Nickel ferrite material (NiFe2O4) simulation

[Madhu Nath]

Dear VAMPIRE users,

I want to create Nickel ferrite material (₂O₄) that has an inverse spinel structure. Now in the octahedral site of Fe how I can replace Fe by Ni in small fraction? What I have to do in the material file?

Also what are the interactions that I should mention in the .ucf file? From where to know these interactions?

Can anyone help me in this regard?

Thanks and regards.

Madhumita

[Richard Evans]

Hi Madhumita,

This is quite easy in the develop version of the code. First you need to define the spinel structure:

create:crystal-structure = spinel

Then in the material file, you can assign material to each atom type in the unit cell:

material[1]:unit-cell-category = 1 # Tet

material[2]:unit-cell-category = 2 # Oct

material[3]:unit-cell-category = 3 # Oxygen

Finally you can define a dopant material:

material[4]:minimum-height = 0

material[4]:maximum-height = 0

And substitute this into material 2 using:

material[2]:host-alloy

material[2]:alloy-fraction[4] = 0.2 # dope 20% of material 4 sites with Ni

Interactions are mostly nearest neighbour in oxides, so you just need to define interactions for 1-2, 1-4, 2-4 and their inverses.

All th best,

Richard 

[Madhu Nath]

Thank you very much for your guidance Dr. Richard.