Effect of oxygen vacancies at grain boundaries on ferroelastic behavior of yttria stabilized zirconia

This work investigates the role of oxygen vacancies at grain boundaries in governing the ferroelastic behavior of tetragonal prime yttria-stabilized zirconia (t’-YSZ). Using molecular dynamics simulations, ferroelastic domains are induced via quenching and subsequently subjected to mechanical deformation to assess the effects of oxygen vacancy concentration and spatial distribution on domain switching. A Buckingham interatomic potential is employed to capture both t’-YSZ phase formation and ferroelastic domain switching. The results reveal that oxygen vacancy accumulation inhibits domain formation and suppresses ferroelastic reorientation via pinning effects, particularly near grain boundaries. These findings show that grain boundaries act as major sites of oxygen vacancy accumulation, with their structural geometry controlling how vacancies redistribute under compression and tension, thereby directly shaping the ferroelastic switching behavior of t’-YSZ.