Ferroelectricity at room temperature in Pr-doped SrTiO3

The influence of Pr ion on the structural and dielectric properties was studied in Sr1−xPrxTiO3 for 0<x<0.075 composition from room temperature to 375°C. X-ray diffraction and x-ray photoelectron spectroscopy studies revealed that the praseodymium ion enters substitutionally in the Sr site with mixed valence in a Pr+3∕Pr+4=2:1 ratio. This substitution yields compressive chemical pressure in the lattice. The polarization measurements at room temperature display hysteresis loops, indicating that the Pr ion induces ferroelectric behavior at room temperature. The permittivity shows a well-defined peak at about 240°C, indicative of a ferroelectric-paraelectric transition with Curie temperature of ∼118°C.