Electronic and ionic conductivity of TiO2 single crystal within the n–p transition range

Nowotny, J.; Radecka, M.; Rękas, M.; Sugihara, S.; Vance, E. R.; Weppner, W.

doi:10.1016/s0272-8842(97)00056-4

Cited by 44 publications

(35 citation statements)

References 14 publications

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“…The presence of Ti 4 O 7 is consistent with the general electronic theory of TiO 2 [10][11][12], which states that when TiO 2 is subjected to a low oxygen atmosphere it begins to equilibrate with the atmosphere. This is achieved via the creation of defects in the crystal structure, which results in TiO 2 being reduced.…”

Section: Resultssupporting

confidence: 83%

In situ synchrotron diffraction of the electrochemical reduction pathway of TiO2

et al. 2010

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Despite over ten years of research into the low-cost electrowinning of titanium direct from the oxide, the reduction sequence of TiO 2 pellets in molten CaCl 2 has been the subject of debate, particularly as the reduction pathway has been inferred from ex-situ studies. Here, for the first time white beam synchrotron X-ray diffraction is used to characterize the phases that form, in-situ during reduction and with ∼100 µm spatial resolution. It is found that TiO 2 becomes sub-stoichiometric very early in reduction facilitating the ionic conduction of oxygen ions, that CaTiO 3 persists to nearly the end of the process and that, finally, CaO forms just before completion of the process. The method is quite generally applicable to the in-situ study of industrial chemical processes. Implications for the industrial scale-up of this method for the low-cost production of titanium are drawn.

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Section: Resultssupporting

confidence: 83%

In situ synchrotron diffraction of the electrochemical reduction pathway of TiO2

et al. 2010

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“…It was shown that in the n-p transition regime both types of electronic charge carriers should be taken into account in the considerations of electrical properties of metal oxides [11,12]. Conseooently, all the components of electrical conductivity, o,, Op and o~, have an impact on the curvature of the log o vs. log p(O2)dependence.…”

Section: Ionic Conductivitymentioning

confidence: 99%

Electronic and ionic conductivity in CaTiO3

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Nowotny

Sorrell

et al. 2004

Ionics

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Abstract. The present work describes the electrical conductivity of undoped CaTiO 3 in terms of the electrical conductivity components corresponding to electrons, electron holes and ionic charge carriers in the temperature range 973 K -1323 K and under controlled oxygen partial pressure (10 Pa -72 kPa). These data are considered in terms of the transference numbers of the respective charge carriers. It appears that the ionic conductivity component assumes maximum at the n-p transition when the ionic transfer number reaches 50% of the total conductivity value at 1323 K. The present study also includes the determination of the activation energy of the conductivity component related to ions (162.1 kJ/mol), electrons (134.2 kJ/mol) and electron holes (86.2 kJ/mol). The data obtained in this work indicate that undoped CaTiO3 exhibits a substantial level of ionic conduction that cannot be ignored in a quantitative analysis of electrical conductivity data.

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“…12. In contrast to the p-to-n transition crystalline titania, Nowotny et al [31] were able to exhibited by coarsened titania at intermediate Po, extract the ionic conductivity from the P, depenone observes an apparent ionic plateau at high P 0 dence of the total conductivity. Interestingly enough, and an n-type regime at low P,,.…”

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confidence: 98%