Effects of Sc3+ ions on local crystal structure and up-conversion luminescence of layered perovskite NaYTiO4: Yb3+/Er3+

Highlights: • The layered perovskite NaYTiO₄:Yb/Er/Sc were prepared by solid state reaction. • Sc³⁺ tri-doping can lower the local site symmetry and ligand field of activators. • The luminescence quantum efficiency of NYT:Yb/Er is enhanced by Sc³⁺ dopants. • TCLs Er³⁺: ⁴F_5/2/⁴F_7/2 for temperature sensing was firstly studied. • Temperature sensitivity of NaYTiO₄:Yb/Er is improved by doping Sc³⁺ ions. -- Abstract: This work focused on influences of Sc³⁺ dopants on local site symmetry and ligand field of Er³⁺ activators as well as its up-conversion luminescence performances sensitized by Yb³⁺ ions in NYTiO₄ (NYT). The structure analysis and Judd-Ofelt calculation confirmed that doping Sc³⁺ ions could lower site symmetry as well changed the ligand field around Er³⁺ ions. The introduction of Sc³⁺ ions induced variations of crystal lattices, regulated distances between Er³⁺ions and Er³⁺ or Yb³⁺ ions, and thus influenced the up-conversion luminescence properties. Besides, time-resolved decay curves figured out the great enhancement of lifetime and luminescence quantum efficiency for both green and red emissions due to Sc³⁺ dopants. For optical temperature sensitivity, thermally coupled levels (TCLs) for blue emission ⁴F_5/2/⁴F_7/2→⁴I_15/2 was studied for the first time. Besides, TCLs for violet emission ⁴G_11/2/²H_9/2→⁴I_15/2 as well as green emission ²H_11/2/⁴S_3/2→⁴I_15/2 were also recorded. By tri-doping Sc³⁺ ions into NYT: Yb/Er, both absolute sensitivity and relative sensitivity of above three TCLs were improved with temperature uncertainty decreasing.