Interface Energy Impact on Phase Transitions: The Case of TiO₂ Nanoparticles

We investigate the interface energy impact on phase stability using the shining example of TiO 2 nanoparticles under pressure. We revisit the previously reported phase diagram of this system and propose a new mechanism allowing the control of pressure-induced amorphization of TiO 2 ultrafine particles. We demonstrate that the size effect is necessary for stabilizing the amorphous state but is not sufficient in the sense that surface chemical functionalization of nanoparticles is determinant. This discovery opens the possibility to select the high-pressure phase in nanomaterials and, consequently, the recovered structure under ambient conditions.