Coulometric titration studies of nonstoichiometric nanocrystalline ceria

Book · Mon Sep 01 04:00:00 EDT 1997

OSTI ID:522293

Porat, O; Tuller, H L; Lavik, E B; Chiang, Y M ^[1]

---

1. Massachusetts Inst. of Tech., Cambridge, MA (United States). Center for Materials Science and Engineering

Oxygen nonstoichiometry measurements in nanocrystalline ceria, x in CeO{sub 2{minus}x}, were performed using coulometric titration. The measurements reveal large apparent deviations from stoichiometry, of the order of 10{sup {minus}3}--10{sup {minus}4} at T = 405--455 C and P{sub O{sub 2}} = 0.21--10{sup {minus}5} atm, as compared to levels of {approximately} 10{sup {minus}9} for coarsened materials under the same conditions. The level of nonstoichiometry is, however, larger then expected from previous electrical conductivity data of nanocrystalline ceria. In addition, x {proportional_to} P{sub O{sub 2}}{sup {minus}1/2} while {sigma} {proportional_to} P{sub O{sub 2}}{sup {minus}1/6}. The observed dependence of X(P{sub O{sub 2}}, T) can be explained by either the formation of neutral oxygen vacancies at or near the interface, or by surface adsorption.

• Sponsoring Organization: National Science Foundation, Washington, DC (United States)
• OSTI ID: 522293
• Report Number(s): CONF-961202--; ISBN 1-55899-361-4
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
ACETATES
CALCINATION
CERIUM OXIDES
CHEMICAL COMPOSITION
EXPERIMENTAL DATA
POTENTIOMETRY
SAMPLE PREPARATION