Stabilization of the (1 1 1) surface of NiO and CoO by segregation of point defects

Epitaxial Co on GaN by decomposition of template CoO

“…31,32 The Perdew-Burke-Ernzerhof 33 exchange-correlation functional was used. Considering the strongly correlated 3d orbitals of Co, we adopted a Hubbard U correction with U = 3 eV as recommended in the work of DFT+U calculations for Co. [34][35][36][37] For the polar N-terminated GaN(000 % 1) surface, the dangling bonds at the bottom of nitrogen layer were saturated with pseudo-hydrogen atoms with a charge q = 0.75 e. The k-point grid for supercell relaxation and density of states calculations was 1 Â 1 Â 1. The cutoff energy for the plane waves was fixed at 500 eV.…”

Segregation and interdiffusion processes in perovskites: a review of recent advances

“…The partial covalent character is a distinctive feature of Me-O bonds, both in volume and at the boundary, and determines the structural distortions of the octahedra. Xing W. et al 71 revealed a strong tendency for the segregation of metal vacancies on the (111) polar surface of NiO and CoO oxides, which has a favourable effect on the surface stability. Based on synergistic combinations of calculations from rst principles DFT simulations for (In, Nb) co-doped TiO 2 lms oriented along (110) and (001) planes, Lu L. et al 72 calculated that double boundaries and summation defects are energetically more preferable to accommodate dopants with larger atomic radii.…”