Defect chemistry and transport properties of nanocrystalline cerium oxide

Jin Ha Hwang, Thomas O Mason

Research output: Contribution to journalArticle

87 Citations (Scopus)

Abstract

Simultaneous conductivity and thermopower measurements were performed on partially sintered nanocrystalline cerium oxide (∼15 nm grain size) over 10-3 to 1 atm of oxygen pressure at 450 to 550°C. Although electronic conduction predominates, mixed conduction is apparent in the oxygen pressure dependence of the conductivity. The electronic mobility is activated with a small polaron hopping energy similar to that of bulk cerium oxide (∼0.5 eV). The oxygen vacancy migration energy is ∼1.6 eV, substantially larger than in bulk ceria, but not inconsistent with grain boundary values or bulk values at low temperatures (due to vacany-dopant association). The enthalpy of reduction of nanoceria is 1.84 eV, less than half of the corresponding value in bulk ceria. Nanoceria therefore has much larger defect populations (vacancies, electrons) if undoped and electron populations if doped (i.e., with trivalent cations). These results are discussed in terms of the role played by the high surface/grain boundary areas in the defect/transport properties of nanocrystalline oxides.

Original languageEnglish
Pages (from-to)21-38
Number of pages18
JournalZeitschrift fur Physikalische Chemie
Volume207
Issue number1-2
Publication statusPublished - 1998

Fingerprint

cerium oxides
Transport properties
transport properties
chemistry
Defects
Cerium compounds
defects
oxygen
grain boundaries
conduction
conductivity
Grain boundaries
Oxygen
electronics
Gene Conversion
pressure dependence
Electrons
Thermoelectric power
electrons
Oxygen vacancies

Keywords

  • Conductivity
  • Defect chemistry
  • Mixed conduction
  • Nanocrystalline cerium oxide
  • Thermopower

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Atomic and Molecular Physics, and Optics

Cite this

Defect chemistry and transport properties of nanocrystalline cerium oxide. / Hwang, Jin Ha; Mason, Thomas O.

In: Zeitschrift fur Physikalische Chemie, Vol. 207, No. 1-2, 1998, p. 21-38.

Research output: Contribution to journalArticle

@article{e49e58cb00724faea8800e83fd666dd4,
title = "Defect chemistry and transport properties of nanocrystalline cerium oxide",
abstract = "Simultaneous conductivity and thermopower measurements were performed on partially sintered nanocrystalline cerium oxide (∼15 nm grain size) over 10-3 to 1 atm of oxygen pressure at 450 to 550°C. Although electronic conduction predominates, mixed conduction is apparent in the oxygen pressure dependence of the conductivity. The electronic mobility is activated with a small polaron hopping energy similar to that of bulk cerium oxide (∼0.5 eV). The oxygen vacancy migration energy is ∼1.6 eV, substantially larger than in bulk ceria, but not inconsistent with grain boundary values or bulk values at low temperatures (due to vacany-dopant association). The enthalpy of reduction of nanoceria is 1.84 eV, less than half of the corresponding value in bulk ceria. Nanoceria therefore has much larger defect populations (vacancies, electrons) if undoped and electron populations if doped (i.e., with trivalent cations). These results are discussed in terms of the role played by the high surface/grain boundary areas in the defect/transport properties of nanocrystalline oxides.",
keywords = "Conductivity, Defect chemistry, Mixed conduction, Nanocrystalline cerium oxide, Thermopower",
author = "Hwang, {Jin Ha} and Mason, {Thomas O}",
year = "1998",
language = "English",
volume = "207",
pages = "21--38",
journal = "Zeitschrift fur Physikalische Chemie",
issn = "0942-9352",
publisher = "Oldenbourg Wissenschaftsverlag GmbH",
number = "1-2",

}

TY - JOUR

T1 - Defect chemistry and transport properties of nanocrystalline cerium oxide

AU - Hwang, Jin Ha

AU - Mason, Thomas O

PY - 1998

Y1 - 1998

N2 - Simultaneous conductivity and thermopower measurements were performed on partially sintered nanocrystalline cerium oxide (∼15 nm grain size) over 10-3 to 1 atm of oxygen pressure at 450 to 550°C. Although electronic conduction predominates, mixed conduction is apparent in the oxygen pressure dependence of the conductivity. The electronic mobility is activated with a small polaron hopping energy similar to that of bulk cerium oxide (∼0.5 eV). The oxygen vacancy migration energy is ∼1.6 eV, substantially larger than in bulk ceria, but not inconsistent with grain boundary values or bulk values at low temperatures (due to vacany-dopant association). The enthalpy of reduction of nanoceria is 1.84 eV, less than half of the corresponding value in bulk ceria. Nanoceria therefore has much larger defect populations (vacancies, electrons) if undoped and electron populations if doped (i.e., with trivalent cations). These results are discussed in terms of the role played by the high surface/grain boundary areas in the defect/transport properties of nanocrystalline oxides.

AB - Simultaneous conductivity and thermopower measurements were performed on partially sintered nanocrystalline cerium oxide (∼15 nm grain size) over 10-3 to 1 atm of oxygen pressure at 450 to 550°C. Although electronic conduction predominates, mixed conduction is apparent in the oxygen pressure dependence of the conductivity. The electronic mobility is activated with a small polaron hopping energy similar to that of bulk cerium oxide (∼0.5 eV). The oxygen vacancy migration energy is ∼1.6 eV, substantially larger than in bulk ceria, but not inconsistent with grain boundary values or bulk values at low temperatures (due to vacany-dopant association). The enthalpy of reduction of nanoceria is 1.84 eV, less than half of the corresponding value in bulk ceria. Nanoceria therefore has much larger defect populations (vacancies, electrons) if undoped and electron populations if doped (i.e., with trivalent cations). These results are discussed in terms of the role played by the high surface/grain boundary areas in the defect/transport properties of nanocrystalline oxides.

KW - Conductivity

KW - Defect chemistry

KW - Mixed conduction

KW - Nanocrystalline cerium oxide

KW - Thermopower

UR - http://www.scopus.com/inward/record.url?scp=1142275326&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=1142275326&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:1142275326

VL - 207

SP - 21

EP - 38

JO - Zeitschrift fur Physikalische Chemie

JF - Zeitschrift fur Physikalische Chemie

SN - 0942-9352

IS - 1-2

ER -