The generation of nanometer-size tantalum particles in a graphite host lattice Original Research Article

Tantalum(V) chloride was intercalated from the gas phase into highly oriented pyrolytic graphite and into natural graphite. Second stage intercalation compounds were produced. The TaCl5–graphite intercalation compounds were heated in a hydrogen atmosphere for 1 week at 200°C. The flakes showed no exfoliation, but reduction was insufficient at this temperature. A reduction for 1 week at 1000°C produced extensively exfoliated samples. After 1 week at 1000°C in a hydrogen atmosphere, it was still possible to detect chlorine in some regions by energy-dispersive X-ray analysis. However, transmission electron microscope images showed the occurrence of nanometer-size particles within the graphite host lattice, located near the prismatic edges and also at the center of the particles. Different morphologies of the particles were observed, namely two-dimensional platelets and numerous one-dimensional `chainsʹ, with particle sizes between 10 and 300 nm. Selected-area electron diffraction patterns of the particles gave evidence as to their chemical nature. Metallic tantalum was formed by the reaction, the patterns gave also evidence that a small amount of TaCl5 had still survived.