Although many studies have focused on the unique plastic deformation behavior of nanocrystalline aluminum (e.g., the positive deviation from Hall-Petch relation, the unusual yield-drop phenomenon in tensile mode, etc.), the data reported by different research groups are inconsistent with each other, possibly because of different fabrication processes. In this study, aluminum samples with a wide grain-size spectrum -from a few micrometers down to 100 nanometers -are manufactured by powder metallurgy. The grain size was measured by X-ray diffraction analysis and transmission electron microscope observation. Furthermore, the tensile behavior, which varied according to a grain size, is discussed with a comparison of the theoretical models.

A simple hydrothermal growth process was developed to deposit conformal manganese oxide nanospheres with a diameter of 10 to 20 nm on mesoporous carbon paper. The coating of nanospheres increased the cyclic-voltammogramic response of carbon paper by a factor of 5 with a slight dependence on the scan rate. For comparison, a related chemistry was also developed to fabricate a dense packing of manganese oxide nanorods with a diameter of 20 to 50 nm and a length of approximately 500 nm. The nanorods also increased the cyclic-voltammogramic response of carbon paper but only by a factor of approximately 3.