Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/327144
Type: Artigo
Title: Hosting Of La3+ Guest Ions In Type-i Ge Clathrates: A First-principles Characterization For Thermoelectric Applications
Hosting of La3+ guest ions in type-I Ge clathrates: a first-principles characterization for thermoelectric applications
Author: González-Romero, Robert L.
Miranda, Caetano R.
Avila, Marcos A.
Antonelli, Alex
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.
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 Ge46 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 Ge46 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 an harmonic 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.
Subject: First-principles Calculations
Clathrates
Phonons
Thermal Conductivity
Thermoelectricity
Cálculos de primeiros princípios
Clatratos
Condutividade térmica
Termoeletricidade
Fonons
Country: Holanda
Editor: Elsevier
Citation: Computational Materials Science. Elsevier Science Bv, v. 122, p. 46 - 56, 2016.
Rights: fechado
Identifier DOI: 10.1016/j.commatsci.2016.05.013
Address: https://www.sciencedirect.com/science/article/pii/S0927025616302270
Date Issue: 2016
Appears in Collections:IFGW - Artigos e Outros Documentos

Files in This Item:
File SizeFormat 
000378516900006.pdf1.7 MBAdobe PDFView/Open


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.