SPUTTERING SYNTHESIS AND PROPERTIES OF MOLYBDENUM NANOCRYSTALS AND AL MO LAYERED NANOCOMPOSITES

Molybdenum nanocrystals (4 nm < particle size < 12 nm) were synthesized in the vapor by sputtering in a thermal gradient at argon pressures between 0.2 and 0.6 Torr. The gradient was achieved by cooling the substrate table with liquid nitrogen in order to enhance the deposition rate of the nanocrystals. The size of these nanocrystals depended on the sputtering argon gas pressure. Using appropriate deposition parameters, these nanocrystals were incorporated, either as a dispersed phase in a major phase produced by normal sputtering or as a layer in a layered structure to produce nanocomposite films. Results of Auger electron spectroscopy (AES) study of the Al/Mo layered nanocomposite films are presented. The Knoop microhardness of these films was increased by as much as a factor of four compared with the hardness of homogeneous Al films. A correlation of the microhardness to the microstructures as revealed by transmission electron microscopy (TEM) is discussed.