Dilatometry tests were carried out

Dilatometry tests were carried out to determine the behavior of TiO2 as a function of temperature and to obtain information on the temperature at which the contraction and phase transition start. As reported from literature, in fact, post annealing thermal treatments have been proven to be effective to finalize CSP sintering of ceramic powders as BaTiO3 or ZrO2-stabilized Y2O3 [37,38]. Given the results obtained in the previous paragraph, all the analysis were concentrated on G5, having the higher CSP sinterability. A maximum temperature of 700 °C was chosen, because anatase generally begins to transform irreversibly into the rutile phase in air at ˜600 °C. Transition temperatures are also reported varying in the range 400–1200 °C [10], since the kinetics of the phase transformation depends on numerous parameters related to the nature of the material, to the heat treatment and to the measurement method. However, the transformation of anatase ― rutile is reconstructive, that is, it involves the breaking and the reformation of bonds: as a result it is not instantaneous, but it is time-dependent.