Effect of Fe2O3 doping on sintering of yttria-stabilized zirconia

Guo, Fangwei; Xiao, Ping

doi:10.1016/j.jeurceramsoc.2012.07.035

Cited by 101 publications

(59 citation statements)

References 40 publications

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“…Fe 2 O 3 . 9,10 Recently, anode-supported SOFCs with YSZ/GDC bi-layer electrolytes have been produced by co-firing with Fe 2 O 3 sintering aid at 1250…”

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confidence: 99%

Anode-Supported Solid Oxide Fuel Cells Fabricated by Single Step Reduced-Temperature Co-Firing

Wang

Gao

Barnett

2015

J. Electrochem. Soc.

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Anode-supported solid oxide fuel cells (SOFCs) consisting of NiO-Y 0.16 Zr 0.92 O 2-δ (YSZ) anode support layer, NiO-YSZ anode functional layer, YSZ electrolyte and (La 0.8 Sr 0.2 ) 0.98 MnO 3-δ (LSM)-YSZ cathode were successfully fabricated by single-step cofiring at 1250 • C. Cells were prepared by tape casting, with Fe 2 O 3 sintering aid used to obtain a nearly dense YSZ electrolyte. Scanning electron microscope (SEM)-energy dispersive X-ray spectroscopy (EDS) showed no evidence of reactions or interdiffusion between layers during co-firing. The cells yielded area specific resistance of 0.44 cm 2 and a maximum power density of 0.91 W/cm 2 at 800 • C. Impedance spectroscopy measurements showed that the LSM-YSZ cathode polarization resistance was higher for the co-fired cathodes than for a cathode that was fired separately at an optimized temperature of 1175 • C. However, reducing the cell co-firing time decreased cathode polarization resistance and increased cell power output. Analysis of SEM images showed that co-firing caused more sintering and coarsening than in the optimally-fired LSM-YSZ, reducing three-phase boundary density and explaining the increased cathode resistance. Anode-supported solid oxide fuel cells (SOFCs) with yttriastabilized zirconia (YSZ) electrolytes are usually fabricated using at least two high-temperature firing steps: co-firing of the anode and electrolyte followed by application and firing of the cathode.1,2 This is based primarily on differences in desired firing temperatures -the YSZ electrolyte is densified at ∼ 1400• C -whereas cathode materials, typically based on (La 0.8 Sr 0.2 ) 0.98 MnO 3-δ (LSM), are usually fired at 1200 • C. Also, the two-step process reduces possible reactions between cathode and electrolyte during firing. On the other hand, there are a number of reasons why single-step fired SOFCs are desirable. First, it simplifies the process, reducing the processing time and input energy, important given the general need to reduce SOFC cost in order to improve commercial viability.3-7 Second, single-step co-firing is a requirement for fabrication strategies where the entire stack, including cells, gas channels and interconnectors, are fired together.8 Third, it allows the fabrication of cells with a cathode-side mechanical support instead of an anode support.In order to achieve single-step firing, the temperature should be reduced to allow a good cathode microstructure, while still densifying the YSZ electrolyte. YSZ electrolyte densification as low as 1200• C has been demonstrated when utilizing an appropriate sintering aid, e.g. Fe 2 O 3 .9,10 Recently, anode-supported SOFCs with YSZ/GDC bi-layer electrolytes have been produced by co-firing with Fe 2 O 3 sintering aid at 1250• C, but with the cathode added in a second lower-temperature firing step.11 These temperatures are still above the ideal firing temperature for LSM-YSZ cathodes of ∼ 1175• C. 12 Also, the shrinkage that occurs during single-step co-firing will exacerbate cathode densification, further reduci...

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“…Fe 2 O 3 . 9,10 Recently, anode-supported SOFCs with YSZ/GDC bi-layer electrolytes have been produced by co-firing with Fe 2 O 3 sintering aid at 1250…”

mentioning

confidence: 99%

Anode-Supported Solid Oxide Fuel Cells Fabricated by Single Step Reduced-Temperature Co-Firing

Wang

Gao

Barnett

2015

J. Electrochem. Soc.

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“…Ionic conductivity of 3 mol% of YSZZn has highest ionic conductivity with 3.55 X 10 -3 mS cm -1 . Besides that, value of conductivity of 3 mol% of cobat was 3.32 X 10 -4 mS cm - [7]. Furthermore, diffusion coefficient, D increases due to contribute of partially interstitial defect of Fe 3+ .…”

Section: Results Of Dta/tgmentioning

confidence: 87%

“…Yttria stabilized zirconia (YSZ) broadly applies as a typical solid ionic conductor such as electrolyte of solid oxide fuel cell (SOFC) [3] and it was established as an oxide ion conducting ceramic [6][7][8]. Properties of SOFC are low thermal conduction, high ionic conductivity and chemical stability in both oxidizing and reducing atmosphere [7,9].…”

Section: Introductionmentioning

confidence: 99%

Microstructure, Crystal structure and ionic conductivity of 3 mol % (Fe, Mn, Co, Zn) doped 8YSZ

et al. 2016

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Abstract. Effect of 3 mol% of transition elements doped 8YSZ such as YSZZn, YSZFe, YSZCo and YSZMn on the ionic conductivity. SOFCs mostly operate at higher temperature. By substitute with dopants, it can reduce the operating temperature and costs. In this experiment, 3 mol% dopants mixed with 8YSZ and sintered at 1550 °C, hold for two hours. Crystal structure, microstructure, sintering behaviour and ionic conductivity at 300 o C were investigated. XRD demonstrates three phases (cubic, monoclinic and tetragonal) were obtained. It was confirmed that small additions of TMOs (Mn, Fe, Co and Zn) promotes densification, grain growth and ionic conductivity compared to pure 8YSZ. YSZZn obtained the highest ionic conductivity, 3.55 X 10 -3 mS cm -1 at 300 °C.

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“…In addition to solve the elevated cost of the sealing materials and interconnects, as well as the durability of the cells. Some experiments have reported the effect of dopants on the sintering, electrical, microstructure and mechanical properties of YSZ [2][3][4]. The ionic conductivity of YSZ are resulting from oxygen vacancies which depends on the type of dopant element and their amount [5].…”

Section: Introductionmentioning

confidence: 99%

The effect of ZnO addition on the phase transformation, microstructure, and ionic conductivity of 8YSZ ceramics

Banjuraizah

Zabar

2016

MATEC Web Conf.

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Abstract. In this paper the effect of zinc oxide (ZnO) addition on the phase transformation and ionic conductivity of 8 mol % Yttria-stabilised Zirconia (8YSZ) is investigated. Pure 8YSZ and ZnO doped YSZ ceramics are prepared using the solid state reaction method sintered at 1550 o C for 2 hours. The X-ray Diffraction (XRD) results reveal the presence of tetragonal, cubic and monoclinic phase of Zirconium dioxide (ZrO 2 ) for all undoped and doped YSZ sintered samples. The phase stability of tetragonal YSZ was found to be increased with the increase in ZnO addition. Minor fraction of monoclinic phase was found in pure YSZ sintered sample and the amount of monoclinic phase decreased with the increasing amount of Zn after sintering at 1550 o C for 2 hours. The fraction of cubic phase was also found to decrease with the increase in Zn concentration. The highest ionic conductivity of 1.03X10 -3 S cm −1 was obtained at room temperature for samples with 3 mol% ZnO. Pure 8YSZ sintered sample on the other hand, yielded 9.88x10 -4 S cm −1 .

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Effect of Fe2O3 doping on sintering of yttria-stabilized zirconia

Cited by 101 publications

References 40 publications

Anode-Supported Solid Oxide Fuel Cells Fabricated by Single Step Reduced-Temperature Co-Firing

Anode-Supported Solid Oxide Fuel Cells Fabricated by Single Step Reduced-Temperature Co-Firing

Microstructure, Crystal structure and ionic conductivity of 3 mol % (Fe, Mn, Co, Zn) doped 8YSZ

The effect of ZnO addition on the phase transformation, microstructure, and ionic conductivity of 8YSZ ceramics

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