Eutectoid decompositions in Ce-containing ABO perovskites: Part I, the case of cooperative growth in CeAlO.

Oxidation of perovskite CeAlO results in the eutectoid transformation to CeO and AlO. This phase transformation was recorded using thermal gravimetric analysis, X-ray diffraction, and scanning transmission electron microscopy. Lamellar features in the resultant microstructure indicates cooperative growth.

Eutectoid decompositions in Ce-containing ABO perovskites: Part II, the case of divorced growth in CeCrO.

A eutectoid phase transformation was exhibited by the perovskite CeCrO when heated in air. The kinetics of the reaction, microstructure of the product, and mechanisms of the transformation were studied using thermogravimetric analysis, X-ray and Raman spectroscopy, X-ray diffraction, and electron microscopy. Fluorite CeO and corundum CrO were formed from the decomposition of CeCrO.

Adlayer formation on C-plane (0001) and R-plane AlO surfaces.

Adlayers on C-plane (0001) and R-plane terminated surfaces of corundum phase aluminum oxide were synthesized by annealing mixtures of two oxide powders, aluminum oxide with an additive. Using high-angle annular dark field scanning transmission electron microscopy, the adsorbed layers were characterized, and image simulations aided interpretation of the results. The adlayers were pseudomorphic, one atomic layer thick and with a fractional site occupancy.

Approaches for the quantitative analysis of oxidation state in cerium oxide nanomaterials.

Cerium oxide nanomaterials (nanoceria, CNMs) are receiving increased attention from the research community due to their unique chemical properties, most prominent of which is their ability to alternate between the Ce and Ce oxidation states. While many analytical techniques and methods have been employed to characterize the amounts of Ce and Ce present (Ce/Ce ratio) within nanoceria materials, to-date no studies have used multiple complementary analytical tools (orthogonal analysis) with technique-independent oxidation state controls for quantitative determinations of the Ce/Ce ratio. Here, we describe the development of analytical methods measuring the oxidation states of nanoceria analytes using technique-independent Ce (CeAlO:Ge) and Ce (CeO) control materials, with a particular focus on x-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) approaches.

Investigation of Electric Field-Induced Structural Changes at Fe-Doped SrTiO₃ Anode Interfaces by Second Harmonic Generation.

We report on the detection of electric field-induced second harmonic generation (EFISHG) from the anode interfaces of reduced and oxidized Fe-doped SrTiO₃ (Fe:STO) single crystals. For the reduced crystal, we observe steady enhancements of the susceptibility components as the imposed -voltage increases. The enhancements are attributed to a field-stabilized electrostriction, leading to Fe:Ti-O bond stretching and bending in Fe:Ti-O₆ octahedra.