This article is cited in 6 papers

Proceedings of the XX All-Russia Conference on Physics of Ferroelectrics (VKS-XX)

Spectroscopy of the pressure-induced virtual phase transition in Hg$_2$I$_2$ crystals

Yu. F. Markov^a, V. Yu. Mirovitskii^b, E. M. Roginskii<sup>a

a</sup> Ioffe Institute, St. Petersburg
^b Institute of Applied Physics Academy of Sciences of Moldova, Kishinev

Abstract: Raman spectra of incipient ferroelastics, namely, Hg$_2$I$_2$ crystals, have been investigated over a wide range of hydrostatic pressures. Linear pressure dependences of phonon frequencies have been obtained at $P < P_c$). It has been found that jumps and breaks are observed in these dependences at the phase transition point $P_c$ = 9 kbar. The Grüneisen parameters of the Hg$_2$I$_2$ crystals have been determined and discussed. The Raman spectra of the ferroelastic phase $(P > P_c)$ in different polarizations exhibit excitation of acoustic vibrations from the X point of the Brillouin zone boundary, including transverse acoustic (TA$_1$ and TA$_2$) and longitudinal acoustic (LA) phonons. The Raman spectra of the ferroelastic phase have been interpreted based on the analysis of the experimental results, and a model of the phase transition in these crystals has been proposed.

 English version: Physics of the Solid State, 2015, 57:3, 480–485

Bibliographic databases:

•