A comprehensive understanding of structure and site occupancy of Y in Y-doped BaZrO3

Han, Donglin; Kishida, Kyosuke; Shinoda, Kōzō; Inui, Haruyuki; Uda, Tetsuya

doi:10.1039/c2ta00675h

Cited by 72 publications

(72 citation statements)

References 24 publications

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“…Only peaks belonging to a single cubic perovskite phase (BaZrO 3 , JCPDS # 00‐006‐0399) were observed with the Sr content varying from 0 to 0.40. Then, the lattice constants were determined by simulating the XRD patterns using a single cubic perovskite ( Pm

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m ) structure model with the Rietveld refinement, and plotted against the Sr content in Figure . It is clear that the lattice constant decreases almost linearly with the increasing Sr content, following the Vegard's law due to the relatively smaller twelve‐coordinated radius of divalent Sr cations (1.44 Å) than that of Ba cations (1.61 Å) .…”

Section: Resultsmentioning

confidence: 99%

Transport properties of proton conductive Y‐doped BaHfO₃ and Ca or Sr‐substituted Y‐doped BaZrO₃

2018

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An electrolyte in fuel cells requires not only high ionic conductivity, but also high transport numbers of ionic conduction. Although Y‐doped BaZrO3 is regarded to be the most promising candidate as the electrolyte in protonic ceramic fuel cells (PCFCs), significant hole conduction generates in wet oxygen at high temperatures. With the aim to increase the transport number of ionic conduction, in this work, Sr and Ca were introduced to partially substitute Ba in BaZr0.8Y0.2O3‐δ. The results revealed that a single cubic perovskite phase was obtained for Ba0.95Ca0.05Zr0.8Y0.2O3‐δ and Ba1‐xSrxZr0.8Y0.2O3‐δ (x = 0.05, 0.10, 0.15, 0.20 or 0.40). However, replacing Ba with Sr resulted in almost no increase in the transport number of ionic conduction in wet oxygen atmosphere, but drastic decrease in proton conductivity at all replacement levels. In addition, Ba0.95Ca0.05Zr0.8Y0.2O3‐δ shows no meaningful change in the transport number of ionic conduction, compared with BaZr0.8Y0.2O3‐δ. Incorporating Ca or Sr into the Ba‐site of BaZr0.8Y0.2O3‐δ appears to impart no positive influence on electrochemical properties. These interesting results also indicate that the hole conductivity decreases with the decrease in proton conductivity, and will aid to consider the hole conduction mechanism. BaHfO3 doped with 10 and 20 mol% Y was also prepared. A bimodal microstructure was observed for BaHf0.9Y0.1O3‐δ, whereas BaHf0.8Y0.2O3‐δ shows uniform grain size after sintering at 1600°C for 24 hours. The transport numbers of ionic conduction and bulk conductivity in such Y‐doped BaHfO3 samples are close to those of BaZrO3 doped with the same amount of Y.

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Section: Resultsmentioning

confidence: 99%

Transport properties of proton conductive Y‐doped BaHfO₃ and Ca or Sr‐substituted Y‐doped BaZrO₃

2018

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“…The lattice constantsw ere determined by Rietveld refinement using ac ubic perovskite model (Pm3m), [46,47] and tend to decrease with increasing amount of NiO, CuO, or ZnO, as shown in Figure4.F urthermore, the lat- Table 1. The lattice constantsw ere determined by Rietveld refinement using ac ubic perovskite model (Pm3m), [46,47] and tend to decrease with increasing amount of NiO, CuO, or ZnO, as shown in Figure4.F urthermore, the lat- Table 1.…”

Section: Hydration Behaviormentioning

confidence: 99%

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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“…[8][9][10][11][12][13][14] And 1300 C is a typical synthesizing temperature for using solid state reaction method to synthesize BZY20. [26][27][28][29][30][31][32] So, a detailed analysis of the as-synthesized BZY20 aer heating at 1300 C is highly necessary.…”

Section: Stem-eds Analysis On Bzy20 Nally Heat-treated At 1300 and 1mentioning

confidence: 99%

“…Such improvement in compositional homogeneity agrees well with our previous work. 27 The difference in compositional homogeneity is a quite interesting and important factor.…”

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Strategy to improve phase compatibility between proton conductive BaZr_0.8Y_0.2O_3−δ and nickel oxide

et al. 2016

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BaZr 0.8 Y 0.2 O 3Àd (BZY20) is a promising candidate as an electrolyte in protonic ceramic fuel cells (PCFCs), and nickel (Ni) is known to show good electrode properties for the anode reaction. However, their compatibility seems to be questionable, since during the co-sintering process for cell fabrication, a second phase of BaY 2 NiO 5 formed due to a reaction between BZY20 and NiO. The results in this work revealed that BaY 2 NiO 5 was unstable against high temperature (1500 and 1600 C), and could also be reduced in a hydrogen atmosphere at 600 C. The products of these reactions may affect fuel cell performance. A systematic work was then performed to provide fundamental insight into the reactivity between BZY20 and NiO, which was found to be impacted significantly by the compositional homogeneity of the BZY20 powder used for cell fabrication, and also the BaO activity during the cosintering process. It is concluded that improving the compositional homogeneity of BZY20, by elevating the final heating temperature for BZY20 from 1300 to 1600 C in this work, and choosing a proper sintering strategy may improve effectively the phase purity of the cell.

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A comprehensive understanding of structure and site occupancy of Y in Y-doped BaZrO3

Cited by 72 publications

References 24 publications

Transport properties of proton conductive Y‐doped BaHfO₃ and Ca or Sr‐substituted Y‐doped BaZrO₃

Transport properties of proton conductive Y‐doped BaHfO₃ and Ca or Sr‐substituted Y‐doped BaZrO₃

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

Strategy to improve phase compatibility between proton conductive BaZr_0.8Y_0.2O_3−δ and nickel oxide

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A comprehensive understanding of structure and site occupancy of Y in Y-doped BaZrO3

Cited by 72 publications

References 24 publications

Transport properties of proton conductive Y‐doped BaHfO3 and Ca or Sr‐substituted Y‐doped BaZrO3

Transport properties of proton conductive Y‐doped BaHfO3 and Ca or Sr‐substituted Y‐doped BaZrO3

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

Strategy to improve phase compatibility between proton conductive BaZr0.8Y0.2O3−δ and nickel oxide

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Transport properties of proton conductive Y‐doped BaHfO₃ and Ca or Sr‐substituted Y‐doped BaZrO₃

Transport properties of proton conductive Y‐doped BaHfO₃ and Ca or Sr‐substituted Y‐doped BaZrO₃

Strategy to improve phase compatibility between proton conductive BaZr_0.8Y_0.2O_3−δ and nickel oxide