Structural Phase Diagram and Size-Dependent Electrical Polarization in Freestanding SrTiO$_{\mathrm{3\thinspace }}$Nanoparticles

The bulk phase of the classic perovskite SrTiO$_{\mathrm{3}}$ (STO) is paraelectric and exhibits a structural phase transition at a pressure P\textasciitilde 6 GPa at room temperature. Understanding the structural phase diagram of nano scale STO has important implications on the basic physics and applications of the general class of oxide perovskites. Previous research indicated a stable polar state in STO over a wide pressure range with small particle size. We have established a size-dependent phase diagram of STO. Meanwhile, we have further investigated polarization properties with freestanding STO nanoparticles with experimental methods and modeling. This work is supported by DOE Grant DE-FG02-07ER46402.