Ferroelectric order driven Eu³⁺ photoluminescence in BaZr_xTi_1-xO₃ perovskite

The ability to tune and enhance the properties of luminescent materials is essential for enlarging their application potential. Recently, the modulation of the photoluminescence emission of lanthanide-doped ferroelectric perovskites by applying an electric field has been reported. Herein, we show that the ferroelectric order and, more generally the polar order, has a direct effect on the photoluminescence of Eu³⁺ in the model BaZr_xTi_1-xO₃ perovskite even in the absence of an external field. The dipole arrangement evolves with increasing x from long-range ferroelectric order to short-range order typical of relaxors until the non-polar paraelectric BaZrO₃ is achieved. The cooperative polar interactions existing in the lattice (x < 1) promote the off-center displacement of the Eu³⁺ ion determining a change of the lanthanide site symmetry and, consequently, an abrupt variation of the photoluminescence emission with temperature. Each type of polar order is characterized by a distinct photoluminescence behaviour.