Figure 3

Formation energy for N-related defects in anatase Ti₁₆O₃₂ (a) O-poor limit Δμ_O = −4.1 eV and Δμ_N = 0 eV. (b) O-rich limit Δμ_O = 0 eV and Δμ_N = 0 eV. (c) O-intermediate (Experimental growth condition) Δμ_O = −1.5 eV. (d) Phase diagram for N-related defects (N)_O, (NO)_O, (N₂)_O. Here, on x-axis Δμ_O is varied in accordance with the corresponding T and \({p}_{{{\rm{O}}}_{2}}\). On y-axis μ_e is varied from valence band maximum to conduction band minimum of the TiO₂. On z-axis the negative \({{\rm{E}}}_{{\rm{f}}}(T,{p}_{{{\rm{O}}}_{2}})\) values are plotted so that only the most stable phases are visible from the top. The region within the rectangular red lines represents the experimentally relevant conditions at T = 848 K with a realistic \({p}_{{{\rm{O}}}_{2}}\) range.