Monoclinic to tetragonal semireconstructive phase transition of zirconia

Abstract

Accurate data, obtained by neutron diffraction, have been used to monitor the first-order reconstructive monoclinic\ensuremath{\leftrightarrow}tetragonal phase transition as a function of the temperature both during heating and cooling. Data analysis supports an orientational relationship $[010{]}_{m}\ensuremath{\Vert}[001{]}_{t}$ and ${(100)}_{m}\ensuremath{\Vert}{(110)}_{t}$ between the tetragonal and the monoclinic phases. The analysis of the oxygen atoms evolution in the tetragonal phase supports a displacive mechanism for the monoclinic\ensuremath{\leftrightarrow}tetragonal phase transition. Based on these data, a microscopic model is proposed explaining the unusual behavior of zirconia.