Metal Oxides Production with Controlled Heating

Description And Advantages

Scientists at U.S Department of Energy's Brook Haven National Laboratory have developed a novel way of making metal oxides. This class of compounds, which includes magnesium oxide and zinc oxide, is commonly used in the growing field of nanotechnology.  
  
The new method allows greater control of particle size and chemical composition of the product. The main difference between the traditional method and the novel one is that the former one requires processing a metal at a higher temperature, while latter one completely avoids the dangers and difficulties of working with the liquid phase. Instead of directly transforming the solid metal into its liquid state, the metal is combined with graphite in a vessel and heated to form the metal carbide, which is an intermediate compound. Then more heat is applied to the metal carbide to decompose it. The metal gas is released as vapour which is then oxidised to form a pure metal oxide powder. As heat can be added in a controlled fashion, the scientists can vary the vapour density. More dense the vapours, larger the particles they produce and the result is the metal oxide powders with uniform particle sizes any where from 5-500 nm.  

The other advantage of the new method is that elements such as chromium, copper, iron, nickel, etc can be added to make complex particles.  

These additives or dopants can alter the electrical, optical and magnetic properties of a final product, so that they can be tailored for a variety of uses. Eg, adding chromium as a dopant to magnesium oxide has resulted in a material that breaks apart nitrogen oxides one hundred times better than commercially available magnesium oxide. This reaction is important in smoke stack scrubbers that aim to prevent nitrogen oxide pollutants from getting into atmosphere.    
 
Source : Chemical Engineering Process