Oxide ion and electron transport properties in lanthanum silicate oxyapatite ceramics

Mineshige, Atsushi; Mieda, Hiroyuki; Manabe, Mitsuaki; Funahashi, Takahiro; Daiko, Yusuke; Yazawa, Tetsuo; Nishi, Mina; Yamaji, Katsuhiko; Horita, Teruhisa; Amezawa, Koji; Yashiro, Keiji; Kawada, Tatsuya; Yoshioka, Hideki

doi:10.1016/j.ssi.2014.04.009

Cited by 13 publications

(5 citation statements)

References 18 publications

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“…Doping Fe on the Si site for LSO oxyapatite signicantly suppresses the formation of the La 2 SiO 5 secondary phase, similar to the effect of the addition of 0.5 mol% FeOg on La 10 (Si 5.8 Al 0.2 )O 26.9 . 38 The added Fe ions might suppress formation of La-rich secondary phases due to additional dissolution of La ions into the oxyapatite phase through the incorporation of Fe ions into the Sisites. The results also indicate that doping A (A ¼ Ba, Sr, and Ca) on the La site for LSFO oxyapatite further prevents the formation of the La 2 SiO 5 secondary phase.…”

Section: Resultsmentioning

confidence: 99%

“…The conductivity and chemical stability were investigated for the La-excess lanthanum silicate oxyapatite with an addition of iron oxide by Mineshige et al [36][37][38][39] It was revealed that Fe had a positive effect on the conductivity and chemical stability of Aldoped lanthanum silicate oxyapatite (La 10 (Si 5.8 Al 0.2 )O 26.9 ) when 0.5 mol% FeOg was added. It was also found that no La 2 SiO 5 and La(OH) 3 secondary phases could be identied in the case of the 0.5 mol% FeOg-added La 10 (Si 5.8 Al 0.2 )O 26.9 , though the content of the ion addition was an extremely low level, which indicates that the addition may suppress the secondary phase formation.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and characterization of lanthanum silicate oxyapatites co-doped with A (A = Ba, Sr, and Ca) and Fe for solid oxide fuel cells

Cao

2014

J. Mater. Chem. A

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The co-doped lanthanum silicate oxyapatites, La 9.5 A 0.5 Si 5.5 Fe 0.5 O 26.5 (A ¼ Ba, Sr, and Ca), are synthesized by the high-temperature solid state reaction process. The phase formation and structure properties of undoped lanthanum silicate oxyapatite (La 9.67 Si 6 O 26.5 , LSO), Fe-doped lanthanum silicate oxyapatite (La 10 Si 5 FeO 26.5 , LSFO) and co-doped lanthanum silicate oxyapatites (La 9.5 A 0.5 Si 5.5 Fe 0.5 O 26.5 , A ¼ Ba, Sr, and Ca) are characterized by X-ray diffraction (XRD) and scanning electron spectroscopy (SEM). The effect of co-doping of A (A ¼ Ba, Sr, Ca) and Fe on the microstructure, sinterability and oxide ion conductivity of lanthanum silicate oxyapatites is investigated in detail. The results show that, as compared to LSO and LSFO oxyapatites, co-doping of A (A ¼ Ba, Sr, and Ca) and Fe significantly benefits the sintering and densification process, and enhances the oxide ion conductivity. For co-doped oxyapatites, the oxide ion conductivities are related to the dopant size, the best properties are obtained for the oxyapatite co-doped with Ca and Fe. The co-doped La 9.5 Ca 0.5 Si 5.5 Fe 0.5 O 26.5 (LCSFO) oxyapatite is a good electrolyte for SOFCs, with an oxide ion conductivity of 1.39 Â 10 À2 S cm À1 at 800 C and a low activation energy of 90.71 kJ mol À1 . The bulk density and oxide ion conductivities of co-doped oxyapatite ceramics increase significantly with the increase of the sintering temperature. The grain bulk and grain boundary resistances of La 9.5 Ba 0.5 Si 5.5 Fe 0.5 O 26.5 (LBSFO), La 9.5 Sr 0.5 Si 5.5 Fe 0.5 O 26.5 (LSSFO) and LCSFO oxyapatite ceramics are significantly smaller than those of LSO and LSFO oxyapatite ceramics sintered under the identical conditions.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of lanthanum silicate oxyapatites co-doped with A (A = Ba, Sr, and Ca) and Fe for solid oxide fuel cells

Cao

2014

J. Mater. Chem. A

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“…Lanthanum silicate oxyapatite (La 9.33+x Si 6 O 26+1.5x ) exhibits higher oxygen ionic conductivity than yttria-stabilized zirconia at temperatures below 700 o C (1)(2)(3)(4)(5)(6), making this material attractive for its potential to decrease the operating temperature of fuel cells. Mineshige et.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, additional components were considered to improve the electrical conductivity. For instance, Al-doping is effective for increasing the electrical conductivity (4); however it is known that a dusting phenomenon occurs when aluminum is doped into the oxyapatite phase (6). It was also reported that the dusting phenomenon could be prevented by doping with a transition metal, e.g.…”

Section: Introductionmentioning

confidence: 99%

“…It was also reported that the dusting phenomenon could be prevented by doping with a transition metal, e.g. Fe or Mn (6), though detailed mechanism of how phase stability changes is still unclear. Understanding the nature of non-doped oxyapatite phase is important to improve the conductivity and phase stability of oxyapatite-based materials.…”

Section: Introductionmentioning

confidence: 99%

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Degradation of Electrical Conductivity in Lanthanum Silicate Oxyapatite

Ishiyama¹,

Maruyama²,

Kishimoto³

et al. 2015

ECS Trans.

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Degradation of electrical conductivity in lanthanum silicate oxyapatite (La 9.33+x Si 6 O 26+1.5x ) was observed at 600~1000 o C. Small particles were detected on the surface of pellets after electrical conductivity measurements for 100~201 h. These particles were identified as La 2 SiO 5 phase using micro-Raman spectroscopy. Lanthanum content in the oxyapatite phase is strongly related to its conductivity, because the excess oxygen is incorporated by charge compensation according to excess lanthanum composition. This study suggests that the decrease in electrical conductivity may be attributed to reduction in electrical charge carriers as a result of the phase degradation of La 2 SiO 5 phase from oxyapatite phase.

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Synthesis and ionic conductivities of M (Mg, Ba, Zr) and Al co-doped apatite-type lanthanum germanate electrolytes for IT-SOFC

Shi

Cai

et al. 2017

J Mater Sci: Mater Electron

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Oxide ion and electron transport properties in lanthanum silicate oxyapatite ceramics

Cited by 13 publications

References 18 publications

Synthesis and characterization of lanthanum silicate oxyapatites co-doped with A (A = Ba, Sr, and Ca) and Fe for solid oxide fuel cells

Synthesis and characterization of lanthanum silicate oxyapatites co-doped with A (A = Ba, Sr, and Ca) and Fe for solid oxide fuel cells

Degradation of Electrical Conductivity in Lanthanum Silicate Oxyapatite

Synthesis and ionic conductivities of M (Mg, Ba, Zr) and Al co-doped apatite-type lanthanum germanate electrolytes for IT-SOFC

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