Hydriding chemical vapor deposition of metal hydride nano-fibers

Abstract

Here we show a novel chemical vapor synthesis technique, which uses high-pressure hydrogen and produces needle-shaped single crystalline made of metal hydride of Mgfy. The principle of this method is based on the gas phase reaction of vaporized metal with high pressure hydrogen sublimating into solid metal hydride (Mg(g) + H 2(g) → MgH 2(s)). This can directly produce pure single-phased metal hydride of MgH 2, while the conventional solid-gas reaction (Mg(s) + H 2(g) → MgH 2(s)) can hardly produce high purity hydride. The X-ray spectrum of as-synthesized product was MgH 2 with rutile structure. The scanning electron micrographs showed the interesting figure of the product; needle-shaped nano fibers with diameter less than 500 nm and length larger than 100 μm. Transmission electron micrograph and related electron diffraction pattern provided that the needle-shaped product was single crystalline of MgH 2 growing into [1 0 1] direction, into which Mg-layers and H-layers are alternately stacked up. The results appealed a revolutionary productive route for metal hydride, which offers many benefits for simplifying the productive procedure, minimizing processing time, saving energy, and upgrading the product. © 2006 The Japan Institute of Metals.