Ultra-fine particles of aluminium formed by electron-beam-induced decomposition of aluminium hydride

Abstract The electron-beam-induced decomposition of AlH 3 , within a transmission electron microscope, results in the formation of ultra-fine particles of aluminium. The product is of two types: the first consists of a conglomerate of individual and discrete particles combined in a manner such that the overall morphology of the parent hydride is retained but with a random orientation between individual crystallites. They are of various sizes and are supported on, and surrounded by, an oxide film and result from direct beam damage and decomposition of the hydride to the metal and hydrogen gas. The second type is widely distributed over the support carbon film and results from the beam-induced dispersion of the initial product. They are of varying size depending principally upon the beam flux. Particles of sizes between 4 and 20 nm diameter are readily manufactured, occasionally being only a few layers thick. Microstructural information is presented for the particles as provided by HREM.