Conductivity recovery by redox cycling of yttrium doped barium zirconate proton conductors and exsolution of Ni-based sintering additives

Nasani, Narendar; Pukazhselvan, D.; Kovalevsky, Andrei V.; Shaula, A.L.; Fagg, Duncan P.

doi:10.1016/j.jpowsour.2016.11.036

Cited by 37 publications

(33 citation statements)

References 46 publications

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“…Figure 5. Furthermore, partial exclusion of nickelw as reported by annealing NiO-dopedB aZr 0.85 Y 0.15 O 3Àd (grain size % 3 mm) at ah ighert emperature of 750 [37] and 800 8C [51] for 15 and 24 h, respectively.T herefore, nickel can be excluded from barium zirconate at such mild temperatures,b ut the process is kinetically slow.T he complete removal of nickel might require ah igher temperature or al onger time, for example, 1400 8C To tal conductivity at 600 8CofB ZY20 containingv arious amounts of NiO, CuO,o rZnO measured in wet O 2 (1st cycle), wet H 2 (2ndcycle),and wet O 2 (3rd cycle)i ns equence.The partial pressure of water vaporw as 0.05 atm. All the samplesw ere prepared by sintering at 1500 8CinO 2 for 10 h. The datao f pure BZY20 sintered at 1600 8Ci nO 2 for 24 hisa lso plottedf or comparison.…”

Section: Transport Numbersmentioning

confidence: 93%

“…Although some researchers have reported degradationo ft he electrical conductivity after the addition of ZnO [12,[17][18][19] or NiO, [35][36][37] there is insufficient concern among researchers on the negative effect of sintering additives on the electrical properties. Although some researchers have reported degradationo ft he electrical conductivity after the addition of ZnO [12,[17][18][19] or NiO, [35][36][37] there is insufficient concern among researchers on the negative effect of sintering additives on the electrical properties.…”

Section: Introductionmentioning

confidence: 99%

“…currentlyt he mainstream methods for the preparation of BZY electrolyte-based fuel cells. Although some researchers have reported degradationo ft he electrical conductivity after the addition of ZnO [12,[17][18][19] or NiO, [35][36][37] there is insufficient concern among researchers on the negative effect of sintering additives on the electrical properties. To the best of our knowledge,t he effect of the addition of these oxideso nt he transport properties of BZY20, which is another very vital factor that restricts the fuel cell performance, has not been investigated.…”

Section: Introductionmentioning

confidence: 99%

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Detrimental Effect of Sintering Additives on Conducting Ceramics: Yttrium‐Doped Barium Zirconate

et al. 2018

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Y-doped BaZrO (BZY) is currently the most promising proton-conductive ceramic-type electrolyte for application in electrochemical devices, including fuel cells and electrolyzer cells. However, owing to its refractory nature, sintering additives, such as NiO, CuO, or ZnO are commonly added to reduce its high sintering temperature from 1600 °C to approximately 1400 °C. Even without deliberately adding a sintering additive, the NiO anode substrate provides another source of the sintering additive; during the co-sintering process, NiO diffuses from the anode into the BZY electrolyte layer. In this work, a systematic study of the effect of NiO, CuO, and ZnO on the electroconductive properties of BaZr Y O (BZY20) is conducted. The results revealed that the addition of NiO, CuO, or ZnO into BZY20 not only degraded the electrical conductivity but also resulted in enhancement of the hole conduction. Removal of these sintering additives can be realized by post-annealing in hydrogen at a mild temperature of 700 °C, but it is kinetically very slow. Therefore, the addition of NiO, CuO, and ZnO is detrimental to the electroconductive properties of BZY20, and significantly restrict its application as an electrolyte. The development of new sintering additives, new anode catalysts, or new methods for preparing BZY electrolyte-based cells is urgently needed.

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Section: Transport Numbersmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Detrimental Effect of Sintering Additives on Conducting Ceramics: Yttrium‐Doped Barium Zirconate

et al. 2018

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“…The proposed mechanism for the solid state reactive sintering is described shortly 31 : Upon decomposition of the barium carbonate precursor, BaO and NiO begin to react at about 1100°C, producing a liquid phase. 31,[48][49][50] In that case, Ni enters the BZY lattice in oxidizing atmosphere and exsolves in reducing conditions. Because of their smaller size (compared to Y 3+ ), Ni 2+ ions first diffuse into the BaZrO 3 grains, with charge compensation being Atmosphere was dry 4% H 2 , balance Ar, identical to above BZY and BZCY experimental conditions.…”

Section: Sample Preparation Using Niomentioning

confidence: 99%

“…When the temperature increases, the BaZrO 3 phase starts to form. [48][49][50] It is important to highlight this difference in mechanism, to exclude the possible effect of NiO exsolution as a factor influencing the lattice parameter in the previously described experiments. Data collected upon cooling.…”

Section: Sample Preparation Using Niomentioning

confidence: 99%

Chemical expansion in BaZr_0.9−xCe_xY_0.1O_3−δ(x= 0 and 0.2) upon hydration determined by high‐temperature X‐ray diffraction

et al. 2017

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Understanding the strain from chemical expansion of proton‐conducting ceramics is crucial to prevent their failure under operating conditions. BZY10 (BaZr0.9Y0.1O3−δ) and BZCY72 (BaZr0.7Ce0.2Y0.1O3−δ) were studied using high‐temperature X‐ray diffraction (HT‐XRD) in moist and dry reducing atmosphere in order to prevent the competition with the oxidation reaction. Both powder and dense specimens were investigated and similar lattice parameters were obtained, demonstrating that the data were recorded on samples that were in equilibrium with the surrounding environment. Two sets of experiments were performed. In the first one, the sample was hydrated in situ in the XRD chamber at high temperature and diffraction data were collected during cooling. For the second set, the samples were pre‐hydrated ex situ in an autoclave and the XRD patterns were recorded during heating under dry conditions. As expected, lattice parameters were larger for the hydrated samples, due to hydration chemical expansion. The chemical expansion was also found to be larger with the presence of Ce. Finally, larger concentrations of protonic defects were present in the lattice of the ex situ pre‐hydrated samples compared with the in situ hydrated samples.

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Insight into Grain and Grain‐Boundary Transport of Proton‐Conducting Ceramics: A Case Report of BaSn_0.8Y_0.2O_3−δ

Starostina,

Starostin,

Akopian

et al. 2023

Adv Funct Materials

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Proton‐conducting ceramic electrolytes offer great potential for the development of low‐ and intermediate‐temperature solid oxide electrochemical devices, e.g., fuel cells and electrolyzers. However, the electrolyte constitutes the main bottleneck in such devices, especially at reduced temperatures, determining their overall performance and efficiency. Herein, for the first time the low‐temperature transport properties of BaSn0.8Y0.2O3−δ as a representative of proton‐conducting materials are investigated. The attention is focussed on grain and grain boundary conductivity of this ceramic material over a wide range of experimental conditions, including temperatures of 400–550 °C, oxygen partial pressures of 10−22–0.21 atm, and water vapor partial pressures of 10−5‐0.03 atm. After analyzing BaSn0.8Y0.2O3−δ with electrochemical impedance spectroscopy under these experimental conditions, the distribution of relaxation times is leveraged to evaluate the resistance, capacitance, and frequency of each electrolytic process. The data show that the BSY ceramic, prepared with CuO as a sintering additive, is characterized by three distinct processes: one is due to grain response, and two others are understood to be related to the responses of the pure and CuO‐covered grain boundaries. Therefore, this work opens a new path for the analysis of ionic, including protonic, transport along grains and grain boundaries.

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Conductivity recovery by redox cycling of yttrium doped barium zirconate proton conductors and exsolution of Ni-based sintering additives

Cited by 37 publications

References 46 publications

Detrimental Effect of Sintering Additives on Conducting Ceramics: Yttrium‐Doped Barium Zirconate

Detrimental Effect of Sintering Additives on Conducting Ceramics: Yttrium‐Doped Barium Zirconate

Chemical expansion in BaZr_0.9−xCe_xY_0.1O_3−δ(x= 0 and 0.2) upon hydration determined by high‐temperature X‐ray diffraction

Insight into Grain and Grain‐Boundary Transport of Proton‐Conducting Ceramics: A Case Report of BaSn_0.8Y_0.2O_3−δ

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Conductivity recovery by redox cycling of yttrium doped barium zirconate proton conductors and exsolution of Ni-based sintering additives

Cited by 37 publications

References 46 publications

Detrimental Effect of Sintering Additives on Conducting Ceramics: Yttrium‐Doped Barium Zirconate

Detrimental Effect of Sintering Additives on Conducting Ceramics: Yttrium‐Doped Barium Zirconate

Chemical expansion in BaZr0.9−xCexY0.1O3−δ(x= 0 and 0.2) upon hydration determined by high‐temperature X‐ray diffraction

Insight into Grain and Grain‐Boundary Transport of Proton‐Conducting Ceramics: A Case Report of BaSn0.8Y0.2O3−δ

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Chemical expansion in BaZr_0.9−xCe_xY_0.1O_3−δ(x= 0 and 0.2) upon hydration determined by high‐temperature X‐ray diffraction

Insight into Grain and Grain‐Boundary Transport of Proton‐Conducting Ceramics: A Case Report of BaSn_0.8Y_0.2O_3−δ