TY  - JOUR
A1  - Chen, Cong
A1  - Müller, Bernd Randolf
A1  - Lebedev, Oleg I.
A1  - Giovannelli, Fabien
A1  - Bruno, Giovanni
A1  - Delorme, Fabian
T1  - Effects of impurities on the stability of the low thermal conductivity in Fe2TiO5 ceramics
JF  - Materials characterization
N2  - 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 metastable micro-/nano-structures and producing stable and reliable data.
KW  - Fe2TiO5
KW  - Impurity segregation
KW  - Thermoclectrics
KW  - X-ray refraction
KW  - Scanning transmission electron microscopy
KW  - Thermal conductivity
Y1  - 2019
U6  - https://doi.org/10.1016/j.matchar.2019.01.021
SN  - 1044-5803
SN  - 1873-4189
VL  - 149
SP  - 111
EP  - 117
PB  - Elsevier
CY  - New York
ER  -