Polarity compensation mechanisms on the perovskite surface KTaO 3 (001)
The stacking of alternating charged planes in ionic crystals creates a diverging electrostatic energy-a "polar catastrophe"-that must be compensated at the surface. We used scanning probe microscopies and density functional theory to study compensation mechanisms at the perovskite potassiu...
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Published in | Science (American Association for the Advancement of Science) Vol. 359; no. 6375; pp. 572 - 575 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Association for the Advancement of Science (AAAS)
02.02.2018
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Subjects | |
Online Access | Get full text |
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Summary: | The stacking of alternating charged planes in ionic crystals creates a diverging electrostatic energy-a "polar catastrophe"-that must be compensated at the surface. We used scanning probe microscopies and density functional theory to study compensation mechanisms at the perovskite potassium tantalate (KTaO
) (001) surface as increasing degrees of freedom were enabled. The as-cleaved surface in vacuum is frozen in place but immediately responds with an insulator-to-metal transition and possibly ferroelectric lattice distortions. Annealing in vacuum allows the formation of isolated oxygen vacancies, followed by a complete rearrangement of the top layers into an ordered pattern of KO and TaO
stripes. The optimal solution is found after exposure to water vapor through the formation of a hydroxylated overlayer with ideal geometry and charge. |
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Bibliography: | USDOE Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division; AC05-00OR22725 |
ISSN: | 0036-8075 1095-9203 |
DOI: | 10.1126/science.aar2287 |