Synthesis of silicon doped SrMO3 (M = Mn, Co): stabilization of the cubic perovskite and enhancement in conductivity

Hancock, Cathryn A.; Slater, Peter R.

doi:10.1039/c1dt10253b

Cited by 51 publications

(47 citation statements)

References 24 publications

(50 reference statements)

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“…In particular, we have shown that the partial substitution of these oxyanions at the In/Sc site in Ba 2 (In/Sc) 2 O 5 leads to the introduction of disorder on the oxygen sublattice and a corresponding enhancement in the low temperature ionic conductivity [14][15][16][17][18]. In terms of electronic conducting materials, we have also reported the successful incorporation of silicate, phosphate and sulphate into SrMO 3 (M = Co, Mn), leading to a large enhancement in the electronic conductivity [19,20]. In these latter examples, this large enhancement in the conductivity could be explained by a change from a 2H-perovskite (containing face sharing of octahedra) to a 3C-perovskite (containing corner sharing of octahedra).…”

Section: Introductionmentioning

confidence: 75%

Synthesis and characterisation of oxyanion-doped manganites for potential application as SOFC cathodes

et al. 2012

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In this paper we report the successful incorporation of borate and phosphate into CaMnO 3 and borate into La 1Ày Sr y MnO 3Àd . For CaMnO 3 , an increase in the electronic conductivity was observed, which can be correlated with electron doping due to the oxyanion doping favoring the introduction of oxide ion vacancies (as well as the higher valence of P 5+ compared to Mn 4+ in the case of phosphate doping). The highest conductivity at 800 C was observed for CaMn 0.95 P 0.05 O 3Àd , 43.0 S cm À1 , in comparison with 7.6 S cm À1 for undoped CaMnO 3 at the same temperature. For La 1Ày Sr y MnO 3Àd the conductivity suffers a decrease for all compositions on borate doping, attributed to a reduction in the hole (Mn 4+ ) concentration. In order to investigate the potential of these materials as SOFC cathodes, the chemical compatibility with Gd 0.1 Ce 0.9 O 1.95 (CGO10) has also been investigated. For the calcium manganites, the lowest temperature examined without reaction was 900 C, with minor amounts of Ca 4 Mn 3 O 10 observed at 1000 C. Composites of these cathode materials with 50% CGO10 were examined on dense CGO10 pellets and the area specific resistances (ASR) in symmetrical cells were determined. The ASR values, at 800 C, were 1.50, 0.37 and 0.30 U$cm 2 for CaMnO 3 , CaMn 0.95 B 0.05 O 3Àd and CaMn 0.95 P 0.05 O 3Àd , respectively. For the lanthanum strontium manganites, the B-doped compositions showed an improvement in the ASR values with respect to the parent compounds, despite the lower electronic conductivity. This may be due to an increase in ionic conductivity due to borate incorporation leading to the formation of oxide ion vacancies. Thus these preliminary results show that oxyanion doping has a beneficial effect on the performance of perovskite manganite cathode materials, and suggests that this doping strategy warrants further investigation in other perovskite cathode systems.

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Section: Introductionmentioning

confidence: 75%

Synthesis and characterisation of oxyanion-doped manganites for potential application as SOFC cathodes

et al. 2012

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“…Nb, Sb, Si has been shown to alter the stacking arrangement of the close packed oxygen layers from purely hexagonal to purely cubic (referred to as 2H and 3C respectively). The consequent change from face-shared to corner linked CoO 6 octahedra, leads to a substantial enhancement in the electronic conductivity [28][29][30][31][32]. This stabilisation of the 3C-perovskite framework on Nb, Sb, Si doping can be attributed to a partial reduction of Co 4+ to Co…”

Section: Introductionmentioning

confidence: 96%

Synthesis, structure and conductivity of sulfate and phosphate doped SrCoO3

Hancock

Slade

Varcoe

et al. 2011

Journal of Solid State Chemistry

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In this paper we report the successful incorporation of sulfate and phosphate into SrCoO 3 leading to a change from a 2H-to a 3C-perovskite polymorph. Structural characterization by neutron diffraction showed extra weak peaks related to oxygen vacancy ordering, and these could be indexed on an expanded tetragonal cell, containing two inequivalent Co sites, similar to previously reported for Sb doped SrCoO 3 .Conductivity measurements on the doped systems showed a large enhancement compared to the undoped hexagonal system, consistent with corner-sharing of CoO 6 octahedra for the former. Further work on the doped samples shows, however, that they are metastable, transforming back to the hexagonal cell on annealing at intermediate temperatures. The incorporation of Fe was shown, however, to improve the stability at intermediate temperatures, and these co-doped phases also showed high conductivities.

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“…Indeed, Kozuka et al [37] have shown that the perovskite structure is not stable for such high substitution rates, but Hancock and Slater [41] have shown that the cubic perovskite structure can be stabilized by substituting 3% cobalt by silicon.…”

Section: Methodsmentioning

confidence: 99%

Synthesis, sintering, and thermoelectric properties of the solid solution La1–xSr x CoO3±δ (0 ≤ x ≤ 1)

et al. 2018

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Abstract:In this work, we synthesized cubic perovskite ceramics of the whole La 1-x Sr x CoO 3 (0 ≤ x ≤ 1) solid solution for the first time. Synthesis was carried out by solid state reaction and conventional sintering to reach dense ceramics. For x > 0.8, it was necessary to substitute 3% cobalt by silicon to stabilize the cubic perovskite structure. Electrical conductivity increased with Sr content to reach 3×10 5 S·m -1 at 330 K for x = 0.3. However, the optimum electrical properties have been found for x = 0.05 at 330 K with PF max = 3.11×10 -4 W·m -1 ·K -2 . Indeed, the Seebeck coefficient was decreasing when x increased to reach values close to 0 for x ≥ 0.3. Thermal conductivity was low at low temperature (≈ 2.5 Wm -1 ·K -1 ) and increased up to 6.5 W·m -1 ·K -1 when temperature increased. As the highest power factor was reached at low temperature as well as the lowest thermal conductivity, La 1-x Sr x CoO 3 compounds with low x values appeared as very promising thermoelectric materials around room temperature, on the contrary to layered cobalt oxides. For high x values, Seebeck coefficient values close to zero made these materials unsuitable for thermoelectric applications.

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Synthesis of silicon doped SrMO3 (M = Mn, Co): stabilization of the cubic perovskite and enhancement in conductivity

Cited by 51 publications

References 24 publications

Synthesis and characterisation of oxyanion-doped manganites for potential application as SOFC cathodes

Synthesis and characterisation of oxyanion-doped manganites for potential application as SOFC cathodes

Synthesis, structure and conductivity of sulfate and phosphate doped SrCoO3

Synthesis, sintering, and thermoelectric properties of the solid solution La1–xSr x CoO3±δ (0 ≤ x ≤ 1)

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