Scientific Results

Synthesis and Raman spectroscopy of a layered SiS2 phase at high pressures

Year: 2018

Authors: Wang Yu., Jiang SQ., Goncharov AF., Alexander F., Gorelli F., Chen XJ., Plasienka D., Martonak R., Tosatti E., Santoro M.

Autors Affiliation: [Wang, Yu; Jiang, Shu-Qing; Goncharov, Alexander F.] Chinese Acad Sci, Key Lab Mat Phys, Inst Solid State Phys, 350 Shushanghu Rd, Hefei 230031, Anhui, Peoples R China and Chinese Acad Sci, Ctr Energy Matter Extreme Environm, Inst Solid State Phys, 350 Shushanghu Rd, Hefei 230031, Anhui, Peoples R China.
[Wang, Yu] Univ Sci & Technol China, Hefei 230026, Anhui, Peoples R China.
[Goncharov, Alexander F.] Carnegie Inst Sci, Geophys Lab, 5251 Broad Branch Rd, Washington, DC 20015 USA.
[Gorelli, Federico A.; Santoro, Mario] CNR, INO, Via N Carrara 1, I-50019 Sesto Fiorentino, Italy and European Lab Non Linear Spect LENS, Via N Carrara 1, I-50019 Sesto Fiorentino, Italy.
[Chen, Xiao-Jia] Ctr High Pressure Sci & Technol Adv Res, Shanghai 201203, Peoples R China.
[Plasienka, Dusan; Martonak, Roman] Comenius Univ, Dept Expt Phys, Fac Math Phys & Informat, Mlynska Dolina F2, Bratislava 84248, Slovakia.
[Tosatti, Erio] Int Sch Adv Studies SISSA, Via Bonomea 265, I-34136 Trieste, Italy and CNR IOM Democritos, Via Bonomea 265, I-34136 Trieste, Italy and Abdus Salam Int Ctr Theoret Phys ICTP, Str Costiera 11, I-34151 Trieste, Italy.

Abstract: Dichalcogenides are known to exhibit layered solid phases, at ambient and high pressures, where 2D layers of chemically bonded formula units are held together by van derWaals forces. These materials are of great interest for solid-state sciences and technology, along with other 2D systems such as graphene and phosphorene. SiS2 is an archetypal model system of the most fundamental interest within this ensemble. Recently, high pressure (GPa) phases with Si in octahedral coordination by S have been theoretically predicted and also experimentally found to occur in this compound. At variance with stishovite in SiO2, which is a 3D network of SiO6 octahedra, the phases with octahedral coordination in SiS2 are 2D layered. Very importantly, this type of semiconducting material was theoretically predicted to exhibit continuous bandgap closing with pressure to a poor metallic state at tens of GPa. We synthesized layered SiS2 with octahedral coordination in a diamond anvil cell at 7.5-9 GPa, by laser heating together elemental S and Si at 1300-1700 K. Indeed, Raman spectroscopy up to 64.4 GPa is compatible with continuous bandgap closing in this material with the onset of either weak metallicity or of a narrow bandgap semiconductor state with a large density of defect-induced, intra-gap energy levels, at about 57 GPa. Importantly, our investigation adds up to the fundamental knowledge of layered dichalcogenides.

Journal/Review: JOURNAL OF CHEMICAL PHYSICS

Volume: 148 (1)      Pages from: 014503-1  to: 014503-7

KeyWords: silicon disulfide
DOI: 10.1063/1.5011333

Citations: 7
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