-metal (alloy) systems are not included except for those systems that include Si, Ge, Sn, P, As, Sb, Bi, Se, and Te - all-metallic systems are covered by the ASM Alloy Phase Diagram Database).
  5. Water at pressures above ambient is designated simply as H2O; water at ambient pressures (most solubility diagrams) is designated as H2O*.
  6. Oxidation and Reduction systems follow special rules.
    • The only circumstance in which a metal is used as part of the classification is when a pure element (or combination of metallic elements) occurs as a phase of the system or when the metal/oxygen (or salt, etc.) ratio is less than 2:1, or greater than the ratio corresponding to the minimum valence of the cation (e.g. Ti3O); i.e., when a formal oxidation state cannot be readily assigned.
    • The use of FeO in the classification scheme implies the true chemistry of the phase FeO1-x and the chemical symbol Fe will not normally be used in classifying systems containing the phase FeO1-x.
  7. Most oxidation and reduction systems are, therefore, classified by using the lowest and highest-valent oxide (or salt, etc.) together with their reaction components.
  8. The symbol O will be used for classification purposes only when diagrammatic construction to an O end-member is more convenient, or the diagram does not extend from the metal to the "naturally-occurring" lowest oxidation state.

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Phase Equilibria Diagrams Products

For information on ordering books, CDs, DVDs, the PC product or Phase Equilibria Diagrams Online go to ACerS Phase Equilibria Diagrams
The PC product can also be purchased from NIST, go to https://www.nist.gov/srd/nist-standard-reference-database-31 or Email: data@nist.gov

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Credits and Acknowledgments

Software Development:
Julia Dana, Tyler Broyles, Michael Faughn, Sam Dana, Art Griesser (Prometheus Computing, LLC)
PED Viewer (JavaScript): Julia Dana
PED Editor (Java): Eric Boesch
Managing Production Editor:
Kimberly Hill
Graphics Technicians:
William Laws and Craig Heimbach
General Editor:
Michael Hill
Literature Editor:
John Hastie
Terrell Vanderah
ACerS Project Managers:
Eileen De Guire and Jonathon Foreman
The fund-raising effort in the 1980's managed by ACerS resulted in a fund of almost $2,000,000 contributed to the program. There are five basic categories of participation in the Ceramic Phase Equilibria Program: Primary Sponsors, $200,000 or more; Sponsors, $100,000 or more; Affiliate Sponsors, $25,000 or more; Contributors, $5,000 or more; and Members and Friends, any smaller amount. Contributions are still welcome. The contributions of individuals and of the following organizations are gratefully acknowledged.
  • Corning Glass Works
  • IBM Corporation
  • Matsushita Corporation
  • The American Ceramic Society
  • NIST
  • Defense Advanced Research Projects Agency
  • Aluminum Co. of America
  • Battelle Memorial Institute
  • Norton Co.
  • Owens Corning Fiberglass Corp.
  • Allied Signal Corp.
  • Asahi Glass Co., Ltd.
  • Asahi Glass Foundation for Industrial Technology
  • AT&T Bell Labs
  • B & B Refractories, Inc.
  • Buehler Ltd.
  • Cabot Corp. Foundation
  • Coors Porcelain Co.
  • E. I. du Pont de Nemours & Co., Inc.
  • Ford Motor Co.
  • General Motors Corporation
  • GTE Labs, Inc.
  • Hitachi Ltd.
  • Kyocera Corp.
  • Murata Mfg. Co., Ltd.
  • NEC Corp. (Japan)
  • NGK Insulators, Ltd.
  • NGK Spark Plug Co., Ltd.
  • PPG Industries
  • Rh^one Poulenc, Inc.
  • 3M Co. Foundation
  • Department of Energy*
  • National Science Foundation*
  • Alcan International, Ltd.
  • Alfred University Foundation for Promotion of Materials Science and Technology in Japan
  • Harbison Walker Refractories, Co., Division of Dresser Industries
  • Hitachi Chemical Co., Ltd.
  • Hitachi Metals Ltd.
  • Korean Ceramic Society
  • Kyoto University
  • Owens-Illinois, Inc.
  • Serbian Academy of Sciences and Arts
  • Shell Development Co.
  • Richard M. Spriggs
  • William Payne
  • 10 ACerS Sections
  • 11 Distinguished Life Members and Past Presidents
  • 584 Individual Members
  • 30 Industrial Matching Gifts
*Through the Joint Program on Critical Compilation of Physical and Chemical Data coordinated by Standard Reference Data at NIST.

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Ceramic Phase Equilibria Data Center

Program Origin and Evolution: Since 1933, the National Institute of Standards and Technology (NIST) (then NBS, the National Bureau of Standards) and The American Ceramic Society (ACerS) have collaborated on the production and publication of evaluated phase diagrams of ceramic systems. These diagrams serve as maps of the equilibrium chemical and structural behaviors exhibited by materials and provide critical starting information for the rational design of materials processing schemes, for quality assurance efforts, and for optimization of the physical and chemical properties of advanced materials. The joint Ceramic Phase Equilibria Program, representing a continuation and expansion of the effort to make ceramic phase information readily and comprehensively available, was formally established in December 1982 along with a fund-raising effort by ACerS which resulted in an endowment fund of almost $2,000,000. The program goal was, and continues to be, to support growth and progress in the ceramic industries and research by providing relevant critically evaluated phase equilibrium diagrams. To achieve this, a Data Center was established at NIST/Gaithersburg to improve currency with the archival literature and to provide critically evaluated phase diagrams for oxides, salts, carbides, pnictides, borides, compound semiconductors, and chalcogenides. At this time, a major goal was established to computerize all data activities.

The first efforts to convert from hard-copy text and India-ink drawings to an electronically accessible system commenced in the 1980's and resulted in a Fortran database system. As part of this effort, Data Center staff developed computer files for all references, commentaries, and chemical classification information, as well as the diagrams themselves in graphics form using an HPBasic program written by the late Dr. Peter K. Schenck - this program was used to digitize all diagrams published after Volume V (1983). Publication of the hard-copy "blue books" continued using this new system, and in 1992 was accompanied by version 1.0 of a computer product which was distributed as a set of ten 3.5-inch disks with text and scanned diagrams from Vols. I-V. Version 2.0, created by Mr. Tom Green using Visual Basic, was released as a CD-ROM in 1995 and included graphics capabilities to manipulate post-Volume V diagrams (zoom, lever rule, curve follow, overlay, mol% to wt%).

The reference series was published from 1964 to 1992 as the well-known Phase Diagrams for Ceramists "blue books", also known as NIST Standard Reference Database (SRD) 31. After the 1992 title change to the more general Phase Equilibria Diagrams - to emphasize that the data are useful to the broader materials community - new content continued to be published in the form of hard-copy topical volumes (in addition to the CD-ROM version). In 2002, after a disastrous system failure during production of the Zirconia volume, a modernization effort was launched by Mr. Jim You to design and implement a new content management system for the Data Center using a relational database (SQL Server) and Visual Basic. As part of this effort, the Data Center hired numerous part-time students from the Geology Department of the University of Maryland at College Park to digitize the 6,254 diagrams from Volumes I-V that existed only as India-ink drawings or scanned images. These efforts resulted in an all-inclusive, searchable CD-ROM version 3 that was released in 2004. All diagrams in the series (approximately 20,000) were finally available as manipulable graphics files.

In 2005, as a result of customer preference for the CD-ROM format which provided inclusive coverage of all material published in the series in addition to analytical capabilities, publication of material-class-oriented hard-copy volumes - the "blue books" - was discontinued. In response, software and editing processes for SRD 31 were modified to convert to continuous publication of new data retrieved from the archival literature, regardless of material class. Volume 14 (2005) was the last hard-copy blue book published. All "Volumes" published thereafter are "virtual" and are only available in electronic form - these volumes now consist of periodic content updates providing 500-1000 new phase diagrams for a wide variety of system-types. However, all post-Volume-14 figures (and revised older figures) were made available to the customer as PDF files which are identical in quality to those in the printed books.

The most recent modernization of the Data Center was launched in late 2010 and has resulted in an entirely new custom-developed content management system (CMS) which is web-based and runs under Ubuntu Linux using the Ruby programming language. The system (developed by Prometheus Computing, LLC) uses the Nginx web server, an SQLite database, and an object relational mapper for the GUI. In a parallel effort, Mr. Eric Boesch developed all-new software for diagram digitization, the PED Editor - a Java program which uses the iText open-source PDF file generation library, Batik open-source SVG file generation library, Jackson open-source JSON file generation library, and the JAMA Java Matrix package. These efforts produced series 4 of the PC and online products, which used an interactive diagram viewer derived from the PED Editor. The full PED Editor program is available as freeware (at https://pages.nist.gov/PEDEditor/) and can be used 1) to digitize phase diagrams and 2) to extract data from phase diagrams or other two-dimensional scientific drawings.

This release, Version 5.2 provides new content for volume 26 and, as for all series-5 versions, includes the JavaScript PED diagram viewer developed by Ms. Julia Dana for interactive display of the diagrams (see Viewer Help next to the main Help menu). The PED application no longer requires the installation of Java, although diagrams can still be downloaded and opened using the legacy (Java-based) PED Viewer (see main Help menu for details). The search interface is very similar to the previous series-4 versions and functions with the same software that resulted from the most recent upgrade of the CMS and the user interface. All PED Figures are available as printable .pdf files which provide the commentary text as well as all diagrams, similar to the previous entries in the hard-copy books. In addition, all phase diagrams in the collection are present in the updated format, can be interactively displayed using the PED Viewer, and can be printed as high-quality .pdf files or downloaded as .png or .jpg files with customized resolution.

Other features for version 5.2 are described in the help pages
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General Discussion of Phase Diagrams

General Discussion of Phase Diagrams (.pdf file, 2,728kB)
By F.P. Hall, H. Insley, E.M. Levin, H.F. McMurdie and C.R. Robbins
From: Phase Diagrams For Ceramists, Volume I; edited by E.M. Levin, C.R. Robbins and H.F. McMurdie, pages 5-36, 1964.

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Contact Us

PED Application Support, Comments and Suggestions:

Subscription Questions:
Jonathon Foreman, Phone: 614-794-5864, Email: jforeman@ceramics.org
Eileen De Guire, Phone: 614-794-5828, Email: edeguire@ceramics.org
ACerS Customer Service, Phone: 866-721-3322, 240-646-7054, Email: customerservice@ceramics.org

General Questions or Business Information
National Institute of Standards and Technology (NIST)
Standard Reference Data Program
100 Bureau Dr. Stop 8500
Gaithersburg, MD 20899-8500
301-975-2200 (VOICE)
Email: data@nist.gov
Web:  https://www.nist.gov/srd/nist-standard-reference-database-31
ACerS Customer Service
Phone: 1-866-721-3322 or 1-240-646-7054
ACerS Headquarters
Phone: 1-614-890-4700
Email: customerservice@ceramics.org
Web: www.ceramics.org
Mailing Address:
The American Ceramic Society (ACerS)
550 Polaris Parkway, Suite 510
Westerville, OH 43082-7045

The American Ceramic Society and the National Institute of Standards and Technology encourage you to send comments and suggestions to phase3@ceramics.org

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