A possible generalization of the phenomenological theory of phase transitions in type II ferroelectrics with incommensurate phase

Korda, V. Yu.; Berezovsky, S. V.; Molev, A. S.; Korda, L. P.; Klepikov, V. F.

doi:10.1016/j.physb.2012.04.043

Cited by 7 publications

(6 citation statements)

References 25 publications

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“…46 Only recently these experimental data have been successfully explained when higher order invariants (including eight and ten powers) as well as biquadratic coupling of the order parameter with its space derivative were accounted in Landau functional. 5,6 Such explanation agrees well with strongly anharmonic three-well local potential of Sn 2 P 2 S 6 -like ferroelectrics, which was obtained by ab inito study of their electronic and dynamical properties. 4 Strong nonlinearity of SPS ferroelectrics allows possibility of specific domain structure with wide domain walls, which include non-polar regions.…”

Section: Discussion Of Experimental Datasupporting

confidence: 83%

“…Strong nonlinearity of the local potential could determine peculiar shape of domain walls and their temperature evolution in ferroelectric phase. [4][5][6] When domain dimension starts to be comparable with modulation wave length in the incommensurate phase, we could expect their interference leading to new interesting phenomena. In materials with the Lifshitz point [7][8][9] (LP, see below) in their compositional (or pressure) -temperature phase diagrams the modulation period could be changed continuously.…”

Section: Introductionmentioning

confidence: 99%

“…The thermodynamic anomalies in the IC phase above the lock-in PT at T c for Sn 2 P 2 Se 6 were described tak-ing into account the high nonlinearity of the local potential. 5,6 In Ref. 3 theoretical and experimental studies of the temperature dependence of spontaneous polarization inhomogeneity revealed typical width of the domains near several tens of micrometers.…”

Section: Introductionmentioning

confidence: 99%

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Observation of nonequilibrium behavior near the Lifshitz point in ferroelectrics with incommensurate phase

et al. 2016

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We have investigated non-equilibrium properties of proper uniaxial Sn2P2(SexS1−x)6 ferroelectrics with the Type II incommensurate phase above Lifshitz point xLP ∼ 0.28. We measured dielectric susceptibility with cooling and heating rate ranging 0.002-0.1 K/min, and high-resolution ultrasound experiments and hypersound Brillouin scattering. For samples with x 0.28 clear anomalies were observed at incommensurate second order transition (Ti) and at first order lock-in transition (Tc) in the regime of very slow cooling rate, whereas the intermediate IC phase is not observed when the rate is faster then 0.1 K/min. In general, increasing the cooling rate leads to smearing the anomaly at Tc. We explain this effect in terms of Kibble-Zurek model for non-equilibrium second order phase transitions. In the ferroelectrics with strongly nonlinear local potential cooling rate defines concentration of domain walls and their size: domain width decreases when cooling rate increases. At certain conditions the size of domain is comparable to the incommensurate phase modulation period, which lies in micrometer scale in the vicinity of Lifshitz point and leads to pinning of the modulation period by domain wall.

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Section: Discussion Of Experimental Datasupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Observation of nonequilibrium behavior near the Lifshitz point in ferroelectrics with incommensurate phase

et al. 2016

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“…As has been shown earlier [21,22] by analysis of Sn 2 P 2 Se 6 crystals heat capacity, dielectric susceptibility and wave number of modulation temperature dependence across the incommensurate phase, the higher order invariants (eight and ten) in the Landau expansion should be considered. Such nonlinearity is related to the presence of the three-well local potential.…”

Section: Discussion Of Resultsmentioning

confidence: 97%

Ferroelectricity in (Pb_ySn_1−y)₂P₂S₆ mixed crystals and random field BEG model

Rushchanskii

Bilanych

Molnar

et al. 2015

Physica Status Solidi (b)

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In Sn2P2S6 ferroelectric under compression, the second‐order phase transition line is observed down to the tricritical point as the transition temperature decreases to 250 K. A tricriticality at a similar temperature is also revealed in the mixed crystals on S→Se substitution. For the mixed crystals with Sn→Pb substitution, ultrasound, hypersound, and low‐frequency dielectric studies also show heterophase features appearing on decrease of the ferroelectric transition temperature below a so‐called “waterline temperature” near 250 K. Such behavior agrees with the Blume–Emery–Griffiths (BEG) model appropriate for the ferroelectric system under investigation with a three‐well local potential for the order parameter fluctuations. The BEG model modified by the random‐field phase diagram in the vicinity of the tricritical point qualitatively explains the influence of the cationic substitution on the (PbySn1−y)2P2S6 ferroelectric properties.

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“…8 In particular, solid solutions of Sn 2 P 2 S 6 and Sn 2 P 2 Se 6 have been recognized as extremely interesting model systems. [9][10][11][12][13][14][15][16][17][18] All of them have an identical parent paraelectric structure at high temperatures (P 2 1 /n) and the same ferroelectric phase at low temperatures (P n). [19][20][21] At ambient pressure, crystals with low Se/S concentration ratio show a direct ferroelectric-paraelectric phase transition, while those of high Se/S concentration exhibit an intermediate incommensurate (IC) phase (see Fig.…”

Section: Introductionmentioning

confidence: 99%

Neutron scattering study of ferroelectric Sn2P2S6under pressure

et al. 2012

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Ferroelectric phase transition in the semiconductor Sn 2 P 2 S 6 single crystal has been studied by means of neutron scattering in the pressure-temperature range adjacent to the anticipated tricritical Lifshitz point (p ≈ 0.18 GPa, T ≈ 296 K). The observations reveal a direct ferroelectric-paraelectric phase transition in the whole investigated pressure range (0.18-0.6 GPa). These results are in a clear disagreement with phase diagrams assumed in numerous earlier works, according to which a hypothetical intermediate incommensurate phase extends over several or even tens of degrees in the 0.5 GPa pressure range. Temperature dependence of the anisotropic quasielastic diffuse scattering suggests that polarization fluctuations present above T C are strongly reduced in the ordered phase. Still, the temperature dependence of the (200) Bragg reflection intensity at p = 0.18 GPa can be remarkably well modeled assuming the order-parameter amplitude growth according to the power law with logarithmic corrections predicted for a uniaxial ferroelectric transition at the tricritical Lifshitz point.

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A possible generalization of the phenomenological theory of phase transitions in type II ferroelectrics with incommensurate phase

Cited by 7 publications

References 25 publications

Observation of nonequilibrium behavior near the Lifshitz point in ferroelectrics with incommensurate phase

Observation of nonequilibrium behavior near the Lifshitz point in ferroelectrics with incommensurate phase

Ferroelectricity in (Pb_ySn_1−y)₂P₂S₆ mixed crystals and random field BEG model

Neutron scattering study of ferroelectric Sn2P2S6under pressure

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A possible generalization of the phenomenological theory of phase transitions in type II ferroelectrics with incommensurate phase

Cited by 7 publications

References 25 publications

Observation of nonequilibrium behavior near the Lifshitz point in ferroelectrics with incommensurate phase

Observation of nonequilibrium behavior near the Lifshitz point in ferroelectrics with incommensurate phase

Ferroelectricity in (PbySn1−y)2P2S6 mixed crystals and random field BEG model

Neutron scattering study of ferroelectric Sn2P2S6under pressure

Contact Info

Product

Resources

About

Ferroelectricity in (Pb_ySn_1−y)₂P₂S₆ mixed crystals and random field BEG model