Mixed electronic and ionic conductivity of LaCo(M)O3 (M=Ga, Cr, Fe or Ni).

Permeabilidad de oxígeno en membranas cerámicas de La(Sr,Pr)Ga(Mg)O_3-δ con metales de transición

“…One should note that, for lanthanum gallate -based phases containing smaller amounts of the alkaline-earth cation, the only permeation-limiting factor at 1073-1223 K is the bulk ionic conductivity [7,9]. In particular, the specific oxygen permeability of LaGa 1-x Ni x O 3-δ (x = 0.20-0.50) and LaGa 0.40 Co 0.60-y Mg y O 3-δ (y = 0.20-0.25) membranes was found independent of the membrane thickness at d > 0.50 mm, whereas the permeation fluxes increased with decreasing thickness [7,9].…”

“…Furthermore, decreasing the concentration of transitionmetal cations in the Ga sublattice is expected to result in a higher stability of ceramic membranes under high oxygen chemical potential gradients. The present work continues our research of LaGaO 3 -based mixed conductors as potential membrane materials [6][7][8][9][10] and is focused on the studies of oxygen permeability, thermal expansion and stability of La 1-x A x Ga 0.80-y Mg y M 0.20 O 3-δ (A = Sr, Pr; M = Fe, Co, Ni) ceramics. [12] and reference cited); the remaining amounts of Bi 2 O 3 are smaller than the low detection limit of standard analytical techniques.…”

“…Advantages of LSGM include relatively low thermal expansion coefficient, close to that of stabilized zirconia, and sufficient chemical stability in a wide range of oxygen partial pressure. An increase in electronic conductivity necessary for the membrane application can be achieved by introducing of transition metal cations, such as Fe, Co or Ni, into the gallium sublattice of LaGaO 3 [7][8][9][10][11]. Significant oxygen permeation fluxes were observed for LaGa 1-x Ni x O 3-δ (x = 0.20-0.50) and LaGa 0.40 Co 0.60-y Mg y O 3-δ (y = 0.20-0.25) dense ceramic membranes [7,9].…”

“…An increase in electronic conductivity necessary for the membrane application can be achieved by introducing of transition metal cations, such as Fe, Co or Ni, into the gallium sublattice of LaGaO 3 [7][8][9][10][11]. Significant oxygen permeation fluxes were observed for LaGa 1-x Ni x O 3-δ (x = 0.20-0.50) and LaGa 0.40 Co 0.60-y Mg y O 3-δ (y = 0.20-0.25) dense ceramic membranes [7,9]. Oxygen permeation through such membranes is limited predominantly by the oxygen ion diffusion in ceramic bulk; the ionic contribution to total conductivity was found less than 2 % at 1073-1223 K. Since ionic transport in doped lanthanum gallates occurs via the oxygen-vacancy diffusion mechanism, further acceptor doping is expected to increase vacancy concentration, ionic conductivity and, consequently, oxygen permeability.…”

“…The characterization of ceramic materials included XRD (Rigaku Geigerflex D/MAX-B), scanning electron microscopy combined with energy dispersive analysis (Hitachi S-4100), dilatometry (Linseis L70/2001), measurements of the total conductivity as function of temperature and oxygen partial pressure (4-probe DC), faradaic efficiency studies, and determination of steady-state oxygen permeation fluxes. Detailed description of experimental equipment and procedures was published elsewhere ( [6][7][8][9][10]13,14] and references therein). The oxygen permeation and faradaic efficiency measurements were performed in temperature range 973-1223 K. All data on the oxygen permeability presented in this paper correspond to the membrane feed-side oxygen partial pressure (p 2 ) equal to 21 kPa (atmospheric air).…”