Effects of impurities on the stability of the low thermal conductivity in Fe2TiO5 ceramics
- The stability of the low thermal conductivity in Fe2TiO5 pseudobrookite ceramics has been studied. An increase in thermal diffusivity is observed after only three cycles of measurement. X-ray refraction shows an increase in the mean value of specific surface after the thermal diffusivity measurements. By using scanning electron microscopy and high-angle annular dark-field scanning transmission electron microscope equipped with energy dispersive Xray spectroscopy, we observe a segregation of Ca- and F-rich nanocrystals at grain boundaries after three cycles of thermal diffusivity measurement. Therefore, impurities seem to be more efficient to scatter phonons as point defects in the pseudobrookite lattice rather than as nanocrystals at pseudobrookite grain boundaries. This emphasizes the importance of precursor purity and the influence of redistribution of impurities on thermoelectric properties: stability of micro-/nano-structures is a key point, and repeated thermoelectric measurements may allow detecting such metastableThe stability of the low thermal conductivity in Fe2TiO5 pseudobrookite ceramics has been studied. An increase in thermal diffusivity is observed after only three cycles of measurement. X-ray refraction shows an increase in the mean value of specific surface after the thermal diffusivity measurements. By using scanning electron microscopy and high-angle annular dark-field scanning transmission electron microscope equipped with energy dispersive Xray spectroscopy, we observe a segregation of Ca- and F-rich nanocrystals at grain boundaries after three cycles of thermal diffusivity measurement. Therefore, impurities seem to be more efficient to scatter phonons as point defects in the pseudobrookite lattice rather than as nanocrystals at pseudobrookite grain boundaries. This emphasizes the importance of precursor purity and the influence of redistribution of impurities on thermoelectric properties: stability of micro-/nano-structures is a key point, and repeated thermoelectric measurements may allow detecting such metastable micro-/nano-structures and producing stable and reliable data.…
Verfasserangaben: | Cong ChenORCiD, Bernd Randolf MüllerORCiD, Oleg I. Lebedev, Fabien Giovannelli, Giovanni BrunoORCiDGND, Fabian Delorme |
---|---|
DOI: | https://doi.org/10.1016/j.matchar.2019.01.021 |
ISSN: | 1044-5803 |
ISSN: | 1873-4189 |
Titel des übergeordneten Werks (Englisch): | Materials characterization |
Verlag: | Elsevier |
Verlagsort: | New York |
Publikationstyp: | Wissenschaftlicher Artikel |
Sprache: | Englisch |
Datum der Erstveröffentlichung: | 01.03.2019 |
Erscheinungsjahr: | 2019 |
Datum der Freischaltung: | 18.03.2021 |
Freies Schlagwort / Tag: | Fe2TiO5; Impurity segregation; Scanning transmission electron microscopy; Thermal conductivity; Thermoclectrics; X-ray refraction |
Band: | 149 |
Seitenanzahl: | 7 |
Erste Seite: | 111 |
Letzte Seite: | 117 |
Fördernde Institution: | French METSA network [FR3507] |
Organisationseinheiten: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
DDC-Klassifikation: | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
Peer Review: | Referiert |