Structural Phase Transitions Studied by Electron Paramagnetic Resonance

Müller, K. A.; Fayet, J. C.

doi:10.1007/978-3-662-10113-1_1

Cited by 31 publications

(24 citation statements)

References 166 publications

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“…It is well known that magnetic resonance represents highly sensitive experimental techniques giving a unique information regarding static and dynamic phenomena accompanying structural phase transitions [8,9]. ESR spectra of Gd 3+ ions in lead germanate have been reported earlier [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

FERROELECTRIC PHASE TRANSITION IN LEAD GERMANATE Pb_{5}Ge_{3}O_{11} STUDIED BY ESR OF Gd^{3+} PROBE

Trubitsyn¹,

Volnianskii²,

Ermakov³

et al. 1999

Condens. Matter Phys.

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ESR spectra of Gd3+ probe have been studied in the range of ferroelectric phase transition T C =451 K in lead germanate Pb 5 Ge 3 O 11 . Measurements of ESR line position have shown that local order parameter behaves in accordance with the mean field theory approach in a broad (∼150 K) temperature interval below T C . Anomalous line width broadening observed around T C can be associated with a quasi-elastic central peak component of excitation spectrum, observed earlier using a light scattering experiment and attributed to static symmetry-breaking defects.

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Section: Introductionmentioning

confidence: 99%

FERROELECTRIC PHASE TRANSITION IN LEAD GERMANATE Pb_{5}Ge_{3}O_{11} STUDIED BY ESR OF Gd^{3+} PROBE

Trubitsyn¹,

Volnianskii²,

Ermakov³

et al. 1999

Condens. Matter Phys.

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“…These conduction electrons play also the main role in the stabilization of the cubic structure of ReO 3 [3]. While many perovskites, as for example SrTiO 3 , BaTiO 3 and KNbO 3 , show upon temperature change a series of phase transitions, caused by condensation of one or more optical modes [4] and accompanied by the electronic and atomic structure changes, the structure of ReO 3 remains non-distorted at atmospheric pressure down to liquid-helium temperature [3]. However, a number of phase transitions can be induced in ReO 3 by applying external pressure [1,5,6] or by hydrogen insertion, that results in the formation of hydrogen rhenium bronzes H x ReO 3 [7][8][9].…”

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confidence: 99%

Influence of hydrogen intercalation on the local structure around Re ions in perovskite‐type ReO ₃

Gaidelene

Kuzmin

Purans

et al. 2005

phys. stat. sol. (c)

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PACS 61.10.Hb, 78.70.Dm In-situ X-ray absorption spectroscopy at the Re L 1 and L 3 edges was used to study a modification of the local atomic and electronic structure around rhenium in perovskite-type ReO 3 upon hydrogen intercalation. The analysis of both EXAFS and XANES parts of the X-ray absorption spectra shows an evidence of the charge disproportionation phenomenon in hydrogenated rhenium trioxide. and explaining the metallic conductivity of ReO 3 . These conduction electrons play also the main role in the stabilization of the cubic structure of ReO 3 [3]. While many perovskites, as for example SrTiO 3 , BaTiO 3 and KNbO 3 , show upon temperature change a series of phase transitions, caused by condensation of one or more optical modes [4] and accompanied by the electronic and atomic structure changes, the structure of ReO 3 remains non-distorted at atmospheric pressure down to liquid-helium temperature [3]. However, a number of phase transitions can be induced in ReO 3 by applying external pressure [1,5,6] or by hydrogen insertion, that results in the formation of hydrogen rhenium bronzes H x ReO 3 [7][8][9].X-ray and neutron diffraction [1,5,6] and X-ray absorption spectroscopy (XAS) [10] studies has revealed that pressure effect results in a rotation (the Re-O-Re angle changes from 180° to 160°) of ReO 6 octahedra, but the octahedra remain regular with the Re-O bond length about 1.88±0.01 Å. Neutron diffraction study [9] of the hydrogen rhenium bronze D 1.36 ReO 3 showed that the hydrogen insertion produces similar effect on the ReO 3 structure. In particular, for x=1.36 the bronze structure is composed of tilted regular ReO 6 octahedra with the Re-O-Re angle equal to 169° and the Re-O distance of about 1.90 Å [9]. More accurate information on the local atomic and electronic structure of the bronzes can be obtained using XAS, which is a structural method complimentary to diffraction. To our knowledge, no such works have been performed until now.In this work, we present the first results of the in-situ XAS study of hydrogen intercalation into ReO 3 . The analysis of both extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) allowed us to reconstruct changes of the local environment around rhenium ions occurring upon hydrogen intercalation and provides an evidence of charge ordering at rhenium sites.X-ray absorption spectra were recorded at the Re L 1 and L 3 -edges in transmission mode at the LURE DCI storage ring on the EXAFS-3 beam line, located at the bending magnet. The storage ring DCI oper-

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“…This transition appears to be displacive and second order in nature according to its zone boundary transverse acoustic mode. [7,8] For the related one of STO, similar conclusions were drawn, [19] but soon this was questioned since substantial order/disorder dynamics precede the transition. [20] More recently, results from birefringence experiments together with a lattice dynamical analysis [21] have clarified that precursor dynamics are manifest in STO, as found in many other perovskite oxides.…”

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confidence: 75%

“…This issue is addressed in the following where a similar analysis of the lattice dynamics of ETO is undertaken as for STO and BaTiO 3 in Refs. [19][20][21][22][23][24]. At very high temperatures TϾT S , the Eu 4f spins can be neglected so that the well-known polarizability model in its original version is applied in the following.…”

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confidence: 99%

Unexpected Precursor Effects to the Structural Phase Transition in EuTiO₃

Bussmann‐Holder

Köhler

Whangbo

2015

Zeitschrift anorg allge chemie

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Abstract. The dynamical properties of EuTiO 3 are investigated to gain insight into its precursor effects analogous to those observed in many other perovskite oxides. In spite of the fact that a competition between the long wave length transverse optic mode and the zone boundary 63.70.+h,In view of the fact that EuTiO 3 (ETO) has been discovered more than 60 years ago, [1] its dynamical, structural, and magnetic properties are much less investigated as compared to, for example, SrTiO 3 , BaTiO 3 , PbTiO 3 and related systems. It is, however, well established that ETO exhibits a G-type antiferromagnetic (AFM) order below T N = 5.5 K. Results and Discussion[2] In addition, strong magneto-electric coupling has been established at low temperatures, [3] accompanied by the softening of a transverse optic mode. [4,5] The structure was believed to be cubic at all temperatures until recently, when a detailed experimental and theoretical study showed that a structural phase transition to a low temperature tetragonal phase takes place at T S = 282 K. [6] From an analysis of the dynamics of this instability, it became apparent that it is analogous to the one in SrTiO 3 (STO) at T S = 105 K, namely, it is driven by the condensation of a zone boundary transverse acoustic mode, [7] which has been quickly confirmed after this prediction.[8] The transition temperature itself remained a matter of controversy since different groups reported different values ranging from as low as 160 [9] to 245 [10] and even to 308 K. [11] In addition, structural modulations below T S have been implicitly deduced in the synchrotron radiation study, [10] but have been claimed to be absent in another structural study.[12] Theoretically, first principles density functional calculations [7,13] arrived at the conclusion that the structure below T S must be distorted due to rotations of TiO 6 octahedra. The very close energetic proximity of different rotational possibilities left some ambiguity in clearly deciding which structural distortion corresponds to the lowest energy state. In addition, various work was done within a Landau free energy expansion, [14][15][16] in which coupling of various order parameters was included. These studies suggested that an AFM order might change to a FM order under strain, and indicated the possibility for simultaneous ferroelectric order. For solid solutions (ETO) 1-x (STO) x , it was proposed that a ferrimagnetic order is followed by ferromagnetism. Experimentally this could not be confirmed. Instead, it was found that AFM order remains robust for all doping levels [17] and is even stabilized under pressure. [18] In the present study we focus on the high temperature phase transition of ETO. This transition appears to be displacive and second order in nature according to its zone boundary transverse acoustic mode. [7,8] For the related one of STO, similar conclusions were drawn, [19] but soon this was questioned since substantial order/disorder dynamics precede the transition. [20] More recently, results from birefring...

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Structural Phase Transitions Studied by Electron Paramagnetic Resonance

Cited by 31 publications

References 166 publications

FERROELECTRIC PHASE TRANSITION IN LEAD GERMANATE Pb_{5}Ge_{3}O_{11} STUDIED BY ESR OF Gd^{3+} PROBE

FERROELECTRIC PHASE TRANSITION IN LEAD GERMANATE Pb_{5}Ge_{3}O_{11} STUDIED BY ESR OF Gd^{3+} PROBE

Influence of hydrogen intercalation on the local structure around Re ions in perovskite‐type ReO ₃

Unexpected Precursor Effects to the Structural Phase Transition in EuTiO₃

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Structural Phase Transitions Studied by Electron Paramagnetic Resonance

Cited by 31 publications

References 166 publications

FERROELECTRIC PHASE TRANSITION IN LEAD GERMANATE Pb_{5}Ge_{3}O_{11} STUDIED BY ESR OF Gd^{3+} PROBE

FERROELECTRIC PHASE TRANSITION IN LEAD GERMANATE Pb_{5}Ge_{3}O_{11} STUDIED BY ESR OF Gd^{3+} PROBE

Influence of hydrogen intercalation on the local structure around Re ions in perovskite‐type ReO 3

Unexpected Precursor Effects to the Structural Phase Transition in EuTiO3

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Influence of hydrogen intercalation on the local structure around Re ions in perovskite‐type ReO ₃

Unexpected Precursor Effects to the Structural Phase Transition in EuTiO₃