Ab initio crystal structure search and modeling of new oxide-based thermoelectric materials
Abstract
The applicant Isabella Concina joined the Experimental Physics group at Luleå University of Technology (LTU) in March 2015, as part of the Division of Materials Science. Her research focuses on the development of new advanced metal-oxide nanostructures for advanced applications. Of special interest is the new class of highly efficient materials, called oxiselenides (RE2O2Se). This new class of materials is multiple component systems consisting of several compounds such as metallic oxides, chalcogenides, and semiconductors. Oxiselenides show superior transport properties including high electrical conductivity, high Seebeck coefficient, good stability, oxidation resistance and no toxicity over conventional alloys, especially at elevated temperatures. As a result of the previously conducted theoretical calculations, two papers were prepared and currently submitted to the peer-reviewed journals. In the continuation of the work more calculations will be conducted for oxide-based semiconductors such as oxiselenides, high-entropy systems (four and more types of atoms), and oxide perovskite that were not studied before.
For this project studies of new oxide-based materials will be done by combining theoretical modeling and experiments. The experimental part carried out by Post-Doc Khabib Yusupov (Experimental Physics Materials, LTU), Ph.D. students Mojtaba Gilzad Kohan and Daria Pankratova ((Experimental Physics Materials, LTU), Post-Doc Andrey Novitsky (NUST MISiS, collaboration in Russia) and the theoretical modeling by Post-Doc Mikael Rasander (Applied Physics, LTU) and Post-Doc Khabib Yusupov (Experimental Physics Materials, LTU). The theoretical part will focus on modeling of oxide semiconductors at the atomic level using Density Functional Theory (DFT). Crystal structures for new material will be predicted from different chemical compositions using DFT together with BoltzTrap 2 (BT2) and "Exciting" softwares. BT2 can simulate transport properties (electrical conductivity, Seebeck coefficient, etc.) basing on the output file from VASP. "Exciting" allows calculating the optical properties of the systems based on the crystal strucutres. By combining theoretical modeling and experiments we aim to increase the understanding of oxide semiconductors, their transport properties, and new compositions achieved by substitution of initial elements.
