Ferroelectric phase transition temperatures of self-flux-grown RbTiOPO4 crystals

The electrical properties of [001]-oriented morphotropic phase boundary (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-33%PT) single crystal have investigated as a function of temperature and frequency. The ac-conductivity exhibited continuous dispersion at all temperatures and frequency range examined and was associated to the thermally activated space charge carriers and local off-centering of Ti4+ and Pb2+ ions. The variations in ferroelectric phase transition temperatures observed in the poled state were associated to the polarization fluctuations and phase co-existence.

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Features of Crystal Structure and Ferroelectric Phase Transitions of KTiOPO4 Doped with Nb and Sb

Materials Science Forum ◽

10.4028/www.scientific.net/msf.443-444.303 ◽

2004 ◽

Vol 443-444 ◽

pp. 303-306

Author(s):

S.A. Ivanov ◽

Sergei Yu. Stefanovich ◽

S.-G. Eriksson ◽

V.I. Voronkova ◽

T.Yu. Losevskaya ◽

...

Keyword(s):

Crystal Structure ◽

Phase Transition ◽

Ferroelectric Phase Transition ◽

Ferroelectric Phase ◽

Structural Features ◽

Neutron Powder Diffraction ◽

Compositional Variation ◽

Phase Transition Temperatures ◽

Linear Optical Properties ◽

Ferroelectric Phase Transitions

The evolution of the crystal structures as a function of temperature of the new solid- solution KTiOPO4 (KTP) isomorphs, namely K1-xNbxTi1-xOPO4 and K1-xSbxTi1-xOPO4 have been studied by neutron powder diffraction below and above the ferroelectric phase transition temperatures. On the basis of the experimental data obtained the cation distribution, among the sublattices of this structure, and the distortion of the framework at the phase transition, have been discussed. The possible correlation between the non-linear optical properties and the dominant structural features tailored by compositional variation has also been studied.

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The influence of BaGeO3 on the properties of Ba(Ti1−xSx)O3 ceramics on the basis of sol-gel powders

10.31219/osf.io/jpydf ◽

2019 ◽

Author(s):

Roberto Köferstein

Keyword(s):

Phase Transition ◽

Ferroelectric Phase Transition ◽

Ferroelectric Phase ◽

Sintering Temperature ◽

Sol Gel ◽

Synthesis Method ◽

Particle Sizes ◽

Dielectric Measurements ◽

Sintering Additive ◽

Phase Transition Temperatures

Ba(Ti1−x−y SnxGey )O3 (BTSG-x-y; x = 0, 0.05; y = 0–0.05) powders were synthesized by a sol-gel (SG) method and for comparative purposes also by a mixed-oxide (MO) method. In this system, BaGeO3 functions as sintering additive. Due to smaller particle sizes of the SG powders a higher sintering activity was found, which resulted in reduced grain growth and in a more homogenous grain size distribution for the corresponding ceramics. The dependence on the paraelectric ⇆ ferroelectric phase transition, i.e. the phase transition temperature, thewidth of the transition region and completeness were examined by dielectric measurements,DTA as well as by SEM, EDX and XRD investigations with respect to the BaGeO3 content, synthesis method and sintering temperature. The phase transition temperatures of the SG ceramics are remarkably higher than those of the MO ceramics with the same nominal compositions. The reason is a lower tin concentration within the grains of SG ceramics as confirmed by EDX and XRD investigations. The presence of BaGeO3 in barium titanate–stannate system on the basis of a SG method caused an improved incorporation of tin in theBaTiO3 lattice.

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Domain Structure, Local Hysteresis and Ferroelectric Phase Transition in (CH 3 NH 3 ) 5 Bi 2 Br 11 (MAPBBB) Single Crystals

Ferroelectrics ◽

10.1080/00150190390239341 ◽

2003 ◽

Vol 295 (1) ◽

pp. 121-129

Author(s):

M. Wojtaś ◽

V. V. Shvartsman ◽

R. Jakubas ◽

A. Kholkin

Keyword(s):

Phase Transition ◽

Single Crystals ◽

Domain Structure ◽

Ferroelectric Phase Transition ◽

Ferroelectric Phase

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Vibrational spectroscopic study of the ferroelectric phase transition in vinylidene fluoride-trifluoroethylene copolymers: 1. Temperature dependence of the Raman spectra

Polymer ◽

10.1016/0032-3861(88)90359-x ◽

1988 ◽

Vol 29 (3) ◽

pp. 426-436 ◽

Cited By ~ 40

Author(s):

Kohji Tashiro ◽

Masamichi Kobayashi

Keyword(s):

Phase Transition ◽

Spectroscopic Study ◽

Temperature Dependence ◽

Raman Spectra ◽

Ferroelectric Phase Transition ◽

Vinylidene Fluoride ◽

Ferroelectric Phase

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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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