Nuclear quadrupole coupling constants and spontaneous polarization in ferroelectrics

Dening, D. C.; Casabella, P. A.

doi:10.1016/0022-2364(80)90278-4

Cited by 3 publications

(7 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The ratio of the values of e2qQ/h for the titanium isotopes yields a ratio for the quadrupole moments "Q/"Q = 0.820 (9), which is in satisfactory agreement with the value of 0.819(1) obtained from atomic beam data [6]. The Ti coupling constants in BaTiO, at room temperature are approximately a factor four smaller than those measured for rutile [3], reflecting the slighter tetragonal distortion from cubic symmetry.…”

Section: Discussionsupporting

confidence: 83%

“…The temperature dependence measurements of the second-order shift provide an interesting check on the temperature variation of the spontaneous polarisation, P,, for which data have been most recently reported in [8]. Dening and Casabella [9] have pointed out that if the atom in question is at a site of inversion symmetry above T,, and the atoms do not change their bonding state at the ferroelectric transition, then the EEG q should be a quadratic function of P,. This implies that the second-order shift, corrected for the chemical shift contribution, should be proportional to P:.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

An NMR study of¹³⁷Ba and^47,49Ti in ferroelectric BaTiO₃

Bastow

1989

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

A complete NMR characterisation, for the isotopes 137Ba, 47Ti and 49Ti, has been made for a single crystal of BaTiO3 in the orthorhombic ferroelectric phase at room temperature. The nuclear quadrupole coupling constant and the axially anisotropic component of the chemical shift tensor have been determined for each isotope. In a variable-temperature study up to the Curie point, the nuclear quadrupole coupling constants were found to vary very nearly as the square of the spontaneous polarisation.

show abstract

Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

An NMR study of¹³⁷Ba and^47,49Ti in ferroelectric BaTiO₃

Bastow

1989

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

show abstract

“…For sites without inversion symmetry, the linear term should be dominant, whereas for sites with inversion symmetry the linear term vanishes and the quadratic term in the expansion becomes relevant. 25 The V zz component follows a quadratic variation for all the atoms in all the compounds studied, with only two exceptions, PbTiO 3 and CaTiO 3 . At the O2 sites of PbTiO 3 and CaTiO 3 there are interchanges of tensor components which make the description of EFG variations in terms of the V zz component inadequate.…”

Section: Technical Detailsmentioning

confidence: 94%

“…In Ref. 25 it was argued that the static part of V zz should have the following behavior with respect to P : either it is proportional to P 2 in sites which have inversion symmetry in the paraelectric structure, or it is proportional to P , like in Rochelle salts. The quadratic relation was supported by experiments in NaNO 2 , 25 in PbHfO 3 not too close to T C (where critical behavior is found), by PAC measurements, 4,26 and by NMR measurements in BaTiO 3 .…”

mentioning

confidence: 99%

Ab initiostudy of the relation between electric polarization and electric field gradients in ferroelectrics

et al. 2012

View full text Add to dashboard Cite

The hyperfine interaction between the quadrupole moment of atomic nuclei and the electric field gradient (EFG) provides information on the electronic charge distribution close to a given atomic site. In ferroelectric materials, the loss of inversion symmetry of the electronic charge distribution is necessary for the appearance of the electric polarization. We present first-principles density functional theory calculations of ferroelectrics such as BaTiO3, KNbO3, PbTiO3 and other oxides with perovskite structures, by focusing on both EFG tensors and polarization. We analyze the EFG tensor properties such as orientation and correlation between components and their relation with electric polarization. This work supports previous studies of ferroelectric materials where a relation between EFG tensors and polarization was observed, which may be exploited to study the ferroelectric order when standard techniques to measure polarization are not easily applied.

show abstract

“…The size of the EFG depends on the magnitude of the structural distortion that causes it. Three different mechanisms of structural distortion may be responsible for an EFG≠0 in the A-site of BNT-xBT: (1) an asymmetric arrangement of neighboring A-site cations due to dissimilar electric charges of Na + , Ba 2+ and Bi 3+ ; (2) polar displacements of all ions, due to the close relationship between electric polarization and the EFG232425; (3) tilting of oxygen octahedra, which causes a deformation of the oxygen cuboctahedron around the A-site cation and results in an asymmetric charge distribution.…”

mentioning

confidence: 99%

Reconciling Local Structure Disorder and the Relaxor State in (Bi1/2Na1/2)TiO3-BaTiO3

Groszewicz

Gröting

Breitzke

et al. 2016

Sci Rep

View full text Add to dashboard Cite

Lead-based relaxor ferroelectrics are key functional materials indispensable for the production of multilayer ceramic capacitors and piezoelectric transducers. Currently there are strong efforts to develop novel environmentally benign lead-free relaxor materials. The structural origins of the relaxor state and the role of composition modifications in these lead-free materials are still not well understood. In the present contribution, the solid-solution (100-x)(Bi1/2Na1/2)TiO3-xBaTiO3 (BNT-xBT), a prototypic lead-free relaxor is studied by the combination of solid-state nuclear magnetic resonance (NMR) spectroscopy, dielectric measurements and ab-initio density functional theory (DFT). For the first time it is shown that the peculiar composition dependence of the EFG distribution width (ΔQISwidth) correlates strongly to the dispersion in dielectric permittivity, a fingerprint of the relaxor state. Significant disorder is found in the local structure of BNT-xBT, as indicated by the analysis of the electric field gradient (EFG) in 23Na 3QMAS NMR spectra. Aided by DFT calculations, this disorder is attributed to a continuous unimodal distribution of octahedral tilting. These results contrast strongly to the previously proposed coexistence of two octahedral tilt systems in BNT-xBT. Based on these results, we propose that considerable octahedral tilt disorder may be a general feature of these oxides and essential for their relaxor properties.

show abstract

Nuclear quadrupole coupling constants and spontaneous polarization in ferroelectrics

Cited by 3 publications

References 8 publications

An NMR study of¹³⁷Ba and^47,49Ti in ferroelectric BaTiO₃

An NMR study of¹³⁷Ba and^47,49Ti in ferroelectric BaTiO₃

Ab initiostudy of the relation between electric polarization and electric field gradients in ferroelectrics

Reconciling Local Structure Disorder and the Relaxor State in (Bi1/2Na1/2)TiO3-BaTiO3

Contact Info

Product

Resources

About

Nuclear quadrupole coupling constants and spontaneous polarization in ferroelectrics

Cited by 3 publications

References 8 publications

An NMR study of137Ba and47,49Ti in ferroelectric BaTiO3

An NMR study of137Ba and47,49Ti in ferroelectric BaTiO3

Ab initiostudy of the relation between electric polarization and electric field gradients in ferroelectrics

Reconciling Local Structure Disorder and the Relaxor State in (Bi1/2Na1/2)TiO3-BaTiO3

Contact Info

Product

Resources

About

An NMR study of¹³⁷Ba and^47,49Ti in ferroelectric BaTiO₃

An NMR study of¹³⁷Ba and^47,49Ti in ferroelectric BaTiO₃