Diagram Example : Non-Chemical Potential Variable (1)

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The chemical potential diagram for the Cr system:

1. The three dimensional surface diagram in the μ(Cr)-1/T-ln (P/atm) plot.

2. Description of Diagram Example : Non-Chemical Potential Variable (1a)
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   • In the present chemical potential diagram, there appear two stable species, namely, Cr metal (condensed phase) and Cr Vapor.
     
   • The stability region of Cr vapor is located below the stability region of Cr metal. The borderline between two stability regions indicates the equilibrium vapor pressure of Cr vapor over Cr metal. This is written as follows;
     
     Cr(c)=Cr(g)
     log p(Cr(g))= - (1 / 2.303 RT){Δ_fG(Cr,g)-Δ_fG(Cr,g)}
     
   • In this sense, this diagram can be regarded as the generalized Arrhenius plot for the equilibrium vapor pressure.
     
   • Generalization is realized in the point that the chemical potential of chromium is given for respective equilibrium point.
     
3. Detailed procedure for reproducing Diagram Example Non-Chemical Potential Variable(1a)
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   • [System] Selection of <Cr> system in MALT : Search Compounds
   • [Project > Chemical System]
   <Chemical System > Dialog
   
   {Selection of Compounds} Page
   
   Selection by Default: Default Compounds
   
   x Condensed phases
   x Respective Gaseous Species
   o Gaseous mixture
   o Aqueous Species
   
   • [Project > Specify Diagram]
   <Diagram Specification> Dialog
   
   {Dimension Selection} Page
   
   Temperature
   
   o Fixed
   x Not Fixed
   
   Pressure
   
   o Fixed x Not Fixed
   • [Run > Calc]
   • [Diagram > Range]
   <Select Range> Dialog
   
   X step value 0.1 => 0.25
   Y step value 1 => 50
   
   • [Diagram > Rotate]
   <Rotation of 3D diagram> Dialog
   
   Z-axis
   
   Horizontal -50 => -10
   Vertical -20 => 10
   
   As a result, the following matrix values are obtained
   
   1.0 0.0 -0.1
   0.0 1.0 -0.1
   
   • [Diagram > Display Mode > Move Location]