Oxygen vacancies as a link between the grain growth and grain boundary conductivity anomalies in titanium-rich strontium titanate
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.
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
unique article identifier WOS:000427668200011
  ciceco authors
  impact metrics
journal analysis (jcr 2017):
journal impact factor 3.794
5 year journal impact factor 3.536
category normalized journal impact factor percentile 98.148
dimensions (citation analysis):
altmetrics (social interaction):



 


Apoio

1suponsers_list_ciceco.jpg