RT Journal Article
T1 Unravelling Crystal Superstructures and Transformations in the La6−xMoO12−δ (0.6 ≤ x ≤ 3.0) Series: A System with Tailored Ionic/ Electronic Conductivity.
A1 López Vergara, Adrián
A1 Vizcaíno-Anaya, Lucía
A1 Porras-Vázquez, José Manuel
A1 Baldinozzi, Gianguido
A1 Dos-Santos-Gómez, Lucía
A1 Canales-Vázquez, J.
A1 Marrero-López, David
A1 Ramírez-Losilla, Enrique
K1 Separación por membrana
K1 Química organometálica
AB Crystalline La6−xMoO12−δ materials with different lanthanum/molybdenumratios (0.6 ≤ x ≤ 3.0) have been prepared via a freeze-drying precursor route. The influence ofthe lanthanum content, sintering temperature, and cooling rate on the phase existence rangeand polymorphism was evaluated. Lanthanum-rich compounds present three differentpolymorphs: a cubic (disordered) fluorite and two complex rhombohedral superstructuresrelated to the fluorite. For the first time, the structural resolution of these rhombohedralsuperstructures, 7 × 7 × 1 and 5 × 5 × 1, has been successfully accomplished by neutronpowder diffraction and transmission electron microscopy studies. As the La/Mo ratiodecreases, the cubic symmetry is stabilized, although a phase transformation from cubic tomonoclinic occurs at a low cooling rate. Impedance spectroscopy measurements underdifferent atmospheres (dry and wet N2 and 5% H2−Ar) show that all materials exhibit mixedproton−electronic conductivity. The n-type electronic conductivity is attributed to Mo6+reduction and increases for those phases with lower lanthanum content, i.e., for quenchedsamples, from 5 mS cm−1 for La5.4MoO11.1 to 9.5 mS cm−1 for La4MoO9 at 700 °C in veryreducing and wet conditions, which are significantly better than the values published to date for mixed lanthanum tungstates/molybdates. This makes these materials potential candidates for hydrogen separation membranes.
PB American Chemical Society
YR 2020
FD 2020-08-03
LK https://hdl.handle.net/10630/28458
UL https://hdl.handle.net/10630/28458
LA eng
DS RIUMA. Repositorio Institucional de la Universidad de Málaga
RD 4 mar 2026