Journal Article

PUBDB-2018-02407

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Pressure-induced changes of the structure and properties of monoclinic $\alpha$-chalcocite $\mathrm{Cu_{2}}S$

Zimmer, D. (Corresponding author)Extern* ; Ruiz-Fuertes, J. ; Morgenroth, W.Extern* ; Friedrich, A.Extern* ; Bayarjargal, L. ; Haussühl, E. ; Santamaría-Pérez, D. ; Frischkorn, S. ; Milman, V. ; Winkler, B.Extern*

2018
APS Woodbury, NY

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Please use a persistent id in citations: doi:10.1103/PhysRevB.97.134111  doi:10.3204/PUBDB-2018-02407

Abstract: The high-pressure behavior of monoclinic $(P2_{1}/c)\alpha$-chalcocite, $\mathrm{Cu_{2}}S$, was investigated at ambient temperature by single-crystal x-ray diffraction, electrical resistance measurements, and optical absorption spectroscopy up to 16 GPa. The experiments were complemented by density-functional-theory-based calculations. Single-crystal x-ray diffraction data show that monoclinic $\alpha$-chalcocite undergoes two pressure-induced first-order phase transitions at ∼3.1 and ∼7.1 GPa. The crystal structure of the first high-pressure polymorph, HP1, was solved and refined in space group $P2_{1}/c$ with $a=10.312(4)Å, b=6.737(3)Å, c=7.305(1)Å$, and β=$100.17(2)∘$ at 6.2(3) GPa. The crystal structure of the second high-pressure polymorph, HP2, was solved and refined in space group $P2_{1}/c$ with $a=6.731(4)Å, b=6.689(2)Å, c=6.967(8)Å$, and β=$93.18(3)∘$ at 7.9(4) GPa. Electrical resistance measurements upon compression and optical absorption experiments upon decompression show that the structural changes in α-chalcocite are accompanied by changes of the electrical and optical properties. Upon pressure release, the band gap $Eg$ of $\alpha$-chalcocite (1.24 eV at ambient conditions) widens across the first structural phase transition, going from 1.24 eV at 2.2 GPa (α-chalcocite) to 1.35 eV at 2.6 GPa (HP1), and closes significantly across the second phase transition, going from 1.32 eV at 4.4 GPa (HP1) to 0.87 eV at 4.9 GPa (HP2). The electrical resistance shows similar behavior: its highest value is for the first high-pressure polymorph (HP1), and its lowest value is for the second high-pressure polymorph (HP2) of $\alpha$-chalcocite. These results are interpreted on the basis of calculated electronic band structures.

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Contributing Institute(s):

1. DOOR-User (DOOR)
2. Universität Frankfurt (UFrankf.)

Research Program(s):

1. 6G3 - PETRA III (POF3-622) (POF3-622)

Experiment(s):

1. PETRA Beamline P02.2 (PETRA III)

Appears in the scientific report 2018

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Database coverage:
; ; ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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