Actinides/Solvent extraction /Redox/Thenoyltrifluoroacetone/ Separations
SummaryThe conditions for relatively rapid separation of actinide ions in oxidation states IV, V and VI using TTA extraction have been developed. The VI and IV species are extracted by TTA from an aqueous phase of pH 3-4, leaving the V in the aqueous phase ( > 99%). Extraction at pH 0.6 removes 98% of the IV but only 2% of the VI into the organic phase. The use of this technique in a study of Np(VI) reduction was demonstrated.
Chemical deposition experiments were performed to determine how surface preparation and film deposition conditions influence the resulting insulator–semiconductor interface composition and chemical structure. Silicon dioxide layers were chemically deposited on indium phosphide by hydrolyzing silicon orthopropoxide. On unoxidized, etched surfaces, coverage was always patchy. On InP with approximately one monolayer of chemisorbed oxygen in a hydrated-phosphatelike environment, a continuous, ∼60-Å-thick SiO2 film was formed at room temperature. SiO2 attached to the substrate through about one monolayer of Si–O–P bonds. Heating to 50 °C during hydrolysis resulted in a mixed Si–In–P oxide, owing to simultaneous hydrolysis and oxidation processes.
A theory to predict the orientation of radio-frequency (rf) sputter-deposited MoS2 films with respect to the substrate surface is presented. Oxygen-containing species such as H2O and -OH are postulated to be active sites that force crystallites to form with their basal planes perpendicular to the surface. X-ray diffraction is used to determine the crystallite orientation in films deposited on smooth, rough, or oxidized Si surfaces, as well as on fused silica or gold surfaces. The results support the theory. To produce MoS2 films with their crystallite basal planes parallel to a substrate surface (which has been suggested to be the low friction orientation), the active sites must be removed from the substrate by, for instance, heating in vacuum.
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