Pathak Nimai, Ghosh Partha Sarathi, Mukherjee Sumanta, Mandal Balaji Prasad
Radiochemistry Division, Bhabha Atomic Research Centre Mumbai 400085 India
Glass and Advanced Materials Division, Bhabha Atomic Research Centre Mumbai 400085 India.
RSC Adv. 2020 Aug 21;10(52):31070-31086. doi: 10.1039/d0ra01869d.
Combined photoluminescence (PL) and dielectric studies have been carried out on both undoped and Eu doped LiNbO 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 Eu 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 Eu 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 Eu ions are energetically preferred to occupy the Nb site and gives rise to red emission. The DFT based results also showed that Eu 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 LiNbO upon Eu doping changes from to , 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.
首次对未掺杂和铕掺杂的铌酸锂化合物进行了光致发光（PL）和介电研究，以探索它们在光电集成方面的潜在应用。研究特别关注同时调节这两种物理性质。光致发光研究表明，未掺杂的化合物是一种蓝色发光材料，而在掺杂铕离子后，通过改变激发波长，发光颜色可以从蓝色调至红色。有趣的是，对这种铁电化合物的电学性质测量表明，掺杂铕离子后，剩余极化显著增加。基于密度泛函理论（DFT）进行了计算，以解释光学和电学性质。研究发现，不同的缺陷中心导致了蓝色的主体发射，而铕离子在能量上更倾向于占据铌位点并产生红色发射。基于DFT的结果还表明，铕离子在附近的铌位点引起了更多畸变，这是剩余极化增强的原因。光致发光研究中的斯塔克分裂模式还表明，铕掺杂后铌酸锂的点对称性从 变为 ，这表明结构变得不那么对称。总体而言，该研究提出了一种设计用于光电集成应用的多功能材料并同时在所需范围内调节其物理性质的新方法。
