Oxide ion conductivity in Sr-doped La10Ge6O27 apatite oxide

Arikawa, H.; Nishiguchi, Hiroyasu; Ishihara, Takeshi; Takita, Yusaku

doi:10.1016/s0167-2738(00)00386-6

Cited by 220 publications

(144 citation statements)

References 6 publications

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“…To account for this an additional lorentzian-type peak profile parameter was included in the refinement, with the broadening vector set along the c-axis. With this parameter included in the refinement, it was again found that P6 3 03 Å 2 , table 3), and yet the conductivity is low. The low conductivity is consistent with previous results that for high conductivity in these apatite systems, nonstoichiometry in the form of cation vacancies and/or oxygen excess is required, however the high value of U 33 might suggest a high conductivity should be observed.…”

Section: -Structural Determinationmentioning

confidence: 92%

“…The Co-k edge positions calculated from XANES spectra of our compositions are presented in 3 . This latter assignment is highlighted by the strong structural distortion seen from the Co EXAFS analysis, in which the local site coordination is lowered from 9 to 6.…”

Section: -Xanes and Exafsmentioning

confidence: 99%

“…Studies have shown that conduction in these systems is wholly anionic 1,3 , with high oxygen transference numbers (>0.9) across a wide range of oxygen partial pressures.…”

Section: Introductionmentioning

confidence: 99%

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Structural studies of apatite-type oxide ion conductors doped with cobalt

et al. 2005

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All compositions were shown to possess the hexagonal apatite structure, and the results confirmed that cobalt can be doped onto both the La and Si sites within the structure depending on the starting composition. The Co doping is shown to cause considerable local distortions within the apatite structure. In the case of Si site doping two compositions showed anisotropic peak broadening, which has been attributed to incommensurate ordering of oxygen within the apatite channels.

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Section: -Structural Determinationmentioning

confidence: 92%

Section: -Xanes and Exafsmentioning

confidence: 99%

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Structural studies of apatite-type oxide ion conductors doped with cobalt

et al. 2005

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“…In terms of the former it is the Lanthanum silicate and germanate materials, La 9.33+z (Si/GeO 4 ) 6 O 2+3z/2 which have attracted considerable attention due to their high oxide ion conductivities at elevated temperatures [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In contrast to the traditional fluorite and perovskite-type oxide ion conductors, where conductivity is mediated by oxide ion vacancies, the weight of experimental and theoretical evidence for the apatite systems indicates that they conduct via an interstitial mechanism.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of hexagonal lanthanum germanate apatites through site selective isovalent doping with yttrium

Kendrick

Slater

2008

Materials Research Bulletin

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“…Research interest in this area has grown following the initial reports by Nakayama et al of high oxide conductivities (>10 -3 Scm -1 at 500°C) in rare earth silicates, Ln 10-x Si 6 O 26+y , with the apatite structure [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The structure of these materials is shown in figure 1.…”

Section: Introductionmentioning

confidence: 99%

Neutron diffraction and atomistic simulation studies of Mg doped apatite-type oxide ion conductors

et al. 2007

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In this paper, detailed studies of the effect of Mg doping in the apatite-type oxide ion conductor La 9.33 Si 6 O 26 are reported. Mg is confirmed as an ambi-site dopant, capable of substituting for both La and Si, depending on the starting composition. A large enhancement in the conductivity is observed for Si site substitution, with a reduction for substitution on the La site. Neutron powder diffraction studies show that in agreement with cation size expectations, an enlargement of the unit cell is observed on Mg substitution for Si, with a corresponding increase in the size of the tetrahedral sites. For Mg substitution on the La site, a contraction of the unit cell is observed, and the neutron diffraction results indicate that there is preferential occupancy of Mg on the La2 (1/3, 2/3, ≈0.5) site. Atomistic simulation studies show significant local structural changes affecting the oxide ion channels in both cases. Mg doping on the Si site leads to a local expansion of the channels, while doping on the La site results in a large displacement of the silicate O4 site, such that it encroaches the oxide ion channels. The observed differences in conductivities are discussed with respect to these observations.

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Oxide ion conductivity in Sr-doped La10Ge6O27 apatite oxide

Cited by 220 publications

References 6 publications

Structural studies of apatite-type oxide ion conductors doped with cobalt

Structural studies of apatite-type oxide ion conductors doped with cobalt

Synthesis of hexagonal lanthanum germanate apatites through site selective isovalent doping with yttrium

Neutron diffraction and atomistic simulation studies of Mg doped apatite-type oxide ion conductors

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