Impedance analysis of Sr-substituted CePO4 with mixed protonic and p-type electronic conduction
authors del Moral, EG; Fagg, DP; Chinarro, E; Abrantes, JCC; Jurado, JR; Mather, GC
nationality International
journal CERAMICS INTERNATIONAL
author keywords Cerium phosphate; Mixed conductor; Hydrogen-separation membrane; Proton conduction; Impedance spectroscopy
keywords TRANSPORT-PROPERTIES; HYDROGEN SEPARATION; LAPO4; MEMBRANE; CERMET
abstract Members of the solid-solution series Ce1-xSrxPO4-delta (x = 0, 0.01, 0.02) with mixed protonic and electronic transport have been synthesized by a nitrate-decomposition method followed by sintering at 1450 degrees C. Impedance spectroscopy is employed to estimate the bulk electrical conductivity in wet (similar to 0.03 atm) and dry atmospheres of O-2 and 10%H-2:90%N-2. Conductivity increases with dopant concentration (x), oxygen partial pressure (pO(2)) and water vapour partial pressure (pH(2)O) reaching similar to 3.5 x 10(-3) S cm(-1) at 600 degrees C for x = 0.02 in wet O-2. Activation energies (E-a) for the bulk conductivity of Ce0.98Sr0.02PO4-delta below 650 degrees C are 0.44 and 0.78 eV for wet oxidising and wet reducing conditions, respectively. A moderate but positive pO(2)(+n) power-law dependence (n < 1/10) of conductivity is exhibited in the pO(2) range 10(-2.5) to 10(-1) atm, consistent with mixed ionic and p-type electronic transport. Thermogravimetric analysis indicates that the Sr-doped materials are stable in a CO2 atmosphere in the temperature range 25-1200 degrees C. (C) 2008 Elsevier Ltd and Techna Group S.r.l. All fights reserved.
publisher ELSEVIER SCI LTD
issn 0272-8842
year published 2009
volume 35
issue 4
beginning page 1481
ending page 1486
digital object identifier (doi) 10.1016/j.ceramint.2008.08.004
web of science category Materials Science, Ceramics
subject category Materials Science
unique article identifier WOS:000265007200025
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