Thermal Conductivity and Thermoelectric Power of Rutile (Ti<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>)

Thurber, W. R.; Mante, A.J.H.

doi:10.1103/physrev.139.a1655

Cited by 91 publications

(49 citation statements)

References 47 publications

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“…I n 2 we read that "for the SP Seebeck coefficient in" pure "samples, y@P) = const should be observed a t T > T, ( 5 We reproduce Fig. 6 from [7] which clearly shows that y in rutile is independent of T till T = 70 to 100 OK (cf. Fig.…”

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confidence: 61%

On the Experimental Observation of Small Polarons in Rutile (TiO₂)

Bogomolov

Firsov

Kudinov

et al. 1969

Physica Status Solidi (b)

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A careful analysis of certain observations concerning the polaron nature of current carriers in rutile is presented. The criticism of our paper [l] given in [2] is shown to be unfounded.KpuTasecmx a a n i e r a~~f i , Some arguments confirming the polaron nature of current carriers in rutile were given in [l]. I n the two first sections of his paper Klinger [2] enumerates the well-known results of small polaron theory. I n Section 3 (see items 1' to 5') he criticizes the analysis of experimental data on rutile given in [l].We shall prove in this paper that all arguments given in 1' to 5' of [2] are misleading and do not invalidate our conclusions obtained in [l].1.' I n 1' one may read that "at T = const, a('P)(w) N (T N Ni (1 -K ) as well as a@p)(w) IV 0'' l ) , where d i p ) is the absorption coefficient for polarons localized on impurity ions, d S p ) the absorption coefficient for free polarons, Ni the impurity concentration, K the compensation degree, and (T the dc conductivity. It means that free carrier absorption and absorption due t o nonionized impurities are both proportional to (T, and if one takes G to be a measure of concentration it is impossible to distinguish between them a t T = const. Separation of these both types of absorption can be achieved in particular by taking into account their different T-dependence. On page 484 in [2] Klinger also mentions about this possibility. It is very strange indeed that he did not notice that precisely this simple method was used in [l], where it was shown that G ( O ) increases with increasing T (whereas diP)(w) should decrease with increasing T). The simultaneous increase of cr and a(w) with T for 300 O K < T < 600 OK in samples with deeper donor levels is shown in our recent papers [3].2'. I n 2 we read that "for the SP Seebeck coefficient in" pure "samples, y@P) = const should be observed a t T > T, ( 5 100 OK), while the experiment shows this rather a t T 2 300 OK". Herewith Klinger refers to papers [4] to [7].We reproduce Fig. 6 from [7] which clearly shows that y in rutile is independent of T till T = 70 to 100 OK (cf. Fig. 1). Thus the T-dependence of y is just the same as it should be in Klinger's opinion for small polarons. 1)The original text quoted from [2] is put in inverted commas.

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mentioning

confidence: 61%

On the Experimental Observation of Small Polarons in Rutile (TiO₂)

Bogomolov

Firsov

Kudinov

et al. 1969

Physica Status Solidi (b)

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“…There is quite a spread in values reported for m Ã e . 11,34,[59][60][61][62][63][64] In this study, a value of ten-times the free electron mass m e is assumed. Figure 5 displays exemplary DLTS spectra measured on Pd/TiO 2 /InGa junctions.…”

Section: A Thermal Admittance Spectroscopymentioning

confidence: 99%

Influence of annealing atmosphere on formation of electrically-active defects in rutile TiO2

Zimmermann

Bonkerud

Herklotz

et al. 2018

Journal of Applied Physics

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Electronic states in the upper part of the bandgap of reduced and/or hydrogenated n-type rutile TiO2 single crystals have been studied by means of thermal admittance and deep-level transient spectroscopy measurements. The studies were performed at sample temperatures between 28 and 300 K. The results reveal limited charge carrier freeze-out even at 28 K and evidence the existence of dominant shallow donors with ionization energies below 25 meV. Interstitial atomic hydrogen is considered to be a major contributor to these shallow donors, substantiated by infrared absorption measurements. Three defect energy levels with positions of about 70 meV, 95 meV, and 120 meV below the conduction band edge occur in all the studied samples, irrespective of the sample production batch and the post-growth heat treatment used. The origin of these levels is discussed in terms of electron polarons, intrinsic point defects, and/or common residual impurities, where especially interstitial titanium atoms, oxygen vacancies, and complexes involving Al atoms appear as likely candidates. In contrast, no common deep-level defect, exhibiting a charge state transition in the 200–700 meV range below the conduction band edge, is found in different samples. This may possibly indicate a strong influence on deep-level defects by the post-growth heat treatments employed.

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“…We believe to see the influence of low lying transverse optical phonon branches. Our way of reasoning can also be applied to measurements on other single crystalline ferroelectric materials near their Curie temperature [7,8].Thermal conductivity measurements have been performed by a steady state heat flow method [9] in a temperature range of 100 -500°K. Differential thermocouples of copper-constantan were used.…”

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confidence: 99%

“…Thermal conductivity measurements have been performed by a steady state heat flow method [9] in a temperature range of 100 -500°K. Differential thermocouples of copper-constantan were used.…”

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The thermal conductivity of BaTiO3 in the neighbourhood of its ferroelectric transition temperatures

Mante

Volger

1967

Physics Letters A

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The thermal conductivity of single crystalline BaTiO 3 has been measured in the temperature range of 100-500OK. In the neighbourhood of the transition temperature a reduction of the thermal conductivity is observed. This result can be explained in view of a current theory on ferroelectricity which introduces the concept of low frequency ferroelectric modes of lattice vibration.Optical phonon effects in thermal conductivity studies have been reported before [1][2][3].In this note we report measurements on BaTiO 3 near its transition temperatures that differ from previous measurements [4][5][6]. We believe to see the influence of low lying transverse optical phonon branches. Our way of reasoning can also be applied to measurements on other single crystalline ferroelectric materials near their Curie temperature [7,8].Thermal conductivity measurements have been performed by a steady state heat flow method [9] in a temperature range of 100 -500°K. Differential thermocouples of copper-constantan were used. A Leeds and Northrup K3 potentiometer together with a Hewlett and Packard 419-A d.c. null detector were used for the thermocouple measurements. The temperature difference was of the order of one to four degrees centigrades. The sample of roughly three milimeter diameter and one milimeter thickness, was grown by floating zone process [10] with a Sr dope of 1.5%. At room temperature under a polarizing microscope it showed a multidomain structure. The heater and the thermocouples of 0.05 mm diameter were glued to the sample and the sample to the heat sink by a high temperature-setting epoxy resin.The result of the measurements is shown in fig. 1. The curve shows dips in the neighbourhood of the transition temperatures. At the high temperature side it is rising. We expect it to merge to a higher lying curve that has a T-1 dependence at these temperatures.

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Thermal Conductivity and Thermoelectric Power of Rutile (TiO2)

Cited by 91 publications

References 47 publications

On the Experimental Observation of Small Polarons in Rutile (TiO₂)

On the Experimental Observation of Small Polarons in Rutile (TiO₂)

Influence of annealing atmosphere on formation of electrically-active defects in rutile TiO2

The thermal conductivity of BaTiO3 in the neighbourhood of its ferroelectric transition temperatures

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Thermal Conductivity and Thermoelectric Power of Rutile (TiO2)

Cited by 91 publications

References 47 publications

On the Experimental Observation of Small Polarons in Rutile (TiO2)

On the Experimental Observation of Small Polarons in Rutile (TiO2)

Influence of annealing atmosphere on formation of electrically-active defects in rutile TiO2

The thermal conductivity of BaTiO3 in the neighbourhood of its ferroelectric transition temperatures

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Product

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On the Experimental Observation of Small Polarons in Rutile (TiO₂)

On the Experimental Observation of Small Polarons in Rutile (TiO₂)