TY - JOUR
T1 - Why the case for clean surfaces does not hold water
T2 - Structure and morphology of hydroxylated nickel oxide (1 1 1)
AU - Ciston, J.
AU - Subramanian, A.
AU - Kienzle, D. M.
AU - Marks, L. D.
N1 - Funding Information:
This work was supported by the National Science Foundation DMR-0455371 (JWC, DMK, and LDM), and DMR-0075834 (AKS). We are greatly indebted to Dr. Karl Merkle for providing (1 1 1) oriented NiO single crystals used in this study. The authors would also like to thank Professor Peter Blaha, and Dr. Fabien Tran for many fruitful discussions regarding hybrid DFT functionals.
PY - 2010/1/15
Y1 - 2010/1/15
N2 - We report an experimental and theoretical analysis of the √3 × √3-R30° and 2 × 2 reconstructions on the NiO (1 1 1) surface combining transmission electron microscopy, X-ray photoelectron spectroscopy, and reasonably accurate density functional calculations using the meta-GGA hybrid functional TPSSh. While the main focus here is on the surface structure, we also observe an unusual step morphology with terraces containing only even numbers of unit cells during annealing of the surfaces. The experimental data clearly shows that the surfaces contain significant coverage of hydroxyl terminations, and the surface structures are essentially the same as those reported on the MgO (1 1 1) surface implying an identical kinetically-limited water-driven structural transition pathway. The octapole structure can therefore be all but ruled out for single crystals of NiO annealed in or transported through humid air. The theoretical analysis indicates, as expected, that simple density functional theory methods for such strongly-correlated oxide surfaces are marginal, while better consideration of the metal d-electrons has a large effect although it is still not perfect.
AB - We report an experimental and theoretical analysis of the √3 × √3-R30° and 2 × 2 reconstructions on the NiO (1 1 1) surface combining transmission electron microscopy, X-ray photoelectron spectroscopy, and reasonably accurate density functional calculations using the meta-GGA hybrid functional TPSSh. While the main focus here is on the surface structure, we also observe an unusual step morphology with terraces containing only even numbers of unit cells during annealing of the surfaces. The experimental data clearly shows that the surfaces contain significant coverage of hydroxyl terminations, and the surface structures are essentially the same as those reported on the MgO (1 1 1) surface implying an identical kinetically-limited water-driven structural transition pathway. The octapole structure can therefore be all but ruled out for single crystals of NiO annealed in or transported through humid air. The theoretical analysis indicates, as expected, that simple density functional theory methods for such strongly-correlated oxide surfaces are marginal, while better consideration of the metal d-electrons has a large effect although it is still not perfect.
KW - Density functional calculations
KW - Hydroxylation
KW - Nickel oxide
KW - Surface structure kinetics
KW - Transmission high-energy electron diffraction
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U2 - 10.1016/j.susc.2009.10.033
DO - 10.1016/j.susc.2009.10.033
M3 - Article
AN - SCOPUS:72649104395
SN - 0039-6028
VL - 604
SP - 155
EP - 164
JO - Surface Science
JF - Surface Science
IS - 2
ER -