The carbonation of two hydrated ordinary portland cements of alkali content 1.03% or 0.43% Na2O equivalent and hydrated calcium aluminate cement (0.1% Na2O equivalent) was studied in a semi-dynamic atmosphere of 100% CO2, and 65% relative humidity at 20 ± 1 °C, for a period of 100 days. The changes of the microstructure before and during the carbonation were characterized by x-ray diffraction, mercury intrusion porosimetry, and scanning electron microscopy. The kinetics of the process was evaluated from the total CaCO3 content by means of thermogravimetric analysis. The changes of the mechanical flexural strength were also studied. The pore solution was collected and analyzed before and after different periods of time. The results were compared with those obtained under natural carbonation conditions. The results showed that the alkali content of cement does not influence the kinetics of the process when the carbonation is accelerated. In the case of natural carbonation, an induction period is produced in the ordinary portland cement of low alkali content and calcium aluminate cement. The carbonation rate of calcium aluminate cement is the slowest for accelerated and natural carbonation.

Aluminum coordination distribution for alumina catalysts supported on mesoporous silica was examined. It was shown that aluminum coordination correlates to activity of the catalysts for plasma-enhanced, selective catalytic reduction of NOx with propene. Catalysts were prepared by incorporating aluminum onto the surface of a mesoporous silica support via three different post-synthesis routes to produce varying aluminum coordination. Aluminum trichloride, sodium aluminate, and aluminum isopropoxide precursors were examined. High-resolution, solid state 27Al nuclear magnetic resonance was used to determine aluminum coordination distributions for the resulting catalysts. Unsaturated aluminum sites (i.e., structural defects) correlated with increased activity at high temperatures while tetrahedrally-coordinated aluminum or BrØnsted acid sites correlated with activity at low temperatures.

The acidic dispersion behavior of fused SiO2 particles was investigated and compared to two fumed SiO2 particles. In contrast, the fused SiO2 particles have a larger particle size, broader size distribution, and lower surface area. Fluoride adsorption was used to study surface activity, and acid–base titration was used to study surface charge in 10−1 to 10−3 M NaCl solutions over the pH range of 2–7.5. Each of the three SiO2 particles exhibited similar titration behavior, with the fused SiO2 particles displaying a higher intrinsic pKa2 value of 7.0 as compared to 6.8 and 6.1 for the two fumed SiO2 particles. Rheological experiments designed to test for dispersion and agglomeration/ gellation at 3 and 6 wt% solids loading in 10−3 M NaCl solutions adjusted to pH 2, 4, and 6 showed the fused SiO2 particles to be more stable in suspension, exhibiting lower viscosity results for all test conditions. Results show that the fused SiO2 particles tested in this report display superior dispersion properties as compared to conventional fumed SiO2 particles for slurry applications under acidic conditions.

Polysilicon films were deposited using low-pressure chemical vapor deposition (LPCVD) onto oxidized silicon substrates, after which substrate curvature as a function of temperature was measured. The curvatures changed with temperature, implying that the thermal expansion of LPCVD polysilicon differs from that of the single crystal silicon substrate. Further, polysilicon films with tensile residual stresses displayed an increased thermal expansion, while polysilicon films with compressive residual stresses displayed a decreased thermal expansion. Following high temperature annealing, the residual stresses of the polysilicon films were reduced to near zero, and the thermal expansion of the polysilicon films matched that of the single crystal substrate. The apparent change in thermal expansion coefficient due to residual stress was much larger than predicted theoretically.

Wafer curvature was used to study the thermal–mechanical behavior of 1-μm Cu thin films capped with a 100-nm-thick Si3N4 layer. These films were grown with either a Ta or a Si3N4 underlayer. Films on Si3N4 that were exposed to oxygen at the film/capping layer interface or at the center of the copper layer exhibited Bauschinger-like yielding at low stress. Stacks deposited under continuous vacuum, with a Ta underlayer, with carbon exposure at the upper surface of the copper film, or with oxygen exposure of only the underlayer did not demonstrate the anomalous yielding. Preferential diffusion of oxygen into copper grain boundaries or interfaces is the likely cause of the early yield behavior. Possible mechanisms include an increase in interface adhesion due to the presence of oxygen in solution and diffusion-induced dislocation glide as an additional driving force for dislocation motion at low applied stress.