Vibrational dynamics and phase diagram of KNbO<sub>3</sub>up to 30 GPa and from 20 to ∼500 K

Pruzan, Ph.; Gourdain, D.; Chervin, J. C.

doi:10.1080/01411590701473176

Cited by 32 publications

(28 citation statements)

References 79 publications

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“…Early papers on BaTiO 3 [21,22], KNbO 3 [23,24], PbTiO 3 [25,26] amply confirmed this view and let to the widely accepted conclusion that polar perovskites adopt for P > P c a cubic P m3m crystal structure. It was thus unexpected to find out in recent years that relaxor ferroelectrics do not stay/become cubic at high-pressure (e.g.…”

Section: Introductionmentioning

confidence: 68%

“…One consequence of the various instabilities is an often complex phase diagram of perovskites, for instance in the P -T or x-T space which are the most explored diagrams. Besides perovskite-type manganites, ferroelectric perovskites are among the most investigated materials with the representative examples PbZr 1−x Ti x O 3 (PZT) for the x-T space [64][65][66] and BaTiO 3 (BTO) or KNbO 3 (KNO) for the P -T space [24,67]. Both examples display complex phase diagrams.…”

Section: Importance Of Non-hydrostatic Stressmentioning

confidence: 99%

“…Nevertheless, it is important to realize that when only one parameter (P , T or x) is changed no more than 3 phase transitions are observed, e.g. the rhombohedral-orthorhombic-tetragonal-to-cubic phase sequence in BTO or KNO under pressure [24,67]. Most other materials display fewer phase transitions under pressure: e.g.…”

Section: Importance Of Non-hydrostatic Stressmentioning

confidence: 99%

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Multiple high-pressure phase transitions in BiFeO3

et al. 2011

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We investigate the high-pressure phase transitions in BiFeO3 by single crystal and powder x-ray diffraction, as well as single crystal Raman spectroscopy. Six phase transitions are reported in the 0-60 GPa range. At low pressures, up to 15 GPa, 4 transitions are evidenced at 4, 5, 7 and 11 GPa. In this range, the crystals display large unit cells and complex domain structures, which suggests a competition between complex tilt systems and possibly off-center cation displacements. The non polar P nma phase remains stable over a large pressure range between 11 and 38 GPa, where the distortion (tilt angles) changes only little with pressure. The two high-pressure phase transitions at 38 and 48 GPa are marked by the occurence of larger unit cells and an increase of the distorsion away from the cubic parent perovskite cell. We find no evidence for a cubic phase at high pressure, nor indications that the structure tends to become cubic. The previously reported insulator-to-metal transition at 50 GPa appears to be symmetry breaking.

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Section: Introductionmentioning

confidence: 68%

Section: Importance Of Non-hydrostatic Stressmentioning

confidence: 99%

Section: Importance Of Non-hydrostatic Stressmentioning

confidence: 99%

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Multiple high-pressure phase transitions in BiFeO3

et al. 2011

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“…PPT) between orthorhombic (O) and tetragonal (T) phases. and then the framework of the established eight-site model will be adopted [36]. In order to obtain a complete description of the dynamical properties through the successive phase transitions, it is useful to know the classification of the optical modes and their correlations between the various phases [37].…”

Section: Lead-free Ferroelectricsmentioning

confidence: 99%

Structural Transformations in Ferroelectrics Discovered by Raman Spectroscopy

Jiang¹,

Xu²,

Zhang³

et al. 2018

Raman Spectroscopy

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Ferroelectrics systems are of great interest from the fundamental as well as applications points, such as ferroelectric random access memories, electro-optic switches and a number of electro-optic devices. Curie temperature (T C ) is one of the important parameters of ferroelectrics for high-temperature applications. Particularly, the optical modes, which are associated with the ferroelectric to paraelectric phase transition, are of great interest. Structural transformations that alter the crystal symmetry often have a significant effect on the Raman spectroscopy. This chapter systematically studies the type ferroelectric oxides and rare earth element doped ferroelectric materials such as (KNN-LN) and so on synthesis of single crystal/ceramic and optical phonon vibration modes and the improvement of the Curie temperature characteristic using spectrometry measurements. The T C , distortion degree, and phase structure of the ferroelectric materials have been investigated by temperaturedependent Raman spectroscopy. Meanwhile, the important physical parameters exhibited a strong dependence on dopants resulting in structural modifications and performance promotion.

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“…The obtained peak positions in orthorhombic KNN-LN crystals and the corresponding symmetry assignments at room temperature are listed in Table I. 15,17,18 Figs. 1(a) and 1(b) depict temperature dependence of Raman scattering for the KNN-LN and KNN-LN-1%MnO 2 crystals, respectively.…”

mentioning

confidence: 99%

Phase transitions and thermotropic phase boundaries in MnO2-doped (K0.5Na0.5)NbO3-0.05LiNbO3 single crystals: Raman scattering evidence at elevated temperatures

Jiang

Zhang

et al. 2015

Applied Physics Letters

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Vibrational dynamics and phase diagram of KNbO₃up to 30 GPa and from 20 to ∼500 K

Cited by 32 publications

References 79 publications

Multiple high-pressure phase transitions in BiFeO3

Multiple high-pressure phase transitions in BiFeO3

Structural Transformations in Ferroelectrics Discovered by Raman Spectroscopy

Phase transitions and thermotropic phase boundaries in MnO2-doped (K0.5Na0.5)NbO3-0.05LiNbO3 single crystals: Raman scattering evidence at elevated temperatures

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Vibrational dynamics and phase diagram of KNbO3up to 30 GPa and from 20 to ∼500 K

Cited by 32 publications

References 79 publications

Multiple high-pressure phase transitions in BiFeO3

Multiple high-pressure phase transitions in BiFeO3

Structural Transformations in Ferroelectrics Discovered by Raman Spectroscopy

Phase transitions and thermotropic phase boundaries in MnO2-doped (K0.5Na0.5)NbO3-0.05LiNbO3 single crystals: Raman scattering evidence at elevated temperatures

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Vibrational dynamics and phase diagram of KNbO₃up to 30 GPa and from 20 to ∼500 K