Diffusion of point defects in calcium titanate

Electronic and ionic conductivity in CaTiO3

“…They also determined the enthalpy of the mobility of electron holes (22 kJ/mol). The latter reported by George and Grace [7,8] was lower (16.7 kJ/mol). They also determined the activation energies of (i) the mobility of oxygen vacancies (54.4 kJ/mol) and (ii) the mobility of electrons.…”

Chemical diffusion in calcium titanate

“…22 along with the data reported by George and Grace [1]. In the determination of the temperature dependence of the chemical diffusion coefficient in the present work the data at 973 K were not taken into account because (i) a substantial departure of these data from the linear dependence established at higher temperatures, and (ii) assumption that these data correspond to a steady-state rather than the gas/solid equilibrium.…”

“…The only studies of the gas/solid equilibration kinetics for O 2 /CaTiO 3 , using the electrical conductivity measurements for monitoring the kinetics in reducing conditions (imposed by the H 2 O/H 2 gas mixture of a constant ratio equal to 0.2 in the range 1373-1573 K) was reported by George and Grace [1]. They considered the temperature dependence of the chemical diffusion coefficient in terms of the enthalpy of mobility of oxygen vacancies (54.4 kJ/mol).…”

Atomistic Study of a CaTiO3‐Based Mixed Conductor: Defects, Nanoscale Clusters, and Oxide‐Ion Migration

“…Schottky defects are highly unfavorable, supporting the hypothesis that the electrical conduction in undoped CaTiO 3 is greatly influenced by the presence of small amounts of acceptor impurities. [27][28][29] Although the lowest-energy defect type is the formation of a pair of Ca and O vacancies, the magnitude of the energy suggests such defects are present in negligible concentration; we may note that this V A ″-V o defect is significantly more favorable in the related SrTiO 3 [30] and CaZrO 3 [31] systems. In addition, anion and cation Frenkel defects were investigated and found to be highly unfavorable (> 3.6 eV), as expected for the close-packed perovskite structure.…”

“…[27] Data were collected in a reducing H 2 /H 2 O atmosphere, corresponding to pO 2 ≈ 10 -10 Pa in the range 1100-1300°C. Higher values were obtained with the same technique for ceramic samples: 0.68 eV in air and 1.39 eV at pO 2 ≈ 10 Pa, [45] which may indicate that impurities or grain boundaries lead to higher resistances in the polycrystalline materials.…”