In this paper, we have studied a method of loading 12-tungstophosphoric acid (H3PW12O40; PWA) into blockcopolymer templated (designated EO20PO70EO20; Pluronic P-123) mesoporous SiO2 framework without a disordering of mesostructure and without remarkable decrease of specific surface area through one-step condensation process. A precursor solution is initially prepared by TEOS (tetraethoxysilane) hydrolyzed with templating polymer (eg. triblock copolymer), and then mixed directly with PWA to condense mesoporous silicate products that incorporate PWA clusters in the framework. Heteropolyanions are possibly incorporated in the framework silicates. Electrochemical properties of these PWA impregnated mesoporous silicates were studied as electrode materials of Li ion battery as well as solid proton conductors.

In the microcrystalline regime, the behavior of grain boundary-controlled electroceramics is well described by the “brick layer model” (BLM). In the nanocrystalline regime, however, grain boundary layers can represent a significant volume fraction of the overall microstructure and simple layer models are no longer valid. This work describes the development of a pixel-based finite-difference approach to treat a “nested cube model” (NCM), which more accurately calculates the current distribution in polycrystalline ceramics when grain core and grain boundary dimensions become comparable. Furthermore, the NCM approaches layer model behavior as the volume fraction of grain cores approaches unity (thin boundary layers) and it matches standard effective medium treatments as the volume fraction of grain cores approaches zero. Therefore, the NCM can model electroceramic behavior at all grain sizes, from nanoscale to microscale. It can also be modified to handle multi-layer grain boundaries and property gradient effects (e.g., due to space charge regions).

A new iron hydroxyl-phosphate, H2Fe14/3(PO4)4(OH)4 has been synthesized under hydrothermal conditions. In this compound, perpendicular chains formed by the face-sharing FeO6 form rod-packing structure. Only about 60% of the chain sites are occupied by iron atoms; other metals, such as manganese, nickel, zinc, can be incorporated into the chain either by filling in the vacancies and/or replacing some of the iron atoms. Reversible insertion and extraction of lithium into this compound shows it to be an excellent cathode material. At current density of 0.1 mA/cm2, 90 % of the theoretical capacity (176 mAh/g) can be obtained. The utilization was reduced to about 70 % on a ten-fold increase of current density. The electrochemical behavior is attributed to the 3-dimensional rod packing structure, where lithium can move freely even at high current densities inside the 3-dimensional framework without altering the host structure. Two of the protons in the lattice may be exchanged by lithium giving Li2Fe14/3(PO4)4(OH)4. These lithium atoms are not removable in electrochemical cycling and similar electrochemical property was found for these two compounds, suggesting an ion-exchange process for the lithiation.

When used as ceramic membranes for the electrically driven separation of oxygen from air, BIMEVOX materials allow the production of high oxygen fluxes at moderate temperature, 300–600°C. However, 18O/16O Isotope Exchange Depth Profile Technique revealed low kinetics of oxygen transfer at the surface of these ceramics when studied under equilibrium. These kinetics were considerably enhanced when a current was applied. The same membranes were characterized under working conditions using X-ray synchrotron and neutron radiations. Their dynamical transformation under bias was confirmed and explained by a slight reduction of the BIMEVOX electrolyte under working conditions.