Speaker
Description
In recent years, multinary chalcogenides have received significant attention as potential energy materials. In their synthesis, mechanochemistry seems to be an effective method for the preparation of various chalcogenide - based nanoscale materials. Due to the creation of structural disorder, defects and nanostructuring in solids via high-energy milling, unique properties can be achieved [1]. Recently, a concept of high-entropy sulphides appeared for compounds created by combination of several elements [2]. For these systems stabilization effect, sluggish diffusion effect, severe lattice distortion effect and cocktail effect are characteristic [2]. Some of these effects are common also for mechanochemistry.
Based on advantages of mechanochemistry and high-entropy concept we investigated properties of (FeSbPbSnS) system subjected to high-energy milling applied during $15$-$2400$ min. The milling was performed in an intermittent regime and protective atmosphere. The synthesized samples were characterized using X-ray diffraction (XRD), nitrogen absorption, EDX-, TEM-, SAED, HRTEM- and HAADF- spectroscopy as well as by magnetic methods. XRD revealed prevailing presence of suredaite (PDF $01$-$070$-$3361$). Micrographs (TEM, SAED, HRTEM) revealed homogeneously aggregated grains with size less than $10$ to few tens of nanometers.
The magnetic nature of the synthesized samples was assessed from measurements in a direct current (DC) and an alternating current (AC) magnetic field. The isothermal magnetization curves measured at $5$ K and the field up to $5$ T reveal suppression of the iron ferromagnetism and the remarkable onset of the paramagnetic behavior with the increasing milling time. The paramagnetic nature is confirmed by the temperature-dependent magnetization curves. The spectra of the AC magnetic susceptibility measured in the frequency range from $1$ Hz to $250$ kHz show the well-relaxed behavior without any significant dispersion. The magnitude of the real part of the complex AC magnetic susceptibility decreases with the increasing milling time.
Acknowledgements
This work was supported by the projects of the Slovak Grant Agency VEGA (2/0112/22, 2/0029/24), and Slovak Research and Development Agency APVV 22-0115.
References
[1] P. Baláž, Mechanochemistry in Nanoscience and Minerals Engineering, Springer-Verlag, Berlin Heidelberg 2008. ISBN: 978-3-540-74854-0
[2] M. A. Buckingham et al., “High entropy metal chalcogenides: synthesis, properties, applications and future directions,” Chemical Communications, vol. 58, no. 58. Royal Society of Chemistry (RSC), pp. 8025–8037, 2022. https://doi.org/10.1039/d2cc01796b
