Electrochemical Investigations of SrTiO3 Boundaries

Abstract

Interfaces (grain boundaries and surfaces) are studied in acceptor (Fe) doped SrTiO3 bicrystals, single crystals, and ceramics as a function of temperature (423 K T 1023 K), oxygen partial pressure (1 Pa Po io Pa), and Fe doping content (1.9 1018 cm3 c 9.5 1O' cm3) using electrochemical methods. In particular, impedance spectroscopy and dc polarization techniques have been applied. The electrochemical investigation of tilt and twist grain boundaries in bicrystals combined with structural and chemical grain boundary charactizationby transmission electron microscopy, electron diffraction x-ray analysis, and electron energy loss spectroscopy allowed us to clarify grain boundary effects in SrTiO3. The use of reversible (nonblocking) YBa2Cu3O6+ electrodes proves to be a convenient technique to measure conductivities without electrode effects, since blocking effects at the sample surface were minimized. These results have been compared with those obtained for grain boundaries in polycrystalline samples as well as with the interfaces between metallic electrodes and SrTiO3 single crystals. Besides individual features, all findings at the investigated boundaries and interfaces could be consistently explained by the appearance of pronounced Schottky barriers which were composed of depletion layers of mobile majority charge carriers (h, V).

Secondary ion mass spectrometry (SIMS) – a powerful tool for studying mass transport over various length scales

“…We attributed this additional profile to D O * being lower in the surface region on account of a space-charge layer depleted of oxygen vacancies being present [22]. It is well documented that grain boundaries in Fe-doped SrTiO 3 have space-charge layers in the adjacent bulk regions [26][27][28][29]; this result indicates that the (001) surface of acceptor-doped SrTiO 3 does too.…”

Oxygen Reduction at Dense Thin-Film Microelectrodes on a Proton-Conducting Electrolyte

“…case (iii). 51,52 One the other hand, an example for different majority carriers in the surface layer as a consequence of changed charge state is nominally undoped CeO 2 at comparably low temperatures. 53 Here V…”

On the use of multichannel data acquisition of impedance spectra

“…Impedance spectroscopy is widely used for electrical and electrochemical characterisation of materials [1][2][3][4][5][6][7][8][9][10][11][12]. It has been used to study microstructural effects on the grain boundary controlled behaviour of electroceramics [2][3][4][5], resistive grain boundaries of solid electrolytes [6][7][8] electrode processes in electrochemical cells [9][10][11][12].…”