Realizing emission color tuning, ratiometric optical thermometry and temperature-induced redshift investigation in novel Eu³⁺-doped Ba₃La(VO₄)₃ phosphors

Rare earth-doped Ba3La(VO4)3 phosphors with tunable emitting colors were firstly explored and their photoluminescence properties were systematically investigated. The experimental results show that the Ba3La(VO4)3 phosphors exhibit high-brightness self-activated emission and enable us to sensitize the luminescence of rare earth activators. Under near-ultraviolet (UV) excitation, both the broadband emission from VO43- groups and the sharp peak emissions from Eu3+ ions are observed in Ba3La(VO4)3:Eu3+ phosphors. Modulation of the emitting color from green to red can be realized by adjusting the Eu3+ doping concentration, which is assigned to an efficient energy transfer from VO43- to Eu3+ ions. Notably, the optical thermometry of Ba3La(VO4)3:Eu3+ was characterized based on the fluorescence intensity ratio of VO43- and Eu3+ emissions in the 298-573 K range, with the maximum absolute and relative sensitivities of 0.0515 K-1 and 1.77% K-1 at 298 K. In addition, similar phenomena were observed in Sm3+ and Dy3+-doped Ba3La(VO4)3 phosphors. These results verify a feasible strategy for varying the emission color and realizing optical thermometry in the single-component phosphors by adjusting the energy transfer between the host and the activator. It provides new possibilities for the design of multifunctional materials for white light-emitting diodes and non-contact thermometry.