Phase equilibriums, oxygen exchange kinetics and diffusion in oxides CaZr1 − xScxO3 − x/2 − δ

• Published in: Russian journal of electrochemistry Vol. 48; no. 9; pp. 879 - 886
• Main Authors: Anan’ev, M. V., Bershitskaya, N. M., Plaksin, S. V., Kurumchin, E. Kh
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01-09-2012
• Subjects: Chemistry; Chemistry and Materials Science; Electrochemistry; Physical Chemistry; oxygen diffusion; calcium zirconate; exchange kinetics; X-ray diffraction analysis
• ISSN: 1023-1935; 1608-3342
• DOI: 10.1134/S1023193512090030

Oxides CaZr
1 −
x
Sc
x
O
3 −
x
/2 - δ
(
x
= 0.00–0.20) were synthesized according to the ceramic technology. The solubility boundary of scandium with formation of solid solutions on the basis of calcium zirconate CaZrO
3 − δ
corresponds to
x
= 0.07–0.08. The second phase of CaSc
2
O
4
is present in the samples with scandium content of
x
= 0.10, 0.15, 0.20. Its fraction grows at an increase in
x
. The method of full-profile Rietveld analysis was used to calculate the structure parameters for oxides CaZr
0.99
Sc
0.01
O
2.995 − δ
and CaZr
0.95
Sc
0.05
O
2.975 − δ
. The method of isotopic exchange with gas phase analysis was used to study the kinetics of gas-phase oxygen interaction with the CaZr
0.95
Sc
0.05
O
2.975 − δ
oxide in the temperature range of 700–850°C and at oxygen pressures of 0.13–6.67 kPa. The values of effective activation energies of the oxygen exchange and diffusion processes were 1.36 ± 0.32 and 1.92 ± 0.21 eV, accordingly. The dependence of the interphase exchange rate on the pressure of oxygen corresponds to the power law with the exponent of 0.31 ± 0.04 at the temperature of 750°C.