Resistivities of reduced rutile (TiO2) from 300 °K to exhaustion range

Iguchi, E.; Yajima, Kazuo; Asahina, T.; Kanamori, Youichi

doi:10.1016/s0022-3697(74)80016-8

Cited by 21 publications

(13 citation statements)

References 13 publications

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“…45,60 Effective masses quite similar to those deduced from transport measurements were found. 45,61,62 Above 250 K, transport properties of TiO 2 63 are well accounted for by donor centers with an activation energy of 10 meV. The coexistence of polaron with free-carriers under photoexcitation or after doping, which was evidenced by infrared on powders 64 was recently supported by theoretical approaches.…”

Section: A Calculation Of Hreels Synthetic Datamentioning

confidence: 86%

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Spectral restoration in high resolution electron energy loss spectroscopy based on iterative semi-blind Lucy-Richardson algorithm applied to rutile surfaces

Lazzari

Jupille

2015

Review of Scientific Instruments

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A new spectral restoration algorithm of reflection electron energy loss spectra is proposed. It is based on the maximum likelihood principle as implemented in the iterative Lucy-Richardson approach. Resolution is enhanced and point spread function recovered in a semi-blind way by forcing cyclically the zero loss to converge towards a Dirac peak. Synthetic phonon spectra of TiO2 are used as a test bed to discuss resolution enhancement, convergence benefit, stability towards noise, and apparatus function recovery. Attention is focused on the interplay between spectral restoration and quasi-elastic broadening due to free carriers. A resolution enhancement by a factor up to 6 on the elastic peak width can be obtained on experimental spectra of TiO2(110) and helps revealing mixed phonon/plasmon excitations.

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Section: A Calculation Of Hreels Synthetic Datamentioning

confidence: 86%

“…Similar conclusion and ω P values were found by infra-red reflectivity analysis 45,46,64 and transport measurements. [61][62][63] Other choices of initial P[l] 0 0 are possible. As explained in Sec.…”

Section: Application Of the Semi-blind Deconvolution To Experimentmentioning

confidence: 99%

Spectral restoration in high resolution electron energy loss spectroscopy based on iterative semi-blind Lucy-Richardson algorithm applied to rutile surfaces

Lazzari

Jupille

2015

Review of Scientific Instruments

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“…The BGS correspond to the optical absorption by a polaronic trapping state due to defect-related excess electrons, a polaron being a quasiparticle made of an electron and the accompanying phonon cloud due to lattice distortions. The slow motion of the atoms allows to freeze the self-trapping potential well during photoemission 12 , which explains why thermal activation energy [28][29][30][31] differs from optical transition energy for excess electrons. The line shape of absorption from polaronic states depends on the degree of electron-phonon coupling, on the temperature or even on the dimensionality of space 94,95 .…”

Section: Defect Induced Band Gap States and Optical Absorptionmentioning

confidence: 99%

“…Reduced rutile is indubitably a n−type semiconductor whose transport properties have been much studied 30,31,105 . But their nature is unclear.…”

Section: Excitation Due To Itinerant Motion Of Carriers: the Drudementioning

confidence: 99%

“…In reduced TiO 2 , BGS related to defects [1][2][3][4][5][6][7][8] are evidenced by (i) a photoemission line at 0.8-1 eV below E F 14-17 that reverberates in Auger transitions involving the valence band 18 , (ii) an electron energy loss of ∼ 1 eV [19][20][21][22] , (iii) features in scanning tunneling spectroscopy 23,24 or (iv) near-infrared absorption 25,26 and electron spin-resonance band 27 . On the other hand, transport measurements [28][29][30][31] favor a conduction mechanism through polarons the radius of which remains an open issue 32 . According to simulations, large polaron or free-like carriers in the conduction band seems to compete with more localized polaronic configurations in TiO 2 rutile 24,33,34 .…”

Section: Introductionmentioning

confidence: 99%

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Dielectric study of the interplay between charge carriers and electron energy losses in reduced titanium dioxide

Lazzari

Jupille

2018

Phys. Rev. B

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The transport mechanism in titanium dioxide through polarons is an open issue. High Resolution Electron Energy Loss Spectroscopy (HREELS) is in principle of great relevance in such context, provided the fingerprints on the loss spectrum of the charge carriers involved in the material are disclosed. The present paper aims at evidencing those fingerprints. Through a suitable parametrization of the dielectric function, a theoretical analysis of EELS excitations in defective TiO2 rutile is developed in the framework of the semi-classical dielectric theory. The focus is put on the interplay between phonons, interband transitions and defect related excitations, namely plasmon and band gap states. Transport properties are demonstrated to be more efficiently grasped through the screening they induce on phonons than through the existence of a defined surface plasmon peak. While the corresponding imaginary part of the dielectric function only yields a slight broadening and temperature dependence of the quasi-elastic peak due to the large static dielectric function and electron effective mass, a sizable upward shift in energy and a decrease in intensity of phonons due to the real part are predicted. Band gap states also screen phonons but with downward shift in energy loss. Due to its large oscillator strength, the high energy lying surface phonon at 95 meV is a very sensitive reporter of the combined effects of transport behavior and band gap states. Finally, it is highlighted that extracting quantitative information out of EELS experiments requires an accurate modeling of the depth profile.

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Electron Transport in TiO2−x at Intermediate Temperatures 300 K < T < 1500 K

Poumellec¹,

Marucco²,

Lagnel³

1985

phys. stat. sol. (a)

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A critical analysis is made of the previous works on conductivity measurements and electron motion in TiO2 (rutile) which show that electronic mobility whatever the direction of current is a decreasing function of the temperature. In order to find an accurate expression of the perpendicular mobility, a fit of Iguchi's results is attempted. Although a good fit is obtained with a defect model based on ionized oxygen vacancies and a quasi‐constant mobility, this is inconsistent with previous works. Furthermore simultaneous conductivity and Seebeck effect measurements are performed in order to eliminate electronic concentration and sift out the temperature variation of the mobility and of the transport term of thermopower. This yields a mobility governed by acoustic phonon scattering within a very large range of temperatures. An influence of optical phonon scattering may occur but only at high temperatures.

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Resistivities of reduced rutile (TiO2) from 300 °K to exhaustion range

Cited by 21 publications

References 13 publications

Spectral restoration in high resolution electron energy loss spectroscopy based on iterative semi-blind Lucy-Richardson algorithm applied to rutile surfaces

Spectral restoration in high resolution electron energy loss spectroscopy based on iterative semi-blind Lucy-Richardson algorithm applied to rutile surfaces

Dielectric study of the interplay between charge carriers and electron energy losses in reduced titanium dioxide

Electron Transport in TiO2−x at Intermediate Temperatures 300 K < T < 1500 K

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