Hosting of La3+ guest ions in type-I Ge clathrates: A first-principles characterization for thermoelectric applications

Author(s)

Gonzalez-Romero, Robert L. ^[1] ; Miranda, Caetano R. ^[2] ; Avila, Marcos A. ^[3] ; Antonelli, Alex ^[1]

Affiliation

^[1] Univ Estadual Campinas, Inst Fis Gleb Wataghin, BR-13083859 Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, Inst Fis, Caixa Postal 66318, BR-05315970 Sao Paulo, SP - Brazil

^[3] Univ Fed ABC UFABC, CCNH, BR-09210580 Santo Andre, SP - Brazil

• Document type: Journal article
• Source: COMPUTATIONAL MATERIALS SCIENCE; v. 122, p. 46-56, SEP 2016.
• Web of Science Citations: 2

Abstract

The conversion of heat to electricity by thermoelectric devices may play a key role in the future for energy harvesting. In order to meet that purpose, a variety of more efficient thermoelectric materials are needed. Intense research has been conducted over the past decade on type-I thermoelectric clathrates, and further developments may arise with successful introduction of trivalent rare-earth elements into the cages of this class of materials. This paper is dedicated to study the hypothetical charge-balanced compound La2Ga6Ge40, using first-principles calculations, in order to evaluate the direct effects of introducing La3+ into Ge-46 without occupying all the other cages with other chemical species. Here we present first-principles calculations on the structural, electronic, vibrational and thermoelectric properties of type-I Ge clathrates hosting La3+ guest ions. Our results indicate that the structures with the lowest formation energies are those in which the La3+ guests are inside the Ge-46 dodecahedral cages (2a Wyckoff positions), with Ga substitution for Zintl charge balance. Furthermore, our calculations show that several features of the system, such as, the equilibrium position of the La3+ guests inside the cages, the electronic structure near the band edges, the vibrational properties and anharmonic effects are significantly affected by the way the Ga atoms are distributed in the lattice. The influence of these features on the thermoelectric properties of these systems is discussed. (C) 2016 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 10/16970-0 - Computational modeling of condensed matter: a multiscale approach
• Grantee: Alex Antonelli
• Support type: Research Projects - Thematic Grants
• FAPESP's process: 12/17562-9 - Preparation of oriented single crystals for studies on electronic, magnetic and thermal anisotropies
• Grantee: Marcos de Abreu Avila
• Support type: Regular Research Grants
• FAPESP's process: 13/14065-7 - A first-principles study of electronic, structural, and transport properties of clathrates for thermoelectric applications
• Grantee: Robert Luis González Romero
• Support type: Scholarships in Brazil - Post-Doctorate
• FAPESP's process: 11/19924-2 - Study and development of advanced novel materials: electronic, magnetic and nanostructured: an interdisciplinary approach
• Grantee: Carlos Rettori
• Support type: Research Projects - Thematic Grants
• FAPESP's process: 13/08293-7 - CCES - Center for Computational Engineering and Sciences
• Grantee: Munir Salomao Skaf
• Support type: Research Grants - Research, Innovation and Dissemination Centers - RIDC