Chemical stability and proton conductivity of doped BaCeO3–BaZrO3 solid solutions

Ryu, Ki‐Hyun; Haile, Sossina M.

doi:10.1016/s0167-2738(99)00196-4

Cited by 663 publications

(475 citation statements)

References 19 publications

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“…The relative density of (covered) sintered pellets of BYZ prepared by the careful procedures outlined above rose from 93% to 99% (with respect to the density of undoped barium zirconate, 6.21 g/cm 3 ) with increasing sintering time (Fig. 2).…”

Section: Resultsmentioning

confidence: 95%

“…Doped perovskites, such as barium cerate (BaCeO 3 ), strontium cerate (SrCeO 3 ), and barium zirconate (BaZrO 3 ), have been widely studied in recent years as proton conducting electrolytes for a variety of electrochemical devices including fuel cells. Among the fuel cell studies, the most impressive results are arguably those of Iguchi et al 1 Using yttrium-doped barium cerate as an electrolyte, these authors demonstrated power densities of 570 mW/cm 2 at 430°C and 780 mW/cm 2 at 510°C under air/hydrogen conditions.…”

Section: Introductionmentioning

confidence: 99%

“…Among the fuel cell studies, the most impressive results are arguably those of Iguchi et al 1 Using yttrium-doped barium cerate as an electrolyte, these authors demonstrated power densities of 570 mW/cm 2 at 430°C and 780 mW/cm 2 at 510°C under air/hydrogen conditions. To circumvent the detrimental reaction of barium cerate with CO 2 , which would otherwise result in the formation of BaCO 3 and CeO 2 , the authors protected the thin electrolyte by depositing it onto a dense layer of palladium foil, a wellknown hydrogen separation material. In contrast to barium cerate, barium zirconate, which exhibits proton conduction by a similar mechanism, 2 is known to be stable in CO 2 -containing atmospheres.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast to barium cerate, barium zirconate, which exhibits proton conduction by a similar mechanism, 2 is known to be stable in CO 2 -containing atmospheres. 3 Thus, fuel cells based on this electrolyte would not require elaborate solutions for ensuring cell longevity. However, the conductivity of doped barium zirconate as reported from 12 independent groups (Table I 4-15 ) varies widely, from a low of ∼1 × 10 −6 to a high of 1 × 10 −2 S/cm at 600°C, introducing major challenges for its implementation in any real device and raising fundamental questions regarding the proton transport mechanism.…”

Section: Introductionmentioning

confidence: 99%

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Processing of yttrium-doped barium zirconate for high proton conductivity

2007

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The factors governing the transport properties of yttrium-doped barium zirconate (BYZ) have been explored, with the aim of attaining reproducible proton conductivity in well-densified samples. It was found that a small initial particle size (50-100 nm) and high-temperature sintering (1600°C) in the presence of excess barium were essential. By this procedure, BaZr 0.8 Y 0.2 O 3−␦ with 93% to 99% theoretical density and total (bulk plus grain boundary) conductivity of 7.9 × 10 −3 S/cm at 600°C [as measured by alternating current (ac) impedance spectroscopy under humidified nitrogen] could be reliably prepared. Samples sintered in the absence of excess barium displayed yttria-like precipitates and a bulk conductivity that was reduced by more than 2 orders of magnitude.

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Section: Resultsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Processing of yttrium-doped barium zirconate for high proton conductivity

2007

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“…While researchers have examined the effects of A-site doping and stoichiometry on increasing the stability of barium cerates while preserving high conductivity [72], there are very few reports on the possibilities of using mixed perovskites as proton conductors for H 2 separation. Furthermore, recent work comparing polycrystalline conductors to single crystal conductors has demonstrated that the grain boundary interface plays a significant role in controlling the total conductivity [73].…”

Section: Perovskitesmentioning

confidence: 99%

Review of proton conductors for hydrogen separation

Phair

Badwal

2006

Ionics

223

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There is a global push to develop a range of hydrogen technologies for timely adoption of the hydrogen economy. This is critical in view of the depleting oil reserves and looming transport fuel shortage, global warming, and increasing pollution. Molecular hydrogen (H 2 ) can be generated by a number of renewable and fossil-fuel-based resources. However, given the high cost of H 2 generation by renewable energy at this stage, fossil or carbon fuels are likely to meet the short-to medium-term demand for hydrogen. In view of this, effective technologies are required for the separation of H 2 from a gas feed (by-products of coal or bio-mass gasification plants, or gases from fossil fuel partial oxidation or reforming) consisting mainly of H 2 and CO 2 with small quantities of other gases such as CH 4 , CO, H 2 O, and traces of sulphur compounds. Several technologies are under development for hydrogen separation. One such technology is based on ion transport membranes, which conduct protons or both protons and electrons. Although these materials have been considered for other applications, such as gas sensors, fuel cells and water electrolysis, the interest in their use as gas separation membranes has developed only recently. In this paper, various classes of proton-conducting materials have been reviewed with specific emphasis on their potential use as H 2 separation membranes in the industrial processes of coal gasification, natural gas reforming, methanol reforming and the watergas shift (WGS) reaction. Key material requirements for their use in these applications have been discussed.

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