Central peak in the strontium titanate crystal near the tetragonal-to-cubic phase transition

Malinovskiǐ, V. K.; Pugachev, A. M.; Суровцев, Н. В.

doi:10.1134/s1063783412050265

Cited by 3 publications

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“…Later, opalescence with a sharp increase in the integrated intensity of scattered light (by 3 or 4 orders in magnitude) has been observed in a narrow temperature range near the α-β structural phase transition (T c =846 K) in crystalline quartz. [6][7][8] Then, the so-called central peak, which is a sharp intensity increase of the narrow-spectral-width (ΔΩ~1cm -1 ) response in light scattering, slow neutron scattering, and X-ray scattering phenomena, was detected in the range of structural phase transitions in some crystals such as SrTiO 3 , [9,10] NaNbO 3 , [11] Sr x Ba 1-x Nb 2 O 6 , [12] LiNbO 3 , [13] and AgNbO 3 . [14] In addition, various crystal physical properties such as the specific heat and elastic constants exhibit anomalies in this temperature range.…”

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confidence: 99%

Raman opalescence of a destabilizing soft mode near the phase transition in quartz monocrystals

Горелик

Pyatyshev²

2019

J Raman Spectroscopy

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A microscopic reason of the opalescence phenomenon observed earlier near the α–β phase transition point at 846 K in crystalline quartz is established. It was shown that the opalescence in quartz crystals is of dynamic nature and results from a sharp increase of Raman scattering spectral intensity (Raman opalescence phenomenon) due to huge fluctuations of the destabilizing soft mode responsible for instability of the crystalline lattice. The Raman opalescence of a destabilizing soft mode is estimated experimentally in the x (zz)y light scattering geometry by recording temperature dependencies of spectral Raman intensity I(ω′,T) (ω′=ω0‐Ω=const) at fixed frequencies ω′. The strong intensity increase of Raman scattering intensity (Raman opalescence) observed at the exact phase‐transition temperature in crystalline quartz is explained by taking into account interaction of the destabilizing soft mode with a low‐frequency high‐finesse oscillator.

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