Measurement of oxygen transport kinetics in epitaxial La2NiO4+δ thin films by electrical conductivity relaxation

Effects of crystallographic orientation on the oxygen exchange rate of La0.7Sr0.3MnO3 thin films

“…Similar oxidation and reduction values for k chem have been observed in ECR measurements on Ga-doped ceria films [49]. However, for ECR measurements made on bulk LSM samples or oxygen vacancy rich samples, such as LSM at low oxygen pressures [24], or iron, cobalt, and nickel perovskites [10,13,42,69], k chem is found to be dependent on the gas pressure [10,13,40,42], including the direction of the pressure change (either on initial or final pressure). The weak pressure dependency of our surface exchange rate may be attributed to several possible factors, such as the narrow pressure range investigated (only one order of magnitude) and the different physical process occurring in cation vacancy rich materials.…”

“…In electrical conductivity relaxation (ECR) measurements [24,[39][40][41][42][43][44][45][46], an abrupt change of oxygen partial pressure is imposed on the sample under test. Under a constant temperature, there is a time dependent change of electrical conductivity, until the system reaches a new thermodynamic equilibrium.…”

Electrical Conductivity and Oxygen Exchange Kinetics of La[sub 2]NiO[sub 4+δ] Thin Films Grown by Chemical Vapor Deposition

“…As the measured La 2 NiO 4+␦ films were relatively thin ͑Ͻ350 nm͒ and largely below the characteristic thickness of the material determined by Kim et al, 20 it was reasonable to assume that the oxygen transport was mainly controlled by the surface exchange rate. 20 For a single surface reaction and a small oxygen pressure change, the normalized conductivity of a plane sheet is…”

“…We relate the short time constant 1 to the film surface exchange process ͑fast͒, whereas the large time constant 2 might be associated either to a slow process limiting the oxygen diffusion at the film-substrate interface or even to a material chemical degradation. 20 Kim et al considered their material formed by two regions of different surface morphology. The slow exchange kinetics was associated to the expected ͑001͒ surface of the c-axis oriented LNO films, while the faster exchange kinetics was assigned to the ͑110͒ and ͑100͒ LNO surface facets, which appeared after the ECR experiments, as detected by XRD.…”

Relationship between Local Structure and Oxide Ionic Diffusion of Nd2NiO4+^|^delta; with K2NiF4 Structure

“…16,18,[20][21][22] The principle mechanism for oxide ion diffusion is considered to involve ionic hopping between interstitial oxygen sites located in alternate LnO rock salt layers along the ab plane of the structure. 18,22 Any possible path for oxygen diffusion along the c axis involves less favorable diffusion through fully occupied oxygen sites in the perovskite blocks.…”