Realizing emission color tuning, ratiometric optical thermometry and temperature-induced redshift investigation in novel Eu-doped BaLa(VO) phosphors.

Rare earth-doped BaLa(VO) phosphors with tunable emitting colors were firstly explored and their photoluminescence properties were systematically investigated. The experimental results show that the BaLa(VO) 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 VO groups and the sharp peak emissions from Eu ions are observed in BaLa(VO):Eu phosphors. Modulation of the emitting color from green to red can be realized by adjusting the Eu doping concentration, which is assigned to an efficient energy transfer from VO to Eu ions. Notably, the optical thermometry of BaLa(VO):Eu was characterized based on the fluorescence intensity ratio of VO and Eu emissions in the 298-573 K range, with the maximum absolute and relative sensitivities of 0.0515 K and 1.77% K at 298 K. In addition, similar phenomena were observed in Sm and Dy-doped BaLa(VO) 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.