STUDIES OF COPPER HYDRIDE .2. TRANSMISSION ELECTRON-MICROSCOPY

Copper hydride decomposes to metallic copper and hydrogen gas when exposed to the electron beam within a transmission electron microscope. Simultaneous melting and decomposition of the hydride occurs and rapid vaporisation disperses copper as nano-sized particles onto the support carbon film. Over 10 000 particles may be produced per decomposition event with a size distribution which varies from ca. 2 to 500 nm in diameter with the majority of particles below 30 nm in diameter. The particle density reaches a maximum close to 300 mu m(-2) at ca. 2000 nm from the beam centre. Most of the particles appear round in projection but a variety of well defined shapes have also been found for particles ca. 100 nm in diameter. Most of these faceted particles are octahedral in shape projected along [111] and truncated along [110]. Multiply twinned particles are fairly common and a high density of stacking faults along (111) and twins on (111) were found. High-resolution electron microscope lattice images indicate that most particles below ca. 400 A in diameter are free of lattice imperfections. Preliminary reactivity studies show that exposure to ammonia vapour causes fragmentation and reconstruction of the particles.