Growth of hollow annular zinc oxide structures

The conditions and mechanisms of the growth of hollow crystals, dendrite st ructures, and whiskers of zinc oxide during the annealing of pressed zinc o xide-carbon mixtures were studied. The growth of hollow structures is due t o the interaction of reagents in pressed tablets, which is accompanied by t he formation of a gas-impermeable external ZnO shell and the transport of Z n vapor and CO2 along the growing tube. Orientation of the hollow crystals is determined by the direction of Zn vapor transport. The process was model ed by the Zn vapor emission from a Knudsen effusion cell. (C) 2000 MAIK "Na uka/Interperiodica".