[Pw_forum] substitution of positive charge into a negative charge.

Winfred Mulwa mulwawinfred at gmail.com
Tue Oct 18 17:05:22 CEST 2016


Thank you so much. I appreciate your response.
Kind regards.


On Tue, Oct 18, 2016 at 4:54 PM, Mostafa Youssef <myoussef at mit.edu> wrote:

> Dear Mulwa Winfred,
>
> Substituting cations such as Nd3+ on anion site (O-site) in TiO2 is not
> expected to be favorable energetically. One good reason  comes from the
> simple ionic picture. Nd3+ will repel the surrounding Ti4+.
>
> However, in spite of this I doubt the value of 634 eV.  Recall that
> calculating the formation energy of Nd defects in TiO2 requires a reference
> state for Nd; for example Nd2O3.
>
> Regards,
> Mostafa Youssef
>
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-- 
Mulwa Winfred.
D Phil Student, Computational Material Science Group,
University of the Free State - QwaQwa,
South Africa.
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