Eur. Phys. J. Special Topics 196, 167-174 (2011)
https://doi.org/10.1140/epjst/e2011-01426-y

Regular Article

Inelastic x-ray scattering measurements of dynamical cross-over in liquid As2Se₃ at high temperature and high pressure

¹ Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8521, Japan
² Department of Physics, Kyoto University, Kyoto 606-8502, Japan
³ Center for Materials Research Using Third-Generation Synchrotron Radiation Facilities, Hiroshima Institute of Technology, Hiroshima 731-5193, Japan
⁴ Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan
⁵ Faculty of Science, Niigata University, Niigata 950-2182, Japan
⁶ SPring-8/JASRI, Hyogo 679-5198, Japan
⁷ RIKEN SPring-8 Center, Hyogo 679-5148, Japan

^a e-mail: masinui@hiroshima-u.ac.jp

Received: 1 December 2010
Revised: 13 April 2011
Published online: 30 May 2011

Abstract

Liquid As₂Se₃ undergoes the semiconductor-metal transition with increasing temperature when pressure is applied to avoid evaporation of the liquid. To investigate the atomic dynamics of liquid As₂Se₃, we have carried out inelastic x-ray scattering experiments of this system at 1073 K and 6 MPa and obtained the dynamic structure factor S(Q,E), from approximately 1.6 nm⁻¹ to 11 nm⁻¹, where Q and E are momentum and energy transfer, respectively. The excitation energy in the semiconducting state at 1073 K disperses as fast as the ultrasonic sound velocity at Q < 2.5 nm⁻¹ but at Q > 2.9 nm⁻¹ it disperses approximately 1.8 times faster. We analyzed S(Q,E) at 1073 K using a simple viscoelastic model and discussed Q dependence of the propagation of the acoustic mode.