by Haiyong Li under the supervision of Dr. Guna Selvaduray.
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What are Ellingham Diagrams
Values of standard Gibbs free energy changes for chemical reactions are often presented in graphical form, with DGº as the ordinate and T, the absolute temperature, as the abscissa.(Ragone) This type of diagram is generally referred to as an Ellingham Diagram.
An example of Ellingham diagram is shown in Figure 1 below. Or you can click the button below to go straight to use the tool.

How can Ellingham Diagrams be used?
When values of Df for oxides are displayed, the Ellingham Diagram offers a simple and useful way to estimate the equilibruim oxygen partial pressure as a function of temperature. Thus, it can be used to predict the temperatures at which a metal is stable and the temperatures over which it will spontaneously oxidize. For temperatures at which the free energy of formation of the oxide is positive, the reverse reaction is favored and the oxide will spontaneously decompose to the metal. For example: From the data provided on Figure 1, it can be calculated that at 1000K, Ca will oxidize in an environment that has an oxygen partial pressure of 10-15 atm or greater.
What is the significance of this web project?
This project is aimed to provide a convienient location on the Internet for Ellingham diagram lookups and saving the time required for related calculation. The goal is to help the user to pinpoint the exact Ellingham diagram and the related data of user's interest in the least amount of time.

Figure 1: Example of Ellingham Diagram
What can you do with this web tool?
The information on this site are mainly drawn from "Thermodynamics of Materials" by David Ragone. The data used for plotting the Ellingham Diagram are cited from "Metallurgical Thermochemistry" by O. Kubaschewisk and E. L. L. Evans. We hope users would find it useful. This is an ongoing work and will remain useful through constant inputs. We would, therefore, appreciate suggestions and critical comments to bring further improvement in this project.
Your opinions are valuable to us. Please let us know how this site can be improved and made more user-friendly. We welcome all of your comments. Please contact Haiyong Li
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