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Materials Science and Engineering: Materials Chemistry
- Aqueous Synthesis of Nb and Ti Containing Oxides
- Chemical Processing and Characterization of Ta2O5-TiO2 Films
- Unique Microstructures in Ferroelectric Perovskites by Reaction Sintering
- Oxidation of Metallic Nanostructures and Structural Transformation of Nanoclusters under Reactive Gas Environment
^ Aqueous Synthesis of Nb and Ti Containing Oxides
D. A. Payne,* D. L. West; W. G. Klemperer, K. A. Marek (Chem.)
U.S. Department of Energy, DE-FG02-91ER45439
(In cooperation with the Frederick Seitz Materials Research Laboratory)
Researchers are developing two synthetic routes to complex Nb and Ti containing oxides. The first exploits the sequestering ability of carboxylic acids and the second exploits the colloidal nature of freshly precipitated hydrous niobia and titania. Both procedures can be carried out without the need for strict control of the ambient atmosphere. Researchers are optimizing both routes with respect to properties of the synthesized product, required raw materials and process steps, and minimization and control of waste generation and process by-products.
^ Chemical Processing and Characterization of Ta2O5-TiO2 Films
D. A. Payne,* S. Hemjinda
U.S. Department of Energy, DE-FG02-91ER45439
(In cooperation with the Frederick Seitz Materials Research Laboratory)
Thin films of TiO2–modified Ta2O5 were prepared by sol-gel processing. Stable solutions were obtained by refluxing of Ta(OEt)5 and Ti(OPri)4 mixture followed by addition of dilute HCL. Hydrolysis were carried out at very slow rates to avoid precipitation of white hydrous oxides. Films were prepared in a controlled environment in order to be crack free and transparent. Crystallization of Ta2O5-TiO2 films took place around 700°C. A low temperature orthorhombic structure was identified. Crystalline films exhibited K=25 with tanδ=0.03 (at 1MHz). Dielectric constant showed no variations with TiO2 content.
^ Unique Microstructures in Ferroelectric Perovskites by Reaction Sintering
D. A. Payne,* D. L. West, P. Han
U.S. Department of Energy, DE-FG02-91ER45439
(In cooperation with the Frederick Seitz Materials Research Laboratory)
Reaction sintering involves reacting and densifying two or more solid phases without the usual intermediate comminution of the reacted single-phase material. In this work, researchers intend to produce ceramic monoliths with tailored microstructures by reaction sintering fine powder mixtures and "seed" particles of carefully controlled composition and morphology.
^ Oxidation of Metallic Nanostructures and Structural Transformation of Nanoclusters under Reactive Gas Environment
J. M. Zuo,* B. Q. Li, Y. F. Shi
Department of Energy, DE-FG02-91ER45439; University of Illinois
(In cooperation with the Frederick Seitz Materials Research Laboratory)
This project is to investigate the reaction of small metal clusters in a controlled gas environment. The experiment is being done in a specially built UHV transmission electron microscope. Metallic clusters first prepared on clean substrates under the UHV condition are then exposed to reactive gas. The reaction of metallic clusters is studied by electron diffraction and direct imaging in real time. Through this investigation, researchers will attempt to learn the kinetic process and structural transformation of chemical reactions and the influence of sizes on the chemical reaction process.
