Metal-to-metal charge transfer band position control and luminescence quenching by cationic substitution in NaNbO3:Pr3+

Abstract

The development of materials showing efficient red-emitting persistent luminescence is still an ongoing challenge. As it shows red emission, around 613 nm, Pr3+ remains a good candidate for such application. Indeed, the transition from its 1D2 excited state to its 3H4 ground state is responsible of the red emission. In this paper the effect of Na substitution in NaNbO3:Pr3+ by K or Li cations in term of Metal-to-Metal Charge Transfer (MMCT) band position and its possible effect on persistent luminescence properties were investigated. MMCT energy shows increasing tendency with increasing average distance between A site (A = Li, Na, K, Pr) of perovskite. The most intense (efficient) photoluminescence was observed under MMCT excitation in Li0.03Na0.97NbO3:Pr3+. The relaxation pathways were discussed based on the configurational coordinate model.