Abstract text (incl. figure legends and references)

The structure of thermoelectric materials largely determines their characteristics. Hence, a better understanding of the details of the structural transformation conditions can open doors for new applications. Therefore, a microscopic comprehension of the impact on the nanoscale structure dynamics is crucial, especially with the progress of intensified miniaturization. In this study, the effect of heat treatment on the structure of phase change MgAgPtSb is investigated [1,2]. The material was heated in-situ in the transmission electron microscope (TEM). Using a combination of scanning transmission electron microscopy (STEM) and energy dispersive spectroscopy (EDS) we unveil the structural and chemical state of the thermoelectric. Thus, we can correlate real-time changes during the heating process with the presence of structural distortions, impurities and compositional transformations. Additionally, the crystal structure of MgAgPtSb thermoelectric material undergoes a phase transformation when the temperature changes. The tetragonal I-centered phase transforms to the P-centered tetragonal crystal system and at approximately 400°C to a cubic Heussler structure [3]. In this work, we study the changes taking place during the phase transitions as it usually leads to increased defects and second phase precipitation [4].

Keywords: thermoelectrics, in-situ transmission electron microscopy, phase transformation

References

[1] Chem. Mater. 2015, 27, 909-913.

[2] Adv. Funct. Mater. 2017, 27, 1604145.

[3] Phys. Rev. B 2012, 85, 144120.

[4] Chem. Mater. 2017, 29, 6378-6388.