Yu. F. Markov, V. Yu. Mirovitskii, E. M. Roginskii, “Pressure behavior of phonons and phase transition effects in Hg$_2$I$_2$ model virtual ferroelastics”, Pisma v Zhurnal Tekhnicheskoi Fiziki, 2014, Volume 40, Issue 22,Pages 12

This article is cited in 2 papers

Pressure behavior of phonons and phase transition effects in Hg$_2$I$_2$ model virtual ferroelastics

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

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

Abstract: The Raman spectra of virtual ferroelastic Hg$_2$I$_2$ crystals have been studied in a broad range of hydrostatic pressures. Linear pressure dependences of phonon frequencies are obtained at $P < P_c$, which exhibit jumps and breaks at the phase transition point ($P_c$ = 9 kbar). Grüneisen parameters of the Hg$_2$I$_2$ crystals are determined. The spectra of a ferroelastic phase $(P > P_c)$ in various polarizations exhibit the excitation of new lines from the $X$ point of the Brillouin zone, including transverse (TA) and longitudinal (LA) acoustic phonons. Based on analysis of the experimental and theoretical results, the Raman spectra of ferroelastic Hg$_2$I$_2$ crystals are interpreted and a model of the phase transition in these crystals is proposed.