Oxide ionic transport features in Gd-doped La nickelates

Correlation between Structural and Transport Properties of Ca-Doped La Nickelates and Their Electrochemical Performance

“…ons [36], most likely in the perovskite layers (as will be indicated below). This is implied by significant difference in the TPIE curves for the LCNO04 sample (generally, high-temperature exchange during the TPIE run) and the other samples (low-intermediate temperature-activated diffusion) (Figure S8) as well as a small fraction of oxygen involved in "fast" diffusion (Table 2).…”

“…Pretreatment was carried out at 700 • C for 30 min in a flow of He + 1% O 2 (flowrate of 25 mL min −1 ). Treatment was conducted in the temperature range of 50-800 • C with a temperature ramp of 5 • C min −1 in a flow of He + 1% C 18 The analysis of the temperature dependences of α was carried out by a mathematical model including the exchange of oxygen in the oxide surface (O (surf) ) with CO 2 molecules in the gas phase with a rate R (heteroexchange rate), oxygen diffusion within the oxide bulk via fast channel with a coefficient D * and exchange between the most mobile oxide anions and neighboring strongly bound oxide anions with a weighted average rate of β [36]. The oxygen surface exchange constant was calculated as follows: k * = R/(ρN O ), where ρ and N O were sample true density and amount of oxygen per unit mass, respectively.…”

“…For the LCNO04 sample, a "slow diffusion" mechanism predominates. Such a mechanism is probably associated with a slow exchange between the most mobile oxide anions and neighboring oxide anions [36], most likely in the perovskite layers (as will be indicated below). This is implied by significant difference in the TPIE curves for the LCNO04 sample (generally, high-temperature exchange during the TPIE run) and the other samples (low-intermediate temperature-activated diffusion) (Figure S8) as well as a small fraction of oxygen involved in "fast" diffusion (Table 2).…”

“…For the LCNO02-04 samples, a certain non-uniformity of oxygen diffusivity was revealed. To describe such a non-uniformity, the mathematical model presented in [36] was used (schematically shown in Figure S11). Such non-uniformity as was observed during the TPIE run can be defined by the relatively fast diffusion via a cooperative mechanism in the low and intermediate temperature range with a subsequent slower exchange of the most mobile oxide anions with more strongly bound adjacent anions of the O sublattice in the high temperature range.…”

Synthesis and Oxygen Mobility of Bismuth Cerates and Titanates with Pyrochlore Structure

“…Finally, the application of triple (protonic-oxide-ionic-electronic) conducting materials in membrane reactors allows for enhance the reactor performance in various catalytic reactions and to improve gas separation characteristics due to coupled transport of electrons/holes, For the Y-doped Bi cerate sample, a similar behavior of isotope substitution dynamics is observed. The same model as that for the undoped sample [48] was used. The difference in the diffusion rate via the Ce-O-Ce channel is insignificant; however, the exchange with other forms of oxygen is significantly faster.…”