Structural Principles and Thermoelectric Properties of Polytypic Group 14 Clathrate-II Frameworks

Antti J. Karttunen; Thomas F. Faessler

doi:10.1002/cphc.201300133

Structural Principles and Thermoelectric Properties of Polytypic Group 14 Clathrate-II Frameworks

Antti J. Karttunen^*
, Thomas F. Faessler

^*Corresponding author for this work

Not published at Aalto University

Research output: Contribution to journal › Article › Scientific › peer-review

14 Citations (Web of Science)

Abstract

We have investigated the structural principles and thermoelectric properties of polytypic group 14 clathrate-II frameworks using quantum chemical methods. The experimentally known cubic 3C polytype was found to be the energetically most favorable framework, but the studied hexagonal polytypes (2H, 4H, 6H, 8H, 10H) lie energetically close to it. In the case of germanium, the energy difference between the 3C and 6H clathrate-II polytypes is ten times smaller than the difference between the experimentally known 3C-Ge (-Ge) and 4H-Ge polytypes. The thermoelectric properties of guest-occupied clathrate-II structures were investigated for compositions Na-Rb-Ga-Ge and Ge-As-I. The clathrate-II structures show promising thermoelectric properties and the highest Seebeck coefficients and thermoelectric power factors were predicted for the 3C polytype. The structural anisotropy of the largest studied hexagonal polytypes affects their thermoelectric power factors by over a factor of two.

Original language	English
Pages (from-to)	1807-1817
Number of pages	11
Journal	ChemPhysChem
Volume	14
Issue number	9
DOIs	https://doi.org/10.1002/cphc.201300133
Publication status	Published - 24 Jun 2013
MoE publication type	A1 Journal article-refereed

Funding

Funding from the Academy of Finland is gratefully acknowledged (A. J. K., grant 138560/2010). A. J. K thanks Mr. Ville Harkonen (University of Jyvaskyla) for helpful discussions and Dr. Roberto Orlando (University of Turin) for providing a modified version of the CRYSTAL09 binaries.

Keywords

allotropy
density functional calculations
energy conversion
solid-state structures
zintl phases
THERMAL-CONDUCTIVITY
LAVES PHASES
CRYSTAL
BA8GA16GE30
GERMANIUM
DIAMOND
SYSTEM
GE
BA8GA16SI30
BA8IN16SN30

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title = "Structural Principles and Thermoelectric Properties of Polytypic Group 14 Clathrate-II Frameworks",

abstract = "We have investigated the structural principles and thermoelectric properties of polytypic group 14 clathrate-II frameworks using quantum chemical methods. The experimentally known cubic 3C polytype was found to be the energetically most favorable framework, but the studied hexagonal polytypes (2H, 4H, 6H, 8H, 10H) lie energetically close to it. In the case of germanium, the energy difference between the 3C and 6H clathrate-II polytypes is ten times smaller than the difference between the experimentally known 3C-Ge (-Ge) and 4H-Ge polytypes. The thermoelectric properties of guest-occupied clathrate-II structures were investigated for compositions Na-Rb-Ga-Ge and Ge-As-I. The clathrate-II structures show promising thermoelectric properties and the highest Seebeck coefficients and thermoelectric power factors were predicted for the 3C polytype. The structural anisotropy of the largest studied hexagonal polytypes affects their thermoelectric power factors by over a factor of two.",

keywords = "allotropy, density functional calculations, energy conversion, solid-state structures, zintl phases, THERMAL-CONDUCTIVITY, LAVES PHASES, CRYSTAL, BA8GA16GE30, GERMANIUM, DIAMOND, SYSTEM, GE, BA8GA16SI30, BA8IN16SN30",

author = "Karttunen, \{Antti J.\} and Faessler, \{Thomas F.\}",

year = "2013",

month = jun,

day = "24",

doi = "10.1002/cphc.201300133",

language = "English",

volume = "14",

pages = "1807--1817",

journal = "ChemPhysChem",

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T1 - Structural Principles and Thermoelectric Properties of Polytypic Group 14 Clathrate-II Frameworks

AU - Karttunen, Antti J.

AU - Faessler, Thomas F.

PY - 2013/6/24

Y1 - 2013/6/24

N2 - We have investigated the structural principles and thermoelectric properties of polytypic group 14 clathrate-II frameworks using quantum chemical methods. The experimentally known cubic 3C polytype was found to be the energetically most favorable framework, but the studied hexagonal polytypes (2H, 4H, 6H, 8H, 10H) lie energetically close to it. In the case of germanium, the energy difference between the 3C and 6H clathrate-II polytypes is ten times smaller than the difference between the experimentally known 3C-Ge (-Ge) and 4H-Ge polytypes. The thermoelectric properties of guest-occupied clathrate-II structures were investigated for compositions Na-Rb-Ga-Ge and Ge-As-I. The clathrate-II structures show promising thermoelectric properties and the highest Seebeck coefficients and thermoelectric power factors were predicted for the 3C polytype. The structural anisotropy of the largest studied hexagonal polytypes affects their thermoelectric power factors by over a factor of two.

AB - We have investigated the structural principles and thermoelectric properties of polytypic group 14 clathrate-II frameworks using quantum chemical methods. The experimentally known cubic 3C polytype was found to be the energetically most favorable framework, but the studied hexagonal polytypes (2H, 4H, 6H, 8H, 10H) lie energetically close to it. In the case of germanium, the energy difference between the 3C and 6H clathrate-II polytypes is ten times smaller than the difference between the experimentally known 3C-Ge (-Ge) and 4H-Ge polytypes. The thermoelectric properties of guest-occupied clathrate-II structures were investigated for compositions Na-Rb-Ga-Ge and Ge-As-I. The clathrate-II structures show promising thermoelectric properties and the highest Seebeck coefficients and thermoelectric power factors were predicted for the 3C polytype. The structural anisotropy of the largest studied hexagonal polytypes affects their thermoelectric power factors by over a factor of two.

KW - allotropy

KW - density functional calculations

KW - energy conversion

KW - solid-state structures

KW - zintl phases

KW - THERMAL-CONDUCTIVITY

KW - LAVES PHASES

KW - CRYSTAL

KW - BA8GA16GE30

KW - GERMANIUM

KW - DIAMOND

KW - SYSTEM

KW - GE

KW - BA8GA16SI30

KW - BA8IN16SN30

U2 - 10.1002/cphc.201300133

DO - 10.1002/cphc.201300133

M3 - Article

SN - 1439-4235

VL - 14

SP - 1807

EP - 1817

JO - ChemPhysChem

JF - ChemPhysChem

IS - 9

ER -

Structural Principles and Thermoelectric Properties of Polytypic Group 14 Clathrate-II Frameworks

Abstract

Funding

Keywords

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