TY - JOUR
T1 - First-principles study of the structures and energetics of stoichiometric brookite Ti O2 surfaces
AU - Gong, Xue Qing
AU - Selloni, Annabella
PY - 2007/12/10
Y1 - 2007/12/10
N2 - First-principles density functional theory calculations at the generalized gradient approximation level are performed to investigate the structures and energetics of ten stoichiometric 1×1 low-index surfaces of brookite, the rarest and least understood of the natural polymorphs of titanium dioxide (Ti O2). For each surface, different possible terminations are considered, and their structural relaxations are analyzed. As a general trend, undercoordinated surface Ti atoms are found to relax inward so as to form Ti Ox polyhedra with O atoms at the vertices, analogous to the Ti O6 octahedra of the bulk structure. For some surfaces, very large relaxations, involving several subsurface layers, are found to occur. From the computed surface formation energies, the relative stabilities of the different terminations are determined and found to be mainly related to the concentration of exposed coordinatively unsaturated metal (Ti) atoms. The equilibrium crystal shape of brookite Ti O2 is also determined, and the relative fraction of each exposed surface is estimated.
AB - First-principles density functional theory calculations at the generalized gradient approximation level are performed to investigate the structures and energetics of ten stoichiometric 1×1 low-index surfaces of brookite, the rarest and least understood of the natural polymorphs of titanium dioxide (Ti O2). For each surface, different possible terminations are considered, and their structural relaxations are analyzed. As a general trend, undercoordinated surface Ti atoms are found to relax inward so as to form Ti Ox polyhedra with O atoms at the vertices, analogous to the Ti O6 octahedra of the bulk structure. For some surfaces, very large relaxations, involving several subsurface layers, are found to occur. From the computed surface formation energies, the relative stabilities of the different terminations are determined and found to be mainly related to the concentration of exposed coordinatively unsaturated metal (Ti) atoms. The equilibrium crystal shape of brookite Ti O2 is also determined, and the relative fraction of each exposed surface is estimated.
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U2 - 10.1103/PhysRevB.76.235307
DO - 10.1103/PhysRevB.76.235307
M3 - Article
AN - SCOPUS:37149015139
SN - 1098-0121
VL - 76
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 23
M1 - 235307
ER -