Negative Surface Energies of Nickel Ferrite Nanoparticles under Hydrothermal Conditions

Figure 1

Slab models with the lowest (111) surface formation energies. The most stable surfaces expose (a) tetrahedral and (b) octahedral Ni/Fe cations. The red balls represent O atoms, and the grey and brown are Ni and Fe, respectively.

(a)

(b)