Oxygen ionic and electronic transport in apatite ceramics
authors Shaula, AL; Kharton, VV; Waerenborgh, JC; Rojas, DP; Marques, FMB
nationality International
journal JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
author keywords electrical conductivity; ionic conductivity; thermal expansion; apatite; fuel cells
keywords SEEBECK COEFFICIENT; CONDUCTIVITY; LA8SR2SI6O26; LA9.33SI6O26; PEROVSKITES; SILICATES; GD; SM; DY; ND
abstract The development of novel oxygen ion conducting solid electrolytes is of great interest for high-temperature electrochemical applications such as solid oxide fuel cells (SOFCs). This work was focused on the study of transport properties of apatite-type La10Si6-xFexO27-x/2 (x = 1-2). Single-phase apatite ceramics with density higher than 98% were prepared by the standard solid-state synthesis route. The materials were characterized by X-ray diffraction, dilatometry, impedance spectroscopy and faradaic efficiency measurements. The total conductivity and Seebeck coefficient were studied as function of the oxygen partial pressure varying in the range 10(-16) Pa to 50 kPa. The ionic conductivity of apatite phases was found to increase with oxygen content. In air, the ion transference numbers of La10Si6-xFexO27-x/2 (x= 1.0-1.5) at 700-950 degrees C are higher than 0.99, whilst the p-type electronic contribution to the total conductivity of La10Si4Fe2O26 is about 3%. Mossbauer spectroscopy showed that the coordination of iron cations, which are all trivalent within the detection limits, increases with oxygen intercalation in the lattice. Reducing P(02) below 10(-8) Pa leads to a decrease in the ionic transport and growing n-type electronic contribution, the role of which increases with iron additions. The average thermal expansion coefficients in air are (8.2-9.9) x 10(-6) K-1 at 100-1000 degrees C. (c) 2005 Elsevier Ltd. All rights reserved.
publisher ELSEVIER SCI LTD
issn 0955-2219
year published 2005
volume 25
issue 12
beginning page 2583
ending page 2586
digital object identifier (doi) 10.1016/j.jeurceramsoc.2005.03.106
web of science category Materials Science, Ceramics
subject category Materials Science
unique article identifier WOS:000230569300126
  ciceco authors
  impact metrics
journal analysis (jcr 2019):
journal impact factor 4.495
5 year journal impact factor 4.283
category normalized journal impact factor percentile 98.214
dimensions (citation analysis):
altmetrics (social interaction):



 


Apoio

1suponsers_list_ciceco.jpg