EPR investigation of substitution position for Fe3+ in LiNbO3:Fe3+ system

Wang, Hui; Kuang, Xiao‐Yu; Die, Dong; Xiong, Yong; Kang-Wei, Zhou

doi:10.1016/j.physb.2005.05.049

Cited by 9 publications

(7 citation statements)

References 31 publications

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“…In conflict with these, several studies using EPR and ESR point to iron occupying the niobium site. 76,77 In addition, other studies support a two site model, in which iron occupies both lithium and niobium sites. 79 The DFT calculations find that iron on the lithium site is favorable under both Nb 2 O 5 -and Li 2 O-rich conditions with different charge compensation mechanisms in the two cases.…”

Section: A Incorporation Site Preference and Charge Compensation Mecmentioning

confidence: 90%

“…͑ii͒ For Fe-doped LiNbO 3 , in spite of extensive efforts to determine the occupied site of iron using various techniques, including optical absorption, 75 electron paramagnetic resonance ͑EPR͒, 76 Mossbauer spectroscopy, 16,17 and PIXE, 22 no conclusion has yet been reached with regards to site occupancy. ENDOR, 15 PIXE, 22 XSW, 77 and EXAFS ͑Ref.…”

Section: A Incorporation Site Preference and Charge Compensation Mecmentioning

confidence: 99%

See 1 more Smart Citation

Stability and charge transfer levels of extrinsic defects inLiNbO3

Chernatynskiy

Lee

et al. 2010

Phys. Rev. B

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The technologically important incorporation of extrinsic defects ͑Mg 2+ , Fe 2+ , Fe 3+ , Er 3+ , and Nd 3+ ͒ in LiNbO 3 is investigated using density-functional theory combined with thermodynamic calculations. Defect energies, the charge compensation mechanisms, and charge transfer levels, are determined for congruent and stoichiometric compositions. In general, under congruent ͑Nb 2 O 5-rich͒ conditions impurities occupy lithium sites, compensated by lithium vacancies. Under stoichiometric ͑Li 2 O-rich͒ conditions, impurities occupy both lithium and niobium sites. The effects of the concentration of Mg on the dominant defect and site occupancy are analyzed. In addition, the thermal ionization energy and relative defect stability order for Fe 2+ and Fe 3+ are evaluated. The charge transfer levels of impurities with regard to the band structure, and their influences on the optical properties of the material are elucidated.

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Section: A Incorporation Site Preference and Charge Compensation Mecmentioning

confidence: 90%

Section: A Incorporation Site Preference and Charge Compensation Mecmentioning

confidence: 99%

Stability and charge transfer levels of extrinsic defects inLiNbO3

Chernatynskiy

Lee

et al. 2010

Phys. Rev. B

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“…Quite surprisingly, there exist few experimental and theoretical studies reporting on the direct investigation of the most basic characteristics of the Fe bound polaron, i.e., the local distortion produced by the self-trapping action and its electronic structure. Generally, the incorporation of Fe in LNB was experimentally studied only from the point of view of lattice site location and determination of the Fe valence state [14][15][16][17][18][19][20][21][22][23][24]. However, some recent XRD results [25] showed that the electron capture by the Fe center produces a strain in the crystal matrix, indicating the onset of a measurable deformation at the Fe centers when their valence is changed from Fe 3+ to Fe 2+ by a reduction treatment.…”

Section: Introductionmentioning

confidence: 99%

Polaronic deformation at theFe2+/3+impurity site inFe:LiNbO3crystals

et al. 2015

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Iron doped LiNbO 3 crystals with different iron valence states are investigated. An extended x-ray absorption fine structure (EXAFS) spectroscopy study highlights evident changes in the local structure around iron that can be ascribed to the presence of small polarons. In particular, when a Fe 3+ replaced a Li ion, the oxygen octahedron shrinked with respect to the pure material, with an average iron-oxygen bond value very similar to that of Fe 2 O 3 hematite. When adding an electron, it localizes at the Fe site in a configuration very close to the atomic Fe d orbitals, inducing a relaxation of the oxygen cage. The same system was modelled by spin-polarized density functional theory (DFT). Several local as well as hybrid exchange-correlation functionals were probed on the bulk LiNbO 3 structural properties. The computation is then extended to the case of hematite and finally to the Fe defect in LiNbO 3. The calculations reproduced with good accuracy the large lattice relaxation of the oxygen ligands associated to the electronic capture at the Fe center that can be interpreted as due to the polaron formation. The calculations reproduce satisfactorily the available EXAFS data, and allow for the estimation of the polaron energies and the optical properties of the defect.

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“…The details of the influence of the − terms on the electronic structures are discussed later. The occupation sites of Fe in LN have been reported as Fe on the Li site (Fe Li ) [33][34][35][36][37][38][39][40] and Fe on the Nb site (Fe Nb ) [38,39] In the model of Fe 2+ Li , the charge neutrality is supposed to be satisfied by the following two possible compensations: one is the formation of the small polaron, Fe 2+…”

Section: Methods Of Dft Calculationsmentioning

confidence: 99%

Electronic Origin of Defect States in Fe-Doped LiNbO₃Ferroelectrics

Noguchi

Inoue

Miyayama

2016

Advances in Condensed Matter Physics

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We investigate the role of Fe in the electronic structure of ferroelectric LiNbO3by density-functional theory calculations. We show that Fe2+on the Li site (Fe2+Li) features a displacement opposite to the direction of spontaneous polarization and acts as a trigger for the bulk photovoltaic (PV) effect. In contrast to Fe3+on the Li site that forms the defect states (1e,a, and 2e) below the conduction band minimum, the reduction from Fe3+to Fe2+accompanied by a lattice relaxation markedly lowers only theastate (dz2) owing to a strong orbital hybridization with Nb-4d. Theastate ofFe2+Liprovides the highest electron-occupied defect state in the middle of the band gap. A reduction treatment of Fe-LN is expected to increase the concentration of Fe2+and therefore to enhance the PV effect under visible light illumination.

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EPR investigation of substitution position for Fe3+ in LiNbO3:Fe3+ system

Cited by 9 publications

References 31 publications

Stability and charge transfer levels of extrinsic defects inLiNbO3

Stability and charge transfer levels of extrinsic defects inLiNbO3

Polaronic deformation at theFe2+/3+impurity site inFe:LiNbO3crystals

Electronic Origin of Defect States in Fe-Doped LiNbO₃Ferroelectrics

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EPR investigation of substitution position for Fe3+ in LiNbO3:Fe3+ system

Cited by 9 publications

References 31 publications

Stability and charge transfer levels of extrinsic defects inLiNbO3

Stability and charge transfer levels of extrinsic defects inLiNbO3

Polaronic deformation at theFe2+/3+impurity site inFe:LiNbO3crystals

Electronic Origin of Defect States in Fe-Doped LiNbO3Ferroelectrics

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Electronic Origin of Defect States in Fe-Doped LiNbO₃Ferroelectrics