The effect of homovalent A-site substitutions on the ionic conductivity of pyrochlore-type Gd2Zr2O7

Díaz-Guillén, J.A.; Fuentes, Antonio F.; Díaz-Guillén, M.R.; Almanza-Robles, J.M.; Santamarı́a, J.; León, Carlos

doi:10.1016/j.jpowsour.2008.09.106

Cited by 107 publications

(49 citation statements)

References 23 publications

(24 reference statements)

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“…The bulk ingot used for the EB-PVD coating process was also analyzed by XRD. The results of the analysis showed that all of the bulk and coating materials consisted of ordered pyrochlore-type structures with fluorite-type structures, 33), 34) as shown in Fig. 1.…”

Section: Resultsmentioning

confidence: 96%

Microstructure controls in Gadolinium Zirconate/YSZ double layers and their properties

Lee

Kim

2014

J. Ceram. Soc. Japan

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In this study, a double-layer thermal barrier coating was designed and deposited by an electron beam physical vapor deposition technique. The microstructure was controlled by using different target ingots during the electron beam physical vapor deposition process. The double layer coating consists of Gd 2 Zr 2 O 7 for the top layer and YSZ for the bottom layer. The microstructure, hardness, and thermal shock properties of the double layer deposited using a single-ingot process were compared with the results obtained with the two-ingot process. The single-ingot process involves forming the Gd 2 Zr 2 O 7 /YSZ double layer using a single YSZ/Gd 2 Zr 2 O 7 double-layered ingot. The two-ingot process involves coating with each of the YSZ and Gd 2 Zr 2 O 7 ingots. While the XRD results indicated that the same pyrochlore-fluorite structures are formed in those ingots, differences in the microstructure and composition were observed by FE-SEM and EDS analyses. These differences influence the hardness and thermal shock resistance of the coating. The results indicate that the finer singular columns produced by the two-ingot process do not improve the hardness, but delay the delamination of the top layer during thermal shock tests due to residual compressive stress and strain tolerance.

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Section: Resultsmentioning

confidence: 96%

Microstructure controls in Gadolinium Zirconate/YSZ double layers and their properties

Lee

Kim

2014

J. Ceram. Soc. Japan

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“…(Gd 0.5 Sm 0.5 ) 2 Zr 2 O 7 exhibited the highest electrical conductivity for (Gd 1−x Sm x ) 2 Zr 2 O 7 (0 ≤ x ≤ 1.0) ceramics at 873 K [15]. However, ionic conductivity of pyrochlore-type Gd 2 Zr 2 O 7 doped with different trivalent cations of Er, Y, Dy, Nd and La at Gd sites remained almost unchanged [16]. The electrical conductivity of (Gd 1−x Eu x ) 2 Zr 2 O 7 (0 ≤ x ≤ 1.0) ceramics was improved by suitable doping homovalent Eu at Gd site in the temperature range of 623-923 K [17].…”

Section: Introductionmentioning

confidence: 97%

“…In the family of pyrochlore-type compounds, Gd 2 Zr 2 O 7 had the highest intrinsic ionic conductivity (10 −3 S cm −1 at 1000 K) at the intermediate temperature as compared with commercially used electrolytes [11]. During the past decades, Gd 2 Zr 2 O 7 doped with different cations has been widely investigated as potential electrolyte materials for intermediate temperature SOFCs [12][13][14][15][16][17][18]. (Gd 0.5 Nd 0.5 ) 2 Zr 2 O 7 exhibited a significant enhancement in ionic conductivity at 622-696 K as compared with pure Gd 2 Zr 2 O 7 [12].…”

Section: Introductionmentioning

confidence: 99%

The influence of pentavalent Nb substitution for Zr on electrical property of oxide-ion conductor Gd2Zr2O7

Xia

Gao

Liu

et al. 2010

Electrochimica Acta

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“…Currently, 8 mol-% Y 2 O 3 -ZrO 2 (YSZ) is used as a solid electrolyte in conventional SOFCs, while anode and cathode materials are Ni-YSZ cermets and La 1-x Sr x MnO 3 oxide, respectively [4][5][6]. However, when SOFCs are operated at high temperatures for a long time, unwanted reactions at the cathode/electrolyte interface will generate insulating zirconates (La 2 Zr 2 O 7 and SrZrO 3 ), which may have a detrimental effect on SOFCs performance [7,8]. Pyrochlore oxides of A 2 Zr 2 O 7 -type (A = lanthanide) structure show excellent electrical properties owing to high compositional diversity, structural flexibility and intrinsic concentration of oxygen vacancies [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

“…The dual Yb+Gd intermix doping causes a distinctly enhanced total conductivity as compared to unmodified Nd 2 ) [7,8,[18][19][20]. Díaz-Guillén et al [7,8] found that electrical conductivity of Gd 2-x La x Zr 2 O 7 (0 ≤ x ≤ 1.0) ceramics was almost La-content independent in the temperature range of 773-1,023 K. A significant increase in electrical conductivity is found by suitable substitution of isovalent rare-earth cations like Nd at the Gd site in Gd 2 Zr 2 O 7 from 622 to 696 K [18]. For (Nd 1-x Yb x ) 2 Zr 2 O 7 (0 ≤ x ≤ 1.0) ceramics, electrical conductivity of pyrochlore-type materials is clearly higher than that of defect fluorite-type materials in the temperature range of 723-1,173 K [19].…”

Section: Introductionmentioning

confidence: 99%

Improvement of Electrical Conductivity of Trivalent Rare‐earth Cation‐doped Neodymium Zirconate by Co‐doping Gadolinium and Ytterbium

2010

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Pyrochlore oxides of A2Zr2O7, where A represents trivalent rare‐earth elements, have a high electrical conductivity, which makes them suitable for applications as high‐temperature solid electrolytes. The influence of Gd and Yb cations co‐doping at the Nd site on structure and electrical conductivity of a pyrochlore oxide Nd2Zr2O7 is investigated using X‐ray diffraction and impedance spectra measurements. Different zirconate ceramics of Nd2Zr2O7, Nd1.8Gd0.2Zr2O7, Nd1.8Gd0.1Yb0.1Zr2O7, Nd1.4Gd0.6Zr2O7 and Nd1.4Gd0.3Yb0.3Zr2O7 are prepared by pressureless‐sintering method at 1,973 K for 10 h in air. Nd2Zr2O7 doped with Gd and Yb cations at the Nd site exhibit a single phase of pyrochlore‐type structure. The measured values of the total conductivity obey the Arrhenius relation. Nd2Zr2O7 and its doped zirconate ceramics are oxide‐ion conductors in the oxygen partial pressure range of 1.0 × 10–4 to 1.0 atm at all test temperature levels. The total conductivity increases with reducing average ionic radii of A‐site rare‐earth cations. The dual Yb+Gd intermix doping causes a distinctly enhanced total conductivity as compared to unmodified Nd2Zr2O7 and singly Gd‐doped zirconate ceramics. The highest total conductivity value obtained in this work is 1.02 × 10–2 S cm × 1 at 1,173 K for Nd1.4Gd0.3Yb0.3Zr2O7 ceramic.

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The effect of homovalent A-site substitutions on the ionic conductivity of pyrochlore-type Gd2Zr2O7

Cited by 107 publications

References 23 publications

Microstructure controls in Gadolinium Zirconate/YSZ double layers and their properties

Microstructure controls in Gadolinium Zirconate/YSZ double layers and their properties

The influence of pentavalent Nb substitution for Zr on electrical property of oxide-ion conductor Gd2Zr2O7

Improvement of Electrical Conductivity of Trivalent Rare‐earth Cation‐doped Neodymium Zirconate by Co‐doping Gadolinium and Ytterbium

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