Single titanium crystals encapsulated in carbon nanocages obtained by laser vaporization of sponge titanium in benzene vapor

A technique, laser vaporization by ablating at a solid target in the vapor phase, is developed to produce encapsulated titanium nanocrystals. By vapor izing sponge titanium in benzene vapor, the single titanium crystals encaps ulated in carbon nanocages have been synthesized in good yields. The sizes of the encapsulated crystals are around 5-15 nm and the numbers of the wrap ped graphitic layers are on the order of 3-10 layers. Characteristic lattic e spacings and angles observed by high-resolution transmission electron mic roscopy identify two phases of the nanocrystals inside the carbon onion cav ities as alpha-Ti and beta-Ti. The latter has never been stable below 850 d egrees C until the experiment. The encapsulated titanium crystals adsorbed a large amount of hydrogen released in the synthesis. (C) 2000 American Ins titute of Physics. [S0003-6951(00)03426-4].