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Title: Ag 2Se to KAg 3Se 2: Suppressing Order–Disorder Transitions via Reduced Dimensionality

Abstract

Here we report an order–disorder phase transition in the 2D semiconductor KAg 3Se 2, which is a dimensionally reduced derivative of 3D Ag 2Se. At ~695 K, the room temperature β-phase (CsAg 3S 2 structure type, monoclinic space group C2/m) transforms to the high temperature α-phase (new structure type, hexagonal space group R$$ \overline{3}\ $$m, a = 4.5638(5) Å, c = 25.4109(6) Å), as revealed by in situ temperature-dependent X-ray diffraction. Significant Ag + ion disorder accompanies the phase transition, which resembles the low temperature (~400 K) superionic transition in the 3D parent compound. Ultralow thermal conductivity of ~0.4 W m –1 K –1 was measured in the “ordered” β-phase, suggesting anharmonic Ag motion efficiently impedes phonon transport even without extensive disordering. The optical and electronic properties of β-KAg 3Se 2 are modified as expected in the context of the dimensional reduction framework. UV–vis spectroscopy shows an optical band gap of ~1 eV that is indirect in nature as confirmed by electronic structure calculations. Electronic transport measurements on β-KAg 3Se 2 yielded n-type behavior with a high electron mobility of ~400 cm 2 V –1 s –1 at 300 K due to a highly disperse conduction band. Finally, our results thus imply that dimensional reduction may be used as a design strategy to frustrate order–disorder phenomena while retaining desirable electronic and thermal properties.

Authors:
ORCiD logo [1];  [2];  [1];  [2];  [3];  [4];  [1]; ORCiD logo [5]
  1. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division
  2. Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry
  3. Center for High Pressure Science and Technology Advanced Research, Shanghai (China); Carnegie Inst. of Washington, Argonne, IL (United States). HPSynC. Geophysical Lab.
  4. Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science
  5. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division; Center for High Pressure Science and Technology Advanced Research, Shanghai (China)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States); Northwestern Univ., Evanston, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
OSTI Identifier:
1482168
Grant/Contract Number:  
[AC02-06CH11357; 5J-30161-0010A; ECCS-1542205]
Resource Type:
Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
[ Journal Volume: 140; Journal Issue: 29]; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Rettie, Alexander J. E., Malliakas, Christos D., Botana, Antia S., Hodges, James M., Han, Fei, Huang, Ruiyun, Chung, Duck Young, and Kanatzidis, Mercouri G. Ag2Se to KAg3Se2: Suppressing Order–Disorder Transitions via Reduced Dimensionality. United States: N. p., 2018. Web. doi:10.1021/jacs.8b04888.
Rettie, Alexander J. E., Malliakas, Christos D., Botana, Antia S., Hodges, James M., Han, Fei, Huang, Ruiyun, Chung, Duck Young, & Kanatzidis, Mercouri G. Ag2Se to KAg3Se2: Suppressing Order–Disorder Transitions via Reduced Dimensionality. United States. doi:10.1021/jacs.8b04888.
Rettie, Alexander J. E., Malliakas, Christos D., Botana, Antia S., Hodges, James M., Han, Fei, Huang, Ruiyun, Chung, Duck Young, and Kanatzidis, Mercouri G. Wed . "Ag2Se to KAg3Se2: Suppressing Order–Disorder Transitions via Reduced Dimensionality". United States. doi:10.1021/jacs.8b04888. https://www.osti.gov/servlets/purl/1482168.
@article{osti_1482168,
title = {Ag2Se to KAg3Se2: Suppressing Order–Disorder Transitions via Reduced Dimensionality},
author = {Rettie, Alexander J. E. and Malliakas, Christos D. and Botana, Antia S. and Hodges, James M. and Han, Fei and Huang, Ruiyun and Chung, Duck Young and Kanatzidis, Mercouri G.},
abstractNote = {Here we report an order–disorder phase transition in the 2D semiconductor KAg3Se2, which is a dimensionally reduced derivative of 3D Ag2Se. At ~695 K, the room temperature β-phase (CsAg3S2 structure type, monoclinic space group C2/m) transforms to the high temperature α-phase (new structure type, hexagonal space group R$ \overline{3}\ $m, a = 4.5638(5) Å, c = 25.4109(6) Å), as revealed by in situ temperature-dependent X-ray diffraction. Significant Ag+ ion disorder accompanies the phase transition, which resembles the low temperature (~400 K) superionic transition in the 3D parent compound. Ultralow thermal conductivity of ~0.4 W m–1 K–1 was measured in the “ordered” β-phase, suggesting anharmonic Ag motion efficiently impedes phonon transport even without extensive disordering. The optical and electronic properties of β-KAg3Se2 are modified as expected in the context of the dimensional reduction framework. UV–vis spectroscopy shows an optical band gap of ~1 eV that is indirect in nature as confirmed by electronic structure calculations. Electronic transport measurements on β-KAg3Se2 yielded n-type behavior with a high electron mobility of ~400 cm2 V–1 s–1 at 300 K due to a highly disperse conduction band. Finally, our results thus imply that dimensional reduction may be used as a design strategy to frustrate order–disorder phenomena while retaining desirable electronic and thermal properties.},
doi = {10.1021/jacs.8b04888},
journal = {Journal of the American Chemical Society},
number = [29],
volume = [140],
place = {United States},
year = {2018},
month = {6}
}

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Works referencing / citing this record:

CSD 1861988: Experimental Crystal Structure Determination: Non-CSD Structure
dataset, August 2018

  • Rettie, Alexander J. E.; Malliakas, Christos D.; Botana, Antia S.
  • Cambridge Structural Database (CSD)
  • DOI: 10.25505/fiz.icsd.cc20hk47