Oxygen-active elements such as Y, Zr and Hf are added to alumina-forming alloys to improve the adhesion of the external α-Al2O3 scale formed during high temperature oxidation. During oxidation at 1000°-1500°C, many such elements are observed to diffuse from the alloy through the scale and form oxide particles at the scale-gas interface. Once nucleated, the volume fraction of these particles increases with oxidation temperature and time. The continued increase in volume fraction with time suggests that diffusion is not merely driven by a concentration gradient of the oxygen-active elements. Pre-coating with a dense, 1 μm-thick, plasma-deposited alumina layer prior to oxidation did not prevent the nucleation and growth of these types of particles at the gas interface of the coating. The driving force for this diffusion phenomenon is attributed to the oxygen potential gradient across the metal-oxide-gas system and the high oxygen affinity of these elements.

Oxide ion conductivity studies have been done on the Lanthanum Gallate based compounds. Yttrium substitution at the Ga site has been attempted to increase the unit cell size. Single phase was obtained for limited Y substituion i.e., La0.9Sr0.1Ga0.7Y0.1Mg0.2O3-x. It is found that the activation energy for the oxide ion conductivity has decreased for this composition. Based on the tolerance factor and B-site radius values, the migration energies were obtained for the LaGaO3 based perovskites. It is observed that migration energy has been significantly reduced upon substitution at the B-site. Absence of an enhancement in the conductivity with Yttrium substitution could be due to the vaccancy ordering inhibiting the oxide ion migration.

Recent studies on Perovskites type compounds revealed an oxide ion conductivity, higher than that of Fluorite structures. The most recent one is doped Lanthanum Gallate, which exhibits a maximum ionic conductivity of 0.14 S cm-1 and is a promising new ion conductor. The objective of this study is to synthesize and investigate the ionic conductivity of a similar compound, namely doped LaTmO3. Single phase compounds of the system La1-xSrxTm1-yMgyO3(X=0-0.2,y=0.1&0.2) were synthesized and the ionic conductivity measured at various temperatures. The results showed that ionic conductivity improved significantly with Sr doping. It showed highest oxygen ion diffusion and catalytic activity for Sr doped LaTmO3.

Li+ has been incorporated in the 3D -framework of PbM3+M4+P3O12 by soft chemistry method using n-butyl lithium at RT. It is shown that the framework of the [NZP] structure remains intact upon Li+ insertion and provides a three dimensional interstitial pathway for Li+ ion diffusion.

The J-U relation of the KTP crystal along its z-axis under low DC field deviates from linearity, which is different from that of the crystal along the other two principle axis. The resistance of the crystal along its z-axis increases with the time under high DC stress and the crystal becomes dark. The dark color can be removed by annealing. Electrode reactions were also observed. The phenomena are related to the easy movement of ions along the z-axis of the KTP crystal.

Numerous observations have been reported in the literature of enhanced mass transport and solid-state reaction rates during microwave heating or processing of a variety of ceramic, glass, and polymer materials. Recent research reveals that these phenomena are probably the result of a previously-unknown driving force for ionic mass transport. The driving force--termed a “ponderomotive” (mass-moving) force--results from the application of intense, high-frequency electric fields near physical interfaces (e.g., free surfaces, grain boundaries). Experiments, theory, and numerical simulations all demonstrate that this driving force can influence solid state reaction kinetics by enhancing mass transport rates.

Chromium diffusion coefficients in alumina single crystals were evaluated from penetration profiles determined by the SIMS technique. The samples were previously annealed at 1000°C (1 hour), 1500°C (4 hours), and 1700°C (24 hours). Diffusion experiments were carried out at 1400°C during 10 hours.

The results show that bulk diffusion coefficients are strongly dependent on preannealing conditions (temperature and time): they decrease by more than an order of magnitude when the preannealing temperature is increased from 1000°C to 1700°C.

These results are discussed taking into account the dislocations and point defects in alumina. We consider the role played by the linear defects resulting from surface polishing, as well as point defects associated with impurities. It is found that the lowest defect concentration is achieved after an annealing treatment at 1700°C during 24 hours. The conditions for obtaining a, «reference material» are proposed.

The interfacing of thin film vapor deposition technologies and solid state electrochemistry has led to the recent development of polarized electrochemical vapor deposition (PEVD). In this study, PEVD was applied to deposit a thin layer of yttria stabilized zirconia (YSZ) over a porous metallic electrode to form the cermet anode of a solid oxide fuel cell (SOFC). During PEVD, oxygen ions are transported through the solid electrolyte of an SOFC under an electrical potential gradient provided by an external dc source. At the metallic electrode (anode) surface, oxygen ions react electrochemically with ZrCl4and YCl3 in the vapor phase to deposit YSZ. The growth of YSZ resembles the mechanisms illustrated in Wagner's tarnishing theory. However, modification has been made to the initial growth of YSZ at both electronically and ionically shorted paths along the metallic electrode and solid electrolyte surfaces, respectively. The initial experimental results in the present study showed that PEVD is capable of depositing a thin layer of YSZ on a porous metallic electrode to form a cermet anode. This layer not only provides a continuous ionic conducting path in the anode to reduce the overpotential loss, but also protects the metallic electrode from further sintering, vapor loss and poisoning in the harsh SOFC operating conditions.