Oxygen isotope exchange in praseodymium nickelate

• Published in: Journal of solid state electrochemistry Vol. 22; no. 7; pp. 2115 - 2126
• Main Authors: Porotnikova, N. M., Khodimchuk, A. V., Ananyev, M. V., Eremin, V. A., Tropin, E. S., Farlenkov, A. S., Pikalova, E. Yu, Fetisov, A. V.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-07-2018; Springer Nature B.V
• Subjects: Activation energy; Analytical Chemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Diffusion coefficient; Diffusion rate; Electrochemistry; Energy Storage; Mathematical analysis; Original Paper; Oxygen isotopes; Physical Chemistry; Praseodymium; Temperature dependence; Oxygen isotope exchange; Dissociative adsorption; Oxygen incorporation; Rate-determining stage; Oxygen diffusion; Praseodymium nickelate
• ISSN: 1432-8488; 1433-0768
• DOI: 10.1007/s10008-018-3919-x

Oxygen surface exchange kinetics and diffusion were studied in Pr
2
NiO
4 + δ
(PNO) by the isotope exchange method with gas phase equilibration in the temperature range of 600–800 °C and oxygen pressure range of 0.33–1.62 kPa. The oxygen heterogeneous exchange rate (
r
H
), oxygen diffusion coefficient (
D
), rates of oxygen dissociative adsorption (
r
a
), and oxygen incorporation (
r
i
) were calculated along with the apparent activation energies of oxygen surface exchange and diffusion processes. The temperature dependence of
r
H
was found to benon-linear in Arrhenius coordinates. The apparent activation energy changed from 1.4 ± 0.2 eV at
T
 > 700 °C to 2.0 ± 0.1 eV. This might be attributed to the change in the rate-determining stage of oxygen exchange for Pr
2
NiO
4 + δ
at
T
~ 700 °C, because of a shift in the ratio between
r
a
and
r
i
caused by the difference in their activation energies. Possible reasons for the observed changes in the rate-determining stage are discussed.