Infrared reflectivity and lattice fundamentals in anatase<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">TiO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>s

Gonzalez, Reinaldo; Zallen, Richard; Berger, H.

doi:10.1103/physrevb.55.7014

Cited by 295 publications

(184 citation statements)

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“…͑See, for example, the EЌc reflectivity of anatase TiO 2 in Ref. 24.͒ This circumstance is indeed supported by the numbers in Table II.…”

Section: Infrared Reflectivity and Dielectric Dispersionsupporting

confidence: 72%

“…With unpolarized incident light and the c axis normal to the surface ͑our experimental geometry͒, it is known that off-normal incidence will produce a shallow dip in an EЌc high-reflectivity plateau at the position of an E ʈ c LO mode. 24,25 Support for this interpretation of the weak 675 cm Ϫ1 feature in the crystal reflectivity is provided by the well-defined 675 cm Ϫ1 reflectivity edge seen in the polycrystalline pellet ͑top panel of Fig. 2͒.…”

Section: Infrared Reflectivity and Dielectric Dispersionmentioning

confidence: 83%

“…[22][23][24] The best-fit parameters are given in the upper part of Table II. The overall fit is quite reasonable.…”

Section: Infrared Reflectivity and Dielectric Dispersionmentioning

confidence: 99%

See 2 more Smart Citations

Infrared activity in the Aurivillius layered ferroelectricSrBi2Ta2O
Moret
¹
,
Zallen
²
,
Newnham
³

et al. 1998
Phys. Rev. B
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Experimental studies were carried out on infrared-active phonons in the Aurivillius ferroelectric SrBi 2 Ta 2 O 9 ͑SBT͒, using reflectivity measurements ͑down to 200 cm Ϫ1 ͒ and transmission measurements ͑down to 100 cm Ϫ1 ͒ on crystals, pellets, and thin films. An analysis was done of the contrasting consequences of the competing orthorhombic and pseudotetragonal symmetries in SBT. Reflectivity results for light polarized in the ab plane show that the anisotropy in this plane is small in the frequency range from 300 to 1200 cm Ϫ1 , indicating the influence of the approximate tetragonal symmetry. Dielectric dispersion properties were derived for this polarization (EЌc) in this frequency range. The transverse-optical ͑TO͒ and longitudinal-optical ͑LO͒ frequencies corresponding to the dominant EЌc band are 613 and 773 cm Ϫ1 , respectively. This strong, highfrequency band arises from a mode dominated by the motion of the oxygen sublattice; its TO and LO frequencies yield an oxygen-ion Szigeti effective charge of Ϫ1.5e. Frequency estimates for the TO ͑LO͒ pairs of other strong bands are 188͑330͒ and 334(451) cm Ϫ1 for EЌc, and 610͑675͒ and 780(815) cm Ϫ1 for Eʈc. In addition to the main infrared bands, the main Raman bands of SBT are also reported.

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“…͑See, for example, the EЌc reflectivity of anatase TiO 2 in Ref. 24.͒ This circumstance is indeed supported by the numbers in Table II.…”

Section: Infrared Reflectivity and Dielectric Dispersionsupporting

confidence: 72%

Section: Infrared Reflectivity and Dielectric Dispersionmentioning

confidence: 83%

See 1 more Smart Citation

Infrared activity in the Aurivillius layered ferroelectricSrBi2Ta2O
Moret
¹
,
Zallen
²
,
Newnham
³

et al. 1998
Phys. Rev. B
Self Cite
60
6
29
0
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“…Thus the relationship α=1/ε ∞ was used to derive α from ε ∞ values obtained experimentally either from optical properties in the IR range or, using the relationship ε=n 2 , from the refractive index at photon energies below the onset of band gap absorption. For anatase 10 an isotropically averaged value ε ∞ =5.68 has been evaluated from IR properties 40 Finally, it can be mentioned that after full structural relaxation the mentioned calculations reproducing the experimental E g values gave for ZnO and anatase the unit cell parameters and metal-oxygen bond lengths summarized in Table 1. It can be seen that these figures approach rather well the experimental values at near-liquid helium temperatures 42,43 (with which these calculations, which do not include thermal effects, should be compared), shown also in the Table.…”

Section: Computing the Band Gaps Of The Single Oxide Phasesmentioning

confidence: 99%

Modeling with Hybrid Density Functional Theory the Electronic Band Alignment at the Zinc Oxide–Anatase Interface

Conesa

2012

J. Phys. Chem. C

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The band alignment at semiconductor interfaces can be theoretically computed using periodic slab models together with hybrid functional DFT methods in which HF exchange mixing coefficients are properly chosen (as justified by their relationship with the dielectric constant) and the calculated electrostatic potential inside each slab is used as reference for the band edge energies. This principle is applied here to the interface between wurtzite-type ZnO and anatase-type TiO 2 , two oxides with nearly identical band gap widths. According to the results, in a composite of both materials the conduction and valence bands of ZnO will lie ca. 0.3 eV lower in energy than those of anatase, influencing the way in which photogenerated electrons and holes will be routed in photocatalytic or photovoltaic systems which include interfaces between these two oxides. The performance improvement observed in dye-sensitized solar cells based on a nanostructured ZnO electrode when the surface of the latter is covered by a thin TiO 2 layer is thus justified. The system may serve as example for the estimation of the band alignment in other semiconductor junctions of interest in different kinds of devices.

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“…Within the semiclassical limit, for excess energies less than the minimum LO phonon energy (∼ 45 meV in TiO 2 [62]), severe constraints in the phonon phase space are expected to result in a dramatic decrease of the intraband cooling rate [13]. However, for polaronic materials governed by the Fröhlich interaction, purely quantum kinetic relaxation channels can open also in the case of small excess energies, leading to an efficient redistribution of the electronic energy into the strongly coupled phonons [63,64].…”

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confidence: 99%

Clocking the Ultrafast Electron Cooling in Anatase Titanium Dioxide Nanoparticles

et al. 2018

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The recent identification of strongly bound excitons in room temperature anatase TiO 2 single crystals and nanoparticles underscores the importance of bulk many-body effects in samples used for applications. Here, for the first time, we unravel the interplay between many-body interactions and correlations in highly-excited anatase TiO 2 nanoparticles using ultrafast two-dimensional deepultraviolet spectroscopy. With this approach, under non-resonant excitation, we disentangle the optical nonlinearities contributing to the bleach of the lowest direct exciton peak. This allows us to clock the ultrafast timescale of the hot electron thermalization in the conduction band with unprecedented temporal resolution, which we determine to be < 50 fs, due to the strong electronphonon coupling in the material. Our findings call for the design of alternative resonant excitation schemes in photonics and nanotechnology.1 arXiv:1703.07818v2 [cond-mat.mes-hall] 13 Jan 2018In the last decades, anatase TiO 2 has attracted huge interest as one of the most promising materials for a variety of challenging applications, ranging from photocatalysis [1,2] and photovoltaics [3] to sensors [4,5]. Since these technologies involve charge transport, thermalization and localization, they call for studies of the fast electron and hole dynamics, which provide a deep knowledge of the nature of the photogenerated/injected charge carriers and of the energy balance therein. These processes intimately depend on the details of the electronic structure and the presence of many body-effects in the material. Since anatase TiO 2 is a d 0 transition metal oxide, strong electron-electron correlations do not play a substantial role in the electronic structure [6]. Hence, this solid can be classified within the simple band insulator scheme, in which the forbidden energy gap arises as a result of band theory and is not a consequence of the strong on-site Coulomb interaction. However, different to conventional band insulators, anatase TiO 2 represents a peculiar example in which electron-phonon interaction and electron-hole correlation become relatively strong and influence the optical spectra. On the one hand, the presence of a moderately large electron-phonon coupling in anatase TiO 2 has often been invoked to interpret experimental results naturally pointing to the polaronic (self-trapped) picture [7][8][9][10][11][12][13]. Notable examples include the low temperature green photoluminescence (PL) due to self-trapped excitons [14][15][16][17][18][19][20] and the room temperature electron mobilities whose values are limited by strong scattering with phonons [10]. On the other hand, many-body correlations have been thought to be negligible in this material and, as such, they remained widely unexplored. Recently, by employing state-of-the-art experimental [21] and computational techniques [21][22][23][24][25], the substantial role of electron-hole Coulomb correlations was unravelled in the anatase polymorph of TiO 2 . Strongly bound direct excitons were...

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Infrared reflectivity and lattice fundamentals in anataseTiO2s

Cited by 295 publications

References 20 publications

Infrared activity in the Aurivillius layered ferroelectricSrBi2Ta2O
Moret
¹
,
Zallen
²
,
Newnham
³

et al. 1998
Phys. Rev. B
Self Cite
60
6
29
0
View full text Add to dashboard Cite

Infrared activity in the Aurivillius layered ferroelectricSrBi2Ta2O
Moret
¹
,
Zallen
²
,
Newnham
³

et al. 1998
Phys. Rev. B
Self Cite
60
6
29
0
View full text Add to dashboard Cite

Modeling with Hybrid Density Functional Theory the Electronic Band Alignment at the Zinc Oxide–Anatase Interface

Clocking the Ultrafast Electron Cooling in Anatase Titanium Dioxide Nanoparticles

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Infrared reflectivity and lattice fundamentals in anataseTiO2s

Cited by 295 publications

References 20 publications

Infrared activity in the Aurivillius layered ferroelectricSrBi2Ta2OMoret1, Zallen2, Newnham3 et al. 1998Phys. Rev. BSelf Cite606290View full textAdd to dashboardCite

Infrared activity in the Aurivillius layered ferroelectricSrBi2Ta2OMoret1, Zallen2, Newnham3 et al. 1998Phys. Rev. BSelf Cite606290View full textAdd to dashboardCite

Modeling with Hybrid Density Functional Theory the Electronic Band Alignment at the Zinc Oxide–Anatase Interface

Clocking the Ultrafast Electron Cooling in Anatase Titanium Dioxide Nanoparticles

Contact Info

Product

Resources

About

Infrared activity in the Aurivillius layered ferroelectricSrBi2Ta2O
Moret
¹
,
Zallen
²
,
Newnham
³

et al. 1998
Phys. Rev. B
Self Cite
60
6
29
0
View full text Add to dashboard Cite

Infrared activity in the Aurivillius layered ferroelectricSrBi2Ta2O
Moret
¹
,
Zallen
²
,
Newnham
³

et al. 1998
Phys. Rev. B
Self Cite
60
6
29
0
View full text Add to dashboard Cite