A comprehensive study on flash sintering of anatase and rutile polymorphs-containing titania nanopowder: phase and microstructure development

Flash sintering has proven to be a novel and cost-efficient technique that enables the successful processing of dissimilar materials. The present work was aimed at investigating how does sintering under electric field input progress in commercial anatase () plus rutile () polymorphs-containing titania. Both phase evolution and sintering dynamics showed to be, with increasing temperature, highly dependent on strength of the field, whose application led to () →  → flash at low fields, while promoting () → flash at high fields. A temperature postponement of flash was verified at low fields, as the event was preceded by the  →  transformation, responsible for a detectable peak in the thermal spectra of current. It is shown that processing temperature, applied electric field and onset flash sintering temperature combine well into a phase diagram graph that summarizes phase development applying for this material. Also noting, in the end, that high-density bodies in the rutile phase were produced after flash under suitable current density, regardless of the field strength considered. Both flash sintering temperature and average grain size decreased with raising field; in line with this, we demonstrate existence of a direct link between grain size and the sample sintering temperature, consistent with the classical grain growth model.