|
authors |
Tkach, A; Amaral, L; Vilarinho, PM; Senos, AMR |
|
nationality |
International |
|
journal |
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY |
|
author keywords |
Strontium titanate; Grain boundary specific area; Vacancies; Oxygen annealing; Impedance spectroscopy; Charge transport; Conduction mechanism |
|
keywords |
K PHASE-TRANSITION; SRTIO3; CERAMICS; CHEMISTRY; MICROSTRUCTURE; DEPENDENCE; CHARGE; DEFECT; BULK |
|
abstract |
Titanium-rich (Sr/Ti = 0.995) strontium titanate (ST) ceramics, air-sintered in a temperature range of 1400-1625 degrees C, were reported to possess anomalies in the grain growth and analogous anomalies in the grain boundary (GB) conductivity activation energy. However, these two interface-related phenomena, occurring at GBs, could not be associated with each other using a simple "brick-layer" model. In this work we revise the topic and advocate that the deviation from the model comes from the oxygen vacancies localized at GBs of the rapidly cooled ST ceramics. To verify this, we annealed the ceramics in oxygen and performed their systematic and comparative analysis using impedance spectroscopy. A levelling-off in the GB conductivity activation energy, which increases for <= 1.24 eV, and a four-fold decrease in the GB permittivity are observed after annealing. Thus, we confirm a key role of oxygen vacancies in relation between the grain growth and GB conductivity anomalies of as-sintered Ti-rich ST ceramics. |
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publisher |
ELSEVIER SCI LTD |
|
issn |
0955-2219 |
|
year published |
2018 |
|
volume |
38 |
|
issue |
6 |
|
beginning page |
2547 |
|
ending page |
2552 |
|
digital object identifier (doi) |
10.1016/j.jeurceramsoc.2018.01.014 |
|
web of science category |
Materials Science, Ceramics |
|
subject category |
Materials Science |
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unique article identifier |
WOS:000427668200011
|
