Synthesis of nanocrystalline rutile-phase titania at low temperatures

Anatase and rutile are the predominant phases in titanium dioxide. In many cases, rutile stable phase is the desired product material, but at low temperatures methods of synthesis ( aqueous route) produce metastable anatase as a major product that reverts to rutile only when heated up to 1000 C. Calcination for obtaining rutile phase is the greatest energy demanding step for titanium dioxide production by the sulphate process, and is responsible for almost 60% of total energy consumption. In this work, an innovative technique involving a sonication pre-treatment in acid medium was developed to change particle reactivity and accelerate the anatase-to-rutile transformation. Scanning electron micrographs and surface area measurements confirmed the alteration in texture and porosity of the powders. Results indicate that it is possible to obtain 100% of rutile phase at temperatures as low as 430 degrees C.