Pressure-induced structural transition and metallization in MnSe 2
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ORIGINAL PAPER
Pressure‑induced structural transition and metallization in MnSe2 Baoyun Wang1,2 · Xiaoning Wang1,2 · Simeng Wang1,2 · Dayong Tan3 · Wansheng Xiao3 · Wen Liang4 · Maoshuang Song1 Received: 10 June 2020 / Accepted: 8 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The high-pressure behavior of manganese diselenide M nSe2 was investigated by synchrotron angle-dispersive X-ray diffraction (ADXRD) and infrared reflection spectroscopy equipped with a diamond-anvil cell. It was found that MnSe2 with a pyrite-type structure undergoes a transformation into a disordered intermediate phase at ~ 12.5 GPa, with a ground state composed of an arsenopyrite-type structure, as confirmed by laser-heating treatment. The pyrite to arsenopyrite phase transition was found to be coupled to a large collapse in the unit-cell volume (∆V ~ 19%) and an electronic transition from a high-spin to low-spin state for manganese cations ( Mn2+). With a fixed value for the pressure derivation of the bulk modulus K’ = 4, fitting of the pressure–volume data to a second-order Birch–Murnaghan equation of state yielded isothermal bulk modulus values of K0 = 56.1(9) GPa and K0 = 93.1(4) GPa for the pyrite-type and arsenopyrite-type phases, respectively. The measured infrared reflectivity (Rsd) for MnSe2 showed a drastic increase at pressures between 13 and 20 GPa, but became insensitive to pressure under further compression, implying a pressure-induced transition from an insulator to metallic state. Keywords Manganese diselenide ( MnSe2) · Arsenopyrite-type structure · Disordered intermediate · Large volume collapse · Pressure-induced metallization
Introduction The transition-metal di-chalcogenides TX2 (T=Mn, Fe, Co, Ni, Cu, Zn, −X=S, Se, Te) with a pyrite-type structure (spacegroup Pa 3 , Fig. 1a) exhibit diverse electrical, magnetic and optical properties (Bither et al. 1968; Lauer et al. 1984; Ogawa 1979; Temmerman et al. 1993), and, hence, have important technical applications in many fields such as electrocatalysts for the hydrogen evolution reaction (Faber et al. 2014; Wu et al. 2019), supercapacitors and * Maoshuang Song [email protected] 1
State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
2
College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
3
Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
4
Key Laboratory of High Temperature and High Pressure Study of the Earth’s Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
lithium-ion batteries (Gudelli et al. 2013; Yu et al. 2016), and thermoelectric materials and spin electronics (Feng et al. 2018; Houari and Blöchl 2018). Quite a large number of experimental and theoretical studies have been conducted for pyrite-type T X2 compounds and many intriguing phenomen
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