Processing and electrical conductivity of lanthanum gallate core-shell heterostructures
The electrical properties of a lanthanum gallate solid electrolyte were modified by selectively doping the grain boundaries with Fe. This was achieved by sandwiching a La0.95Sr0.05Ga0.90Mg0.10O3-δ (LSGM) dense pellet between LaFeO3 samples. Annealing at 1550°C in air for several hours promoted Fe di...
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| Format: | Article |
| Language: | English |
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Elsevier
2006-06-01
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| Series: | Boletín de la Sociedad Española de Cerámica y Vidrio |
| Subjects: | |
| Online Access: | http://ceramicayvidrio.revistas.csic.es/index.php/ceramicayvidrio/article/view/294/313 |
| _version_ | 1811263579334115328 |
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| author | Gomes, Eduarda Figueiredo, F. M. Marquesa, F. M. B. |
| author_facet | Gomes, Eduarda Figueiredo, F. M. Marquesa, F. M. B. |
| author_sort | Gomes, Eduarda |
| collection | DOAJ |
| description | The electrical properties of a lanthanum gallate solid electrolyte were modified by selectively doping the grain boundaries with Fe. This was achieved by sandwiching a La0.95Sr0.05Ga0.90Mg0.10O3-δ (LSGM) dense pellet between LaFeO3 samples. Annealing at 1550°C in air for several hours promoted Fe diffusion into LSGM via the grain boundaries. Scanning electron microscopy and energy-dispersive spectroscopy analyses showed that iron was located at the grain boundary while the grain bulk preserved the LSGM composition. Impedance spectra obtained at low temperature consist of the two usual bulk and grain boundary contributions. A significant increase in total conductivity was observed for the iron-doped samples, the effect being greater for the grain boundary contribution. The total conductivity measured for the iron-containing material revealed a slight decrease with decreasing oxygen partial pressure, suggesting the onset of p-type electronic conduction. Estimates of the p-type electronic conductivity (σp) were obtained by fitting the low temperature impedance spectra to a simple equivalent circuit including one parallel electronic branch. The value for σp in air at 300°C is 3.1×10-6 S/cm and the activation energy is 75.1 kJ/mol between 300 and 400°C.<br><br>Las propiedades elécticas de un electrolito sólido de galato de lantano se han modificado mediante un dopado eléctrico de Fe en borde de grano. Esto se consiguió preparando una estructura de sandwich con una plantilla densa de La0.95Sr0.05Ga0.90Mg0.10O3-δ (LSGM) entre las muestras de LaFeO3. Un tratamiento de varias horas a 1550ºC en aire favoreció la difusión de Fe a lo largo de los bordes de grano. Los análisis mediante microscopia electrónica de barrido y espectroscopía de energía dispersada muestran que el hierro se localiza en borde de grano mientras que se preserva la composición de LSGM en el interior de grano. En las muestras dopadas con hierro se observa un aumento de la conductividad total siendo el efecto más notable en el borde del grano. La conductividad total del material que contiene hierro presentó un ligero descenso al reducirse la presión parcial de oxígeno, lo que sugiere la presencia de conducción electrónica tipo p. La conductividad electrónica tipo (σp) se evaluó ajustando el espectro de impedancia de baja temperatura a un circuito equivalente sencillo con una resistencia electrónica en paralelo. El valor de σp en aire a 300ºC es 3,1×10-6 S/cm y la energía de actuación 75,1 kJ/mol entre 300 y 400ºC. |
| first_indexed | 2024-04-12T19:47:47Z |
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| id | doaj.art-a119a546ea9742e082427b4739039c79 |
| institution | Directory Open Access Journal |
| issn | 0366-3175 |
| language | English |
| last_indexed | 2024-04-12T19:47:47Z |
| publishDate | 2006-06-01 |
| publisher | Elsevier |
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| series | Boletín de la Sociedad Española de Cerámica y Vidrio |
| spelling | doaj.art-a119a546ea9742e082427b4739039c792022-12-22T03:18:55ZengElsevierBoletín de la Sociedad Española de Cerámica y Vidrio0366-31752006-06-01453144149Processing and electrical conductivity of lanthanum gallate core-shell heterostructuresGomes, EduardaFigueiredo, F. M.Marquesa, F. M. B.The electrical properties of a lanthanum gallate solid electrolyte were modified by selectively doping the grain boundaries with Fe. This was achieved by sandwiching a La0.95Sr0.05Ga0.90Mg0.10O3-δ (LSGM) dense pellet between LaFeO3 samples. Annealing at 1550°C in air for several hours promoted Fe diffusion into LSGM via the grain boundaries. Scanning electron microscopy and energy-dispersive spectroscopy analyses showed that iron was located at the grain boundary while the grain bulk preserved the LSGM composition. Impedance spectra obtained at low temperature consist of the two usual bulk and grain boundary contributions. A significant increase in total conductivity was observed for the iron-doped samples, the effect being greater for the grain boundary contribution. The total conductivity measured for the iron-containing material revealed a slight decrease with decreasing oxygen partial pressure, suggesting the onset of p-type electronic conduction. Estimates of the p-type electronic conductivity (σp) were obtained by fitting the low temperature impedance spectra to a simple equivalent circuit including one parallel electronic branch. The value for σp in air at 300°C is 3.1×10-6 S/cm and the activation energy is 75.1 kJ/mol between 300 and 400°C.<br><br>Las propiedades elécticas de un electrolito sólido de galato de lantano se han modificado mediante un dopado eléctrico de Fe en borde de grano. Esto se consiguió preparando una estructura de sandwich con una plantilla densa de La0.95Sr0.05Ga0.90Mg0.10O3-δ (LSGM) entre las muestras de LaFeO3. Un tratamiento de varias horas a 1550ºC en aire favoreció la difusión de Fe a lo largo de los bordes de grano. Los análisis mediante microscopia electrónica de barrido y espectroscopía de energía dispersada muestran que el hierro se localiza en borde de grano mientras que se preserva la composición de LSGM en el interior de grano. En las muestras dopadas con hierro se observa un aumento de la conductividad total siendo el efecto más notable en el borde del grano. La conductividad total del material que contiene hierro presentó un ligero descenso al reducirse la presión parcial de oxígeno, lo que sugiere la presencia de conducción electrónica tipo p. La conductividad electrónica tipo (σp) se evaluó ajustando el espectro de impedancia de baja temperatura a un circuito equivalente sencillo con una resistencia electrónica en paralelo. El valor de σp en aire a 300ºC es 3,1×10-6 S/cm y la energía de actuación 75,1 kJ/mol entre 300 y 400ºC.http://ceramicayvidrio.revistas.csic.es/index.php/ceramicayvidrio/article/view/294/313Core-shellgallategrain boundarymixed conductorimpedance spectroscopyCore-shellgalatoborde de granoconductor mixtoespectroscopía de impedancia |
| spellingShingle | Gomes, Eduarda Figueiredo, F. M. Marquesa, F. M. B. Processing and electrical conductivity of lanthanum gallate core-shell heterostructures Boletín de la Sociedad Española de Cerámica y Vidrio Core-shell gallate grain boundary mixed conductor impedance spectroscopy Core-shell galato borde de grano conductor mixto espectroscopía de impedancia |
| title | Processing and electrical conductivity of lanthanum gallate core-shell heterostructures |
| title_full | Processing and electrical conductivity of lanthanum gallate core-shell heterostructures |
| title_fullStr | Processing and electrical conductivity of lanthanum gallate core-shell heterostructures |
| title_full_unstemmed | Processing and electrical conductivity of lanthanum gallate core-shell heterostructures |
| title_short | Processing and electrical conductivity of lanthanum gallate core-shell heterostructures |
| title_sort | processing and electrical conductivity of lanthanum gallate core shell heterostructures |
| topic | Core-shell gallate grain boundary mixed conductor impedance spectroscopy Core-shell galato borde de grano conductor mixto espectroscopía de impedancia |
| url | http://ceramicayvidrio.revistas.csic.es/index.php/ceramicayvidrio/article/view/294/313 |
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