Studies of oxygen transport mechanism in electrolytes based on doped lanthanum silicate with apatite structure using techniques of oxygen isotopic heteroexchange and impedance spectroscopy

Temperature-programmed C18O2 SSITKA for powders of fast oxide-ion conductors: Estimation of oxygen self-diffusion coefficients

“…Single-phase samples of La 10 − x (SiO 4 ) 6 − y (XO 4 ) y O 2+ δ , (X = Al, Fe, Al + Fe) were prepared via the mechanochemical or sol-gel routes and calcined under air at 900-1200°C, their structural features being described in details elsewhere [7,10,12,13]. Powders of samples were pressed into pellets under 20 MPa [7] or 300 MPa [10] and sintered under air at temperatures up to 1600°C.…”

“…These results were compared with the data obtained for dense ceramics of selected apatite samples using traditional techniques of IEDP/SIMS and specific Solid State Ionics xxx (2014) xxx-xxx conductivity measurements [7,10]. For comparison, more traditional Sc 0.1 Ce 0.01 Zr 0.89 O 2 electrolyte [11] was studied as well.…”

“…In this work, the temperature-programmed oxygen exchange in the SSITKA mode between C 18 O 2 and solid electrolytes has been studied for the case of doped lanthanum silicates with the apatite structure-a new promising class of fast oxide ion conductors [7,10]. These results were compared with the data obtained for dense ceramics of selected apatite samples using traditional techniques of IEDP/SIMS and specific Solid State Ionics xxx (2014) xxx-xxx conductivity measurements [7,10].…”

“…[5][6][7][8][9]. For traditional 18 O 2 isotope heteroexchange on the oxide-ion conductors, the total process is often controlled by the surface exchange reaction, which makes impossible reliable estimation of D o without special procedures of the surface modification [4,7]. Since the rate of CO 2 exchange on the surface of oxides is faster than that of O 2 , the experiments on the oxygen exchange between C 18 O 2 and powders of mixed ionic-electronic conducting perovskite-fluorite nanocomposites (La 1 − x Bi x MnO 3 + δ - [9]) in the flow reactor in so called SSITKA (Steady-State Isotope Transient Kinetics) mode allowed to estimate D o values with a reasonable precision.…”

“…on the transport properties of electrolytes and mixed ionicelectronic nanocomposites comprised of these electrolytes and electronic conductors (perovskites, etc.) [5][6][7][8][9]. For traditional 18 O 2 isotope heteroexchange on the oxide-ion conductors, the total process is often controlled by the surface exchange reaction, which makes impossible reliable estimation of D o without special procedures of the surface modification [4,7].…”