Reaction of Anatase and Rutile with Barium Carbonate

Abstract

PTC materials with the nominal composition (Ba 0.997 La 0.003 ) (Ti 1.012 Mn0. 0005 )O 3.025 were prepared from reagent‐grade barium carbonate and commercial grades of anatase and rutile. Both forms of TiO 2 had approximately the same crystallite size. The solid state reaction was followed by thermal analysis and by X‐ray diffraction and gravimetric measurements during isothermal heat treatments. The reaction kinetics for both mixtures were virtually the same. However, some variations in microstructural development during sintering were observed, which may be related to subtle differences in crystallite character deriving from the different crystal structures of the TiO 2 .