IngentaConnect High-pressure phase transformation of the silicon clathrate Si136

Authors: Ramachandran G.K.¹; McMillan P.F.¹; Deb S.K.²; Somayazulu M.²; Gryko J.³; Dong J.⁴; Sankey O.F.⁴

Source: Journal of Physics: Condensed Matter, Volume 12, Number 17, 2000 , pp. 4013-4020(8)

Publisher: Institute of Physics Publishing

Abstract:

The compressional behaviour of a new expanded form of silicon, the cubic Si₁₃₆ clathrate, is studied by energy dispersive x-ray diffraction in a diamond anvil cell experiment. The ambient temperature bulk modulus and its pressure derivative are determined to be [iopmath latex="$K_0=90(3)$"] K₀ = 90(3) [/iopmath] GPa and [iopmath latex="$K_0'=5.2(8)$"] K₀' = 5.2(8) [/iopmath] , in agreement with LDA theoretical calculations. At pressures between 8 and 10 GPa, the structure transforms into the thermodynamically stable [iopmath latex="$\beta$"] [/iopmath] -Sn phase. This behaviour is analogous to that of diamond-structured silicon. However, the metastable transition from Si₁₃₆ to the [iopmath latex="$\beta$"] [/iopmath] -Sn structure should occur at a much lower pressure (3-4 GPa), from consideration of free energy-pressure relations. The observation can be related to the absence of a convenient low-energy pathway for the IV- to VI-fold coordination change involved in the transition from Si₁₃₆ to [iopmath latex="$\beta$"] [/iopmath] -Sn.

Language: English

Document Type: Miscellaneous

Affiliations: 1: Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA 2: Center for Solid State Science, Arizona State University, Tempe, AZ 85287, USA 3: Department of Earth and Physical Sciences, Jacksonville State University, AL 36235, USA 4: Department of Physics and Astronomy, Arizona State University, Tempe, AZ 85287, USA

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