Cd Substitution in M_xZn_4−-xSb₃: Effect on Thermal Stability, Crystal Structure, Phase Transitions, and Thermoelectric Performance

Abstract

The effects of Cd substitution in M x Zn4−x Sb3 on the high-temperature thermal stability, low-temperature phase transitions and thermoelectric properties have been studied on three samples with a substitution degree of 0.1, 1, and 2 at % Cd (x = 0.004, 0.04, 0.08). The high-temperature thermal stability in atmospheric air of a 1% substituted sample is compared with an unsubstituted Zn4Sb3 sample. Multitemperature synchrotron powder diffraction data reveals that while only ∼42 wt % of the original Zn4Sb3 phase remains in the unsubstituted sample after three heating cycles to 625 K, 78 wt % is preserved in the Cd-substituted sample. Thus, Cd-substitution provides a significant improvement of the thermal stability of Zn4Sb3. Multitemperature synchrotron powder diffraction data measured between 90 and 300 K reveal that Cd substitution has a suppressing effect on the α′−α−β phase transitions. With increasing substitution, there is also a significant change in the individual Zn site occupancies. Differential scanning calorimetry shows an apparent correlation between Cd content and phase transition temperature. Thermoelectric properties have been measured from 2 to 400 K for all samples, and although some physical properties are significantly affected by doping, no immediate improvement of ZT was achieved.

Atomistic mechanisms governing structural stability change of zinc antimony thermoelectrics

“…This microscopic mechanism explains the physical reason why the thermoelectric performance of zinc antimony is sensible to slight variation in Zn composition. This is consistent with experimental observations [23] and is applicable to super-ionic frameworks in large lattice (e.g.…”

In Operando Study of High‐Performance Thermoelectric Materials for Power Generation: A Case Study of β‐Zn4sb3

“…proposed by Kim et al the highest values reported so far on Zn-Sb based materials [11,24] . Since the doping amount of…”

“…The decomposition of the Zn4Sb3 phase has been studied quantitatively using synchrotron powder X-ray diffraction (PXRD) [22][23][24][25][26] as well as by extensive evaluation of physical properties [27,28] . Attempts have also been made to substitute the Zn-sites with various elements such as Mg [22] , Cd [23,24,29] , and Pb [25] . The results showed that these doped samples are more stable than the non-doped sample under thermal cycling and during heat treatment.…”

Thermal Stability of High Performance Thermoelectric β‐Zn4Sb3 in Argon

“…It should also be mentioned that doping of Zn 4 Sb 3 has been shown by Iversen et al as a way to improve the stability. [14,15] In the present work, we study the degradation behavior of quench synthesised β-Zn 4 Sb 3 by heating the sample in argon atmosphere while measuring high resolution synchrotron powder X-ray diffraction (PXRD) data.…”