Grain size dependence of electrical properties of Gd-doped ceria

Hara, Akihiro; Hirata, Yoshihiro; Sameshima, Soichiro; Matsunaga, Naoki; Horita, Teruhisa

doi:10.2109/jcersj2.116.291

Cited by 30 publications

(23 citation statements)

References 13 publications

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“…While the ratio was not influenced by the temperature, the ratio increased with decreasing the grain size. This result was agreement with that of the literature [1] which reported that the ratio was 0.3 and 0.5 for GDC samples with a grain size of 510 and 290 nm, respectively.…”

Section: Ac Impedancesupporting

confidence: 93%

“…Figures 3 and 4 show the complex impedance plots for the GDC samples sintered using the SPS process and the normal sintering process, respectively. The shape of the obtained complex impedance plot was similar to that reported in the literature [1]. That is, (1) the complex impedance plot obtained below 350 ºC showed three , k: constant).…”

Section: Measurement Of Electrical Conductivitysupporting

confidence: 86%

“…Recently, the influences of grain size on the material properties of ceria have been reported. The ionic conductivity [1,2] and the lattice parameter [3] for the doped or undoped ceria varied with the grain size. The variation of the ionic conductivity with the grain size was demonstrated based on the curvature of grain in a literature [4].…”

Section: Introductionmentioning

confidence: 99%

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Electrical conductivity of Gd-doped ceria with nano-sized grain

Shimonosono

Sakka

Hirata

2009

Trans. Mat. Res. Soc. Japan

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Ce 0.8 Gd 0.2 O 1.9 (Gd-doped ceria, GDC) powder synthesized by glycine-nitrate combustion process was densified to 96 % of theoretical density at 900 ºC for 5 min using spark plasma sintering (SPS) process. The grain size of the GDC sintered using the SPS process was about 20 nm. The electrical conductivity of GDC sintered using SPS process was obtained from the AC impedance measured at a frequency range of 42 Hz to 5 MHz, and was compared with that of GDC sintered at 1200 ºC for 4 h in air using normal sintering process with a grain size of 150 nm. The electrical conductivity of GDC sintered using SPS process was one order of magnitude lower than that of GDC sintered using normal sintering process. The contributions of the bulk and the grain boundary to the total electrical conductivity were distinguished by analyzing the AC impedance of the GDC sample. The conductivity of the bulk slightly decreased with decreasing the grain size, while the conductivity of grain boundary increased with decreasing the grain size.

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Section: Ac Impedancesupporting

confidence: 93%

Section: Measurement Of Electrical Conductivitysupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

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Electrical conductivity of Gd-doped ceria with nano-sized grain

Shimonosono

Sakka

Hirata

2009

Trans. Mat. Res. Soc. Japan

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“…The calculation is based on a single grain-boundary thickness of 3 nm and a relative dielectric constant of 1.72. 14) These results suggest that the arc in the low-frequency range represents the charge transfer characteristics at the electrodes. The ohmic resistance increased from 1.95 ³ in the case of no added GDC to 5.3 ³ in the cases of electrodes with 10 and 50 mass % GDC.…”

Section: ¹mentioning

confidence: 88%

Influence of cathode on electric power of solid oxide fuel cells

Furukawa

Sameshima

Hirata

et al. 2014

J. Ceram. Soc. Japan

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The electric power produced by a Ni/Gd-doped ceria (GDC) anode-supported solid oxide fuel cell with a GDC electrolyte (40¯m thick) and a (La 0.8 Sr 0.2 )(Co 0.8 Fe 0.2 )O 3 (LSCF) cathode using a 3 vol % H 2 O-containing H 2 fuel was measured. The addition of 10 or 50 mass % GDC powder (Ce 0.8 Gd 0.2 O 1.9 ) to the LSCF cathode reduced the power density from 320 mW/cm 2 in the case of no GDC to 137 or 122 mW/cm 2 , respectively. The added GDC particles blocked the conduction path between LSFC particles. The as-prepared LSCF powder was ball-milled using ¡-Al 2 O 3 balls. The milling decreased the charge transfer resistance at the cathode and increased the power density of the fuel cell.©2014 The Ceramic Society of Japan. All rights reserved.Key-words : Solid oxide fuel cell, Cathode, Power density, Overpotential, Gd-doped ceria [Received September 2, 2013; Accepted December 24, 2013] Solid oxide fuel cells (SOFCs) are attractive electric power generators because of their high energy conversion efficiency, their ability to utilize a variety of fuels, the possibility of utilizing their high-temperature exhaust gas, and their leakage-proof property because of the use of solid electrolytes. A conventional SOFC with a yttria-stabilized zirconia (YSZ) electrolyte is typically operated at approximately 800°C to enhance the diffusion of oxide ions formed at its cathode. Gd-doped ceria (GDC) and Sm-doped ceria are also candidate electrolytes for SOFCs because they exhibit greater oxide-ion conductivity than YSZ. Decreasing the charge transfer resistance of electrochemical reactions at the electrodes (especially the cathode) is another strategy to increase the electric power generated by SOFCs. At the cathode, the diffusing oxygen molecules adsorb onto the cathode material and dissociate into oxygen atoms. The oxygen atoms react with electrons to form oxide ions at the triple-phase boundary (TPB, the gascathodeelectrolyte interface). The cathode material is a mixed conductor of electrons and oxide ions. A cathode composed of a mixture of GDC and LSCF is expected to exhibit enhanced electrocatalytic activity for the reaction of O 2 and electrons. Shah et al.3) measured the performance of a cathode fabricated by impregnating a porous GDC scaffold with a mixed nitrate solution of LSCF precursor. The formed nanometer-scale (50 nm) LSCF network reduced the charge transfer resistance at an operating temperature of 650°C over 300 h. Liu et al. 4) prepared an LSCFGDC composite cathode by impregnating the porous GDC scaffold with a mixed nitrate solution of La, Sr, Co, and Fe and measured the degradation in the composite cathode performance at 750°C in air over 500 h. The GDC scaffold method was effective in expanding the triple-phase boundary (GDC electrolyteLSCF cathodeO 2 gas). However, the charge transfer resistance and ohmic resistance increased because of grain growth of the LSCF nanoparticles. The authors suppressed the grain growth of LSCF by adding MgO and LaNi 0.6 Fe 0.4 O 3 particles.In this study, a GDCLSCF mixed cat...

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“…conductivity at the higher temperature with decreasing grain size may be attributed to the increase in the fraction of the low conductivity grain boundary. 23) On the other hand, the increase in electrical conductivity at the lower temperature with decreasing grain size may be due to the increase in the fraction of the high conductivity cubic phase. This suggestion comes from the results of the X-ray diffraction measurement which indicated the cubic phase for the ScSZ with a smallest grain size fabricated by SPS process, and the thermal expansion measurement which showed the hysteresis curve due to the phase transition for the ScSZ with larger grain size heated at 1300 or 1500°C.…”

Section: Introductionmentioning

confidence: 99%

Effect of grain size on electrical properties of scandia-stabilized zirconia

Shimonosono

Kimura

Sakka

2010

J. Ceram. Soc. Japan

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10 mol % Sc 2 O 3 -stabilized ZrO 2 (10ScSZ) was sintered by several processes including spark plasma sintering, milliwave sintering and conventional sintering. The electrical conductivity of the sintered 10ScSZ samples was obtained by AC impedance spectra, and compared with grain size and the crystal phase. As average grain size decreased, the electrical conductivities decreased and increased at temperatures higher and lower than the phase transition point, respectively. These trends suggested that the fraction of a low conductivity rhombohedral phase increases with increasing grain size at a temperature lower than the phase transition point, and that the total thickness of the grain boundary affects the electrical conductivity at a temperature higher than the phase transition point.

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Grain size dependence of electrical properties of Gd-doped ceria

Cited by 30 publications

References 13 publications

Electrical conductivity of Gd-doped ceria with nano-sized grain

Electrical conductivity of Gd-doped ceria with nano-sized grain

Influence of cathode on electric power of solid oxide fuel cells

Effect of grain size on electrical properties of scandia-stabilized zirconia

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