TY - JOUR
T1 - Operando X-ray scattering study of segmented thermoelectric Zn4Sb3
AU - Thorup, Peter Skjøtt
AU - Christensen, Rasmus Stubkjær
AU - Roelsgaard, Martin
AU - Iversen, Bo Brummerstedt
PY - 2023/2/1
Y1 - 2023/2/1
N2 - The inexpensive and high-performing thermoelectric material β-Zn
4Sb
3 is a mixed ionic-electronic conductor, which suffers from stability issues due to Zn migration in the structure under thermoelectric operating conditions. Previous ex situ studies have shown that ion migration in β-Zn
4Sb
3 and Cu
2Se can be reduced in segmented modules, where ion-blocking interfaces increase the critical voltage across the module before metallic whiskers are observed at the surface. Here, we use spatially resolved operando X-ray scattering measurements across the pellet coupled with electrical resistivity measurements to examine the stability improvement obtained in segmented β-Zn
4Sb
3 pellets with ion-blocking steel interfaces under thermoelectric operating conditions. Quantitative phase analysis shows that β-Zn
4Sb
3 decomposes into ZnSb and Zn, but the rate is significantly reduced in segmented pellets compared with unsegmented pellets. The greatest improvement is found under the mildest conditions investigated, with a hot side temperature of 250 °C and an applied current density of 0.5 A mm
−2. Microstructure analysis by scanning electron microscopy and energy dispersive X-ray spectroscopy after stability tests reveals a Zn phase front during migration, as well as residual β-Zn
4Sb
3 islands trapped inside the decomposed ZnSb phase. Overall, the operando approach provides a dynamic atomic structure basis for the effect of segmentation on the stability of β-Zn
4Sb
3 under thermoelectric working conditions.
AB - The inexpensive and high-performing thermoelectric material β-Zn
4Sb
3 is a mixed ionic-electronic conductor, which suffers from stability issues due to Zn migration in the structure under thermoelectric operating conditions. Previous ex situ studies have shown that ion migration in β-Zn
4Sb
3 and Cu
2Se can be reduced in segmented modules, where ion-blocking interfaces increase the critical voltage across the module before metallic whiskers are observed at the surface. Here, we use spatially resolved operando X-ray scattering measurements across the pellet coupled with electrical resistivity measurements to examine the stability improvement obtained in segmented β-Zn
4Sb
3 pellets with ion-blocking steel interfaces under thermoelectric operating conditions. Quantitative phase analysis shows that β-Zn
4Sb
3 decomposes into ZnSb and Zn, but the rate is significantly reduced in segmented pellets compared with unsegmented pellets. The greatest improvement is found under the mildest conditions investigated, with a hot side temperature of 250 °C and an applied current density of 0.5 A mm
−2. Microstructure analysis by scanning electron microscopy and energy dispersive X-ray spectroscopy after stability tests reveals a Zn phase front during migration, as well as residual β-Zn
4Sb
3 islands trapped inside the decomposed ZnSb phase. Overall, the operando approach provides a dynamic atomic structure basis for the effect of segmentation on the stability of β-Zn
4Sb
3 under thermoelectric working conditions.
UR - https://www.scopus.com/pages/publications/85149062609
U2 - 10.1039/d2ta09948a
DO - 10.1039/d2ta09948a
M3 - Journal article
SN - 2050-7488
VL - 11
SP - 5819
EP - 5829
JO - Journal of Materials Chemistry A
JF - Journal of Materials Chemistry A
IS - 11
ER -