Ag2Se to KAg3Se2: Suppressing Order-Disorder Transitions via Reduced Dimensionality

Alexander J.E. Rettie, Christos D. Malliakas, Antia S. Botana, James M. Hodges, Fei Han, Ruiyun Huang, Duck Young Chung, Mercouri G Kanatzidis

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

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 R3m, 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. 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.

Original languageEnglish
Pages (from-to)9193-9202
Number of pages10
JournalJournal of the American Chemical Society
Volume140
Issue number29
DOIs
Publication statusPublished - Jul 25 2018

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Order disorder transitions
Temperature
Phase Transition
Phase structure
Electronic properties
Phase transitions
Phonons
Thermal Conductivity
Semiconductors
Electron mobility
Optical band gaps
Conduction bands
Ultraviolet spectroscopy
X-Ray Diffraction
Electronic structure
Thermal conductivity
Spectrum Analysis
Thermodynamic properties
Optical properties
Hot Temperature

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Ag2Se to KAg3Se2 : Suppressing Order-Disorder Transitions via Reduced Dimensionality. / Rettie, Alexander J.E.; Malliakas, Christos D.; Botana, Antia S.; Hodges, James M.; Han, Fei; Huang, Ruiyun; Chung, Duck Young; Kanatzidis, Mercouri G.

In: Journal of the American Chemical Society, Vol. 140, No. 29, 25.07.2018, p. 9193-9202.

Research output: Contribution to journalArticle

Rettie, AJE, Malliakas, CD, Botana, AS, Hodges, JM, Han, F, Huang, R, Chung, DY & Kanatzidis, MG 2018, 'Ag2Se to KAg3Se2: Suppressing Order-Disorder Transitions via Reduced Dimensionality', Journal of the American Chemical Society, vol. 140, no. 29, pp. 9193-9202. https://doi.org/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. In: Journal of the American Chemical Society. 2018 ; Vol. 140, No. 29. pp. 9193-9202.
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