Transforming incipient to real ferroelectrics in SrTiO3 upon doping luminescent Eu3+ /Tb3+ ions and the generation of white light for piezo-phototronics application

Abstract

A novel effort has been given to transform the incipient ferroelectrics behavior to real in SrTiO3 and to generate white-light emission by doping luminescent Eu3+ and Tb3+ ions. Ferroelectric study showed that upon doping Eu3+ ion, SrTiO3 became pure ferroelectric in nature and upon co-doping Tb3+ ion there is a significant enhancement of the saturation polarization. Photoluminescence study showed that both the Eu3+ doped and Eu3+& Tb3+ co-doped compounds are white-light-emitting materials due to perfect combination of blue light originated from defect centers present in the host with the green and red emissions from the dopant ions. Such white-light-emitting materials with controlled piezo potential may not need external excitation energy and have potential application in many flexible optoelectronic devices. Lifetime study confirmed the existence of two components for both the dopant ions and suggested that there is an asymmetric environment created due to distortion of geometry, which is linked to ferroelectric property. Finally, all the experimental results were supported by Hybrid functional based theoretical calculation. We have observed that the bond angle variance (BAV) parameter and distortion index (DI), which are directly linked with the distortion in the matrix, are responsible for ferroelectric behavior and they follow the order with the dopant ions as Eu3+&Tb3+>Tb3+>Eu3+. This corroborates well with the experimentally observed trend of the saturation polarization.