Nanocrystalline thoria powders via glycine-nitrate combustion

Nanocrystalline thoria powders were prepared by the combustion technique using glycine as a fuel and nitrate as an oxidizer. The technique involves the exothermic decomposition of viscous liquid prepared by thermal dehydration of the aqueous solution containing thorium nitrate and glycine. Thoria powders of different crystallite sizes, surface areas and sinterabilities were prepared by starting with two different fuel-to-oxidant molar ratios. The exothermic decomposition of viscous liquid, at about 200 degreesC, containing thorium nitrate-to-glycine in molar ratio 1:1.2 yielded the well-crystalline nano-sized ThO2 powder. Thoria powders prepared by this technique were shown to have a higher surface area (> 50 m(2)/g) and could be sintered to highly dense pellets (greater than or equal to 93% th.d.) at relatively low sintering temperature of 1300 degreesC for 3 h. (C) 2001 Elsevier Science B.V. All rights reserved.