Mass Diffusivity (solid)

The Mass Diffusivity of a Solidcalculator computes the diffusivity or diffusion coefficient for a pair of materials based on the max diffusion coefficient, activation energy and absolute temperature.

INSTRUCTIONS: Choose units and enter the following:

• (D₀) This is the maximum diffusion coefficient assuming theoretical infinite temperature
• (E_A) This is the activation energy for diffusion, the height of the potential energy barrier to at which diffusion will begin
• (T) - This is the Kelvin absolute temperature of the material

Mass Diffusivity of a Solid (D):  The diffusivity is returned in stokes (cm²/s).

Diffusivity Equation

• Mass Diffusivity of a Liquid
• Mass Diffusivity of a Solid
• Mass Diffusivity of a Gas

The Math  / Science

The Mass Diffusivity of Solid equation computes the mass diffusivity or diffusion coefficient for a pair of materials.  The formula for the mass diffusivity of a solid  ]is:

              `D  = D_0 * exp( - E_A/(RT) )`

where:

• D is the Mass Diffusivity of Solid 
• D₀ is the maximum diffusion coefficient assuming theoretical infinite temperature
• E_A is the activation energy for diffusion, the height of the potential energy barrier to at which diffusion will begin
• T is the Kelvin absolute temperature of the material
• R is the universal gas constant.

The diffusivity or diffusion coefficient characterizes the relationship between the molar flux due to molecular diffusion and the gradient force of a c concentration of the material's molecules that drives diffusion.

Diffusivity is specified for one substance relative to another.  In this case there are two substances labeled substance 1 and substance 2. Each of the two substances is at a different temperature and at that temperature exhibits a characteristic of dynamic viscosity.