Effect of crystallite size and calcination temperature on the thermal stability of single nanocrystal of transition metal oxides

Abstract

Single nanocrystalline chromium(III)oxide, Cr2O3, has been synthesized by glycothermal reaction of chromium acetylacetonate in 1,4-butanediol at 250ฐC and 300 ํC. The amorphous products changed to chromium oxide crystal after calcined at 350 ํC. The product obtained from lower reaction temperature has smaller crystallite size. The product was calcined at temperature range of 500 to 900 ํC. In this work thermal stability was defined as BET/BET0 where BET is the surface area of the product after calcined at various temperatures and BET0 is the surface area of the as-synthesized product. Chromium oxide with larger crystallite size exhibited higher thermal stability. Titanium(IV)oxide (TiO2), manganese(III)oxide (Mn2O3), iron(III)oxide (Fe2O3), zinc(II)oxide (ZnO) and nickel(II)oxide (NiO) were synthesized by the same preparation method and the thermal stability of transition metal oxides were compared. The thermal stability of the metal oxides revealed in the order of; TiO2> Cr2O3> Mn2O3> Fe2O3> ZnO> NiO, which resulted from the difference in the bond dissociation energy of these metal oxides.