Thermal analyses of yttrium-doped barium zirconate with phosphor pentoxide, boron oxide and zinc oxide addition

Muccillo, R.; Muccillo, E.N.S.; Andrade, T. F.; Oliveira, Orlando

doi:10.1007/s10973-017-6523-x

Cited by 8 publications

(4 citation statements)

References 44 publications

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“…Tao and Irvine [26] added ∼3.4 mol% ZnO to BZY20 and obtained densification of 96% TD after sintering at 1325°C. Muccillo et al [27] added ∼6.8 mol% ZnO to BZY20, and a densification of 98.9% TD was obtained for the sample sintered at 1500°C. In this work, 0.5 mol% ZnO addition was very efficient to promote 95% TD densification after sintering at 1300°C.…”

Section: Resultsmentioning

confidence: 99%

Influence of ZnO addition on microstructure and proton electrical conductivity of BaZr0.8Y0.2O3-δ ceramics

Wendler

Ramos

Souza

2021

PAC

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Sintering aids are widely used to promote densification and grain growth for electrolytes based on yttriumdoped barium zirconate. However, there are some discrepancies in the literature about the influence of these sintering aids on the microstructure development. Some authors consider that ZnO remains on grain boundaries, forming an amorphous phase that promotes sintering, and others proposed that ZnO forms a solid solution with barium zirconate. Even considering different mechanisms, it was proposed that ZnO addition compromised protonic conductivity. In this work BaZr0.8Y0.2O3-? (BZY20) was prepared by conventional oxide mixture (solid state sintering), adding ZnO as sintering aid. We proposed a mechanism for the ZnO actuation on the microstructure development, by the formation of a liquid phase during sintering and formation of a vitreous phase throughout grain boundaries during cooling. This could be the reason for poor protonic conductivity in comparison to the undoped BZY20 electrolytes. The proposed mechanism was established through the scanning electron microscopy analyses and electrical conductivity measurements under several different atmospheres by impedance spectroscopy. High density samples were obtained by using ZnO, but with compromised electrical conductivity compared to the undoped samples.

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Section: Resultsmentioning

confidence: 99%

Influence of ZnO addition on microstructure and proton electrical conductivity of BaZr0.8Y0.2O3-δ ceramics

Wendler

Ramos

Souza

2021

PAC

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“…In the range between 150-900 • C, there was no major weight loss, as indicated by the constant curve, since all the organic compounds were already decomposed/evaporated during the sintering process. Furthermore, thermal testing reveals that no chemical reaction occurred in the IT-SOFC in this temperature range [39].…”

Section: Thermal Analysismentioning

confidence: 89%

Electrochemical Investigations of BaCe0.7-xSmxZr0.2Y0.1O3-δ Sintered at a Low Sintering Temperature as a Perovskite Electrolyte for IT-SOFCs

et al. 2021

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Perovskite materials have gained a lot of interest in solid oxide fuel cell (SOFC) applications owing to their exceptional properties; however, ideal perovskites exhibit proton conduction due to availability of low oxygen vacancies, which limit their application as SOFC electrolytes. In the current project, Sm was doped at the B-site of a BaCe0.7-xSmxZr0.2Y0.1O3-δ perovskite electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFCs). BaCe0.7-xSmxZr0.2Y0.1O3-δ electrolytes were synthesized through a cost-effective coprecipitation method and were sintered at a low sintering temperature. The effects of samarium (Sm) doping on the electrochemical performance of BaCe0.7-xSmxZr0.2Y0.1O3-δ were investigated. X-ray diffraction (XRD) analysis confirmed that the BaCe0.7-xSmxZr0.2Y0.1O3-δ electrolyte material retained the perovskite structure. The secondary phase of Sm2O3 was observed for BaCe0.4Sm0.3Zr0.2Y0.1O3-δ. Scanning electron microscopic (SEM) imaging displayed the dense microstructure for all the compositions, while prominent crystal growth was observed for composition x = 0.3. The formation of the perovskite structure and the presence of the hydroxyl groups of metal oxides for all the compositions were confirmed by Fourier transform infrared spectroscopy (FTIR). An increased symmetrical disturbance was also observed for the increased doping ratio of the Sm. Thermogravimetric analysis (TGA) of all the compositions showed no major weight loss in the SOFC operating temperature range. It was also noted that the conductivity of BaCe0.7-xSmxZr0.2Y0.1O3-δ gradually decreased with the increased contents of the Sm metal. The maximum power density of 390 mW cm−2, and an open-circuit voltage (OCV) of 1.0 V at 600 °C, were obtained, showing that BaCe0.7-xSmxZr0.2Y0.1O3-δ, synthesized by a cost-effective method and sintered at a low temperature, can be used as a proton-conducting electrolyte for IT-SOFCs.

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“…Nonetheless, it has also been demonstrated that increased amounts of Zr negatively impact the total conductivity of these materials, due to an increase in their refractive nature and in their grain growth, which aggravate the problem of resistive grain boundaries. As such, much lower values of total conductivity are, typically, reported for the zirconate materials than for their cerate analogues, even though their bulk protonic conductivities are actually greater [9,[26][27][28][29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Electrochemical Transport Properties of Doped Barium Cerate for Proton Conductivity in Low Humidity Conditions: A Review

Holz¹,

Graça²,

Loureiro³

et al. 2021

Analytical Chemistry - Advancement, Perspectives and Applications

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Proton-conducting perovskites are among the most promising electrolytes for Proton Ceramic Fuel Cells (PCFCs), electrolysers and separation membranes. Particularly, yttrium-doped barium cerate, BaCe1-xYxO3-δ (BCY), shows one of the highest protonic conductivities at intermediate temperatures (σ ∼ 10−3 S cm−1 at 400°C); values that are typically achieved under humidified atmospheres (p H2O ∼ 10−2 atm). However, BCY has commonly been discarded for such applications due to its instability in the presence of water vapour and carbonaceous atmospheres. A recent discovery has shown that BCY10 exhibits pure protonic conductivity under very low humidity contents (∼10−5–10−4 atm), owing to its very high equilibrium constant for hydration. This peculiar characteristic allows this material to retain its functionally as a proton conductor in such conditions, while preventing its decomposition. Hence, this chapter explores the electrochemical properties of the BaCe0.9Y0.1O3-δ (BCY10) composition, comprehensively establishing its limiting operation conditions through defect chemistry and thermodynamic analyses. Moreover, the importance of such conditions is highlighted with respect to potential industrially relevant hydrogenation/de-hydrogenation reactions at low temperatures under low humidity.

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Thermal analyses of yttrium-doped barium zirconate with phosphor pentoxide, boron oxide and zinc oxide addition

Cited by 8 publications

References 44 publications

Influence of ZnO addition on microstructure and proton electrical conductivity of BaZr0.8Y0.2O3-δ ceramics

Influence of ZnO addition on microstructure and proton electrical conductivity of BaZr0.8Y0.2O3-δ ceramics

Electrochemical Investigations of BaCe0.7-xSmxZr0.2Y0.1O3-δ Sintered at a Low Sintering Temperature as a Perovskite Electrolyte for IT-SOFCs

Analysis of the Electrochemical Transport Properties of Doped Barium Cerate for Proton Conductivity in Low Humidity Conditions: A Review

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