Fast Fluoride Ion Conduction in Molecular Cation-Containing Compounds, NH4(Mg1-xLix)F3-x and (NH4)2(Mg1-xLix)F4-x

Aiming development of the fast anion conductors, we proposed a new material design using flexible molecular cation as a host cation, and demonstrated it with fluoride ion conduction in NH4(Mg1-xLix)F3-x and (NH4)2(Mg1-xLix)F4-x. Relatively high fluoride ion conductivities of 4.8×10-5 S cm-1 and 8.4×10-6 S cm-1 were achieved at 323 K in (NH4)2(Mg0.85Li0.15)F3.85 and NH4(Mg0.9Li0.1)F2.9, respectively. Our findings suggest molecular cation-containing compounds can be attractive material groups for fast anion conductors.

Effect of chemical redox on Gd-doped ceria mass diffusion

Cations’ valence and size influence mass diffusion and oxygen defects in ceria. Mass diffusion is limited by Gd3+ under oxidative conditions, where Ce4+ is the host cation, while it is unleashed under reducing conditions, where Ce3+ and Gd3+ have the same charge and similar size. Solid solutions with enhanced electrochemical properties are formed under controlled thermo-chemical conditions.

In Situ Analytical Electron Microscopy Studies of Redox Reactions at a YSZ/Pt Interface

Redox reactions were studied at a single yttria-stabilized zirconia (YSZ)/Pt electrode interface, in parallel with pure YSZ with no catalyst electrode, by in situ analytical electron microscopy at elevated temperatures and in an oxygen atmosphere. In situ electron holography showed that the oxide underwent reduction at elevated temperatures in a vacuum and was consequently reoxidized upon exposure to an oxygen flux at the same temperature. In situ energy loss spectroscopy measurements were in agreement with in situ electron holography observations and indicated that the oxidation state of the host cation zirconium was altered in the reduced state of the YSZ to the metastable state Zr3+.

Effects of La2O3 and Nb2O5 Doping on the Dielectric Properties of Ba0.9Sr0.1TiO3 Ceramics

Ba0.9Sr0.1TiO3 ferroelectric ceramics with dopants of La2O3(0, 0.1, 0.1, 0.2 mol%) and Nb2O5(0, 0, 0.1, 0.1 mol%) were prepared in solid state process. The double donor substitutions can weaken lattice size effect by the two different size substitutions. XRD method was used to analyze the crystal structure of the samples, and SEM was used to observe the topography, grain’s size and ceramics density. The results of dielectric-frequency relation indicate that when the contents of La2O3and Nb2O5are both 0.10 mol%, the permittivity can reach to 150 000, and the dielectric loss keeps only 0.118. When the total donor content is lower than 0.40 mol%, compensation effect is dominated by electrons. The giant permittivity is attributed to electrons inside grain and insulated grain boundary. When the dopant content is higher than 0.40 mol%, the compensation effect is dominated by the host cation vacancies. The permittivity decreases rapidly with the increase of the donor concentration.