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Title: Using the 18-Electron Rule To Understand the Nominal 19-Electron Half-Heusler NbCoSb with Nb Vacancies

Abstract

The 18-electron rule is a widely used criterion in the search for new half-Heusler thermoelectric materials. However, several 19-electron compounds such as NbCoSb have been found to be stable and exhibit thermoelectric properties rivaling state-of-the art materials. Using synchrotron X-ray diffraction and density functional theory calculations, we show that samples with nominal (19-electron) composition NbCoSb actually contain a half-Heusler phase with composition Nb0.84CoSb. The large amount of stable Nb vacancies reduces the overall electron count, which brings the stoichiometry of the compound close to an 18-electron count, and stabilizes the material. Excess electrons beyond 18 electrons provide heavy doping needed to make these good thermoelectric materials. This work demonstrates that considering possible defect chemistry and allowing small variation of electron counting leads to extra degrees of freedom for tailoring thermoelectric properties and exploring new compounds. Here we discuss the 18-electron rule as a guide to find defect-free half-Heusler semiconductors. As a result, other electron counts such as 19-electron NbCoSb can also be expected to be stable as n-type metals, perhaps with cation vacancy defects to reduce the electron count.

Authors:
ORCiD logo [1];  [2];  [3];  [4];  [4]; ORCiD logo [4]; ORCiD logo [2];  [2]
  1. Justus-Liebig-Univ. Giessen, Giessen (Germany)
  2. Northwestern Univ., Evanston, IL (United States)
  3. Xihua Univ., Sichuan (China)
  4. Univ. of Houston, Houston, TX (United States)
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Solid-State Solar-Thermal Energy Conversion Center (S3TEC)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1388395
Grant/Contract Number:  
SC0001299; FG02-09ER46577; SC0014520; AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 29; Journal Issue: 3; Related Information: S3TEC partners with Massachusetts Institute of Technology (lead); Boston College; Oak Ridge National Laboratory; Rensselaer Polytechnic Institute; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; solar (photovoltaic); solar (thermal); solid state lighting; phonons; thermal conductivity; thermoelectric, defects; mechanical behavior; charge transport; spin dynamics; materials and chemistry by design; optics; synthesis (novel materials); synthesis (self-assembly); synthesis (scalable processing)

Citation Formats

Zeier, Wolfgang G., Anand, Shashwat, Huang, Lihong, He, Ran, Zhang, Hao, Ren, Zhifeng, Wolverton, Chris, and Snyder, G. Jeffrey. Using the 18-Electron Rule To Understand the Nominal 19-Electron Half-Heusler NbCoSb with Nb Vacancies. United States: N. p., 2017. Web. doi:10.1021/acs.chemmater.6b04583.
Zeier, Wolfgang G., Anand, Shashwat, Huang, Lihong, He, Ran, Zhang, Hao, Ren, Zhifeng, Wolverton, Chris, & Snyder, G. Jeffrey. Using the 18-Electron Rule To Understand the Nominal 19-Electron Half-Heusler NbCoSb with Nb Vacancies. United States. https://doi.org/10.1021/acs.chemmater.6b04583
Zeier, Wolfgang G., Anand, Shashwat, Huang, Lihong, He, Ran, Zhang, Hao, Ren, Zhifeng, Wolverton, Chris, and Snyder, G. Jeffrey. Tue . "Using the 18-Electron Rule To Understand the Nominal 19-Electron Half-Heusler NbCoSb with Nb Vacancies". United States. https://doi.org/10.1021/acs.chemmater.6b04583. https://www.osti.gov/servlets/purl/1388395.
@article{osti_1388395,
title = {Using the 18-Electron Rule To Understand the Nominal 19-Electron Half-Heusler NbCoSb with Nb Vacancies},
author = {Zeier, Wolfgang G. and Anand, Shashwat and Huang, Lihong and He, Ran and Zhang, Hao and Ren, Zhifeng and Wolverton, Chris and Snyder, G. Jeffrey},
abstractNote = {The 18-electron rule is a widely used criterion in the search for new half-Heusler thermoelectric materials. However, several 19-electron compounds such as NbCoSb have been found to be stable and exhibit thermoelectric properties rivaling state-of-the art materials. Using synchrotron X-ray diffraction and density functional theory calculations, we show that samples with nominal (19-electron) composition NbCoSb actually contain a half-Heusler phase with composition Nb0.84CoSb. The large amount of stable Nb vacancies reduces the overall electron count, which brings the stoichiometry of the compound close to an 18-electron count, and stabilizes the material. Excess electrons beyond 18 electrons provide heavy doping needed to make these good thermoelectric materials. This work demonstrates that considering possible defect chemistry and allowing small variation of electron counting leads to extra degrees of freedom for tailoring thermoelectric properties and exploring new compounds. Here we discuss the 18-electron rule as a guide to find defect-free half-Heusler semiconductors. As a result, other electron counts such as 19-electron NbCoSb can also be expected to be stable as n-type metals, perhaps with cation vacancy defects to reduce the electron count.},
doi = {10.1021/acs.chemmater.6b04583},
journal = {Chemistry of Materials},
number = 3,
volume = 29,
place = {United States},
year = {Tue Jan 17 00:00:00 EST 2017},
month = {Tue Jan 17 00:00:00 EST 2017}
}

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Works referenced in this record:

Complex thermoelectric materials
journal, February 2008

  • Snyder, G. Jeffrey; Toberer, Eric S.
  • Nature Materials, Vol. 7, Issue 2, p. 105-114
  • DOI: 10.1038/nmat2090

Rapid Microwave Preparation of Thermoelectric TiNiSn and TiCoSb Half-Heusler Compounds
journal, June 2012

  • Birkel, Christina S.; Zeier, Wolfgang G.; Douglas, Jason E.
  • Chemistry of Materials, Vol. 24, Issue 13
  • DOI: 10.1021/cm3011343

Recent progress of half-Heusler for moderate temperature thermoelectric applications
journal, October 2013


Nanoscale structural heterogeneity in Ni-rich half-Heusler TiNiSn
journal, October 2014

  • Douglas, Jason E.; Chater, Philip A.; Brown, Craig M.
  • Journal of Applied Physics, Vol. 116, Issue 16
  • DOI: 10.1063/1.4900497

Compositions and thermoelectric properties of XNiSn (X = Ti, Zr, Hf) half-Heusler alloys
journal, January 2015

  • Downie, R. A.; Barczak, S. A.; Smith, R. I.
  • Journal of Materials Chemistry C, Vol. 3, Issue 40
  • DOI: 10.1039/C5TC02025E

Metal Distributions, Efficient n-Type Doping, and Evidence for in-Gap States in TiNiM y Sn (M = Co, Ni, Cu) half-Heusler Nanocomposites
journal, March 2015

  • Downie, Ruth A.; Smith, Ronald I.; MacLaren, Donald A.
  • Chemistry of Materials, Vol. 27, Issue 7
  • DOI: 10.1021/cm5045682

Recent progress in half-Heusler thermoelectric materials
journal, April 2016


Electronic structure and optical, mechanical, and transport properties of the pure, electron-doped, and hole-doped Heusler compound CoTiSb
journal, July 2012


Charge carrier concentration optimization of thermoelectric p -type half-Heusler compounds
journal, April 2015

  • Rausch, Elisabeth; Balke, Benjamin; Deschauer, Torben
  • APL Materials, Vol. 3, Issue 4
  • DOI: 10.1063/1.4916526

The intrinsic disorder related alloy scattering in ZrNiSn half-Heusler thermoelectric materials
journal, November 2014

  • Xie, Hanhui; Wang, Heng; Fu, Chenguang
  • Scientific Reports, Vol. 4, Issue 1
  • DOI: 10.1038/srep06888

Evaluation of Half-Heusler Compounds as Thermoelectric Materials Based on the Calculated Electrical Transport Properties
journal, October 2008

  • Yang, Jiong; Li, Huanming; Wu, Ting
  • Advanced Functional Materials, Vol. 18, Issue 19, p. 2880-2888
  • DOI: 10.1002/adfm.200701369

Enhancement in Thermoelectric Figure-Of-Merit of an N-Type Half-Heusler Compound by the Nanocomposite Approach
journal, May 2011

  • Joshi, Giri; Yan, Xiao; Wang, Hengzhi
  • Advanced Energy Materials, Vol. 1, Issue 4, p. 643-647
  • DOI: 10.1002/aenm.201100126

Thermoelectric performance of nanostructured p-type Zr0.5Hf0.5Co0.4Rh0.6Sb1−xSnx half-Heusler alloys
journal, June 2013

  • Maji, Pramathesh; Makongo, Julien P. A.; Zhou, Xiaoyuan
  • Journal of Solid State Chemistry, Vol. 202
  • DOI: 10.1016/j.jssc.2013.03.024

Simultaneous Large Enhancements in Thermopower and Electrical Conductivity of Bulk Nanostructured Half-Heusler Alloys
journal, November 2011

  • Makongo, Julien P. A.; Misra, Dinesh K.; Zhou, Xiaoyuan
  • Journal of the American Chemical Society, Vol. 133, Issue 46
  • DOI: 10.1021/ja206491j

Recent Advances in Nanostructured Thermoelectric Half-Heusler Compounds
journal, November 2012

  • Xie, Wenjie; Weidenkaff, Anke; Tang, Xinfeng
  • Nanomaterials, Vol. 2, Issue 4
  • DOI: 10.3390/nano2040379

Large Enhancements of Thermopower and Carrier Mobility in Quantum Dot Engineered Bulk Semiconductors
journal, May 2013

  • Liu, Yuanfeng; Sahoo, Pranati; Makongo, Julien P. A.
  • Journal of the American Chemical Society, Vol. 135, Issue 20
  • DOI: 10.1021/ja311059m

Thermoelectric Property Study of Nanostructured p-Type Half-Heuslers (Hf, Zr, Ti)CoSb 0.8 Sn 0.2
journal, May 2013


Stronger phonon scattering by larger differences in atomic mass and size in p-type half-Heuslers Hf1−xTixCoSb0.8Sn0.2
journal, January 2012

  • Yan, Xiao; Liu, Weishu; Wang, Hui
  • Energy & Environmental Science, Vol. 5, Issue 6, p. 7543-7548
  • DOI: 10.1039/c2ee21554c

Beneficial Contribution of Alloy Disorder to Electron and Phonon Transport in Half-Heusler Thermoelectric Materials
journal, April 2013

  • Xie, Hanhui; Wang, Heng; Pei, Yanzhong
  • Advanced Functional Materials, Vol. 23, Issue 41
  • DOI: 10.1002/adfm.201300663

Engineering half-Heusler thermoelectric materials using Zintl chemistry
journal, May 2016

  • Zeier, Wolfgang G.; Schmitt, Jennifer; Hautier, Geoffroy
  • Nature Reviews Materials, Vol. 1, Issue 6
  • DOI: 10.1038/natrevmats.2016.32

High Efficiency Half-Heusler Thermoelectric Materials for Energy Harvesting
journal, July 2015

  • Zhu, Tiejun; Fu, Chenguang; Xie, Hanhui
  • Advanced Energy Materials, Vol. 5, Issue 19
  • DOI: 10.1002/aenm.201500588

Band engineering of high performance p-type FeNbSb based half-Heusler thermoelectric materials for figure of merit zT > 1
journal, January 2015

  • Fu, Chenguang; Zhu, Tiejun; Liu, Yintu
  • Energy & Environmental Science, Vol. 8, Issue 1
  • DOI: 10.1039/C4EE03042G

Simple rules for the understanding of Heusler compounds
journal, May 2011


(Zr,Hf)Co(Sb,Sn) half-Heusler phases as high-temperature (>700°C) p-type thermoelectric materials
journal, July 2008

  • Culp, Slade R.; Simonson, J. W.; Poon, S. Joseph
  • Applied Physics Letters, Vol. 93, Issue 2
  • DOI: 10.1063/1.2959103

A new n-type half-Heusler thermoelectric material NbCoSb
journal, October 2015


Synthesis and thermoelectric properties of n-type half-Heusler compound VCoSb with valence electron count of 19
journal, January 2016


Thinking Like a Chemist: Intuition in Thermoelectric Materials
journal, April 2016

  • Zeier, Wolfgang G.; Zevalkink, Alex; Gibbs, Zachary M.
  • Angewandte Chemie International Edition, Vol. 55, Issue 24
  • DOI: 10.1002/anie.201508381

Recent advances in magnetic structure determination by neutron powder diffraction
journal, October 1993


Density Functional Theory of Electronic Structure
journal, January 1996

  • Kohn, W.; Becke, A. D.; Parr, R. G.
  • The Journal of Physical Chemistry, Vol. 100, Issue 31
  • DOI: 10.1021/jp960669l

Ab initio molecular-dynamics simulation of the liquid-metal–amorphous-semiconductor transition in germanium
journal, May 1994


Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set
journal, October 1996


From ultrasoft pseudopotentials to the projector augmented-wave method
journal, January 1999


Projector augmented-wave method
journal, December 1994


Generalized Gradient Approximation Made Simple
journal, October 1996

  • Perdew, John P.; Burke, Kieron; Ernzerhof, Matthias
  • Physical Review Letters, Vol. 77, Issue 18, p. 3865-3868
  • DOI: 10.1103/PhysRevLett.77.3865

The Open Quantum Materials Database (OQMD): assessing the accuracy of DFT formation energies
journal, December 2015


Materials Design and Discovery with High-Throughput Density Functional Theory: The Open Quantum Materials Database (OQMD)
journal, September 2013


The alloy theoretic automated toolkit: A user guide
journal, December 2002


Automating first-principles phase diagram calculations
journal, August 2002


Synthesis and characterization of Fe-Ti-Sb intermetallic compounds: Discovery of a new Slater-Pauling phase
journal, March 2016


Nonstoichiometry in the Zintl Phase Yb 1−δ Zn 2 Sb 2 as a Route to Thermoelectric Optimization
journal, September 2014

  • Zevalkink, Alex; Zeier, Wolfgang G.; Cheng, Ethan
  • Chemistry of Materials, Vol. 26, Issue 19
  • DOI: 10.1021/cm502588r

In-gap Electronic States Responsible for the Excellent Thermoelectric Properties of Ni-based Half-Heusler Alloys
journal, July 2008

  • Miyamoto, Koji; Kimura, Akio; Sakamoto, Kazuaki
  • Applied Physics Express, Vol. 1
  • DOI: 10.1143/APEX.1.081901

Electronic and Local Crystal Structures of the ZrNiSn Half-Heusler Thermoelectric Material
journal, January 2014


Direct observation of the electronic structure in thermoelectric half-Heusler alloys Zr 1− x M x NiSn ( M  = Y and Nb)
journal, May 2015

  • Hattori, Kengo; Miyazaki, Hidetoshi; Yoshida, Kento
  • Journal of Applied Physics, Vol. 117, Issue 20
  • DOI: 10.1063/1.4921812

Interrelation between atomic switching disorder and thermoelectric properties of ZrNiSn half-Heusler compounds
journal, January 2012

  • Xie, Han-Hui; Mi, Jian-Li; Hu, Li-Peng
  • CrystEngComm, Vol. 14, Issue 13
  • DOI: 10.1039/c2ce25119a

Special quasirandom structures
journal, July 1990


Unfolding spinor wave functions and expectation values of general operators: Introducing the unfolding-density operator
journal, January 2015


Extracting E versus k effective band structure from supercell calculations on alloys and impurities
journal, February 2012


High Thermoelectric Performance SnTe–In 2 Te 3 Solid Solutions Enabled by Resonant Levels and Strong Vacancy Phonon Scattering
journal, November 2015


Influence of Compensating Defect Formation on the Doping Efficiency and Thermoelectric Properties of Cu 2-y Se 1– x Br x
journal, October 2015


Determining conductivity and mobility values of individual components in multiphase composite Cu 1.97 Ag 0.03 Se
journal, October 2014

  • Day, Tristan W.; Zeier, Wolfgang G.; Brown, David R.
  • Applied Physics Letters, Vol. 105, Issue 17
  • DOI: 10.1063/1.4897435

Works referencing / citing this record:

Temperature Dependent n-Type Self Doping in Nominally 19-Electron Half-Heusler Thermoelectric Materials
journal, September 2018

  • Anand, Shashwat; Xia, Kaiyang; Zhu, Tiejun
  • Advanced Energy Materials, Vol. 8, Issue 30
  • DOI: 10.1002/aenm.201801409

The Effects of Excess Co on the Phase Composition and Thermoelectric Properties of Half-Heusler NbCoSb
journal, May 2018

  • Huang, Lihong; Wang, Junchen; Chen, Xi
  • Materials, Vol. 11, Issue 5
  • DOI: 10.3390/ma11050773

Design of High‐Performance Disordered Half‐Heusler Thermoelectric Materials Using 18‐Electron Rule
journal, August 2019

  • Liu, Zihang; Guo, Shuping; Wu, Yixuan
  • Advanced Functional Materials, Vol. 29, Issue 44
  • DOI: 10.1002/adfm.201905044

Impact of Nb vacancies and p-type doping of the NbCoSn–NbCoSb half-Heusler thermoelectrics
journal, January 2018

  • Ferluccio, Daniella A.; Smith, Ronald I.; Buckman, Jim
  • Physical Chemistry Chemical Physics, Vol. 20, Issue 6
  • DOI: 10.1039/c7cp07521a

Band Structures and Transport Properties of High-Performance Half-Heusler Thermoelectric Materials by First Principles
journal, May 2018

  • Fang, Teng; Zhao, Xinbing; Zhu, Tiejun
  • Materials, Vol. 11, Issue 5
  • DOI: 10.3390/ma11050847

Low thermal conductivity and promising thermoelectric performance in A x CoSb (A = V, Nb or Ta) half-Heuslers with inherent vacancies
journal, January 2019

  • Ferluccio, Daniella A.; Halpin, John E.; MacIntosh, Kathryn L.
  • Journal of Materials Chemistry C, Vol. 7, Issue 22
  • DOI: 10.1039/c9tc00743a

A valence balanced rule for discovery of 18-electron half-Heuslers with defects
journal, January 2018

  • Anand, Shashwat; Xia, Kaiyang; I. Hegde, Vinay
  • Energy & Environmental Science, Vol. 11, Issue 6
  • DOI: 10.1039/c8ee00306h

Improving the Thermoelectric Properties of the Half-Heusler Compound VCoSb by Vanadium Vacancy
journal, May 2019

  • Huang, Lihong; Wang, Junchen; Mo, Xiaobo
  • Materials, Vol. 12, Issue 10
  • DOI: 10.3390/ma12101637

Enhanced Thermoelectric Performance in 18-Electron Nb 0.8 CoSb Half-Heusler Compound with Intrinsic Nb Vacancies
journal, January 2018

  • Xia, Kaiyang; Liu, Yintu; Anand, Shashwat
  • Advanced Functional Materials, Vol. 28, Issue 9
  • DOI: 10.1002/adfm.201705845

Short-range order in defective half-Heusler thermoelectric crystals
journal, January 2019

  • Xia, Kaiyang; Nan, Pengfei; Tan, Shihua
  • Energy & Environmental Science, Vol. 12, Issue 5
  • DOI: 10.1039/c8ee03654c

Vacancy and anti-site disorder scattering in AgBiSe 2 thermoelectrics
journal, January 2017

  • Böcher, Felix; Culver, Sean P.; Peilstöcker, Jan
  • Dalton Transactions, Vol. 46, Issue 12
  • DOI: 10.1039/c7dt00381a

High performance p-type half-Heusler thermoelectric materials
journal, February 2018

  • Yu, Junjie; Xia, Kaiyang; Zhao, Xinbing
  • Journal of Physics D: Applied Physics, Vol. 51, Issue 11
  • DOI: 10.1088/1361-6463/aaaa58

The Effects of Excess Co on the Phase Composition and Thermoelectric Properties of Half-Heusler NbCoSb
journal, May 2018

  • Huang, Lihong; Wang, Junchen; Chen, Xi
  • Materials, Vol. 11, Issue 5
  • DOI: 10.3390/ma11050773

Band Structures and Transport Properties of High-Performance Half-Heusler Thermoelectric Materials by First Principles
journal, May 2018

  • Fang, Teng; Zhao, Xinbing; Zhu, Tiejun
  • Materials, Vol. 11, Issue 5
  • DOI: 10.3390/ma11050847

Improving the Thermoelectric Properties of the Half-Heusler Compound VCoSb by Vanadium Vacancy
journal, May 2019

  • Huang, Lihong; Wang, Junchen; Mo, Xiaobo
  • Materials, Vol. 12, Issue 10
  • DOI: 10.3390/ma12101637