A novel titanate-based oxygen ion conductor: Gd2Ti2O7

Kramer, S.

doi:10.1016/0167-2738(95)00156-z

Cited by 221 publications

(83 citation statements)

References 3 publications

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“…10, 14 The results of this work demonstrate that (Table 2). Co-substituted (Gd 1Àx Ca x ) 2 (Ti 0.95 Mo 0.05 ) 2 O 7Àd (x ¼ 0.07-0.10) ceramics are both mixed ionic-electronic conductors at reduced oxygen partial pressure (Table 2), but exhibit lower total electrical conductivity compared to Mo-free composition at intermediate oxygen partial pressures (Fig.…”

supporting

confidence: 64%

“…Differences relative to other reported results 30 may be related to contents of aliovalent additives, with expected impact on defect interactions and mobility. The n-type contribution in this composition was also evaluated from the average ionic transport numbers under air/H 2 gradient; this was combined with eqn (14) and a typical value of electron mobility m n z 0.014 cm 2 V À1 s À1 at 900 C (ref. 44) to evaluate the order of magnitude of the equilibrium constant of the reduction reaction (eqn (9)) k red z 10 47 cm À9 atm 1/2 .…”

Section: Defect Chemistrymentioning

confidence: 99%

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Mixed ionic-electronic conductivity and thermochemical expansion of Ca and Mo co-substituted pyrochlore-type Gd₂Ti₂O₇

et al. 2016

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supporting

confidence: 64%

Section: Defect Chemistrymentioning

confidence: 99%

Mixed ionic-electronic conductivity and thermochemical expansion of Ca and Mo co-substituted pyrochlore-type Gd₂Ti₂O₇

et al. 2016

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“…The present findings are quite consistent with the experimental investigation that Gd 2−x Ca x Ti 2 O 7−δ with x∼0.2 shows the highest oxide-ion conductivity within the pyrochlore compounds. 9,58 Because the ionic radius of Ca is slightly larger than that of Gd, Ca substitution for Gd sites can introduce local expansion, which should lower the migration energy of O(48f). However, excessive expansion promotes the stability of the O(8a), which increases the migration energy of O(48f) by the other possible migration mechanism of O(8a)-V O(48f) .…”

Section: O(48f) Migration Inmentioning

confidence: 99%

Theoretical and experimental investigation of defect formation / migration in Gd2Ti2O7: General rule of oxide-ion migration in A2B2O7 pyrochlore

et al. 2016

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We investigated the intrinsic defect formation energy and oxide-ion migration mechanism in Gd2Ti2O7 pyrochlore. It was found that the vacancy formation energy of Gd is lower than that of Ti. For the oxygen vacancy, O(48f) was found to show lower vacancy formation energy than O(8b). The formation energy of the vacancy complex showed that the Gd vacancy is accompanied with the O(48f) vacancy, which is consistent with our experiment. The migration energy of O(48f) along the <100> direction, which is dominant migration path for ionic conduction, was calculated to be 0.43 eV. On the other hand, we found that Gd vacancy increases O(48f) migration energy. For example, the migration energy of O(48f) along the <100> direction was increased to be 1.36 eV by the local compressive strain around Gd vacancy. This finding could explain our previous experimental result of decreasing conductivity with increasing Gd deficiency. Along with the oxide-ion migration mechanism in Gd2Ti2O7, O(48f) migration energies along both <100> and <110> directions for various A2B2O7 pyrochlore structures were investigated. As a general trend of oxide-ion migration in the pyrochlore structure, we propose that O(48f) migration along the <100> direction is governed by the strength of B–O bonding. On the other hand, the ratio of ionic radius B/A is proposed to determine O(48f) migration along the <110> direction in A2B2O7 pyrochlore.

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“…Oxygen concentration cell measurements were used to determine the ionic transference number, as some pyrochlores are known to exhibit significant levels of ionic conductivity due to either intrinsic Frenkel disorder [15] or acceptor doping [16].…”

Section: Introductionmentioning

confidence: 99%

The Electrical and Defect Properties of Bi₃Zn₂Sb₃O₁₄Pyrochlore: A Grain-Boundary Phase in ZnO-Based Varistors

Clayton

Takamura

Metz

et al. 2001

Journal of Electroceramics

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Abstract. The electrical conductivity of Bi 3 Zn 2 Sb 3 O 14 pyrochlore was studied as a function of temperature and partial pressure of oxygen. Conductivity measurements by ac complex impedance analysis and ionic transference number measurements show this pyrochlore to be a mixed ionic-electronic conductor with an energy band gap of 3.15 ± 0.9 eV. A defect model in which Frenkel defects on the oxygen lattice are dominant is confirmed. Enthalpies of reduction, oxidation and the sum of oxygen vacancy formation and migration were found to be 4.82 ± 0.8 eV, 1.48 ± 1.0 eV and 1.67 ± 1.0 eV respectively.

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A novel titanate-based oxygen ion conductor: Gd2Ti2O7

Cited by 221 publications

References 3 publications

Mixed ionic-electronic conductivity and thermochemical expansion of Ca and Mo co-substituted pyrochlore-type Gd₂Ti₂O₇

Mixed ionic-electronic conductivity and thermochemical expansion of Ca and Mo co-substituted pyrochlore-type Gd₂Ti₂O₇

Theoretical and experimental investigation of defect formation / migration in Gd2Ti2O7: General rule of oxide-ion migration in A2B2O7 pyrochlore

The Electrical and Defect Properties of Bi₃Zn₂Sb₃O₁₄Pyrochlore: A Grain-Boundary Phase in ZnO-Based Varistors

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A novel titanate-based oxygen ion conductor: Gd2Ti2O7

Cited by 221 publications

References 3 publications

Mixed ionic-electronic conductivity and thermochemical expansion of Ca and Mo co-substituted pyrochlore-type Gd2Ti2O7

Mixed ionic-electronic conductivity and thermochemical expansion of Ca and Mo co-substituted pyrochlore-type Gd2Ti2O7

Theoretical and experimental investigation of defect formation / migration in Gd2Ti2O7: General rule of oxide-ion migration in A2B2O7 pyrochlore

The Electrical and Defect Properties of Bi3Zn2Sb3O14Pyrochlore: A Grain-Boundary Phase in ZnO-Based Varistors

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Mixed ionic-electronic conductivity and thermochemical expansion of Ca and Mo co-substituted pyrochlore-type Gd₂Ti₂O₇

Mixed ionic-electronic conductivity and thermochemical expansion of Ca and Mo co-substituted pyrochlore-type Gd₂Ti₂O₇

The Electrical and Defect Properties of Bi₃Zn₂Sb₃O₁₄Pyrochlore: A Grain-Boundary Phase in ZnO-Based Varistors