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Title: From NaZn 4Sb 3 to HT-Na 1–xZn 4–ySb 3 : Panoramic Hydride Synthesis, Structural Diversity, and Thermoelectric Properties

Abstract

Two new sodium zinc antimonides NaZn 4Sb 3 and $HT$-Na 1-xZn 4-ySb 3 were synthesized by using reactive sodium hydride, NaH, as a precursor. The hydride route provides uniform mixing and comprehensive control over the composition, facilitating fast reactions and high-purity samples, whereas traditional synthesis using sodium metal results in inhomogeneous samples with a significant fraction of the more stable NaZnSb compound. NaZn 4Sb 3 crystalizes in the hexagonal $P$6 3/$mmc$ space group (No. 194, Z=2, a=4.43579(4) Å, c = 23.41553(9) Å), and is stable upon heating in vacuum up to 736 K. The layered crystal structure of NaZn 4Sb 3 is related to the structure of the well-studied thermoelectric antimonides AeZn 2Sb 2 (Ae = Ca, Sr, Eu). Upon heating in vacuum NaZn 4Sb 3 transforms to $HT$-Na 1-xZn 4-ySb 3 (x = 0.047(3), $y$ = 0.135(1)) due to partial Na/Zn evaporation/elimination, as was determined from high-temperature in-situ synchrotron powder X-ray diffraction. $HT$-Na 1-xZn 4-ySb 3 has a complex monoclinic structure with considerable degrees of structural disorder ($$P2_1/c$$ (No. 14, $Z$=32), a=19.5366(7) Å, b=14.7410(5) Å, c = 20.7808(7) Å, $β$ = 90.317(2)°) and is stable exclusively in a narrow temperature range of 736-885 K. Further heating of HT-Na 1-xZn 4-ySb 3 leads to a reversible transformation to NaZnSb above 883 K. Both compounds exhibit similarly low thermal conductivity at room temperature (0.9 W∙m -1 K -1) and positive Seebeck coefficients (38–52 $μ$V/K) indicative of holes as the main charge carriers. However, resistivities of the two phases differ by two orders of magnitude.

Authors:
 [1]; ORCiD logo [2];  [1];  [1];  [1];  [2]; ORCiD logo [3];  [3]; ORCiD logo [4];  [4]; ORCiD logo [1]
  1. Iowa State Univ., Ames, IA (United States). Dept. of Chemistry
  2. Iowa State Univ., Ames, IA (United States). Dept. of Chemistry; Ames Lab., Ames, IA (United States)
  3. Ames Lab., Ames, IA (United States)
  4. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States). Dept of Physics & Astronomy,
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1572381
Report Number(s):
IS-J 10066
Journal ID: ISSN 0897-4756
Grant/Contract Number:  
AC02-07CH11358
Resource Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 31; Journal Issue: 21; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Gvozdetskyi, Volodymyr, Owens-Baird, Bryan, Hong, Sangki, Cox, Tori, Bhaskar, Gourab, Harmer, Colin, Sun, Yang, Zhang, Feng, Wang, Cai-Zhuang, Ho, Kai-Ming, and Zaikina, Julia V. From NaZn4Sb3 to HT-Na1–xZn4–ySb3 : Panoramic Hydride Synthesis, Structural Diversity, and Thermoelectric Properties. United States: N. p., 2019. Web. doi:10.1021/acs.chemmater.9b02239.
Gvozdetskyi, Volodymyr, Owens-Baird, Bryan, Hong, Sangki, Cox, Tori, Bhaskar, Gourab, Harmer, Colin, Sun, Yang, Zhang, Feng, Wang, Cai-Zhuang, Ho, Kai-Ming, & Zaikina, Julia V. From NaZn4Sb3 to HT-Na1–xZn4–ySb3 : Panoramic Hydride Synthesis, Structural Diversity, and Thermoelectric Properties. United States. doi:10.1021/acs.chemmater.9b02239.
Gvozdetskyi, Volodymyr, Owens-Baird, Bryan, Hong, Sangki, Cox, Tori, Bhaskar, Gourab, Harmer, Colin, Sun, Yang, Zhang, Feng, Wang, Cai-Zhuang, Ho, Kai-Ming, and Zaikina, Julia V. Thu . "From NaZn4Sb3 to HT-Na1–xZn4–ySb3 : Panoramic Hydride Synthesis, Structural Diversity, and Thermoelectric Properties". United States. doi:10.1021/acs.chemmater.9b02239.
@article{osti_1572381,
title = {From NaZn4Sb3 to HT-Na1–xZn4–ySb3 : Panoramic Hydride Synthesis, Structural Diversity, and Thermoelectric Properties},
author = {Gvozdetskyi, Volodymyr and Owens-Baird, Bryan and Hong, Sangki and Cox, Tori and Bhaskar, Gourab and Harmer, Colin and Sun, Yang and Zhang, Feng and Wang, Cai-Zhuang and Ho, Kai-Ming and Zaikina, Julia V.},
abstractNote = {Two new sodium zinc antimonides NaZn4Sb3 and $HT$-Na1-xZn4-ySb3 were synthesized by using reactive sodium hydride, NaH, as a precursor. The hydride route provides uniform mixing and comprehensive control over the composition, facilitating fast reactions and high-purity samples, whereas traditional synthesis using sodium metal results in inhomogeneous samples with a significant fraction of the more stable NaZnSb compound. NaZn4Sb3 crystalizes in the hexagonal $P$63/$mmc$ space group (No. 194, Z=2, a=4.43579(4) Å, c = 23.41553(9) Å), and is stable upon heating in vacuum up to 736 K. The layered crystal structure of NaZn4Sb3 is related to the structure of the well-studied thermoelectric antimonides AeZn2Sb2 (Ae = Ca, Sr, Eu). Upon heating in vacuum NaZn4Sb3 transforms to $HT$-Na1-xZn4-ySb3 (x = 0.047(3), $y$ = 0.135(1)) due to partial Na/Zn evaporation/elimination, as was determined from high-temperature in-situ synchrotron powder X-ray diffraction. $HT$-Na1-xZn4-ySb3 has a complex monoclinic structure with considerable degrees of structural disorder ($P2_1/c$ (No. 14, $Z$=32), a=19.5366(7) Å, b=14.7410(5) Å, c = 20.7808(7) Å, $β$ = 90.317(2)°) and is stable exclusively in a narrow temperature range of 736-885 K. Further heating of HT-Na1-xZn4-ySb3 leads to a reversible transformation to NaZnSb above 883 K. Both compounds exhibit similarly low thermal conductivity at room temperature (0.9 W∙m-1 K-1) and positive Seebeck coefficients (38–52 $μ$V/K) indicative of holes as the main charge carriers. However, resistivities of the two phases differ by two orders of magnitude.},
doi = {10.1021/acs.chemmater.9b02239},
journal = {Chemistry of Materials},
number = 21,
volume = 31,
place = {United States},
year = {2019},
month = {10}
}

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This content will become publicly available on October 3, 2020
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