Oxygen surface exchange and diffusion in Pr_1.75Sr_0.25Ni_0.75Co_0.25O_4±δ

Abstract

Oxygen surface exchange and diffusion in Pr1.75Sr0.25Ni0.75Co0.25O4±δ have been investigated using two methods: pulsed isotope exchange (PIE) and oxygen isotope exchange with gas phase equilibration (IE GPE).

Design of Mixed Ionic-Electronic Materials for Permselective Membranes and Solid Oxide Fuel Cells Based on Their Oxygen and Hydrogen Mobility

“…The Ruddlesden–Popper (RP) phases with the general formula of (AO)(ABO 3 ) n or A n+1 B n O 3n+1 consist of the perovskite layers ABO 3−δ alternating with the rock salt layers A 2 O 2+δ [ 58 , 60 , 63 , 69 , 129 , 159 , 285 , 286 , 287 , 288 , 289 , 290 ]. The important feature of RP phases, which makes them attractive SOFC cathodes and oxygen-separation-membrane materials, is a fine oxygen transport provided via the cooperative mechanism of oxygen migration.…”

“…This allows them to reach superior oxygen mobility compared to other MIECs ( Figure 21 ). On the other hand, doping with alkaline earth metals (Ca, Sr, Ba), which significantly improves total conductivity, leads to an apparent decrease in the oxygen tracer diffusion coefficient values due to a decrease in the interstitial oxygen content and a larger size of dopant cations resulting in steric hindrances for the oxygen transport [ 287 , 288 , 292 , 298 , 299 , 300 ]. In some cases, it leads to the formation of slow diffusion channels with complicated pathways ( Figure 21 ).…”

“… Arrhenius plots for oxygen tracer diffusion coefficient of first-order RP phases: 1—La 2 NiO 4+δ [ 291 ], 2—La 1.7 Ca 0.3 NiO 4+δ [ 291 ], 3—Pr 2 NiO 4+δ [ 299 ], 4—Pr 1.7 Ca 0.3 NiO 4+δ [ 299 ], 5—Nd 2 NiO 4+δ [ 300 ], 6—Nd 1.7 Ca 0.3 NiO 4+δ [ 300 ], 7—La 2 Ni 0.5 Cu 0.5 O 4+δ [ 286 ], 8—La 2 CuO 4+δ [ 286 ], 9—Pr 1.75 Sr 0.25 Ni 0.75 Co 0.25 O 4+δ [ 287 ]. …”

Consistent interpretation of isotope and chemical oxygen exchange relaxation kinetics in SrFe0.85Mo0.15O3−δ ferrite

“…Among them, the most suitable and effective are coulometric titration, 10–16 electrical conductivity relaxation 17–24 and other methods based on relaxation 25–28 and quasi-equilibrium 29,30 approaches, as well as methods using oxygen isotopes to study the exchange rate in non-stationary regimes. 31–41 Several basic models for the data processing are generally accepted 42 and agree that the O 2 transport can be described by two main stages: the dissociation of an O 2 molecule on the oxide surface (surface exchange) or the movement of oxygen atoms in the volume of a solid (bulk diffusion). 43–46…”

“…Among them, the most suitable and effective are coulometric titration, [10][11][12][13][14][15][16] electrical conductivity relaxation [17][18][19][20][21][22][23][24] and other methods based on relaxation [25][26][27][28] and quasi-equilibrium 29,30 approaches, as well as methods using oxygen isotopes to study the exchange rate in non-stationary regimes. [31][32][33][34][35][36][37][38][39][40][41] Several basic models for the data processing are generally accepted 42 and agree that the O 2 transport can be described by two main stages: the dissociation of an O 2 molecule on the oxide surface (surface exchange) or the movement of oxygen atoms in the volume of a solid (bulk diffusion). [43][44][45][46] Such a large variety of methods and their specific implementations provide advantages for studying the oxygen transport parameters under a wide range of conditions in terms of temperature and O 2 partial pressure, as well as significantly different morphologies (powders, compact samples, and membranes of various thicknesses).…”