Phase-transition character in (Ba0.50,Sr0.50)TiO3 nanodots from first principles

A first-principles-derived scheme combined with an efficient Monte Carlo technique is performed to investigate the character of phase transitions in (Ba0.50,Sr0.50)TiO3 (BST50) nanodots under ideal short-circuit (SC) and open-circuit (OC) electrical boundary conditions, and the corresponding properties are subsequently compared to the properties of bulk BST50. Our calculations indicate that the ferroelectric properties change dramatically when transitioning from 3D (bulk) to 0D (nanodot) systems under short-circuit conditions. While BST bulk exhibits three first-order ferroelectric phase transitions, BST dot shows a single second-order ferroelectric phase transition. On the other hand, new insight into the character and signature of the phase transition associated with a toroid moment of polarization, which occurs in nanodots under open-circuit conditions, is provided.