Two‐Fold Diffusion Kinetics of Oxygen Re‐Equilibration in Donor‐Doped BaTiO₃

Abstract

Meaning as-calculated from the batch composition (irrespective of phase purity), which was formulated on the basis of the presumption ½La Ba 4½V 00 00 Ti .

Crystal Structure, Hydration, and Two-Fold/Single-Fold Diffusion Kinetics in Proton-Conducting Ba0.9La0.1Zr0.25Sn0.25In0.5O3−a Oxide

“…Such change implies the presence of the electronic hole conductivity, as can be expected from the discussed characteristics of the EIS data recorded at higher (≥600 °C) temperatures. It should be clarified that, in the case of ECR profiles fitted at 600 °C and above, only R0 component was considered, which is in accordance with the direct current measurements presented in the literature [33,36]. Table 2 values of the proton conductivity are lower [43].…”

“…Such change implies the presence of the electronic hole conductivity, as can be expected from the discussed characteristics of the EIS data recorded at higher (≥600 • C) temperatures. It should be clarified that, in the case of ECR profiles fitted at 600 • C and above, only R 0 component was considered, which is in accordance with the direct current measurements presented in the literature [33,36]. All the measured ECR data allowed to prepare the Arrhenius-type graph (Figure 10), in which calculated values of the chemical diffusion coefficient D and the surface exchange coefficient k are presented as a function of temperature.…”

“…25 In 0.5 O 3−a material during an abrupt change of the surrounding atmospheres from dry to humidified air, as recorded at 450 • C and 650 • C. As can be seen, while the results from the lower temperature show single-fold character, data from the higher temperature are evidently pointing to a decoupled transport of hydrogen and oxygen. Using similar reasoning as presented in work [33], this corresponds to a qualitative change of the diffusion process, which from the coupled, ambipolar transfer of protons and oxygen (i.e., water) becomes decoupled, and both charge carries move independently. Such change implies the presence of the electronic hole conductivity, as can be expected from the discussed characteristics of the EIS data recorded at higher (≥600 • C) temperatures.…”

Modeling of transport properties of interfacially controlled electroceramics: Application to n-conducting barium titanate

“…According to the defect chemistry of donor-doped BaTiO 3 the incorporation of oxygen leads to the formation of a titania-rich phase (e.g. Ba 6 Ti 17 O 40 ) at the grain boundaries and cation vacancies in the bulk of barium titanate ceramics [13][14][15] …”

“…The composition of grain boundary regions depends strongly on the defect chemistry of the grain interior (bulk) as well as on preparation conditions, such as sintering temperature, dwell time, and cooling rate. The defect chemistry of donor-doped barium titanate has been treated extensively in literature [13][14][15]. It is generally accepted that at oxidizing conditions the donor dopants in n-type BaTiO 3 are compensated by acceptor co-dopants, cation vacancies, and electrons.…”