Lattice Instability of Cs2HgCl4 Crystals

Kityk, A. V.; Shchur, Ya.; Zadorozhna, A. V.; Trach, I.; Girnyk, I.; Martynyuk-Lototska, I.; Vlokh, O. G.

doi:10.1002/(sici)1521-3951(199902)211:2<631::aid-pssb631>3.0.co;2-1

Cited by 6 publications

(6 citation statements)

References 2 publications

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“…Such a coupling becomes obvious through the phenomenological treatment. Let us restrict ourselves by the following terms of the free-energy density expansion in the prototype phase [30]…”

Section: Ferroelastic Phase Transition In Tdpmentioning

confidence: 99%

Phase transitions in TlH₂PO₄and TlD₂PO₄crystals: lattice dynamical treatment

Shchur¹

2010

J. Phys.: Condens. Matter

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Lattice dynamics simulation of TlH(2)PO(4) and TlD(2)PO(4) crystals was performed within the semi-phenomenological atomistic model in the high temperature P2(1)/b2/c2(1)/n structural phase. Combining the results of phenomenological Landau-Ginzburg theory and lattice dynamics simulation, it was shown that the ferroelastic phase transition in TlH(2)PO(4) occurs due to the bilinear interaction between the soft B(3g) optic and B(1u) acoustic modes. According to our simulation, the hydrogen H(1) atoms placed on the shorter hydrogen bonds play the key role in the ferroelastic phase transition in TlH(2)PO(4), whereas the D(2) atoms located on the longer hydrogen bonds exert the main effect on the antiferroelectric phase transition in TlD(2)PO(4) crystal.

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“…Such a coupling becomes obvious through the phenomenological treatment. Let us restrict ourselves by the following terms of the free-energy density expansion in the prototype phase [30]…”

Section: Ferroelastic Phase Transition In Tdpmentioning

confidence: 99%

Phase transitions in TlH₂PO₄and TlD₂PO₄crystals: lattice dynamical treatment

Shchur¹

2010

J. Phys.: Condens. Matter

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“…These crystals possess ferroelastic phase transformation occurred after passing through intermediate incommensurate phase (this phase is denoted as I in Table 1). The acoustooptic figure of merit can achieve m/s [26][27][28]. We have this exceptional result because of the fact that the photoelastic coefficient providing the acoustooptic interaction with the transverse acoustic wave is order of magnitude smaller than the appropriate coefficient referred to the interaction with longitudinal waves.…”

Section: Comparison Of Acoustooptic Properties Of Different Ferroelasmentioning

confidence: 99%

Ferroelastic crystals as effective acoustooptic materials

Vlokh¹,

Martynyuk-Lototska²

2009

Ukr. J. Phys. Opt.

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In this paper we analyse acoustooptic properties of ferroelastic crystals. It is shown that proper ferroelastics are the most attractive materials for utilisation in acoustooptic devices, due to low velocities of acoustic waves caused by anomalous behaviour of elastic properties in the vicinity of phase transition. A number of new ferroelastic compounds promising for acoustooptic applications are described.

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“…Additional experimental and theoretical investigations (e.g. simulation of temperature changes of phonon spectra in phase IV, like in reference [24]) are desirable in order to find unambiguously the soft mode and order parameter for the IV-V phase transition.…”

Section: Phase IV (P 2 1 /N11)mentioning

confidence: 99%

Lattice dynamics simulation of Cs₂CdBr₄crystal

Shchur

Kamba

Petzelt

1999

J. Phys.: Condens. Matter

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Lattice dynamics calculations for the Cs 2 CdBr 4 crystal in the high-temperature orthorhombic phase (P nma) and in the monoclinic phase (P 2 1 /n11) at ∼195 K were carried out. The model was based on the atom-atom potential function which comprised the longrange Coulombic, short-range and covalent interactions. Comparison of the calculated phonon frequencies with the experimental ones obtained from far-infrared reflectivity and Raman scattering measurements gives a reasonable agreement in most cases. A possible origin of the incommensurate phase transition was discussed on the basis of a coupling between low-lying 2 phonon branches. Using group-theory analysis and the calculated phonon dispersion branches, it is shown that the P 2 1 /n11-P 1 phase transition is very probably induced by the condensation of a phonon mode at the Brillouin zone boundary.

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Lattice Instability of Cs2HgCl4 Crystals

Cited by 6 publications

References 2 publications

Phase transitions in TlH₂PO₄and TlD₂PO₄crystals: lattice dynamical treatment

Phase transitions in TlH₂PO₄and TlD₂PO₄crystals: lattice dynamical treatment

Ferroelastic crystals as effective acoustooptic materials

Lattice dynamics simulation of Cs₂CdBr₄crystal

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Lattice Instability of Cs2HgCl4 Crystals

Cited by 6 publications

References 2 publications

Phase transitions in TlH2PO4and TlD2PO4crystals: lattice dynamical treatment

Phase transitions in TlH2PO4and TlD2PO4crystals: lattice dynamical treatment

Ferroelastic crystals as effective acoustooptic materials

Lattice dynamics simulation of Cs2CdBr4crystal

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Phase transitions in TlH₂PO₄and TlD₂PO₄crystals: lattice dynamical treatment

Phase transitions in TlH₂PO₄and TlD₂PO₄crystals: lattice dynamical treatment

Lattice dynamics simulation of Cs₂CdBr₄crystal