Zintl phase Yb1−xCaxCd2Sb2 with tunable thermoelectric properties induced by cation substitution

Abstract

It has been shown previously that the thermoelectric properties of the Zintl phase compound YbCd2Sb2 can be finely tuned via Zn substitution at the Cd-site in the anionic (Cd2Sb2)2− framework. Here we report the results of the investigation of isoelectronic substitution of Yb by Ca. The p-type Yb1−xCaxCd2Sb2 (0.2≤x≤0.8) samples have been synthesized via a solid-state reaction followed by suitable cooling, annealing, grinding, and spark plasma sintering densification processes. In samples with x=0.2, 0.4, 0.5, 0.6, 0.8, the electrical conductivity, Seebeck coefficient, and thermal conductivity measurements have been carried out in the temperature range from 300 to 650 K. It is found that the Ca substitution effectively lowers the thermal conductivity for all samples at high temperature, while it significantly increases the Seebeck coefficient. As a result, the dimensionless figure of merit ZT of 0.96 has been attained at 650 K for samples with x=0.4, while the value is 0.78 for the unsubstituted YbCd2Sb2

CdI2 structure type as potential thermoelectric materials: Synthesis and high temperature thermoelectric properties of the solid solution TiSxSe2−x

“…For example, several compounds crystallizing in the layered structures type CaAl 2 Si 2 and CdI 2 have respectable thermoelectric properties and more importantly demonstrate that there is a great deal of compounds susceptible of possessing interesting thermoelectric properties precisely because of the flexibility 0925-8388/$ -see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2012.01.067 of the structures and thus because of the numerous chemical compositions that can adopt such adaptable structures [7][8][9][10][11][12]15,17]. In these structures, whereas various species can be intercalated between the layers, it is also often possible to introduce compositional disorder within the layer itself by using multiple cations (transition metals) and/or multiple anions.…”

“…In fact, the past few years have witnessed the emergence of new families of compounds, some of which are now regarded as promising thermoelectric materials. It is the case of certain Zintl phases such as Yb 14 MnSb 11 and its derivative for high temperature spatial applications [2][3][4][5][6], or some members of the CaAl 2 Si 2 structure type [7][8][9][10][11][12]. Other such new families are the molybdenum selenides based on Mo 9 Se 11 clusters [13], and layered sulfides [14,15], oxyselenides [16] or selenides [17].…”

Thermoelectric properties of Na-doped Zintl compound: Mg3−Na Sb2

“…Zintl phase compounds, formed between the alkali or alkaline-earth metals and the post-transition elements from group 13-15, have been shown to be promising candidates for thermoelectric materials [2,27] due to their complex crystal structures, resulting in low lattice thermal conductivities. A variety of Zintl phases, such as Yb 14 MnSb 11 [28], YbZn 2 Sb 2 [29], YbCd 2 Sb 2 [30], Eu 5 In 2 Sb 6 [31], Ba 8 Ga 16 Ge 30 [32], and CsBi 4 Te 6 [33] have been widely investigated for their thermoelectric properties. However, most of Zintl phase materials are made of expensive rare earth elements and/or toxic elements, resulting in limitation for their application in power generation and refrigeration.…”

Designing high-performance layered thermoelectric materials through orbital engineering

“…Here, taking layered CaAl 2 Si 2 -type Zintl compounds as an example, we combine first principles calculations and reported experimental data18192021222324252627282930313233 to demonstrate how the TE properties can be rationalized in terms of a simple crystal field scheme of orbitals splitting. Thereby, a powerful selection rule only based on band structure parameters is established as a simplified descriptor of electrical transport performance.…”