Simultaneous tuning of optical and electrical properties in a multifunctional LiNbO3matrix upon doping with Eu3+ions

Abstract

Combined photoluminescence (PL) and dielectric studies have been carried out on both undoped and Eu3+ doped LiNbO3 compounds for their potential application in optical-electrical integration for the first time. Special focus has been given to simultaneously tuning both these physical properties. A PL study reveals that the blank compound is a blue emitting material, while upon doping with Eu3+ ions, the emitting color can be tuned from blue to red upon changing the excitation wavelength. Interestingly, the electrical property measurement of this ferroelectric compound showed that upon doping with Eu3+ ions, the remnant polarization was increased significantly. Density Functional Theory (DFT) based calculations were carried out to explain both the optical and electrical properties. It has been found that different defect centers are responsible for the bluish host emission while Eu3+ ions are energetically preferred to occupy the Nb site and gives rise to red emission. The DFT based results also showed that Eu3+ ions induced more distortion into the nearby Nb-site, which is responsible for enhancement of the remnant polarization. Stark-splitting patterns in the PL study also showed that the point symmetry of LiNbO3 upon Eu3+ doping changes from C6v to D3, which indicates that the structure becomes less symmetric. Overall, the study presents a novel approach to designing multifunctional materials for optical-electrical integration application and to tuning their physical properties simultaneously in the desired range.