Mechanochemical effects on the kinetics of zinc titanate formation

Abstract

In this work, mixtures Zn-TiO2 (anatase) in molar ratio 1:1 were mechanochemically activated in air atmosphere, and submitted to thermal treatments in order to study its thermal transformations. The behavior of the system during the milling was followed by X-ray diffraction (XRD), differential thermal analyses (DTA) and thermogravimetric analyses (TGA). Mechanochemical activation produces a progressive loss in crystallinity of the starting powders, with simultaneous oxidation of metallic Zn. However, the formation of neither ZnTiO3 nor Zn2TiO4 could be detected. At temperatures above 600°C, the thermal treatments resulted in the formation of ZnTiO3 and Zn2TiO4, at lower temperatures and shorter holding times for samples activated during longer times. The non-activated mixture exhibited a very different behavior, yielding Zn2Ti3O8 and Zn2TiO4 without evidence of ZnTiO3 formation. The obtained results are explained on the basis of reaction mechanisms taking place in the activated and non-activated samples.