Structural phase transitions coupled with prominent dielectric anomalies and dielectric relaxation in [(CH3)3NH]2[KCo(CN)6] and mixed [(CH3)3NH]2[KFexCo1−x(CN)6] double perovskite hybrids

Characterization of the onset of a phase transition is often challenging due to the fluctuations of the correlation length scales of the order parameters. This is especially true for second-order structural-phase transition due to minute changes involved in the relevant lattice constants. A classic example is the cubic-to-tetragonal second-order phase transition in SrTiO3(STO), which is so subtle that it is still unresolved. Here, we demonstrate an approach to resolve this issue by epitaxially grown rhombohedral La0.7Sr0.3MnO3(LSMO) thin films on the cubic STO (100) substrate. The shear strain induced nanotwinning waves in the LSMO film are extremely sensitive to the cubic-to-tetragonal structural-phase transitions of the STO substrate. Upon cooling from room temperature, the development of the nanotwinning waves is spatially inhomogeneous. Untwinned, atomically flat domains, ranging in size from 100 to 300 nm, start to appear randomly in the twinned phase between 265 and 175 K. At ∼139 K, the untwinned, atomically flat domains start to grow rapidly into micrometer scale and finally become dominant at ∼108 K. These results indicate that the low-temperature tetragonal precursor phase of STO has already nucleated at 265 K, significantly higher than the critical temperature of STO (∼105 K). Our work paves a pathway to visualize the onset stages of structural-phase transitions that are too subtle to be observed using direct-imaging methods.

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The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe

npj Computational Materials ◽

10.1038/s41524-021-00523-7 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Đorđe Dangić ◽

Olle Hellman ◽

Stephen Fahy ◽

Ivana Savić

Keyword(s):

Phase Transition ◽

Thermal Conductivity ◽

Phase Transitions ◽

Thermoelectric Materials ◽

Ferroelectric Phase Transition ◽

Lattice Thermal Conductivity ◽

Ferroelectric Phase ◽

Structural Phase ◽

High Symmetry ◽

Structural Phase Transitions

AbstractThe proximity to structural phase transitions in IV-VI thermoelectric materials is one of the main reasons for their large phonon anharmonicity and intrinsically low lattice thermal conductivity κ. However, the κ of GeTe increases at the ferroelectric phase transition near 700 K. Using first-principles calculations with the temperature dependent effective potential method, we show that this rise in κ is the consequence of negative thermal expansion in the rhombohedral phase and increase in the phonon lifetimes in the high-symmetry phase. Strong anharmonicity near the phase transition induces non-Lorentzian shapes of the phonon power spectra. To account for these effects, we implement a method of calculating κ based on the Green-Kubo approach and find that the Boltzmann transport equation underestimates κ near the phase transition. Our findings elucidate the influence of structural phase transitions on κ and provide guidance for design of better thermoelectric materials.

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On the high-temperature phase transitions of some KDP-family compounds: a structural phase transition? A transition to a bulk-high proton conducting phase?

Solid State Ionics ◽

10.1016/s0167-2738(99)00173-3 ◽

1999 ◽

Vol 125 (1-4) ◽

pp. 177-185 ◽

Cited By ~ 36

Author(s):

E Ortiz ◽

R.A Vargas ◽

B.-E Mellander

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

High Temperature ◽

Structural Phase Transition ◽

Structural Phase ◽

High Temperature Phase ◽

Temperature Phase ◽

Conducting Phase ◽

Proton Conducting ◽

High Proton

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Behavior of thermal properties of AgCu1−xFexS compounds under non-isothermal conditions

International Journal of Modern Physics B ◽

10.1142/s0217979219503399 ◽

2019 ◽

Vol 33 (28) ◽

pp. 1950339 ◽

Cited By ~ 7

Author(s):

Y. I. Aliyev ◽

P. R. Khalilzade ◽

Y. G. Asadov ◽

T. M. Ilyasli ◽

F. M. Mammadov ◽

...

Keyword(s):

Phase Transition ◽

Thermal Analysis ◽

Differential Thermal Analysis ◽

Thermal Properties ◽

Phase Transitions ◽

Structural Phase Transition ◽

Structural Phase ◽

Partial Replacement ◽

Isothermal Conditions ◽

The Given

AgCu[Formula: see text]Fe[Formula: see text]S compounds were synthesized by partial Cu[Formula: see text][Formula: see text][Formula: see text]Fe replacement in the AgCuS crystal at a concentration range of 0[Formula: see text][Formula: see text][Formula: see text]x[Formula: see text][Formula: see text][Formula: see text]0.03. In the differential thermal analysis spectrum obtained at a temperature range of 300 K[Formula: see text][Formula: see text][Formula: see text]T[Formula: see text][Formula: see text][Formula: see text]1300 K, endoeffect corresponding to the structural phase transition in the AgCuS compound was observed at the temperature T[Formula: see text]=[Formula: see text]938 K. It has been determined that this result is also observed in the AgCu[Formula: see text]Fe[Formula: see text]S compound obtained by partial replacement of Cu atoms by Fe atoms. However, in the compound of AgCu[Formula: see text]Fe[Formula: see text]S this effect was observed at higher temperatures. The thermal capacities and enthalpies of phase transitions were calculated for the given compounds.

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X-ray diffraction and Raman study of DL-alanine at high pressure: revision of phase transitions

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768112028972 ◽

2012 ◽

Vol 68 (4) ◽

pp. 412-423 ◽

Cited By ~ 24

Author(s):

Nikolay A. Tumanov ◽

Elena V. Boldyreva

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

Structural Phase ◽

Group Symmetry ◽

Second Phase ◽

Structural Phase Transitions ◽

X Ray Diffraction ◽

X Ray ◽

Cell Parameters ◽

Raman Study

The effect of pressure on DL-alanine has been studied by X-ray powder diffraction (up to 8.3 GPa), single-crystal X-ray diffraction and Raman spectroscopy (up to ∼ 6 GPa). No structural phase transitions have been observed. At ∼ 1.5–2 GPa, cell parameters b and c become accidentally equal to each other, but the space-group symmetry does not change. There is no phase transition between 1.7 and 2.3 GPa, contrary to what has been reported earlier [Belo et al. (2010). Vibr. Spectrosc. 54, 107–111]. The presence of the second phase transition, which was claimed to appear within the pressure range from 6.0 to 7.3 GPa (Belo et al., 2010), is also argued. The changes in the Raman spectra have been shown to be continuous in all the pressure ranges studied.

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Structural phase transitions coupled with prominent dielectric anomalies and dielectric relaxation in a one-dimensional organic–inorganic hybrid compound [C3H4NS][CdCl3]

Journal of Materials Chemistry C ◽

10.1039/c5tc02023a ◽

2015 ◽

Vol 3 (33) ◽

pp. 8535-8541 ◽

Cited By ~ 15

Author(s):

Guang-Quan Mei ◽

Wei-Qiang Liao

Keyword(s):

Phase Transitions ◽

Dielectric Relaxation ◽

Structural Phase ◽

Structural Phase Transitions ◽

Two Phase ◽

Hybrid Compound ◽

Inorganic Hybrid ◽

One Dimensional

A one-dimensional organic–inorganic hybrid exhibits two phase transitions at 288 and 215 K, coupled with remarkable dielectric performances.

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Structural phase transitions at high-temperature in double perovskite Sr2GdRuO6

Physica B Condensed Matter ◽

10.1016/j.physb.2011.12.050 ◽

2012 ◽

Vol 407 (16) ◽

pp. 3150-3154 ◽

Cited By ~ 5

Author(s):

C.A. Triana ◽

L.T. Corredor ◽

D.A. Landínez Téllez ◽

J. Roa-Rojas

Keyword(s):

Phase Transitions ◽

High Temperature ◽

Structural Phase ◽

Double Perovskite ◽

Structural Phase Transitions

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X-Ray Diffraction Study on the Structural Phase Transitions of (KCN)x(KBr) 1-x Mixed Crystals

Journal of the Physical Society of Japan ◽

10.1143/jpsj.68.3292 ◽

1999 ◽

Vol 68 (10) ◽

pp. 3292-3302 ◽

Cited By ~ 4

Author(s):

Yukio Yoshimura ◽

Toshiharu Okazaki ◽

Tokio Tsuruta ◽

Sachio Fujita ◽

Atsushi Ishikawa ◽

...

Keyword(s):

Phase Transitions ◽

Diffraction Study ◽

Structural Phase ◽

Mixed Crystals ◽

Structural Phase Transitions ◽

X Ray Diffraction ◽

X Ray

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Computer simulation of the structural phase transitions in thin ferroelectric films

Journal of Advanced Dielectrics ◽

10.1142/s2010135x17500047 ◽

2017 ◽

Vol 07 (01) ◽

pp. 1750004 ◽

Cited By ~ 2

Author(s):

O. G. Maksimova ◽

A. V. Maksimov ◽

O. S. Baruzdina

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

Boundary Conditions ◽

Order Parameter ◽

Mixed Boundary ◽

Structural Phase ◽

Film Surface ◽

Mixed Boundary Conditions ◽

Structural Phase Transitions ◽

Ferroelectric Films

The influence of free surface and depolarizing field on structural phase transitions in thin ferroelectric films from an ordered state to a disordered one is investigated. The dependences of the order parameter on the distance from the free film surface are calculated. It is shown that with the presence of the depolarizing field and in its absence, the effective thickness of the surface layer depends on the temperature. Nearby the phase transition point, the thickness increases indefinitely. Calculations considering depolarizing field showed that the phase transition points for the bulk ferroelectrics and the film under given boundary conditions coincide. Also shown that in the absence of depolarizing field with mixed boundary conditions, the film thickness does not affect the order parameter, and in presence of the field, this influence is observed.

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A structural phase transition in NaTaOGeO4 and its relation to phase transitions in titanite

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768107026213 ◽

2007 ◽

Vol 63 (4) ◽

pp. 545-550 ◽

Cited By ~ 4

Author(s):

Thomas Malcherek

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

Transition Metal ◽

Structural Phase Transition ◽

Order Parameter ◽

Diffuse Scattering ◽

Structural Phase ◽

Group Symmetry ◽

Critical Temperatures ◽

Symmetry Properties

A structural phase transition from space-group symmetry P21/c to C2/c is reported for NaTaOGeO4 (NTGO). The critical temperature has been located at T c = 116 K, based on the appearance of sharp diffraction maxima at positions h + k = 2n + 1 of reciprocal space on cooling below this temperature. Strongly anisotropic diffuse scattering in sheets normal to [001] is observable for T > T c and persists up to ambient temperature. Similarities to phase transitions observed in other compounds of the titanite structure type are discussed. The symmetry properties of these phase transitions are reassessed on the basis of the structural data available. The primary order parameter is identified with the displacement of the transition metal cation M (M = Ta in NTGO) away from the centre of symmetry that it nominally occupies in the paraphase. The order parameter transforms as the Y_{2}^{-} representation. The anisotropic diffuse scattering is attributed to the one-dimensional correlation of local M displacements parallel to the direction of chains of trans-corner-sharing MO6 octahedra. The critical temperatures of the isomorphous phase transitions in various titanite-type compounds depend linearly on the squared transition-metal displacement measured in the ordered P21/c phase.

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