Electroconductivity and transport numbers of solid electrolytes La10?x
CaxA6O27?δ and La9.33+δA6?x
AlxO26 (A = Si, Ge) with apatite-like structure |
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Authors: | M Yu Gorshkov A D Neuimin N M Bogdanovich D I Bronin |
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Institution: | (1) Institute of High-Temperature Electrochemistry, Ural Division, Russian Academy of Sciences, ul. S. Kovalevskoi 22, Yekaterinburg, 620219, Russia |
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Abstract: | The ion-oxygen conductivity of apatite-like compounds based on lanthanum silicates and germanates La10A6O27 (A = Si, Ge), La10?x CaxSi6O27?δ (x = 0.25, 0.5, 1.0), La9.75Ca0.25Ge6O27?δ and La9.33+δSi6?x AlxO26(x=0.4, 0.8, 1.5) is studied in the interval of partial oxygen pressures pO2 extending from 10?16 to 105 Pa, at temperatures of 500–1000°C. The electroconductivity of undoped compounds La10A6O27 (A = Si, Ge) exceeds that of yttria-stabilized zirconia. The electroconductivity of lanthanum germanate (1.7 × 10?2 and 8.5 × 10?2S cm?1 at 700 and 900°C, respectively) is substantially higher than that of lanthanum silicate (9.8 × 10?3 and 3.5 × 10?2 S cm?1 at 700 and 900°C). Doping lanthanum germanate with calcium raises its electroconductivity (2.7 × 10?2 and 1.3 × 10?1 S cm?1 for La9.75Ca0.25Ge6O27?δ at 700 and 900°C). Conversely, doping lanthanum silicate with ions of calcium or aluminum reduces the conductivity. In the pO2 interval studied, the above compounds are ionic conductors and represent a class of solid electrolytes of promise for various electrochemical devices. |
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Keywords: | apatites ion-oxygen solid electrolytes lanthanum silicates lanthanum germanates electroconductivity transport numbers for ions |
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