Chemical and structural investigation of high-resolution patterning with HafSO(x).

High-resolution transmission electron microscopy (TEM) imaging and energy-dispersive X-ray spectroscopy (EDS) chemical mapping have been used to examine key processing steps that enable sub-20-nm lithographic patterning of the material Hf(OH)4-2x-2y(O2)x(SO4)y·qH2O (HafSOx). Results reveal that blanket films are smooth and chemically homogeneous. Upon exposure with an electron beam, the films become insoluble in aqueous tetramethylammonium hydroxide [TMAH(aq)]. The mobility of sulfate in the exposed films, however, remains high, because it is readily exchanged with hydroxide from the TMAH(aq) solution. Annealing the films after soaking in TMAH(aq) results in the formation of a dense hafnium hydroxide oxide material that can be converted to crystalline HfO2 with a high electron-beam dose. A series of 9 nm lines is written with variable spacing to investigate the cross-sectional shape of the patterned lines and the residual material found between them.

Effect of metal powder packing on the conductivity of nanometal ink.

The power of nanotechnology is realized in its application in numerous areas. One such area is undoubtedly the use of metallic nanoparticles as a direct write application. An effort in this area has resulted in a conductive ink whose conductivity approaches 60-70% that of the bulk copper. Such an ink has been developed by reducing silver, gold, and copper nano-sized powders by a wet method and followed by a heat treatment at less than 400 degrees C. The conductivity of the resulting ink product was found to be very much affected by how various sizes of metal powders are packed when particles were dried and packed on various substrates. The effect of packing and various kinds of metal powders on the eventual conductivity of the final product of the ink has been described and discussed in this paper.

Nanocrystalline metal oxides as destructive adsorbents for organophosphorus compounds at ambient temperatures.

Nanocrystals of magnesium oxide react with organophosphorus compounds at room temperature by dissociative chemisorption, which we term "destructive adsorption". This process involves cleavage of P-O and P-F bonds (but not P-C bonds) and immobilization of the resultant molecular fragments. These ultrafine powders have unusual crystalline shapes and possess high surface concentrations of reactive edge/corner and defect sites, and thereby display higher surface reactivity, normalized for surface area, than typical polycrystalline material. This high surface reactivity coupled with high surface area allows their use for effective decontamination of chemical warfare agents and related toxic substances. Herein data is presented for paraoxon, diisopropylfluorophosphate (DFP), and (CH3CH2O)2P(O)CH2-SC6H5 (DEPTMP). Solid-state NMR and IR spectroscopy indicate that all OR and F groups dissociate; this leaves bound -PO4, -F, and -OR groups for paraoxon, DFP, and DEPTMP, respectively. For paraoxon, it was shown that one monolayer reacts. For DEPTMP, the OR groups dissociate, but not the P-CH2SC6H5 group. The nanocrystalline MgO reacts much faster and in higher capacity than typical activated carbon samples, which physisorb but do not destructively adsorb these phosphorous compounds.

Catalyzed destructive adsorption of environmental toxins with nanocrystalline metal oxides. Fluoro-, chloro-, bromocarbons, sulfur, and organophosophorus compounds.

In the temperature range of 300-500 degrees C, solid nanocrystalline oxides react nearly stoichiometrically with numerous halocarbons, sulfur, and organophosphorus compounds. In some cases, the reaction efficiencies can be improved by the presence of a small amount of transition-metal oxide as catalyst; for example, Fe2O3 on CaO and mobile intermediate species such as FeCl3 or Fe(SO3)x are important in the catalytic process. Herein, a series of environmentally problematic compounds are discussed, including CCl4, COS, CS2, C2Cl4, CHCl3, CH2Cl2, CH3Cl, and (CH3O)2P(O)CH3. Nanocrystals of CaO coated with a thin layer of Fe2O3 (or other transition metals) =[Fe2O3]CaO, or intimately mixed =Fe2O3/CaO were compared with pure CaO. It was found that (a) the presence of a small amount of surface [Fe2O3] or other transition-metal oxide can have a marked effect on the destructive adsorption activity, (b) for some reagents, such as CCl4, C2Cl4, SO2 and others, the nanocrystalline CaO can react in stoichiometric amounts, especially if a transition-metal oxide catalyst is present, (c) although the reaction with dimethylmethylphosphonate is surface-limited, the nanocrystalline calcium oxide performed well and in high capacity, (d) nanocrystalline calcium oxide exhibits near stoichiometric activitywith several interesting sulfur-containing compounds, such as COS and CS2, (e) unfortunately, most fluorocarbons were not destructively adsorbed at 500 degrees C under the conditions employed; however, some of these can be effectively mineralized over the calcium oxide at higher temperatures. These compounds include C2F6, C3F6, C2ClF3, and CHF3, and (f) upon reaction, surface areas decreased considerably, from about 100 to about 10 m2/g. The results of these experiments further demonstrate that, with the proper choice of catalytic material, some solid-gas reactions can be engineered to be rapid and essentially stoichiometric.