Influence of Line Defects on the Electrical Properties of Single Crystal TiO₂

Abstract

One-dimensional defects are created in [001] and [110] oriented TiO 2 single crystals by uniaxial pressure. Transmission electron microscopy (TEM) characterization shows them to preferably lie on {110} planes. Electrical properties studied as a function of oxygen partial pressure reveal their infl uence on ionic and electronic charge carriers. At high oxygen partial pressures (1 bar-10 − 5 bar) the conductivity due to positive charge carriers is strongly enhanced, e.g., the ionic conductivity is increased by more than two orders of magnitude, when the electrical measurement axis lies on the slip plane. In contrary, no changes are observed when the measurement axis does not lie on the slip planes. At low oxygen partial pressures ( < 10 − 15 bar), irrespective of orientation and presence of dislocation, there is no change in the n-type conductivity. The observed phenomena can be well explained within the space charge model, assuming the dislocation cores to exhibit an excess negative charge (increased titanium vacancy concentration). The present study gives a clear correlation between line defects and point defect concentrations in such an oxide for the fi rst time.

Influence of Dislocations in Transition Metal Oxides on Selected Physical and Chemical Properties

“…The plastic deformation in rutile TiO 2 was also found to take place by activating {101}<101> and {100}<010> slip systems [192]. The dislocations have been confirmed to affect the electrical properties of TiO 2 single crystals [19] and the ionic conductivity of polycrystalline TiO 2 [20]. However, the relationship between the dislocation core structures and properties is still unclear because the general knowledge on the atomic-structures of dislocations has not been well characterized.…”

Management on the location and concentration of Ti3+ in anatase TiO2 for defects-induced visible-light photocatalysis

“…Recently, the chemistry of structurally defective TiO 2 with Ti 3+ self-doping (or oxygen vacancies) has been developed to tackle the above challenges [14][15][16][17]. In general, Ti 3+ selfdoping is induced by reducing solid TiO 2 particles with a suitable reductant in gas or solution phase.…”

3D Dislocation structure evolution in strontium titanate: Spherical indentation experiments and MD simulations

“…Recently, it has been demonstrated that dislocations can have a strong effect on the electrical properties of ceramic materials . Inducing dislocations by plastic deformation can potentially provide a strategy to modify the charge carrier transport and/or ionic surface exchange kinetics in solid oxides . In case of strontium titanate (STO), which is a prototypical perovskite oxide ceramic, the transport of oxygen along dislocations is a current center of attention due to its potential implementation as resistive switching memory .…”