Surface Space‐Charge Potential and Oxygen Surface Exchange Coefficient of SrTiO 3 : The Effect of Surface Orientation
Abstract 18 O 2 / 16 O 2 exchange experiments on terminated (100), (110), and (111) oriented samples of single‐crystal SrTiO 3 are used to study the effect of surface orientation on the oxygen surface exchange coefficient and the surface space‐charge potential Φ 0 . Isotope exchanges are carried out...
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Published in | Advanced materials interfaces Vol. 10; no. 2 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
01.01.2023
|
Online Access | Get full text |
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Summary: | Abstract
18
O
2
/
16
O
2
exchange experiments on terminated (100), (110), and (111) oriented samples of single‐crystal SrTiO
3
are used to study the effect of surface orientation on the oxygen surface exchange coefficient and the surface space‐charge potential Φ
0
. Isotope exchanges are carried out at temperatures 922 <
T
/K < 1073 at an oxygen activity
a
O
2
= 0.2 in dry conditions (
a
H
2
O < 10
−7.7
); isotope profiles are measured subsequently by secondary ion mass spectrometry. Isothermal values are found to vary by less than one order of magnitude, with . All data are consistent with a change in the activation enthalpy of surface exchange from 3.0 eV at high temperatures to 1.8 eV at lower temperatures. The transition is attributed to a change from a charge‐transfer mechanism at high temperatures to a mechanism involving surface OH species. The transition temperature depends on the surface orientation,
T
tr
(111) ≈
T
tr
(110) >
T
tr
(100). Values of Φ
0
obtained varied between 0.50 V and 0.37 V, with isothermal values obeying Φ
0
(111) ≈ Φ
0
(110) < Φ
0
(100). Φ
0
data is analysed to obtain the OH
−
surface coverage for the low‐temperature regime. Similarities between the behavior of Φ
0
and that of are highlighted. |
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ISSN: | 2196-7350 2196-7350 |
DOI: | 10.1002/admi.202201434 |