Sillén-Aurivillius phase bismuth niobium oxychloride, Bi4NbO8Cl, as a New Oxide Ion Conductor

Sillén-Aurivillius phase Bi4NbO8Cl consists of Bi2O22+/NbO43-/Bi2O22+/Cl- layers and the partial substitution of Bi was successfully performed by Ca2+, Sr2+, Ba2+, La3+, Ga3+ and Sn4+. It was found that substitution with...

Fabrication of YSZ-Carbon Felt Composite Materials by Spark Plasma Sintering Process

Dual-phase membrane composed of oxide ion conductor and electron conductor was fabricated for application to oxygen separation membranes. 8 mol% yttria-stabilized zirconia (8YSZ) and carbon felt were used for the oxide ion conducting phase and the electron conductiing phase, respectively. Carbon felt was impregnated with YSZ aqueous suspension (40 wt%), dried, then sintered by a spark plasma sintering (SPS) process under the applied pressure of 80 MPa at 1200, 1400 and 1600 ° C for 10 min. When sintered at 1600 ° C, the XRD pattern showed small peaks indicating the formation of the zirconium carbide phase, but the microstructure observed by SEM showed that the YSZ was well densified and tightly bonded with carbon felt. This method has been demonstrated to be an effective process for the fabrication of YSZ-Carbon composites with both phases percolation structure.

Modulated structure determination and ion transport mechanism of oxide-ion conductor CeNbO4+δ

CeNbO4+δ, a family of oxygen hyperstoichiometry materials with varying oxygen content (CeNbO4, CeNbO4.08, CeNbO4.25, CeNbO4.33) that shows mixed electronic and oxide ionic conduction, has been known for four decades. However, the oxide ionic transport mechanism has remained unclear due to the unknown atomic structures of CeNbO4.08 and CeNbO4.33. Here, we report the complex (3 + 1)D incommensurately modulated structure of CeNbO4.08, and the supercell structure of CeNbO4.33 from single nanocrystals by using a three-dimensional electron diffraction technique. Two oxide ion migration events are identified in CeNbO4.08 and CeNbO4.25 by molecular dynamics simulations, which was a synergic-cooperation knock-on mechanism involving continuous breaking and reformation of Nb2O9 units. However, the excess oxygen in CeNbO4.33 hardly migrates because of the high concentration and the ordered distribution of the excess oxide ions. The relationship between the structure and oxide ion migration for the whole series of CeNbO4+δ compounds elucidated here provides a direction for the performance optimization of these compounds.

From insulator to oxide-ion conductor by a synergistic effect from defect chemistry and microstructure: acceptor-doped Bi-excess sodium bismuth titanate Na0.5Bi0.51TiO3.015

Low levels of acceptor-type dopants can introduce appreciable levels of oxide-ion conductivity into NB0.51T due to a synergistic effect from defect chemistry and ceramic microstructure.

Dion–Jacobson-type oxide-ion conductor CsLa2Ti2NbO10−δ without phase transitions

We present the first example of the Dion–Jacobson-type oxide-ion conductor without phase transitions CsLa2Ti2NbO10−δ (where δ represents the oxygen-vacancy content).