Low temperature synthesis of nanocrystalline proton conducting BaZr0.8Y0.2O3−δ by sol–gel method

Cervera, Rinlee Butch M.; Oyama, Yukiko; Yamaguchi, Shu

doi:10.1016/j.ssi.2007.01.010

Cited by 51 publications

(27 citation statements)

References 26 publications

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“…19). Several approaches have been reported to tackle the challenge of processing dense BZY electrolyte membranes: in addition to the preparation of BCY-BZY solid solutions to compromise between the two materials properties 14,15,20 , the synthesis of ultrafine BZY powders allowed reduction of the sintering temperature while keeping the grain size small [21][22][23] , and the use of extreme sintering temperatures 24 and of sintering aids 25,26 led to full densification and grain growth but did not improve BZY conductivity owing to a change in the materials stoichiometry. A significant improvement in conductivity has been reported recently for BZY pellets with a grain size larger than 1 µm, fabricated according to an improved sintering protocol without using sintering aids 27 .…”

Section: R Educing the Sofc Operating Temperature In The Intermediatementioning

confidence: 99%

High proton conduction in grain-boundary-free yttrium-doped barium zirconate films grown by pulsed laser deposition

et al. 2010

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Reducing the operating temperature in the 500-750 • C, is one of the major targets in present SOFC research 1,2 , and it is also a requisite for the development of miniaturized SOFCs for portable power supply 3,4 . Improving the electrolyte performance for intermediate-temperature operation can be achieved by reducing the electrolyte thickness 5,6 , and by using alternative materials to yttria-stabilized zirconia with a larger ionic conductivity in the intermediate temperature range 7 . With respect to the oxygen-ion conductors conventionally used in SOFCs, electrolytes based on high-temperature proton conductors (HTPCs) take advantage of their lower activation energy for charge transport 8 and of water formation at the cathode side 9,10 , thereby resulting in suitable conductivity in the intermediate temperature range and avoiding fuel dilution with water.Among HTPCs, Y-doped barium cerate (BCY) electrolytes have shown rather high protonic conductivity (10 −2 S cm −1 at 600 • C; ref. 11), although BCY strongly reacts with CO 2 (ref. 12) and water vapour 13 , hindering technological applications. On the other hand, despite a very good chemical stability of Y-doped barium zirconate (BZY) under fuel-cell operating environments, the total proton conductivity of BZY sintered pellets is generally significantly lower (about 10 −3 S cm −1 at 600 ; refs 14,15). This is due to the poor sinterability of BZY (ref. 16), together with the poor conducting properties of BZY grain boundary regions 17 . Scattered conductivity values for BZY samples are reported in the literature, and mostly depend on the processing parameters (see Supplementary Fig. S1).However, about a decade ago electrochemical impedance spectroscopy (EIS) measurements at temperatures below 200• C, that is, in the temperature range where impedance spectra allowed separation of the bulk and the grain boundary contribution,

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Section: R Educing the Sofc Operating Temperature In The Intermediatementioning

confidence: 99%

High proton conduction in grain-boundary-free yttrium-doped barium zirconate films grown by pulsed laser deposition

et al. 2010

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“…at low calcination temperature [16,17,[22][23][24][25]. Figure 5 shows a FE-SEM micrograph of the BZY powder synthesised using EG as a solvent and a ratio of CA to TM set at 2:1, calcined at 1,100°C for 5 h. Agglomerates of BZY nanoparticles were observed.…”

Section: Powder Synthesismentioning

confidence: 99%

“…Among those compounds, doped barium cerate [14,15] and doped barium zirconate [16][17][18] have been widely investigated as HTPC electrolytes. Yttrium-doped barium cerate (BCY) shows the best performance in terms of fuel cell power density at the lowest temperatures, but it reacts with CO 2 , SO 2 and water vapour [19,20].…”

Section: Introductionmentioning

confidence: 99%

Design of BaZr_0.8Y_0.2O_3–δ Protonic Conductor to Improve the Electrochemical Performance in Intermediate Temperature Solid Oxide Fuel Cells (IT‐SOFCs)

et al. 2008

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BaZr0.8Y0.2O3–δ, (BZY), a protonic conductor candidate as an electrolyte for intermediate temperature (500–700 °C) solid oxide fuel cells (IT‐SOFCs), was prepared using a sol–gel technique to control stoichiometry and microstructural properties. Several synthetic parameters were investigated: the metal cation precursors were dissolved in two solvents (water and ethylene glycol), and different molar ratios of citric acid with respect to the total metal content were used. A single phase was obtained at a temperature as low as 1,100 °C. The powders were sintered between 1,450 and 1,600 °C. The phase composition of the resulting specimens was investigated using X‐ray diffraction (XRD) analysis. Microstructural characterisation was performed using field emission scanning electron microscopy (FE‐SEM). Chemical stability of the BZY oxide was evaluated upon exposure to CO2 for 3 h at 900 °C, and BZY showed no degradation in the testing conditions. Fuel cell polarisation curves on symmetric Pt/BZY/Pt cells of different thicknesses were measured at 500–700 °C. Improvements in the electrochemical performance were obtained using alternative materials for electrodes, such as NiO‐BZY cermet and LSCF (La0.8Sr0.2Co0.8Fe0.2O3), and reducing the thickness of the BZY electrolyte, reaching a maximum value of power density of 7.0 mW cm–2 at 700 °C.

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“…A wide range of soft chemistry techniques have been employed to form barium zirconate based materials such as, coprecipitation [6][7][8], hydrothermal synthesis [9,10], sol-gel techniques [11][12][13][14], thermal decomposition of nitrate [15], spray pyrolysis [16,17] and combustion synthesis [4,12]. However, several disadvantages have been noted with many of these techniques such as, the evaporation of solvents due to nonhomogeneity causing the formation of segregation phases or alteration of stoichiometry due to incomplete precipitation processes [18], expensive chemicals and time consuming processes [11][12][13][14] and the discharge of pollutant gases [4,6,12,15]. Furthermore, the formation of BaCO 3 as an impurity phase on decomposition of organics is a common occurrence in many of these processes which requires additional calcinations steps to remove and may add to compositional inhomogeneity [4,6,12,14,15,18] and efficient method with which to achieve highly reactive, homogeneous, nanopowders.…”

Section: Introductionmentioning

confidence: 99%

Mechanosynthesis of nanopowders of the proton-conducting electrolyte material Ba(Zr, Y)O3−δ

Antunes

Brandão

Figueiredo

et al. 2009

Journal of Solid State Chemistry

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Low temperature synthesis of nanocrystalline proton conducting BaZr0.8Y0.2O3−δ by sol–gel method

Cited by 51 publications

References 26 publications

High proton conduction in grain-boundary-free yttrium-doped barium zirconate films grown by pulsed laser deposition

High proton conduction in grain-boundary-free yttrium-doped barium zirconate films grown by pulsed laser deposition

Design of BaZr_0.8Y_0.2O_3–δ Protonic Conductor to Improve the Electrochemical Performance in Intermediate Temperature Solid Oxide Fuel Cells (IT‐SOFCs)

Mechanosynthesis of nanopowders of the proton-conducting electrolyte material Ba(Zr, Y)O3−δ

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Low temperature synthesis of nanocrystalline proton conducting BaZr0.8Y0.2O3−δ by sol–gel method

Cited by 51 publications

References 26 publications

High proton conduction in grain-boundary-free yttrium-doped barium zirconate films grown by pulsed laser deposition

High proton conduction in grain-boundary-free yttrium-doped barium zirconate films grown by pulsed laser deposition

Design of BaZr0.8Y0.2O3–δ Protonic Conductor to Improve the Electrochemical Performance in Intermediate Temperature Solid Oxide Fuel Cells (IT‐SOFCs)

Mechanosynthesis of nanopowders of the proton-conducting electrolyte material Ba(Zr, Y)O3−δ

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Design of BaZr_0.8Y_0.2O_3–δ Protonic Conductor to Improve the Electrochemical Performance in Intermediate Temperature Solid Oxide Fuel Cells (IT‐SOFCs)