Spectroscopy of the pressure-induced virtual phase transition in Hg2I2 crystals

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 t...

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Bibliographic Details
Published in:Physics of the solid state 2015-03, Vol.57 (3), p.480-485
Main Authors: Markov, Yu. F., Mirovitskii, V. Yu, Roginskii, E. M.
Format: Article
Language:English
Subjects:
2014
August 18–22
Physics
Physics and Astronomy
Proceedings of the XX All-Russia Conference on Physics of Ferroelectrics (VKS-XX) (Krasnoyarsk
Russia
Solid State Physics
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Summary: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.
ISSN:1063-7834
1090-6460
DOI:10.1134/S1063783415030130