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MM: Fachverband Metall- und Materialphysik

MM 12: Computational Materials Modelling: Physics of Ensembles 1

MM 12.6: Vortrag

Dienstag, 6. September 2022, 11:45–12:00, H44

Revealing the ambient and high-pressure phases of group IV monochalcogenides and monoxides with an evolutionary algorithm — •long nguyen and guy makov — Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel

Group IV chalcogenides and oxides are candidates for incorporation into optoelectronic and thermoelectric conversion devices. These functional materials are mostly p-type semiconductors that provide low-cost, environmentally friendly, abundant, and high-efficiency. To expand the possible phases and study their stability upon compression, a combination of DFT modelling with evolutionary algorithm (EA) is applied to extensively investigate across the group IV monochalcogenides and oxides. We will report our results from the implementation of the EA to search for stable phases. In group IV monoxides, our results include multiple structural transitions of SnO and PbO upon compression. Two new high-pressure polymorphs are predicted, the orthorhombic Pbcm SnO and the octahedral monoclinic C2/m PbO. Weakening of the lone pairs and elastic instability are the main drivers for the structural transitions. Among the monochalcogenides, SnS and GeS phase families are examined together with their electronic and optical properties. At ambient conditions, GeS and SnS can present several polymorphs with bandgaps in the range from 0.3 to 1.6 eV, which can be attractive for a variety of optoelectronics applications. Upon compression, we found a similar convergence of SnS and GeS into the Cmcm and later the Pm3m phase. The transition mechanism is discussed through the lone pairs' influence on the structural distortion.