Low temperature dielectric properties of Ce 0.8Gd 0.2O 1.9 films

Victor Shelukhin, Ilya Zon, Ellen Wachtel, Yishay Feldman, Igor Lubomirsky

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Although Gd-doped ceria is one of the most important and well-studied of oxygen ion conductors, the relationship between its mechanical and electrical properties is not completely understood. In particular the low temperature electrical behavior of Gd-doped ceria, and its response to mechanical strain, have not been characterized. We have used impedance spectroscopy (1 Hz-1 MHz) to investigate the dielectric properties of both Si substrate-supported and self-supported Ce 0.8Gd 0.2O 1.9 thin (450 ± 50 nm) films in the temperature range of 35-440 K. We find that the grain boundary electronic conductivity for both types of Ce 0.8Gd 0.2O 1.9 films freezes out between 120 and 150 K. Upon cooling to 40 K, the effective dielectric constant of the substrate-supported films decreases uniformly, remaining within the range of 20.5 ± 2.5. In contrast, all (17) self-supported films investigated exhibit small (~ 2%) but readily detectable instability of the dielectric constant between 80 and 140 K. Furthermore, below 90 K, the dielectric constant of the self-supported films depends on the applied voltage and displays hysteretic behavior. This strongly suggests that even below 100 K, the self-supported films can undergo structural changes. Comparison of the lattice parameter at 300 K and at 100 K shows that the self-supported films contract upon cooling with a thermal expansion coefficient close to that of the bulk material, whereas the substrate-supported films exhibit a thermal expansion coefficient which is approximately twice as large. On the basis of our earlier findings concerning the inelastic behavior of Gd-doped ceria films, we propose that a probable explanation for the observed differences between the self-supported and the substrate-supported films is that in the self-supported films, oxygen vacancy-cerium complexes are able to undergo partial ordering. In substrate-supported films these changes are suppressed by the tensile strain imposed by the substrate upon cooling.

Original languageEnglish
Pages (from-to)12-19
Number of pages8
JournalSolid State Ionics
Volume211
DOIs
Publication statusPublished - Mar 15 2012

Fingerprint

Dielectric properties
dielectric properties
Temperature
Cerium compounds
Substrates
Permittivity
permittivity
Cooling
cooling
Thermal expansion
thermal expansion
Cerium
Tensile strain
Oxygen vacancies
coefficients
oxygen ions
cerium
Lattice constants
lattice parameters
Grain boundaries

Keywords

  • Dielectric properties
  • Doped ceria
  • Self-supported films
  • Stress in thin films

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Chemistry(all)

Cite this

Low temperature dielectric properties of Ce 0.8Gd 0.2O 1.9 films. / Shelukhin, Victor; Zon, Ilya; Wachtel, Ellen; Feldman, Yishay; Lubomirsky, Igor.

In: Solid State Ionics, Vol. 211, 15.03.2012, p. 12-19.

Research output: Contribution to journalArticle

Shelukhin, Victor ; Zon, Ilya ; Wachtel, Ellen ; Feldman, Yishay ; Lubomirsky, Igor. / Low temperature dielectric properties of Ce 0.8Gd 0.2O 1.9 films. In: Solid State Ionics. 2012 ; Vol. 211. pp. 12-19.
@article{4cc7aaa5d22a420694e507dc6446c8b8,
title = "Low temperature dielectric properties of Ce 0.8Gd 0.2O 1.9 films",
abstract = "Although Gd-doped ceria is one of the most important and well-studied of oxygen ion conductors, the relationship between its mechanical and electrical properties is not completely understood. In particular the low temperature electrical behavior of Gd-doped ceria, and its response to mechanical strain, have not been characterized. We have used impedance spectroscopy (1 Hz-1 MHz) to investigate the dielectric properties of both Si substrate-supported and self-supported Ce 0.8Gd 0.2O 1.9 thin (450 ± 50 nm) films in the temperature range of 35-440 K. We find that the grain boundary electronic conductivity for both types of Ce 0.8Gd 0.2O 1.9 films freezes out between 120 and 150 K. Upon cooling to 40 K, the effective dielectric constant of the substrate-supported films decreases uniformly, remaining within the range of 20.5 ± 2.5. In contrast, all (17) self-supported films investigated exhibit small (~ 2{\%}) but readily detectable instability of the dielectric constant between 80 and 140 K. Furthermore, below 90 K, the dielectric constant of the self-supported films depends on the applied voltage and displays hysteretic behavior. This strongly suggests that even below 100 K, the self-supported films can undergo structural changes. Comparison of the lattice parameter at 300 K and at 100 K shows that the self-supported films contract upon cooling with a thermal expansion coefficient close to that of the bulk material, whereas the substrate-supported films exhibit a thermal expansion coefficient which is approximately twice as large. On the basis of our earlier findings concerning the inelastic behavior of Gd-doped ceria films, we propose that a probable explanation for the observed differences between the self-supported and the substrate-supported films is that in the self-supported films, oxygen vacancy-cerium complexes are able to undergo partial ordering. In substrate-supported films these changes are suppressed by the tensile strain imposed by the substrate upon cooling.",
keywords = "Dielectric properties, Doped ceria, Self-supported films, Stress in thin films",
author = "Victor Shelukhin and Ilya Zon and Ellen Wachtel and Yishay Feldman and Igor Lubomirsky",
year = "2012",
month = "3",
day = "15",
doi = "10.1016/j.ssi.2012.01.014",
language = "English",
volume = "211",
pages = "12--19",
journal = "Solid State Ionics",
issn = "0167-2738",
publisher = "Elsevier",

}

TY - JOUR

T1 - Low temperature dielectric properties of Ce 0.8Gd 0.2O 1.9 films

AU - Shelukhin, Victor

AU - Zon, Ilya

AU - Wachtel, Ellen

AU - Feldman, Yishay

AU - Lubomirsky, Igor

PY - 2012/3/15

Y1 - 2012/3/15

N2 - Although Gd-doped ceria is one of the most important and well-studied of oxygen ion conductors, the relationship between its mechanical and electrical properties is not completely understood. In particular the low temperature electrical behavior of Gd-doped ceria, and its response to mechanical strain, have not been characterized. We have used impedance spectroscopy (1 Hz-1 MHz) to investigate the dielectric properties of both Si substrate-supported and self-supported Ce 0.8Gd 0.2O 1.9 thin (450 ± 50 nm) films in the temperature range of 35-440 K. We find that the grain boundary electronic conductivity for both types of Ce 0.8Gd 0.2O 1.9 films freezes out between 120 and 150 K. Upon cooling to 40 K, the effective dielectric constant of the substrate-supported films decreases uniformly, remaining within the range of 20.5 ± 2.5. In contrast, all (17) self-supported films investigated exhibit small (~ 2%) but readily detectable instability of the dielectric constant between 80 and 140 K. Furthermore, below 90 K, the dielectric constant of the self-supported films depends on the applied voltage and displays hysteretic behavior. This strongly suggests that even below 100 K, the self-supported films can undergo structural changes. Comparison of the lattice parameter at 300 K and at 100 K shows that the self-supported films contract upon cooling with a thermal expansion coefficient close to that of the bulk material, whereas the substrate-supported films exhibit a thermal expansion coefficient which is approximately twice as large. On the basis of our earlier findings concerning the inelastic behavior of Gd-doped ceria films, we propose that a probable explanation for the observed differences between the self-supported and the substrate-supported films is that in the self-supported films, oxygen vacancy-cerium complexes are able to undergo partial ordering. In substrate-supported films these changes are suppressed by the tensile strain imposed by the substrate upon cooling.

AB - Although Gd-doped ceria is one of the most important and well-studied of oxygen ion conductors, the relationship between its mechanical and electrical properties is not completely understood. In particular the low temperature electrical behavior of Gd-doped ceria, and its response to mechanical strain, have not been characterized. We have used impedance spectroscopy (1 Hz-1 MHz) to investigate the dielectric properties of both Si substrate-supported and self-supported Ce 0.8Gd 0.2O 1.9 thin (450 ± 50 nm) films in the temperature range of 35-440 K. We find that the grain boundary electronic conductivity for both types of Ce 0.8Gd 0.2O 1.9 films freezes out between 120 and 150 K. Upon cooling to 40 K, the effective dielectric constant of the substrate-supported films decreases uniformly, remaining within the range of 20.5 ± 2.5. In contrast, all (17) self-supported films investigated exhibit small (~ 2%) but readily detectable instability of the dielectric constant between 80 and 140 K. Furthermore, below 90 K, the dielectric constant of the self-supported films depends on the applied voltage and displays hysteretic behavior. This strongly suggests that even below 100 K, the self-supported films can undergo structural changes. Comparison of the lattice parameter at 300 K and at 100 K shows that the self-supported films contract upon cooling with a thermal expansion coefficient close to that of the bulk material, whereas the substrate-supported films exhibit a thermal expansion coefficient which is approximately twice as large. On the basis of our earlier findings concerning the inelastic behavior of Gd-doped ceria films, we propose that a probable explanation for the observed differences between the self-supported and the substrate-supported films is that in the self-supported films, oxygen vacancy-cerium complexes are able to undergo partial ordering. In substrate-supported films these changes are suppressed by the tensile strain imposed by the substrate upon cooling.

KW - Dielectric properties

KW - Doped ceria

KW - Self-supported films

KW - Stress in thin films

UR - http://www.scopus.com/inward/record.url?scp=84857791821&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84857791821&partnerID=8YFLogxK

U2 - 10.1016/j.ssi.2012.01.014

DO - 10.1016/j.ssi.2012.01.014

M3 - Article

AN - SCOPUS:84857791821

VL - 211

SP - 12

EP - 19

JO - Solid State Ionics

JF - Solid State Ionics

SN - 0167-2738

ER -