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

Autor(es)

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

Afiliação do(s) autor(es)

^[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

• Tipo de documento: Artigo Científico
• Fonte: COMPUTATIONAL MATERIALS SCIENCE; v. 122, p. 46-56, SEP 2016.
• Citações Web of Science: 2

Resumo

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)

• Processo FAPESP: 13/08293-7 - CECC - Centro de Engenharia e Ciências Computacionais
• Beneficiário: Munir Salomao Skaf
• Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs
• Processo FAPESP: 12/17562-9 - Preparação de monocristais orientados para estudos de anisotropias eletrônicas, magnéticas e térmicas
• Beneficiário: Marcos de Abreu Avila
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 11/19924-2 - Estudo e desenvolvimento de novos materiais avançados: eletrônicos, magnéticos e nanoestruturados: uma abordagem interdisciplinar
• Beneficiário: Carlos Rettori
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 13/14065-7 - Estudo das Propriedades Eletrônicas, Estruturais e de Transporte de Clatratos para Aplicações Termoelétricas através de Cálculos de Primeiros Princípios
• Beneficiário: Robert Luis González Romero
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 10/16970-0 - Modelagem computacional da matéria condensada: uma abordagem em múltiplas escalas
• Beneficiário: Alex Antonelli
• Modalidade de apoio: Auxílio à Pesquisa - Temático