COMEX · COmputational Modelling for EXtreme conditions
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2018-05-01 → 2020-08-29
- EU contribution
- €170,122
- Participants
- 1
- Scheme
- MSCA-IF
Lines connect the coordinator with its partners.
Results in brief
COmputational Modelling for EXtreme conditions
Pressure is an important thermodynamic variable in order to understand the properties of materials because it allows for a precise control over the interatomic distances and hence the atomic interactions. Moreover, the application of high pressure (HP), many times in combination with high temperature (HT), allows the synthesis of new phases of materials with completely different properties to those from stable materials at room conditions (RC). Sesquichalcogenides (SCs) are compounds with A2X3 stoichiometry (A being a trivalent cation and X=S,Se,Te) which have been studied because of their many interesting applications. In particular, Bi2Te3 is considered the best thermoelectric material (TM) at RC. A great activity in the study of SCs and respective behaviour at HP has occurred in the last years since the discovery of the topological insulating (TI) and superconducting behaviour of tetradymite-like (R-3m phase) Bi2Se3, Bi2Te3 and Sb2Te3. In fact, a strong interest has aroused regarding the bridge between the TIs and high-performance TM materials. Several studies have contributed to the understanding of the pressure-induced electronic topological transition and the TI behaviour of SCs at HP. More recently, a HP study on Sb2S3 has discussed pressure-induced second-order isostructural phase transitions and electronic topological transitions at HP in several SCs, similar to what occurs for Sb2Se3 and Bi2S3. These interesting properties have motivated great interest to explore the properties of SCs. Moreover, studies of the properties of SCs are still required since their behaviours at HP and HT are not fully understood and these have been scarcely explored, especially regarding some the crystalline phases of SCs with A=As,Sb. In particular, the R-3m phase of Sb2Se3 (β-Sb2Se3) has been predicted to be TI, but such a phase has not been reported to date. On the other hand, the R-3m phase of As2Te3 (β-As2Te3) has been reported and predicted to become a TI under compression, but this prediction has yet to be experimentally confirmed. Finally, almost nothing is known about the properties of the different crystalline phases of As2S3 (orpiment and anorpiment) and As2Se3 (α, β and γ) even at RC. It is possible that γ-As2Se3 could crystallize in the R-3m phase and show TI properties. Thus, the objective of this project is to study, from a theoretical perspective, the characterization of the structural, vibrational and electronic properties of SCs, which are potential candidates for TI and/or TM when induced under extreme conditions. This work will complement experimental studies of SCs and provide basic understanding of respective physical-chemical properties, which will be important for respective implementation in technological devices.
Data: CORDIS, © European Union
Project objective
Pressure is an important thermodynamic variable in order to understand the properties of the materials, even at room pressure, because it allows for a precise control over the interatomic distances and hence the atomic interactions. Moreover, the application of high pressure, many times in combination with high temperatures, allows the synthesis of new phases of materials with completely different properties to those from stable materials at room conditions. New phases of materials may be metastable at room conditions and thus lead to new technological advances.Sesquichalcogenides (A2X3 stoichiometry) have been traditionally studied due to their many interesting applications at high pressure. These interesting properties, together with the search for miniaturization, which includes isolating layers to form 2D mono- or bi-layer systems, have motivated an increased interest to explore the properties of the A2X3 compounds in the nanosize regime as well. In this regime, quantum confinement effects could become dominant thus altering the structural, electronic and optical behaviour when compared with the bulk material. In this context, studies of the properties of many bulk and nanocrystalline sesquichalcogenides are still required since their high pressure and high temperature phases have not yet been fully explored. Thus, the goal of this project is to study, from a theoretical perspective by employing ab-initio calculations, the structural, vibrational, elastic, and electronic properties of sesquichalcogenides under extreme conditions of high pressure and temperature and predict stable and metastable phases of these materials under these extreme conditions. The proposed work will complement experimental studies and will provide basic understanding of the physical-chemical properties of these materials, which will be important for respective implementation in technological devices.
Original text from CORDIS.
Participants
- UNIVERSITAT POLITECNICA DE VALENCIA · ValenciaCoordinatorSpain
Links
Data: CORDIS, © European Union